ATMEL AT91SAM9G20 Incorporates the arm926ej-s arm thumb processor Datasheet

Features
• Incorporates the ARM926EJ-S™ ARM® Thumb® Processor
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– DSP Instruction Extensions, ARM Jazelle® Technology for Java® Acceleration
– 32-KByte Data Cache, 32-KByte Instruction Cache, Write Buffer
– CPU Frequency 400 MHz
– Memory Management Unit
– EmbeddedICE™, Debug Communication Channel Support
Additional Embedded Memories
– One 64-KByte Internal ROM, Single-cycle Access at Maximum Matrix Speed
– Two 16-KByte Internal SRAM, Single-cycle Access at Maximum Matrix Speed
External Bus Interface (EBI)
– Supports SDRAM, Static Memory, ECC-enabled SLC NAND Flash and
CompactFlash®
USB 2.0 Full Speed (12 Mbits per second) Device Port
– On-chip Transceiver, 2,432-byte Configurable Integrated DPRAM
USB 2.0 Full Speed (12 Mbits per second) Host and Dual Port
– Single or Dual On-chip Transceivers
– Integrated FIFOs and Dedicated DMA Channels
Ethernet MAC 10/100 Base T
– Media Independent Interface or Reduced Media Independent Interface
– 128-byte FIFOs and Dedicated DMA Channels for Receive and Transmit
Image Sensor Interface
– ITU-R BT. 601/656 External Interface, Programmable Frame Capture Rate
– 12-bit Data Interface for Support of High Sensibility Sensors
– SAV and EAV Synchronization, Preview Path with Scaler, YCbCr Format
Bus Matrix
– Six 32-bit-layer Matrix
– Boot Mode Select Option, Remap Command
Fully-featured System Controller, including
– Reset Controller, Shutdown Controller
– Four 32-bit Battery Backup Registers for a Total of 16 Bytes
– Clock Generator and Power Management Controller
– Advanced Interrupt Controller and Debug Unit
– Periodic Interval Timer, Watchdog Timer and Real-time Timer
Reset Controller (RSTC)
– Based on a Power-on Reset Cell, Reset Source Identification and Reset Output
Control
Clock Generator (CKGR)
– Selectable 32,768 Hz Low-power Oscillator or Internal Low Power RC Oscillator on
Battery Backup Power Supply, Providing a Permanent Slow Clock
– 3 to 20 MHz On-chip Oscillator, One up to 800 MHz PLL and One up to 100 MHz PLL
Power Management Controller (PMC)
– Very Slow Clock Operating Mode, Software Programmable Power Optimization
Capabilities
– Two Programmable External Clock Signals
Advanced Interrupt Controller (AIC)
– Individually Maskable, Eight-level Priority, Vectored Interrupt Sources
– Three External Interrupt Sources and One Fast Interrupt Source, Spurious
Interrupt Protected
Debug Unit (DBGU)
– 2-wire UART and Support for Debug Communication Channel, Programmable ICE
Access Prevention
AT91 ARM
Thumb
Microcontrollers
AT91SAM9G20
6384E–ATARM–05-Feb-10
– Mode for General Purpose 2-wire UART Serial Communication
• Periodic Interval Timer (PIT)
– 20-bit Interval Timer plus 12-bit Interval Counter
• Watchdog Timer (WDT)
– Key-protected, Programmable Only Once, Windowed 16-bit Counter Running at Slow Clock
• Real-time Timer (RTT)
– 32-bit Free-running Backup Counter Running at Slow Clock with 16-bit Prescaler
• One 4-channel 10-bit Analog-to-Digital Converter
• Three 32-bit Parallel Input/Output Controllers (PIOA, PIOB, PIOC)
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2
– 96 Programmable I/O Lines Multiplexed with up to Two Peripheral I/Os
– Input Change Interrupt Capability on Each I/O Line
– Individually Programmable Open-drain, Pull-up Resistor and Synchronous Output
– All I/O Lines are Schmitt Trigger Inputs
Peripheral DMA Controller Channels (PDC)
One Two-slot MultiMedia Card Interface (MCI)
– SDCard/SDIO and MultiMediaCard™ Compliant
– Automatic Protocol Control and Fast Automatic Data Transfers with PDC
One Synchronous Serial Controller (SSC)
– Independent Clock and Frame Sync Signals for Each Receiver and Transmitter
– I²S Analog Interface Support, Time Division Multiplex Support
– High-speed Continuous Data Stream Capabilities with 32-bit Data Transfer
Four Universal Synchronous/Asynchronous Receiver Transmitters (USART)
– Individual Baud Rate Generator, IrDA® Infrared Modulation/Demodulation, Manchester Encoding/Decoding
– Support for ISO7816 T0/T1 Smart Card, Hardware Handshaking, RS485 Support
– Full Modem Signal Control on USART0
Two 2-wire UARTs
Two Master/Slave Serial Peripheral Interfaces (SPI)
– 8- to 16-bit Programmable Data Length, Four External Peripheral Chip Selects
– Synchronous Communications
Two Three-channel 16-bit Timer/Counters (TC)
– Three External Clock Inputs, Two Multi-purpose I/O Pins per Channel
– Double PWM Generation, Capture/Waveform Mode, Up/Down Capability
– High-Drive Capability on Outputs TIOA0, TIOA1, TIOA2
One Two-wire Interface (TWI)
– Compatible with Standard Two-wire Serial Memories
– One, Two or Three Bytes for Slave Address
– Sequential Read/Write Operations
– Master, Multi-master and Slave Mode Operation
– Bit Rate: Up to 400 Kbits
– General Call Supported in Slave Mode
– Connection to Peripheral DMA Controller (PDC) Channel Capabilities Optimizes Data Transfers in Master Mode
IEEE® 1149.1 JTAG Boundary Scan on All Digital Pins
Required Power Supplies
– 0.9V to 1.1V for VDDBU, VDDCORE, VDDPLL
– 1.65 to 3.6V for VDDOSC
– 1.65V to 3.6V for VDDIOP (Peripheral I/Os)
– 3.0V to 3.6V for VDDUSB
– 3.0V to 3.6V VDDANA (Analog-to-digital Converter)
– Programmable 1.65V to 1.95V or 3.0V to 3.6V for VDDIOM (Memory I/Os)
Available in a 217-ball LFBGA and 247-ball TFBGA RoHS-compliant Package
AT91SAM9G20
6384E–ATARM–05-Feb-10
AT91SAM9G20
1. Description
The AT91SAM9G20 is based on the integration of an ARM926EJ-S processor with fast ROM
and RAM memories and a wide range of peripherals.
The AT91SAM9G20 embeds an Ethernet MAC, one USB Device Port, and a USB Host controller. It also integrates several standard peripherals, such as the USART, SPI, TWI, Timer
Counters, Synchronous Serial Controller, ADC and MultiMedia Card Interface.
The AT91SAM9G20 is architectured on a 6-layer matrix, allowing a maximum internal bandwidth
of six 32-bit buses. It also features an External Bus Interface capable of interfacing with a wide
range of memory devices.
The AT91SAM9G20 is an enhancement of the AT91SAM9260 with the same peripheral features. It is pin-to-pin compatible with the exception of power supply pins. Speed is increased to
reach 400 MHz on the ARM core and 133 MHz on the system bus and EBI.
3
6384E–ATARM–05-Feb-10
WDT
OSC
PLLB
RSTC
MCI
PDC
POR
VDDCORE
SHDC
RTT
M
CD
B0
-M
CD
M
CD MC B3
C
A
0
-M DB
C
M DA
C 3
C
D
M A
CC
K
NRST
POR
OSC
4GPREG
PIT
PMC
PDC
DBGU
AIC
System
Controller
PLLA
RC
Filter Filter
SHDN
WKUP
VDDBU
OSCSEL
XIN32
XOUT32
XIN
XOUT
DRXD
DTXD
PCK0-PCK1
FIQ
IRQ0-IRQ2
TST
SLAVE
TWI
PDC
PIOA
PIOC
PIOB
PDC
USART0
USART1
USART2
USART3
USART4
USART5
TD
TDI
TMO
TC S
RTK
CK
JT
AG
SE
L
MMU
TC0
TC1
TC2
Fast SRAM
16 Kbytes
Bus Interface
PDC
SPI0
SPI1
ROM
64 Kbytes
I
ICache
32K bytes
D
TC3
TC4
TC5
Fast SRAM
16 Kbytes
DCache
32K bytes
ARM926EJ-S Processor
In-Circuit Emulator
JTAG Selection and Boundary Scan
APB
TW
C TW D
T
CK
R S0
T
SC S0 CT
S
RX K0 -RT 3
- S
TXD0- SCK3
D0 RX 2
-T D5
DSXD5
DCR0
D0
R
DT I0
R0
S
PDC
BM
SSC
ET
E X
C
T
K
E XE -E
C
R
N
ERRS -E XC
T
ERXE -EC XE K
R O
E X0 -E L R
T
R
M X0 ER XD
D - X
M C ETX 3 V
D
3
F1 IO
00
DMA
4-channel
10-bit
ADC
PDC
Peripheral
Bridge
SPI0_, SPI1_
USB
Device
DPRAM
DMA
DMA
ECC
Controller
Static
Memory
Controller
SDRAM
Controller
CompactFlash
NAND Flash
EBI
USB
OHCI
Transc.
HD
P
HD B
M
B
Image
Sensor
Interface
Transceiver
24-channel
Peripheral
DMA
FIFO
6-layer Matrix
FIFO
10/100 Ethernet
MAC
Transc.
IS
I
_M
IS CK
I_
IS PC
I_ K
IS DO
I_ -I
V
IS S SI_
I
_H YNC D7
SY
NC
H
D
HD PA
M
A
NP
N CS
P
NPCS3
NPCS2
C 1
SP S0
M CK
O
T
M SI
C
IS
L
O
TI K0
O -T
TI A0- CL
O T K
TC B0 IOA2
-T 2
L
TI K3 IOB
O TI A3 TC 2
L
O
B3-TIOK5
-T A
IO 5
B5
TK
TF
TD
RD
RF
RK
AD
0AD
AD
3
TR
IG
AD
VR
EF
V
D
DA
NA
ND
AN
A
4
G
D0-D15
A0/NBS0
A1/NBS2/NWR2
A2-A15, A18-A20
A16/BA0
A17/BA1
NCS0
NCS1/SDCS
NRD/CFOE
NWR0/NWE/CFWE
NWR1/NBS1/CFIOR
NWR3/NBS3/CFIOW
SDCK, SDCKE
RAS, CAS
SDWE, SDA10
NANDOE, NANDWE
A21/NANDALE, A22/NANDCLE
D16-D31
NWAIT
A23-A24
NCS4/CFCS0
NCS5/CFCS1
A25/CFRNW
CFCE1-CFCE2
NCS2, NCS6, NCS7
NCS3/NANDCS
Figure 2-1.
DD
DDM
P
MASTER
2. AT91SAM9G20 Block Diagram
AT91SAM9G20 Block Diagram
AT91SAM9G20
6384E–ATARM–05-Feb-10
AT91SAM9G20
3. Signal Description
Table 3-1.
Signal Description List (Continued)
Signal Name
Function
Type
Active
Level
Comments
Power Supplies
VDDIOM
EBI I/O Lines Power Supply
Power
1.65V to 1.95V or 3.0V to 3.6V
VDDIOP
Peripherals I/O Lines Power Supply
Power
1.65V to 3.6V
VDDBU
Backup I/O Lines Power Supply
Power
0.9V to 1.1V
VDDANA
Analog Power Supply
Power
3.0V to 3.6V
VDDPLL
PLL Power Supply
Power
0.9V to 1.1V
VDDOSC
Oscillator Power Supply
Power
1.65V to 3.6V
VDDCORE
Core Chip Power Supply
Power
0.9V to 1.1V
VDDUSB
USB Power Supply
Power
1.65V to 3.6V
GND
Ground
Ground
GNDANA
Analog Ground
Ground
GNDBU
Backup Ground
Ground
GNDUSB
USB Ground
Ground
GNDPLL
PLL Ground
Ground
Clocks, Oscillators and PLLs
XIN
Main Oscillator Input
XOUT
Main Oscillator Output
Input
XIN32
Slow Clock Oscillator Input
XOUT32
Slow Clock Oscillator Output
OSCSEL
Slow Clock Oscillator Selection
PCK0 - PCK1
Programmable Clock Output
Output
Input
Output
Accepts between 0V and
VDDBU.
Input
Output
Shutdown, Wakeup Logic
SHDN
Shutdown Control
WKUP
Wake-up Input
Output
Accepts between 0V and
VDDBU.
Input
ICE and JTAG
NTRST
Test Reset Signal
Input
Low
Pull-up resistor
TCK
Test Clock
Input
No pull-up resistor
TDI
Test Data In
Input
No pull-up resistor
TDO
Test Data Out
TMS
Test Mode Select
Input
No pull-up resistor
JTAGSEL
JTAG Selection
Input
Pull-down resistor. Accepts
between 0V and VDDBU.
RTCK
Return Test Clock
Output
Output
5
6384E–ATARM–05-Feb-10
Table 3-1.
Signal Description List (Continued)
Signal Name
Function
Type
Active
Level
I/O
Low
Comments
Reset/Test
NRST
Microcontroller Reset
Pull-up resistor
TST
Test Mode Select
Input
Pull-down resistor. Accepts
between 0V and VDDBU.
BMS
Boot Mode Select
Input
No pull-up resistor
BMS = 0 when tied to GND.
BMS = 1 when tied to VDDIOP.
Debug Unit - DBGU
DRXD
Debug Receive Data
Input
DTXD
Debug Transmit Data
Output
Advanced Interrupt Controller - AIC
IRQ0 - IRQ2
External Interrupt Inputs
Input
FIQ
Fast Interrupt Input
Input
PIO Controller - PIOA - PIOB - PIOC
PA0 - PA31
Parallel IO Controller A
I/O
Pulled-up input at reset
PB0 - PB31
Parallel IO Controller B
I/O
Pulled-up input at reset
PC0 - PC31
Parallel IO Controller C
I/O
Pulled-up input at reset
External Bus Interface - EBI
D0 - D31
Data Bus
I/O
A0 - A25
Address Bus
NWAIT
External Wait Signal
Pulled-up input at reset
Output
Input
0 at reset
Low
Static Memory Controller - SMC
NCS0 - NCS7
Chip Select Lines
Output
Low
NWR0 - NWR3
Write Signal
Output
Low
NRD
Read Signal
Output
Low
NWE
Write Enable
Output
Low
NBS0 - NBS3
Byte Mask Signal
Output
Low
CompactFlash Support
CFCE1 - CFCE2
CompactFlash Chip Enable
Output
Low
CFOE
CompactFlash Output Enable
Output
Low
CFWE
CompactFlash Write Enable
Output
Low
CFIOR
CompactFlash IO Read
Output
Low
CFIOW
CompactFlash IO Write
Output
Low
CFRNW
CompactFlash Read Not Write
Output
CFCS0 - CFCS1
CompactFlash Chip Select Lines
Output
6
Low
AT91SAM9G20
6384E–ATARM–05-Feb-10
AT91SAM9G20
Table 3-1.
Signal Description List (Continued)
Signal Name
Function
Type
Active
Level
Comments
NAND Flash Support
NANDCS
NAND Flash Chip Select
Output
Low
NANDOE
NAND Flash Output Enable
Output
Low
NANDWE
NAND Flash Write Enable
Output
Low
NANDALE
NAND Flash Address Latch Enable
Output
Low
NANDCLE
NAND Flash Command Latch Enable
Output
Low
SDRAM Controller
SDCK
SDRAM Clock
Output
SDCKE
SDRAM Clock Enable
Output
High
SDCS
SDRAM Controller Chip Select
Output
Low
BA0 - BA1
Bank Select
Output
SDWE
SDRAM Write Enable
Output
Low
RAS - CAS
Row and Column Signal
Output
Low
SDA10
SDRAM Address 10 Line
Output
Multimedia Card Interface MCI
MCCK
Multimedia Card Clock
Output
MCCDA
Multimedia Card Slot A Command
I/O
MCDA0 - MCDA3
Multimedia Card Slot A Data
I/O
MCCDB
Multimedia Card Slot B Command
I/O
MCDB0 - MCDB3
Multimedia Card Slot B Data
I/O
Universal Synchronous Asynchronous Receiver Transmitter USARTx
SCKx
USARTx Serial Clock
I/O
TXDx
USARTx Transmit Data
I/O
RXDx
USARTx Receive Data
Input
RTSx
USARTx Request To Send
CTSx
USARTx Clear To Send
DTR0
USART0 Data Terminal Ready
DSR0
USART0 Data Set Ready
Input
DCD0
USART0 Data Carrier Detect
Input
RI0
USART0 Ring Indicator
Input
Output
Input
Output
Synchronous Serial Controller - SSC
TD
SSC Transmit Data
Output
RD
SSC Receive Data
Input
TK
SSC Transmit Clock
I/O
RK
SSC Receive Clock
I/O
TF
SSC Transmit Frame Sync
I/O
RF
SSC Receive Frame Sync
I/O
7
6384E–ATARM–05-Feb-10
Table 3-1.
Signal Description List (Continued)
Signal Name
Function
Type
Active
Level
Comments
Timer/Counter - TCx
TCLKx
TC Channel x External Clock Input
Input
TIOAx
TC Channel x I/O Line A
I/O
TIOBx
TC Channel x I/O Line B
I/O
Serial Peripheral Interface - SPIx_
SPIx_MISO
Master In Slave Out
I/O
SPIx_MOSI
Master Out Slave In
I/O
SPIx_SPCK
SPI Serial Clock
I/O
SPIx_NPCS0
SPI Peripheral Chip Select 0
I/O
Low
SPIx_NPCS1-SPIx_NPCS3
SPI Peripheral Chip Select
Output
Low
Two-Wire Interface
TWD
Two-wire Serial Data
I/O
TWCK
Two-wire Serial Clock
I/O
USB Host Port
HDPA
USB Host Port A Data +
Analog
HDMA
USB Host Port A Data -
Analog
HDPB
USB Host Port B Data +
Analog
HDMB
USB Host Port B Data -
Analog
USB Device Port
DDM
USB Device Port Data -
Analog
DDP
USB Device Port Data +
Analog
Ethernet 10/100
ETXCK
Transmit Clock or Reference Clock
Input
MII only, REFCK in RMII
ERXCK
Receive Clock
Input
MII only
ETXEN
Transmit Enable
Output
ETX0-ETX3
Transmit Data
Output
ETX0-ETX1 only in RMII
ETXER
Transmit Coding Error
Output
MII only
ERXDV
Receive Data Valid
Input
RXDV in MII, CRSDV in RMII
ERX0-ERX3
Receive Data
Input
ERX0-ERX1 only in RMII
ERXER
Receive Error
Input
ECRS
Carrier Sense and Data Valid
Input
MII only
ECOL
Collision Detect
Input
MII only
EMDC
Management Data Clock
EMDIO
Management Data Input/Output
8
Output
I/O
AT91SAM9G20
6384E–ATARM–05-Feb-10
AT91SAM9G20
Table 3-1.
Signal Description List (Continued)
Signal Name
Function
Type
Active
Level
Comments
Image Sensor Interface
ISI_D0-ISI_D11
Image Sensor Data
Input
ISI_MCK
Image Sensor Reference Clock
ISI_HSYNC
Image Sensor Horizontal Synchro
Input
ISI_VSYNC
Image Sensor Vertical Synchro
Input
ISI_PCK
Image Sensor Data clock
Input
Output
Analog to Digital Converter
AD0-AD3
Analog Inputs
Analog
ADVREF
Analog Positive Reference
Analog
ADTRG
ADC Trigger
Note:
Digital pulled-up inputs at reset
Input
No PLLRCA line present on the AT91SAM9G20.
4. Package and Pinout
• The AT91SAM9G20 is available in a 217-ball, 15 x 15 mm, LFBGA package (0.8 mm pitch)
(Figure 4-1).
• The AT91SAM9G20 is available in a 247-ball, 10 x 10 x 1.1 mm, TFBGA Green package, (0.5
mm pitch) (Figure 4-1).
4.1
217-ball LFBGA Package Outline
Figure 4-1 shows the orientation of the 217-ball LFBGA package.
A detailed mechanical description is given in the section “AT91SAM9G20 Mechanical Characteristics” of the product datasheet.
Figure 4-1.
217-ball LFBGA Package (Top View)
17
16
15
14
13
12
11
10
9
8
7
6
5
4
3
2
1
A B C D E F G H J K L M N P R T U
Ball A1
9
6384E–ATARM–05-Feb-10
AT91SAM9G20
4.2
217-ball LFBGA Pinout
Table 4-1.
Pinout for 217-ball LFBGA Package
Pin
Signal Name
Pin
Signal Name
Pin
Signal Name
Pin
Signal Name
A1
A2
A3
A4
A5
A6
A7
A8
A9
A10
A11
A12
A13
A14
A15
A16
A17
B1
B2
B3
B4
B5
B6
B7
B8
B9
B10
B11
B12
B13
B14
B15
B16
B17
C1
C2
C3
C4
C5
C6
C7
C8
C9
C10
C11
C12
C13
C14
C15
C16
C17
D1
D2
D3
D4
CFIOW/NBS3/NWR3
NBS0/A0
NWR2/NBS2/A1
A6
A8
A11
A13
BA0/A16
A18
A21
A22
CFWE/NWE/NWR0
CFOE/NRD
NCS0
PC5
PC6
PC4
SDCK
CFIOR/NBS1/NWR1
SDCS/NCS1
SDA10
A3
A7
A12
A15
A20
NANDWE
PC7
PC10
PC13
PC11
PC14
PC8
WKUP
D8
D1
CAS
A2
A4
A9
A14
BA1/A17
A19
NANDOE
PC9
PC12
DDP
HDMB
NC
VDDUSB
SHDN
D9
D2
RAS
D0
D5
D6
D7
D8
D9
D10
D11
D12
D13
D14
D15
D16
D17
E1
E2
E3
E4
E14
E15
E16
E17
F1
F2
F3
F4
F14
F15
F16
F17
G1
G2
G3
G4
G14
G15
G16
G17
H1
H2
H3
H4
H8
H9
H10
H14
H15
H16
H17
J1
J2
J3
J4
J8
J9
J10
A5
GND
A10
GND
VDDCORE
GNDUSB
VDDIOM
GNDUSB
DDM
HDPB
NC
VDDBU
XIN32
D10
D5
D3
D4
HDPA
HDMA
GNDBU
XOUT32
D13
SDWE
D6
GND
OSCSEL
BMS
JTAGSEL
TST
PC15
D7
SDCKE
VDDIOM
GND
NRST
RTCK
TMS
PC18
D14
D12
D11
GND
GND
GND
VDDCORE
TCK
NTRST
PB18
PC19
PC17
VDDIOM
PC16
GND
GND
GND
J14
J15
J16
J17
K1
K2
K3
K4
K8
K9
K10
K14
K15
K16
K17
L1
L2
L3
L4
L14
L15
L16
L17
M1
M2
M3
M4
M14
M15
M16
M17
N1
N2
N3
N4
N14
N15
N16
N17
P1
P2
P3
P4
P5
P6
P7
P8
P9
P10
P11
P12
P13
P14
P15
P16
TDO
PB19
TDI
PB16
PC24
PC20
D15
PC21
GND
GND
GND
PB4
PB17
GND
PB15
GND
PC26
PC25
VDDOSC
PA28
PB9
PB8
PB14
VDDCORE
PC31
GND
PC22
PB1
PB2
PB3
PB7
XIN
VDDPLL
PC23
PC27
PA31
PA30
PB0
PB6
XOUT
VDDPLL
PC30
PC28
PB11
PB13
PB24
VDDIOP
PB30
PB31
PA1
PA3
PA7
PA9
PA26
PA25
P17
R1
R2
R3
R4
R5
R6
R7
R8
R9
R10
R11
R12
R13
R14
R15
R16
R17
T1
T2
T3
T4
T5
T6
T7
T8
T9
T10
T11
T12
T13
T14
T15
T16
T17
U1
U2
U3
U4
U5
U6
U7
U8
U9
U10
U11
U12
U13
U14
U15
U16
U17
PB5
NC
GNDANA
PC29
VDDANA
PB12
PB23
GND
PB26
PB28
PA0
PA4
PA5
PA10
PA21
PA23
PA24
PA29
NC
GNDPLL
PC0
PC1
PB10
PB22
GND
PB29
PA2
PA6
PA8
PA11
VDDCORE
PA20
GND
PA22
PA27
GNDPLL
ADVREF
PC2
PC3
PB20
PB21
PB25
PB27
PA12
PA13
PA14
PA15
PA19
PA17
PA16
PA18
VDDIOP
10
6384E–ATARM–05-Feb-10
AT91SAM9G20
4.3
247-ball TFBGA Package Outline
Figure 4-2 shows the orientation of the 247-ball TFBGA package.
A detailed mechanical description is given in the section “AT91SAM9G20 Mechanical Characteristics” of the product datasheet.
Figure 4-2.
247-ball TFBGA Package (Top View)
Ball A1
1
2
3
4
5
6
7
8
9
10
11 12
13 14 15 16 17 18
19
A
B
C
D
E
F
G
H
J
K
L
M
N
P
R
T
U
V
W
11
6384E–ATARM–05-Feb-10
AT91SAM9G20
4.4
247-ball TFBGA Package Pinout
Table 4-2.
Pinout for 247-ball TFBGA Package
Pin
Signal Name
Pin
Signal Name
Pin
Signal Name
Pin
Signal Name
A1
A2
A12
A14
A16
A18
A19
B1
B2
B3
B4
B5
B6
B7
B8
B9
B10
B11
B13
B15
B17
B19
C2
C3
C4
C5
C6
C7
C8
C9
C10
C11
C12
C14
C16
C18
D2
D3
D13
D15
D17
D19
E2
E3
E5
E6
E7
E8
E9
E10
E11
E12
E13
E14
E15
E16
E18
E19
F2
F3
F5
F6
D13
D12
A9
A13
A20
A22
NANDOE
D15
D14
D10
D9
D7
D3
D2
RAS
CAS
NWR2/NBS2/A1
A3
A10
A18
A21
VDDUSB
PC15
D11
D8
SDCKE
SDWE
SDCK
D1
SDCS/NCS1
A2
A7
A11
A19
GNDUSB
CFWE/NWE/NWR0
PC17
PC16
A14
NANDWE
CFOE/NRD
NCS0
PC18
PC19
D6
D5
D0
CFIOW/NBS3/NWR3
GND
A4
A8
VDDIOM
BA0/A16
PC8
PC4
PC5
PC7
PC6
PC22
PC23
PC20
D4
F7
F8
F9
F10
F11
F12
F13
F14
F15
F16
F17
F18
G2
G3
G5
G6
G8
G9
G10
G11
G12
G14
G15
G17
G18
H2
H3
H5
H6
H7
H8
H9
H10
H11
H12
H13
H14
H15
H17
H18
J2
J3
J5
J6
J7
J8
J9
J10
J11
J12
J13
J14
J15
J17
J18
K2
K3
K5
K6
K7
K8
K9
CFIOR/NBS1/NWR1
SDA10
NBS0/A0
A6
A12
A15
BA1/A17
PC10
PC14
VDDUSB
PC9
PC12
PC26
PC25
PC24
PC21
VDDCORE
A5
VDDCORE
VDDCORE
VDDCORE
PC13
GND
GNDUSB
PC11
PC31
PC30
PC28
PC27
PC29
GND
GND
VDDIOM
VDDIOM
GND
VDDCORE
SHDW
VDDBU
HDPB
HDMB
VDDOSC
VDDPLL
XOUT
XIN
VDDPLL
GND
VDDIOM
VDDIOM
VDDIOM
GND
GND
WKUP
DDP
DDM
VDDIOP
GNDPLL
GND
NC
GNDPLL
VDDANA
GND
GND
K10
K11
K12
K13
K14
K15
K17
K18
L2
L3
L5
L6
L7
L8
L9
L10
L11
L12
L13
L14
L15
L17
L18
M2
M3
M5
M6
M7
M8
M9
M10
M11
M12
M13
M14
M15
M17
M18
N2
N3
N5
N6
N8
N11
N12
N14
N15
N17
N18
P2
P3
P5
P6
P7
P8
P9
P10
P11
P12
P13
P14
P15
GND
VDDIOM
GND
GND
XOUT32
XIN32
HDPA
HDMA
NC
NC
ADVREF
PC2
GND
GND
GND
GND
VDDCORE
GND
OSCSEL
GNDBU
GND
NRST
TCK
PC0
PC1
PC3
NTRST
GND
GND
GND
PA16
VDDCORE
GND
VDDIOP
TST
JTAGSEL
PB18
TMS
PB20
PB13
PB11
BMS
GND
PA17
PA23
GND
VDDIOP
TDO
TDI
PB24
PB22
GND
GND
PA6
PA7
PA11
GND
PA18
PA24
PA28
PB3
PB5
P17
P18
R2
R3
R5
R6
R7
R8
R9
R10
R11
R12
R13
R14
R15
R17
R18
T2
T3
T17
T18
U2
U3
U4
U5
U6
U7
U8
U9
U10
U11
U12
U13
U14
U15
U16
U17
U18
V1
V2
V3
V4
V5
V6
V7
V8
V9
V10
V11
V12
V13
V14
V15
V16
V17
V18
V19
W1
W2
W18
W19
RTCK
PB16
GND
PB29
PB26
PB27
PA5
GND
PA12
GND
PA19
PA26
PB1
GND
PB7
PB14
PB9
PA1
PB10
PB19
PB17
GNDANA
PB21
PB28
PB31
PA4
PA3
PA9
GND
PA15
PA21
PA25
PA29
PA27
PA31
GND
PB2
GND
PB12
PB23
PB30
PA2
PA8
PA10
PA13
VDDIOP
PA14
VDDIOP
PA20
PA22
VDDIOP
PA30
PB0
GND
PB4
GND
PB6
PB25
PA0
PB8
PB15
12
6384E–ATARM–05-Feb-10
AT91SAM9G20
5. Power Considerations
5.1
Power Supplies
The AT91SAM9G20 has several types of power supply pins:
• VDDCORE pins: Power the core, including the processor, the embedded memories and the
peripherals; voltage ranges from 0.9V to 1.1V, 1.0V nominal.
• VDDIOM pins: Power the External Bus Interface I/O lines; voltage ranges between 1.65V and
1.95V (1.8V typical) or between 3.0V and 3.6V (3.3V nominal). The voltage range is
selectable by software.
• VDDIOP pins: Power the Peripherals I/O lines; voltage ranges from 1.65V to 3.6V.
• VDDBU pin: Powers the Slow Clock oscillator, the internal RC oscillator and a part of the
System Controller; voltage ranges from 0.9V to 1.1V, 1.0V nominal.
• VDDPLL pin: Powers the PLL cells; voltage ranges from 0.9V to 1.1V.
• VDDOSC pin: Powers the Main Oscillator cells; voltage ranges from 1.65V to 3.6V
• VDDANA pin: Powers the Analog to Digital Converter; voltage ranges from 3.0V to 3.6V, 3.3V
nominal.
• VDDUSB pin: Powers USB transceiver; voltage ranges from 3.0V to 3.6V.
Ground pins GND are common to VDDCORE, VDDIOM, VDDOSC and VDDIOP pins power
supplies. Separated ground pins are provided for VDDBU, VDDPLL, VDDUSB and VDDANA.
These ground pins are respectively GNDBU, GNDPLL, GNDUSB and GNDANA.
5.2
Programmable I/O Lines
The power supplies pins VDDIOM accept two voltage ranges. This allows the device to reach its
maximum speed either out of 1.8V or 3.3V external memories.
The maximum speed is 133 MHz on the pin SDCK (SDRAM Clock) loaded with 10 pF. The other
signals (control, address and data signals) do not go over 66 MHz, loaded with 30 pF for power
supply at 1.8V and 50 pF for power supply at 3.3V.
The EBI I/Os accept two slew rate modes, Fast and Slow. This allows to adapt the rising and falling time on SDRAM clock, control and data to the bus load.
The voltage ranges and the slew rates are determined by programming VDDIOMSEL and IOSR
bits in the Chip Configuration registers located in the Matrix User Interface.
At reset, the selected voltage defaults to 3.3V nominal and power supply pins can accept either
1.8V or 3.3V. The user must make sure to program the EBI voltage range before getting the
device out of its Slow Clock Mode.
At reset, the selected slew rates defaults are Fast.
6. I/O Line Considerations
6.1
JTAG Port Pins
TMS, TDI and TCK are schmitt trigger inputs and have no pull-up resistors.
TDO and RTCK are outputs, driven at up to VDDIOP, and have no pull-up resistor.
13
6384E–ATARM–05-Feb-10
The JTAGSEL pin is used to select the JTAG boundary scan when asserted at a high level. It
integrates a permanent pull-down resistor of about 15 kΩ to GND, so that it can be left unconnected for normal operations.
The NTRST signal is described in the Reset Pins paragraph.
All the JTAG signals are supplied with VDDIOP.
6.2
Test Pin
The TST pin is used for manufacturing test purposes when asserted high. It integrates a permanent pull-down resistor of about 15 kΩ to GNDBU, so that it can be left unconnected for normal
operations. Driving this line at a high level leads to unpredictable results.
This pin is supplied with VDDBU.
6.3
Reset Pins
NRST is an open-drain output integrating a non-programmable pull-up resistor. It can be driven
with voltage at up to VDDIOP.
NTRST is an input which allows reset of the JTAG Test Access port. It has no action on the
processor.
As the product integrates power-on reset cells, which manages the processor and the JTAG
reset, the NRST and NTRST pins can be left unconnected.
The NRST and NTRST pins both integrate a permanent pull-up resistor of 100 kΩ minimum to
VDDIOP.
The NRST signal is inserted in the Boundary Scan.
6.4
PIO Controllers
All the I/O lines are Schmitt trigger inputs and all the lines managed by the PIO Controllers integrate a programmable pull-up resistor of 75 kΩ typical with the exception of P4 - P31. For details,
refer to the section “AT91SAM9G20 Electrical Characteristics”. Programming of this pull-up
resistor is performed independently for each I/O line through the PIO Controllers.
6.5
I/O Line Drive Levels
The PIO lines drive current capability is described in the DC Characteristics section of the product datasheet.
6.6
Shutdown Logic Pins
The SHDN pin is a tri-state output only pin, which is driven by the Shutdown Controller. There is
no internal pull-up. An external pull-up to VDDBU is needed and its value must be higher than
1 MΩ. The resistor value is calculated according to the regulator enable implementation and the
SHDN level.
The pin WKUP is an input-only. It can accept voltages only between 0V and VDDBU.
14
AT91SAM9G20
6384E–ATARM–05-Feb-10
AT91SAM9G20
7. Processor and Architecture
7.1
ARM926EJ-S Processor
• RISC Processor Based on ARM v5TEJ Architecture with Jazelle technology for Java
acceleration
• Two Instruction Sets
– ARM High-performance 32-bit Instruction Set
– Thumb High Code Density 16-bit Instruction Set
• DSP Instruction Extensions
• 5-Stage Pipeline Architecture:
– Instruction Fetch (F)
– Instruction Decode (D)
– Execute (E)
– Data Memory (M)
– Register Write (W)
• 32-Kbyte Data Cache, 32-Kbyte Instruction Cache
– Virtually-addressed 4-way Associative Cache
– Eight words per line
– Write-through and Write-back Operation
– Pseudo-random or Round-robin Replacement
• Write Buffer
– Main Write Buffer with 16-word Data Buffer and 4-address Buffer
– DCache Write-back Buffer with 8-word Entries and a Single Address Entry
– Software Control Drain
• Standard ARM v4 and v5 Memory Management Unit (MMU)
– Access Permission for Sections
– Access Permission for large pages and small pages can be specified separately for
each quarter of the page
– 16 embedded domains
• Bus Interface Unit (BIU)
– Arbitrates and Schedules AHB Requests
– Separate Masters for both instruction and data access providing complete Matrix
system flexibility
– Separate Address and Data Buses for both the 32-bit instruction interface and the
32-bit data interface
– On Address and Data Buses, data can be 8-bit (Bytes), 16-bit (Half-words) or 32-bit
(Words)
7.2
Bus Matrix
• 6-layer Matrix, handling requests from 6 masters
• Programmable Arbitration strategy
– Fixed-priority Arbitration
15
6384E–ATARM–05-Feb-10
– Round-Robin Arbitration, either with no default master, last accessed default master
or fixed default master
• Burst Management
– Breaking with Slot Cycle Limit Support
– Undefined Burst Length Support
• One Address Decoder provided per Master
– Three different slaves may be assigned to each decoded memory area: one for
internal boot, one for external boot, one after remap
• Boot Mode Select
– Non-volatile Boot Memory can be internal or external
– Selection is made by BMS pin sampled at reset
• Remap Command
– Allows Remapping of an Internal SRAM in Place of the Boot Non-Volatile Memory
• Allows Handling of Dynamic Exception Vectors
7.2.1
Matrix Masters
The Bus Matrix of the AT91SAM9G20 manages six Masters, which means that each master can
perform an access concurrently with others, according the slave it accesses is available.
Each Master has its own decoder that can be defined specifically for each master. In order to
simplify the addressing, all the masters have the same decodings.
Table 7-1.
7.2.2
List of Bus Matrix Masters
Master 0
ARM926™ Instruction
Master 1
ARM926 Data
Master 2
PDC
Master 3
ISI Controller
Master 4
Ethernet MAC
Master 5
USB Host DMA
Matrix Slaves
Each Slave has its own arbiter, thus allowing to program a different arbitration per Slave.
Table 7-2.
Slave 0
Internal SRAM0 16 KBytes
Slave 1
Internal SRAM1 16 KBytes
Slave 2
16
List of Bus Matrix Slaves
Internal ROM
USB Host User Interface
Slave 3
External Bus Interface
Slave 4
Internal Peripherals
AT91SAM9G20
6384E–ATARM–05-Feb-10
AT91SAM9G20
7.2.3
Masters to Slaves Access
All the Masters can normally access all the Slaves. However, some paths do not make sense,
like as example allowing access from the Ethernet MAC to the Internal Peripherals. Thus, these
paths are forbidden or simply not wired, and shown “-” in Table 7-3.
Table 7-3.
AT91SAM9G20 Masters to Slaves Access
Master
0&1
2
3
4
5
Slave
ARM926
Instruction &
Data
Peripheral
DMA
Controller
ISI
Controller
Ethernet
MAC
USB Host
Controller
0
Internal SRAM
16 Kbytes
X
X
X
X
X
1
Internal SRAM
16 Kbytes
X
X
X
X
X
Internal ROM
X
X
-
-
-
UHP User Interface
X
X
-
-
-
3
External Bus Interface
X
X
X
X
X
4
Internal Peripherals
X
X
-
-
-
2
7.3
Peripheral DMA Controller
• Acting as one Matrix Master
• Allows data transfers from/to peripheral to/from any memory space without any intervention
of the processor.
• Next Pointer Support, forbids strong real-time constraints on buffer management.
• Twenty-four channels
– Two for each USART
– Two for the Debug Unit
– Two for the Serial Synchronous Controller
– Two for each Serial Peripheral Interface
– One for Multimedia Card Interface
– One for Analog-to-Digital Converter
– Two for the Two-wire Interface
The Peripheral DMA Controller handles transfer requests from the channel according to the following priorities (Low to High priorities):
– TWI Transmit Channel
– DBGU Transmit Channel
– USART5 Transmit Channel
– USART4 Transmit Channel
– USART3 Transmit Channel
– USART2 Transmit Channel
– USART1 Transmit Channel
– USART0 Transmit Channel
– SPI1 Transmit Channel
17
6384E–ATARM–05-Feb-10
– SPI0 Transmit Channel
– SSC Transmit Channel
– TWI Receive Channel
– DBGU Receive Channel
– USART5 Receive Channel
– USART4 Receive Channel
– USART3 Receive Channel
– USART2 Receive Channel
– USART1 Receive Channel
– USART0 Receive Channel
– ADC Receive Channel
– SPI1 Receive Channel
– SPI0 Receive Channel
– SSC Receive Channel
– MCI Transmit/Receive Channel
7.4
Debug and Test Features
• ARM926 Real-time In-circuit Emulator
– Two real-time Watchpoint Units
– Two Independent Registers: Debug Control Register and Debug Status Register
– Test Access Port Accessible through JTAG Protocol
– Debug Communications Channel
• Debug Unit
– Two-pin UART
– Debug Communication Channel Interrupt Handling
– Chip ID Register
• IEEE1149.1 JTAG Boundary-scan on All Digital Pins
18
AT91SAM9G20
6384E–ATARM–05-Feb-10
AT91SAM9G20
8. Memories
Figure 8-1.
AT91SAM9G20 Memory Mapping
Internal Memory Mapping
Address Memory Space
0x0000 0000
Notes :
(1) Can be ROM, EBI_NCS0 or SRAM
depending on BMS and REMAP
0x0000 0000
Boot Memory (1)
Internal Memories
256M Bytes
0x10 0000
ROM
0x0FFF FFFF
EBI
Chip Select 0
Reserved
256M Bytes
0x20 0000
SRAM0
16K Bytes
0x20 4000
0x1FFF FFFF
0x2000 0000
0x2FFF FFFF
32K Bytes
0x10 8000
0x1000 0000
Reserved
EBI
Chip Select 1/
SDRAMC
256M Bytes
0x30 0000
SRAM1
16K Bytes
0x30 4000
Reserved
0x3000 0000
0x50 0000
EBI
Chip Select 2
256M Bytes
0x50 4000
EBI
Chip Select 3/
NANDFlash
256M Bytes
0x0FFF FFFF
EBI
Chip Select 4/
Compact Flash
Slot 0
256M Bytes
EBI
Chip Select 5/
Compact Flash
Slot 1
256M Bytes
UHP
16K Bytes
0x3FFF FFFF
0x4000 0000
Reserved
0x4FFF FFFF
0x5000 0000
0x5FFF FFFF
0x6000 0000
0x6FFF FFFF
Peripheral Mapping
0xF000 0000
System Controller Mapping
Reserved
0x7000 0000
0xFFFA 0000
EBI
Chip Select 6
256M Bytes
0x7FFF FFFF
0x8000 0000
TCO, TC1, TC2
16K Bytes
0xFFFF C000
UDP
16K Bytes
0xFFFF E800
MCI
16K Bytes
0xFFFF EA00
TWI
16K Bytes
Reserved
0xFFFA 4000
0xFFFA 8000
EBI
Chip Select 7
256M Bytes
0xFFFA C000
0x8FFF FFFF
0x9000 0000
ECC
512 Bytes
SDRAMC
512 Bytes
SMC
512 Bytes
0xFFFF EC00
0xFFFB 0000
USART0
16K Bytes
0xFFFB 4000
0xFFFF EE00
USART1
16K Bytes
USART2
16K Bytes
SSC
16K Bytes
ISI
16K Bytes
EMAC
16K Bytes
0xFFFB 8000
MATRIX
0xFFFF EF10
0xFFFF F000
0xFFFB C000
512 Bytes
CCFG
AIC
512 Bytes
0xFFFF F200
0xFFFC 0000
0xFFFC 4000
1,518M Bytes
SPI0
16K Bytes
0xFFFC C000
SPI1
16K Bytes
USART3
PIOB
16K Bytes
0xFFFD 8000
USART5
0xFFFF FC00
16K Bytes
0xFFFF FD00
TC3, TC4, TC5
ADC
16K Bytes
16K Bytes
256 Bytes
16 Bytes
SHDC
0xFFFF FD20
16 Bytes
RTTC
0xFFFF FD30
16 Bytes
PITC
16 Bytes
WDTC
16 Bytes
GPBR
16 Bytes
0xFFFF FD40
0xFFFE 4000
0xFFFF FD50
0xFFFF FD60
Reserved
0xFFFF C000
SYSC
0xFFFF FFFF
PMC
RSTC
0xFFFF FD10
0xFFFE 0000
0xFFFF FFFF
512 bytes
0xFFFF FA00
16K Bytes
0xFFFD C000
256M Bytes
512 bytes
Reserved
USART4
Internal Peripherals
512 Bytes
0xFFFF F800
0xFFFD 4000
0xEFFF FFFF
PIOA
PIOC
0xFFFD 0000
0xF000 0000
512 Bytes
0xFFFF F600
0xFFFC 8000
Undefined
(Abort)
DBGU
0xFFFF F400
16K Bytes
Reserved
0xFFFF FFFF
19
6384E–ATARM–05-Feb-10
A first level of address decoding is performed by the Bus Matrix, i.e., the implementation of the
Advanced High Performance Bus (AHB) for its Master and Slave interfaces with additional
features.
Decoding breaks up the 4G bytes of address space into 16 banks of 256 Mbytes. The banks 1 to
7 are directed to the EBI that associates these banks to the external chip selects EBI_NCS0 to
EBI_NCS7. Bank 0 is reserved for the addressing of the internal memories, and a second level
of decoding provides 1 Mbyte of internal memory area. Bank 15 is reserved for the peripherals
and provides access to the Advanced Peripheral Bus (APB).
Other areas are unused and performing an access within them provides an abort to the master
requesting such an access.
Each Master has its own bus and its own decoder, thus allowing a different memory mapping
per Master. However, in order to simplify the mappings, all the masters have a similar address
decoding.
Regarding Master 0 and Master 1 (ARM926 Instruction and Data), three different Slaves are
assigned to the memory space decoded at address 0x0: one for internal boot, one for external
boot, one after remap. Refer to Table 8-1, “Internal Memory Mapping,” on page 20 for details.
A complete memory map is presented in Figure 8-1 on page 19.
8.1
Embedded Memories
• 64-KByte ROM
– Single Cycle Access at full matrix speed
• Two 16-Kbyte Fast SRAM
– Single Cycle Access at full matrix speed
8.1.1
Boot Strategies
Table 8-1 summarizes the Internal Memory Mapping for each Master, depending on the Remap
status and the BMS state at reset.
Table 8-1.
Internal Memory Mapping
REMAP = 0
REMAP = 1
Address
0x0000 0000
BMS = 1
BMS = 0
ROM
EBI_NCS0
SRAM0 16K
0x0010 0000
ROM
0x0020 0000
SRAM0 16K
0x0030 0000
SRAM1 16K
0x0050 0000
USB Host User Interface
The system always boots at address 0x0. To ensure a maximum number of possibilities for boot,
the memory layout can be configured with two parameters.
REMAP allows the user to lay out the first internal SRAM bank to 0x0 to ease development. This
is done by software once the system has booted. When REMAP = 1, BMS is ignored. Refer to
the Bus Matrix Section for more details.
20
AT91SAM9G20
6384E–ATARM–05-Feb-10
AT91SAM9G20
When REMAP = 0, BMS allows the user to lay out to 0x0, at his convenience, the ROM or an
external memory. This is done via hardware at reset.
Note:
Memory blocks not affected by these parameters can always be seen at their specified base
addresses. See the complete memory map presented in Figure 8-1 on page 19.
The AT91SAM9G20 matrix manages a boot memory that depends on the level on the BMS pin
at reset. The internal memory area mapped between address 0x0 and 0x000F FFFF is reserved
for this purpose.
If BMS is detected at 1, the boot memory is the embedded ROM.
If BMS is detected at 0, the boot memory is the memory connected on the Chip Select 0 of the
External Bus Interface.
8.1.1.1
BMS = 1, Boot on Embedded ROM
The system boots using the Boot Program.
• Boot on slow clock (On-chip RC or 32,768 Hz)
• Auto baudrate detection
• Downloads and runs an application from external storage media into internal SRAM
• Downloaded code size depends on embedded SRAM size
• Automatic detection of valid application
• Bootloader on a non-volatile memory
– SDCard (boot ROM does not support high capacity SDCards.)
– NAND Flash
– SPI DataFlash® and Serial Flash connected on NPCS0 and NPCS1 of the SPI0
– EEPROM on TWI
• SAM-BA® Boot in case no valid program is detected in external NVM, supporting
– Serial communication on a DBGU
– USB Device HS Port
8.1.1.2
BMS = 0, Boot on External Memory
• Boot on slow clock (On-chip RC or 32,768 Hz)
• Boot with the default configuration for the Static Memory Controller, byte select mode, 16-bit
data bus, Read/Write controlled by Chip Select, allows boot on 16-bit non-volatile memory.
The customer-programmed software must perform a complete configuration.
To speed up the boot sequence when booting at 32 kHz EBI CS0 (BMS=0), the user must take
the following steps:
1. Program the PMC (main oscillator enable or bypass mode).
2. Program and start the PLL.
3. Reprogram the SMC setup, cycle, hold, mode timings registers for CS0 to adapt them
to the new clock.
4. Switch the main clock to the new value.
8.2
External Memories
The external memories are accessed through the External Bus Interface. Each Chip Select line
has a 256-Mbyte memory area assigned.
21
6384E–ATARM–05-Feb-10
Refer to the memory map in Figure 8-1 on page 19.
8.2.1
External Bus Interface
• Integrates three External Memory Controllers
– Static Memory Controller
– SDRAM Controller
– ECC Controller
• Additional logic for NAND Flash
• Full 32-bit External Data Bus
• Up to 26-bit Address Bus (up to 64MBytes linear)
• Up to 8 chip selects, Configurable Assignment:
– Static Memory Controller on NCS0
– SDRAM Controller or Static Memory Controller on NCS1
– Static Memory Controller on NCS2
– Static Memory Controller on NCS3, Optional NAND Flash support
– Static Memory Controller on NCS4 - NCS5, Optional CompactFlash support
– Static Memory Controller on NCS6-NCS7
8.2.2
Static Memory Controller
• 8-, 16- or 32-bit Data Bus
• Multiple Access Modes supported
– Byte Write or Byte Select Lines
– Asynchronous read in Page Mode supported (4- up to 32-byte page size)
• Multiple device adaptability
– Compliant with LCD Module
– Control signals programmable setup, pulse and hold time for each Memory Bank
• Multiple Wait State Management
– Programmable Wait State Generation
– External Wait Request
– Programmable Data Float Time
• Slow Clock mode supported
8.2.3
SDRAM Controller
• Supported devices
– Standard and Low-power SDRAM (Mobile SDRAM)
• Numerous configurations supported
– 2K, 4K, 8K Row Address Memory Parts
– SDRAM with two or four Internal Banks
– SDRAM with 16- or 32-bit Datapath
• Programming facilities
– Word, half-word, byte access
– Automatic page break when Memory Boundary has been reached
22
AT91SAM9G20
6384E–ATARM–05-Feb-10
AT91SAM9G20
– Multibank Ping-pong Access
– Timing parameters specified by software
– Automatic refresh operation, refresh rate is programmable
• Energy-saving capabilities
– Self-refresh, power down and deep power down modes supported
• Error detection
– Refresh Error Interrupt
• SDRAM Power-up Initialization by software
• CAS Latency of 1, 2 and 3 supported
• Auto Precharge Command not used
8.2.4
Error Corrected Code Controller
• Hardware Error Corrected Code (ECC) Generation
– Detection and Correction by Software
• Supports NAND Flash and SmartMedia™ Devices with 8- or 16-bit Data Path.
• Supports NAND Flash/SmartMedia with Page Sizes of 528, 1056, 2112 and 4224 Bytes,
Specified by Software
• Supports 1 bit correction for a page of 512,1024,2048 and 4096 Bytes with 8- or 16-bit Data
Path
• Supports 1 bit correction per 512 bytes of data for a page size of 512, 2048 and 4096 Bytes
with 8-bit Data Path
• Supports 1 bit correction per 256 bytes of data for a page size of 512, 2048 and 4096 Bytes
with 8-bit Data Path
23
6384E–ATARM–05-Feb-10
9. System Controller
The System Controller is a set of peripherals, which allow handling of key elements of the system, such as power, resets, clocks, time, interrupts, watchdog, etc.
The System Controller User Interface embeds also the registers allowing to configure the Matrix
and a set of registers for the chip configuration. The chip configuration registers allows
configuring:
– EBI chip select assignment and Voltage range for external memories
The System Controller’s peripherals are all mapped within the highest 16 Kbytes of address
space, between addresses 0xFFFF E800 and 0xFFFF FFFF.
However, all the registers of System Controller are mapped on the top of the address space. All
the registers of the System Controller can be addressed from a single pointer by using the standard ARM instruction set, as the Load/Store instruction has an indexing mode of ±4 Kbytes.
Figure 9-1 on page 25 shows the System Controller block diagram.
Figure 8-1 on page 19 shows the mapping of the User Interfaces of the System Controller
peripherals.
24
AT91SAM9G20
6384E–ATARM–05-Feb-10
AT91SAM9G20
9.1
System Controller Block Diagram
Figure 9-1.
AT91SAM9G20 System Controller Block Diagram
System Controller
VDDCORE Powered
irq0-irq2
fiq
periph_irq[2..24]
nirq
nfiq
Advanced
Interrupt
Controller
pit_irq
rtt_irq
wdt_irq
dbgu_irq
pmc_irq
rstc_irq
int
MCK
periph_nreset
Debug
Unit
dbgu_irq
dbgu_txd
dbgu_rxd
MCK
debug
periph_nreset
pit_irq
Watchdog
Timer
wdt_irq
periph_nreset
Reset
Controller
periph_nreset
proc_nreset
backup_nreset
VDDBU
VDDBU
POR
VDDBU Powered
UHPCK
periph_clk[20]
periph_nreset
Real-Time
Timer
rtt_irq
rtt_alarm
UDPCK
SLCK
SHDN
periph_clk[10]
WKUP
RC
OSC
USB Host
Port
periph_irq[20]
SLCK
SLCK
backup_nreset
backup_nreset
Shut-Down
Controller
periph_nreset
USB
Device
Port
periph_irq[10]
rtt0_alarm
SLOW
CLOCK
OSC
4 General-Purpose
Backup Registers
SLCK
XIN
Bus Matrix
rstc_irq
por_ntrst
jtag_nreset
VDDCORE
POR
XOUT
Boundary Scan
TAP Controller
MCK
NRST
XIN32
PCK
debug
Periodic
Interval
Timer
wdt_fault
WDRPROC
XOUT32
ARM926EJ-S
proc_nreset
jtag_nreset
SLCK
debug
idle
proc_nreset
OSCSEL
ntrst
por_ntrst
periph_clk[2..27]
pck[0-1]
int
MAIN
OSC
MAINCK
PLLA
PLLACK
PLLB
PLLBCK
PCK
Power
Management
Controller
UDPCK
UHPCK
MCK
pmc_irq
periph_nreset
periph_clk[6..24]
idle
periph_nreset
periph_nreset
periph_clk[2..4]
dbgu_rxd
PA0-PA31
PB0-PB31
PC0-PC31
PIO
Controllers
periph_irq[2..4]
irq0-irq2
fiq
dbgu_txd
Embedded
Peripherals
periph_irq[6..24]
in
out
enable
25
6384E–ATARM–05-Feb-10
9.2
Reset Controller
• Based on two Power-on-Reset cell
– one on VDDBU and one on VDDCORE
• Status of the last reset
– Either general reset (VDDBU rising), wake-up reset (VDDCORE rising), software
reset, user reset or watchdog reset
• Controls the internal resets and the NRST pin output
– Allows shaping a reset signal for the external devices
9.3
Shutdown Controller
• Shutdown and Wake-Up logic
– Software programmable assertion of the SHDWN pin
– Deassertion Programmable on a WKUP pin level change or on alarm
9.4
Clock Generator
• Embeds a Low Power 32768 Hz Slow Clock Oscillator and a Low power RC oscillator
selectable with OSCSEL signal
– Provides the permanent Slow Clock SLCK to the system
• Embeds the Main Oscillator
– Oscillator bypass feature
– Supports 3 to 20 MHz crystals
• Embeds 2 PLLs
– The PLL A outputs 400-800 MHz clock
– The PLL B outputs 100 MHz clock
– Both integrate an input divider to increase output accuracy
– PLL A and PLL B embed their own filters
26
AT91SAM9G20
6384E–ATARM–05-Feb-10
AT91SAM9G20
Figure 9-2.
Clock Generator Block Diagram
Clock Generator
OSCSEL
On Chip
RC OSC
XIN32
Slow Clock
SLCK
Slow Clock
Oscillator
XOUT32
XIN
Main
Oscillator
Main Clock
MAINCK
PLL and
Divider A
PLLA Clock
PLLACK
PLL and
Divider B
PLLB Clock
PLLBCK
XOUT
Status
Control
Power
Management
Controller
9.5
Power Management Controller
• Provides:
– the Processor Clock PCK
– the Master Clock MCK, in particular to the Matrix and the memory interfaces.The
MCK divider can be 1,2,4,6
– the USB Device Clock UDPCK
– independent peripheral clocks, typically at the frequency of MCK
– 2 programmable clock outputs: PCK0, PCK1
• Five flexible operating modes:
– Normal Mode, processor and peripherals running at a programmable frequency
– Idle Mode, processor stopped waiting for an interrupt
– Slow Clock Mode, processor and peripherals running at low frequency
– Standby Mode, mix of Idle and Backup Mode, peripheral running at low frequency,
processor stopped waiting for an interrupt
– Backup Mode, Main Power Supplies off, VDDBU powered by a battery
27
6384E–ATARM–05-Feb-10
Figure 9-3.
AT91SAM9G20 Power Management Controller Block Diagram
Processor
Clock
Controller
Divider
/1,/2
PCK
int
Idle Mode
Master Clock Controller
SLCK
MAINCK
PLLACK
PLLBCK
Prescaler
/1,/2,/4,.../64
Divider
/1,/2,/4,/6
MCK
Peripherals
Clock Controller
periph_clk[..]
ON/OFF
Programmable Clock Controller
SLCK
MAINCK
PLLACK
PLLBCK
ON/OFF
Prescaler
/1,/2,/4,...,/64
pck[..]
USB Clock Controller
PLLBCK
9.6
Divider
/1,/2,/4
ON/OFF
UDPCK
Periodic Interval Timer
• Includes a 20-bit Periodic Counter, with less than 1 µs accuracy
• Includes a 12-bit Interval Overlay Counter
• Real Time OS or Linux®/Windows CE® compliant tick generator
9.7
Watchdog Timer
• 16-bit key-protected only-once-Programmable Counter
• Windowed, prevents the processor being in a dead-lock on the watchdog access
9.8
Real-time Timer
• Real-time Timer 32-bit free-running back-up Counter
• Integrates a 16-bit programmable prescaler running on slow clock
• Alarm Register capable of generating a wake-up of the system through the Shutdown
Controller
9.9
General-purpose Back-up Registers
• Four 32-bit backup general-purpose registers
9.10
Advanced Interrupt Controller
• Controls the interrupt lines (nIRQ and nFIQ) of the ARM Processor
• Thirty-two individually maskable and vectored interrupt sources
28
AT91SAM9G20
6384E–ATARM–05-Feb-10
AT91SAM9G20
– Source 0 is reserved for the Fast Interrupt Input (FIQ)
– Source 1 is reserved for system peripherals
– Programmable Edge-triggered or Level-sensitive Internal Sources
– Programmable Positive/Negative Edge-triggered or High/Low Level-sensitive
• Three External Sources plus the Fast Interrupt signal
• 8-level Priority Controller
– Drives the Normal Interrupt of the processor
– Handles priority of the interrupt sources 1 to 31
– Higher priority interrupts can be served during service of lower priority interrupt
• Vectoring
– Optimizes Interrupt Service Routine Branch and Execution
– One 32-bit Vector Register per interrupt source
– Interrupt Vector Register reads the corresponding current Interrupt Vector
• Protect Mode
– Easy debugging by preventing automatic operations when protect models are
enabled
• Fast Forcing
– Permits redirecting any normal interrupt source on the Fast Interrupt of the
processor
9.11
Debug Unit
• Composed of two functions:
– Two-pin UART
– Debug Communication Channel (DCC) support
• Two-pin UART
– Implemented features are 100% compatible with the standard Atmel ® USART
– Independent receiver and transmitter with a common programmable Baud Rate
Generator
– Even, Odd, Mark or Space Parity Generation
– Parity, Framing and Overrun Error Detection
– Automatic Echo, Local Loopback and Remote Loopback Channel Modes
– Support for two PDC channels with connection to receiver and transmitter
• Debug Communication Channel Support
– Offers visibility of and interrupt trigger from COMMRX and COMMTX signals from
the ARM Processor’s ICE Interface
9.12
Chip Identification
• Chip ID:0x019905A1
• JTAG ID: 0x05B2403F
• ARM926 TAP ID:0x0792603F
29
6384E–ATARM–05-Feb-10
10. Peripherals
10.1
User Interface
The peripherals are mapped in the upper 256 Mbytes of the address space between the
addresses 0xFFFA 0000 and 0xFFFC FFFF. Each User Peripheral is allocated 16 Kbytes of
address space. A complete memory map is presented in Figure 8-1 on page 19.
10.2
Identifiers
Table 10-1 defines the Peripheral Identifiers of the AT91SAM9G20. A peripheral identifier is
required for the control of the peripheral interrupt with the Advanced Interrupt Controller and for
the control of the peripheral clock with the Power Management Controller.
Table 10-1.
30
AT91SAM9G20 Peripheral Identifiers (Continued)
Peripheral ID
Peripheral Mnemonic
Peripheral Name
External Interrupt
0
1
AIC
Advanced Interrupt Controller
FIQ
SYSC
System Controller Interrupt
2
PIOA
Parallel I/O Controller A
3
PIOB
Parallel I/O Controller B
4
PIOC
Parallel I/O Controller C
5
ADC
Analog to Digital Converter
6
US0
USART 0
7
US1
USART 1
8
US2
USART 2
9
MCI
Multimedia Card Interface
10
UDP
USB Device Port
11
TWI
Two-wire Interface
12
SPI0
Serial Peripheral Interface 0
13
SPI1
Serial Peripheral Interface 1
14
SSC
Synchronous Serial Controller
15
-
Reserved
16
-
Reserved
17
TC0
Timer/Counter 0
18
TC1
Timer/Counter 1
19
TC2
Timer/Counter 2
20
UHP
USB Host Port
21
EMAC
Ethernet MAC
22
ISI
Image Sensor Interface
23
US3
USART 3
24
US4
USART 4
25
US5
USART 5
26
TC3
Timer/Counter 3
27
TC4
Timer/Counter 4
28
TC5
Timer/Counter 5
AT91SAM9G20
6384E–ATARM–05-Feb-10
AT91SAM9G20
Table 10-1.
Note:
AT91SAM9G20 Peripheral Identifiers (Continued)
Peripheral ID
Peripheral Mnemonic
Peripheral Name
External Interrupt
29
AIC
Advanced Interrupt Controller
IRQ0
30
AIC
Advanced Interrupt Controller
IRQ1
31
AIC
Advanced Interrupt Controller
IRQ2
Setting AIC, SYSC, UHP, ADC and IRQ0-2 bits in the clock set/clear registers of the PMC has no effect. The ADC clock is automatically started for the first conversion. In Sleep Mode the ADC clock is automatically stopped after each conversion.
10.2.1
Peripheral Interrupts and Clock Control
10.2.1.1
System Interrupt
The System Interrupt in Source 1 is the wired-OR of the interrupt signals coming from:
• the SDRAM Controller
• the Debug Unit
• the Periodic Interval Timer
• the Real-time Timer
• the Watchdog Timer
• the Reset Controller
• the Power Management Controller
The clock of these peripherals cannot be deactivated and Peripheral ID 1 can only be used
within the Advanced Interrupt Controller.
10.2.1.2
10.3
External Interrupts
All external interrupt signals, i.e., the Fast Interrupt signal FIQ or the Interrupt signals IRQ0 to
IRQ2, use a dedicated Peripheral ID. However, there is no clock control associated with these
peripheral IDs.
Peripheral Signal Multiplexing on I/O Lines
The AT91SAM9G20 features 3 PIO controllers (PIOA, PIOB, PIOC) that multiplex the I/O lines
of the peripheral set.
Each PIO Controller controls up to 32 lines. Each line can be assigned to one of two peripheral
functions, A or B. Table 10-2 on page 32, Table 10-3 on page 33 and Table 10-4 on page 34
define how the I/O lines of the peripherals A and B are multiplexed on the PIO Controllers. The
two columns “Function” and “Comments” have been inserted in this table for the user’s own
comments; they may be used to track how pins are defined in an application.
Note that some peripheral functions which are output only might be duplicated within both
tables.
The column “Reset State” indicates whether the PIO Line resets in I/O mode or in peripheral
mode. If I/O appears, the PIO Line resets in input with the pull-up enabled, so that the device is
maintained in a static state as soon as the reset is released. As a result, the bit corresponding to
the PIO Line in the register PIO_PSR (Peripheral Status Register) resets low.
If a signal name appears in the “Reset State” column, the PIO Line is assigned to this function
and the corresponding bit in PIO_PSR resets high. This is the case of pins controlling memories,
in particular the address lines, which require the pin to be driven as soon as the reset is
released. Note that the pull-up resistor is also enabled in this case.
31
6384E–ATARM–05-Feb-10
10.3.1
PIO Controller A Multiplexing
Table 10-2.
Multiplexing on PIO Controller A
PIO Controller A
I/O Line
Peripheral A
Peripheral B
PA0
SPI0_MISO
PA1
SPI0_MOSI
PA2
SPI0_SPCK
PA3
SPI0_NPCS0
PA4
Application Usage
Reset State
Power Supply
MCDB0
I/O
VDDIOP
MCCDB
I/O
VDDIOP
I/O
VDDIOP
MCDB3
I/O
VDDIOP
RTS2
MCDB2
I/O
VDDIOP
PA5
CTS2
MCDB1
I/O
VDDIOP
PA6
MCDA0
I/O
VDDIOP
PA7
MCCDA
I/O
VDDIOP
PA8
MCCK
I/O
VDDIOP
PA9
MCDA1
I/O
VDDIOP
PA10
MCDA2
ETX2
I/O
VDDIOP
PA11
MCDA3
ETX3
I/O
VDDIOP
PA12
ETX0
I/O
VDDIOP
PA13
ETX1
I/O
VDDIOP
PA14
ERX0
I/O
VDDIOP
PA15
ERX1
I/O
VDDIOP
PA16
ETXEN
I/O
VDDIOP
PA17
ERXDV
I/O
VDDIOP
PA18
ERXER
I/O
VDDIOP
PA19
ETXCK
I/O
VDDIOP
PA20
EMDC
I/O
VDDIOP
PA21
EMDIO
I/O
VDDIOP
PA22
ADTRG
ETXER
I/O
VDDIOP
PA23
TWD
ETX2
I/O
VDDIOP
PA24
TWCK
ETX3
I/O
VDDIOP
PA25
TCLK0
ERX2
I/O
VDDIOP
PA26
TIOA0
ERX3
I/O
VDDIOP
PA27
TIOA1
ERXCK
I/O
VDDIOP
PA28
TIOA2
ECRS
I/O
VDDIOP
PA29
SCK1
ECOL
I/O
VDDIOP
PA30
SCK2
RXD4
I/O
VDDIOP
PA31
SCK0
TXD4
I/O
VDDIOP
32
Comments
Function
Comments
AT91SAM9G20
6384E–ATARM–05-Feb-10
AT91SAM9G20
10.3.2
PIO Controller B Multiplexing
Table 10-3.
Multiplexing on PIO Controller B
PIO Controller B
I/O Line
Peripheral A
Peripheral B
PB0
SPI1_MISO
PB1
Application Usage
Comments
Reset State
Power Supply
TIOA3
I/O
VDDIOP
SPI1_MOSI
TIOB3
I/O
VDDIOP
PB2
SPI1_SPCK
TIOA4
I/O
VDDIOP
PB3
SPI1_NPCS0
TIOA5
I/O
VDDIOP
PB4
TXD0
I/O
VDDIOP
PB5
RXD0
I/O
VDDIOP
PB6
TXD1
TCLK1
I/O
VDDIOP
PB7
RXD1
TCLK2
I/O
VDDIOP
PB8
TXD2
I/O
VDDIOP
PB9
RXD2
I/O
VDDIOP
PB10
TXD3
ISI_D8
I/O
VDDIOP
PB11
RXD3
ISI_D9
I/O
VDDIOP
PB12
TXD5
ISI_D10
I/O
VDDIOP
PB13
RXD5
ISI_D11
I/O
VDDIOP
PB14
DRXD
I/O
VDDIOP
PB15
DTXD
I/O
VDDIOP
PB16
TK0
TCLK3
I/O
VDDIOP
PB17
TF0
TCLK4
I/O
VDDIOP
PB18
TD0
TIOB4
I/O
VDDIOP
PB19
RD0
TIOB5
I/O
VDDIOP
PB20
RK0
ISI_D0
I/O
VDDIOP
PB21
RF0
ISI_D1
I/O
VDDIOP
PB22
DSR0
ISI_D2
I/O
VDDIOP
PB23
DCD0
ISI_D3
I/O
VDDIOP
PB24
DTR0
ISI_D4
I/O
VDDIOP
PB25
RI0
ISI_D5
I/O
VDDIOP
PB26
RTS0
ISI_D6
I/O
VDDIOP
PB27
CTS0
ISI_D7
I/O
VDDIOP
PB28
RTS1
ISI_PCK
I/O
VDDIOP
PB29
CTS1
ISI_VSYNC
I/O
VDDIOP
PB30
PCK0
ISI_HSYNC
I/O
VDDIOP
PB31
PCK1
ISI_MCK
I/O
VDDIOP
Function
Comments
33
6384E–ATARM–05-Feb-10
10.3.3
PIO Controller C Multiplexing
Table 10-4.
Multiplexing on PIO Controller C
PIO Controller C
I/O Line
Peripheral A
Application Usage
Peripheral B
Comments
Reset State
Power Supply
PC0
SCK3
AD0
I/O
VDDANA
PC1
PCK0
AD1
I/O
VDDANA
PC2
PCK1
AD2
I/O
VDDANA
PC3
SPI1_NPCS3
AD3
I/O
VDDANA
PC4
A23
SPI1_NPCS2
A23
VDDIOM
PC5
A24
SPI1_NPCS1
A24
VDDIOM
PC6
TIOB2
CFCE1
I/O
VDDIOM
PC7
TIOB1
CFCE2
I/O
VDDIOM
PC8
NCS4/CFCS0
RTS3
I/O
VDDIOM
PC9
NCS5/CFCS1
TIOB0
I/O
VDDIOM
PC10
A25/CFRNW
CTS3
A25
VDDIOM
PC11
NCS2
SPI0_NPCS1
I/O
VDDIOM
PC12
IRQ0
NCS7
I/O
VDDIOM
PC13
FIQ
NCS6
I/O
VDDIOM
PC14
NCS3/NANDCS
IRQ2
I/O
VDDIOM
PC15
NWAIT
IRQ1
I/O
VDDIOM
PC16
D16
SPI0_NPCS2
I/O
VDDIOM
PC17
D17
SPI0_NPCS3
I/O
VDDIOM
PC18
D18
SPI1_NPCS1
I/O
VDDIOM
PC19
D19
SPI1_NPCS2
I/O
VDDIOM
PC20
D20
SPI1_NPCS3
I/O
VDDIOM
PC21
D21
I/O
VDDIOM
PC22
D22
I/O
VDDIOM
PC23
D23
I/O
VDDIOM
PC24
D24
I/O
VDDIOM
PC25
D25
I/O
VDDIOM
PC26
D26
I/O
VDDIOM
PC27
D27
I/O
VDDIOM
PC28
D28
I/O
VDDIOM
PC29
D29
I/O
VDDIOM
PC30
D30
I/O
VDDIOM
PC31
D31
I/O
VDDIOM
34
TCLK5
Function
Comments
AT91SAM9G20
6384E–ATARM–05-Feb-10
AT91SAM9G20
10.4
10.4.1
Embedded Peripherals
Serial Peripheral Interface
• Supports communication with serial external devices
– Four chip selects with external decoder support allow communication with up to 15
peripherals
– Serial memories, such as DataFlash and 3-wire EEPROMs
– Serial peripherals, such as ADCs, DACs, LCD Controllers, CAN Controllers and
Sensors
– External co-processors
• Master or slave serial peripheral bus interface
– 8- to 16-bit programmable data length per chip select
– Programmable phase and polarity per chip select
– Programmable transfer delays between consecutive transfers and between clock
and data per chip select
– Programmable delay between consecutive transfers
– Selectable mode fault detection
• Very fast transfers supported
– Transfers with baud rates up to MCK
– The chip select line may be left active to speed up transfers on the same device
10.4.2
Two-wire Interface
• Compatibility with standard two-wire serial memory
• One, two or three bytes for slave address
• Sequential read/write operations
• Supports either master or slave modes
• Compatible with standard two-wire serial memories
• Master, multi-master and slave mode operation
• Bit rate: up to 400 Kbits
• General Call supported in slave mode
• Connection to Peripheral DMA Controller (PDC) capabilities optimizes data transfers in
master mode only
– One channel for the receiver, one channel for the transmitter
– Next buffer support
10.4.3
USART
• Programmable Baud Rate Generator
• 5- to 9-bit full-duplex synchronous or asynchronous serial communications
– 1, 1.5 or 2 stop bits in Asynchronous Mode or 1 or 2 stop bits in Synchronous Mode
– Parity generation and error detection
– Framing error detection, overrun error detection
– MSB- or LSB-first
– Optional break generation and detection
35
6384E–ATARM–05-Feb-10
– By 8 or by-16 over-sampling receiver frequency
– Hardware handshaking RTS-CTS
– Optional modem signal management DTR-DSR-DCD-RI
– Receiver time-out and transmitter timeguard
– Optional Multi-drop Mode with address generation and detection
– Optional Manchester Encoding
• RS485 with driver control signal
• ISO7816, T = 0 or T = 1 Protocols for interfacing with smart cards
– NACK handling, error counter with repetition and iteration limit
• IrDA modulation and demodulation
– Communication at up to 115.2 Kbps
• Test Modes
– Remote Loopback, Local Loopback, Automatic Echo
The USART contains features allowing management of the Modem Signals DTR, DSR, DCD
and RI. In the AT91SAM9G20, only the USART0 implements these signals, named DTR0,
DSR0, DCD0 and RI0.
The USART1 and USART2 do not implement all the modem signals. Only RTS and CTS (RTS1
and CTS1, RTS2 and CTS2, respectively) are implemented in these USARTs for other features.
Thus, programming the USART1, USART2 or the USART3 in Modem Mode may lead to unpredictable results. In these USARTs, the commands relating to the Modem Mode have no effect
and the status bits relating the status of the modem signals are never activated.
10.4.4
Serial Synchronous Controller
• Provides serial synchronous communication links used in audio and telecom applications
(with CODECs in Master or Slave Modes, I2S, TDM Buses, Magnetic Card Reader, etc.)
• Contains an independent receiver and transmitter and a common clock divider
• Offers a configurable frame sync and data length
• Receiver and transmitter can be programmed to start automatically or on detection of
different event on the frame sync signal
• Receiver and transmitter include a data signal, a clock signal and a frame synchronization
signal
10.4.5
Timer Counter
• Two blocks of three 16-bit Timer Counter channels
• Each channel can be individually programmed to perform a wide range of functions including:
– Frequency Measurement
– Event Counting
– Interval Measurement
– Pulse Generation
– Delay Timing
– Pulse Width Modulation
– Up/down Capabilities
• Each channel is user-configurable and contains:
36
AT91SAM9G20
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AT91SAM9G20
– Three external clock inputs
– Five internal clock inputs
– Two multi-purpose input/output signals
• Each block contains two global registers that act on all three TC Channels
Note:
10.4.6
TC Block 0 (TC0, TC1, TC2) and TC Block 1 (TC3, TC4, TC5) have identical user interfaces. See
Figure 8-1, “AT91SAM9G20 Memory Mapping,” on page 19 for TC Block 0 and TC Block 1 base
addresses.
Multimedia Card Interface
• One double-channel MultiMedia Card Interface
• Compatibility with MultiMedia Card Specification Version 3.11
• Compatibility with SD Memory Card Specification Version 1.1
• Compatibility with SDIO Specification Version V1.0.
• Card clock rate up to Master Clock divided by 2
• Embedded power management to slow down clock rate when not used
• MCI has two slots, each supporting
– One slot for one MultiMediaCard bus (up to 30 cards) or
– One SD Memory Card
• Support for stream, block and multi-block data read and write
10.4.7
USB Host Port
• Compliance with Open HCI Rev 1.0 Specification
• Compliance with USB V2.0 Full-speed and Low-speed Specification
• Supports both Low-Speed 1.5 Mbps and Full-speed 12 Mbps devices
• Root hub integrated with two downstream USB ports in the 217-LFBGA package
• Two embedded USB transceivers
• Supports power management
• Operates as a master on the Matrix
10.4.8
USB Device Port
• USB V2.0 full-speed compliant, 12 MBits per second
• Embedded USB V2.0 full-speed transceiver
• Embedded 2,432-byte dual-port RAM for endpoints
• Suspend/Resume logic
• Ping-pong mode (two memory banks) for isochronous and bulk endpoints
• Six general-purpose endpoints
– Endpoint 0 and 3: 64 bytes, no ping-pong mode
– Endpoint 1 and 2: 64 bytes, ping-pong mode
– Endpoint 4 and 5: 512 bytes, ping-pong mode
• Embedded pad pull-up
10.4.9
Ethernet 10/100 MAC
• Compatibility with IEEE Standard 802.3
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6384E–ATARM–05-Feb-10
• 10 and 100 MBits per second data throughput capability
• Full- and half-duplex operations
• MII or RMII interface to the physical layer
• Register Interface to address, data, status and control registers
• DMA Interface, operating as a master on the Memory Controller
• Interrupt generation to signal receive and transmit completion
• 28-byte transmit and 28-byte receive FIFOs
• Automatic pad and CRC generation on transmitted frames
• Address checking logic to recognize four 48-bit addresses
• Support promiscuous mode where all valid frames are copied to memory
• Support physical layer management through MDIO interface
10.4.10
Image Sensor Interface
• ITU-R BT. 601/656 8-bit mode external interface support
• Support for ITU-R BT.656-4 SAV and EAV synchronization
• Vertical and horizontal resolutions up to 2048 x 2048
• Preview Path up to 640 x 480 in RGMB mode, 2048 x2048 in grayscale mode
• Support for packed data formatting for YCbCr 4:2:2 formats
• Preview scaler to generate smaller size image
• Programmable frame capture rate
10.4.11
Analog-to-Digital Converter
• 4-channel ADC
• 10-bit 312K samples/sec. Successive Approximation Register ADC
• -2/+2 LSB Integral Non Linearity, -1/+1 LSB Differential Non Linearity
• Individual enable and disable of each channel
• External voltage reference for better accuracy on low voltage inputs
• Multiple trigger source – Hardware or software trigger – External trigger pin – Timer Counter
0 to 2 outputs TIOA0 to TIOA2 trigger
• Sleep Mode and conversion sequencer – Automatic wakeup on trigger and back to sleep
mode after conversions of all enabled channels
• Four analog inputs shared with digital signals
38
AT91SAM9G20
6384E–ATARM–05-Feb-10
AT91SAM9G20
11. ARM926EJ-S Processor Overview
11.1
Overview
The ARM926EJ-S processor is a member of the ARM9™ family of general-purpose microprocessors. The ARM926EJ-S implements ARM architecture version 5TEJ and is targeted at multitasking applications where full memory management, high performance, low die size and low
power are all important features.
The ARM926EJ-S processor supports the 32-bit ARM and 16-bit THUMB instruction sets,
enabling the user to trade off between high performance and high code density. It also supports
8-bit Java instruction set and includes features for efficient execution of Java bytecode, providing a Java performance similar to a JIT (Just-In-Time compilers), for the next generation of Javapowered wireless and embedded devices. It includes an enhanced multiplier design for
improved DSP performance.
The ARM926EJ-S processor supports the ARM debug architecture and includes logic to assist
in both hardware and software debug.
The ARM926EJ-S provides a complete high performance processor subsystem, including:
• an ARM9EJ-S™ integer core
• a Memory Management Unit (MMU)
• separate instruction and data AMBA AHB bus interfaces
• separate instruction and data TCM interfaces
39
6384E–ATARM–05-Feb-10
11.2
Block Diagram
Figure 11-1. ARM926EJ-S Internal Functional Block Diagram
CP15 System
Configuration
Coprocessor
External Coprocessors
ETM9
External
Coprocessor
Interface
Trace Port
Interface
Write Data
ARM9EJ-S
Processor Core
Instruction
Fetches
Read
Data
Data
Address
Instruction
Address
MMU
DTCM
Interface
Data TLB
Instruction
TLB
ITCM
Interface
Data TCM
Instruction TCM
Instruction
Address
Data
Address
Data Cache
AHB Interface
and
Write Buffer
Instruction
Cache
AMBA AHB
40
AT91SAM9G20
6384E–ATARM–05-Feb-10
AT91SAM9G20
11.3
11.3.1
ARM9EJ-S Processor
ARM9EJ-S Operating States
The ARM9EJ-S processor can operate in three different states, each with a specific instruction
set:
• ARM state: 32-bit, word-aligned ARM instructions.
• THUMB state: 16-bit, halfword-aligned Thumb instructions.
• Jazelle state: variable length, byte-aligned Jazelle instructions.
In Jazelle state, all instruction Fetches are in words.
11.3.2
Switching State
The operating state of the ARM9EJ-S core can be switched between:
• ARM state and THUMB state using the BX and BLX instructions, and loads to the PC
• ARM state and Jazelle state using the BXJ instruction
All exceptions are entered, handled and exited in ARM state. If an exception occurs in Thumb or
Jazelle states, the processor reverts to ARM state. The transition back to Thumb or Jazelle
states occurs automatically on return from the exception handler.
11.3.3
Instruction Pipelines
The ARM9EJ-S core uses two kinds of pipelines to increase the speed of the flow of instructions
to the processor.
A five-stage (five clock cycles) pipeline is used for ARM and Thumb states. It consists of Fetch,
Decode, Execute, Memory and Writeback stages.
A six-stage (six clock cycles) pipeline is used for Jazelle state It consists of Fetch,
Jazelle/Decode (two clock cycles), Execute, Memory and Writeback stages.
11.3.4
Memory Access
The ARM9EJ-S core supports byte (8-bit), half-word (16-bit) and word (32-bit) access. Words
must be aligned to four-byte boundaries, half-words must be aligned to two-byte boundaries and
bytes can be placed on any byte boundary.
Because of the nature of the pipelines, it is possible for a value to be required for use before it
has been placed in the register bank by the actions of an earlier instruction. The ARM9EJ-S control logic automatically detects these cases and stalls the core or forward data.
11.3.5
Jazelle Technology
The Jazelle technology enables direct and efficient execution of Java byte codes on ARM processors, providing high performance for the next generation of Java-powered wireless and
embedded devices.
The new Java feature of ARM9EJ-S can be described as a hardware emulation of a JVM (Java
Virtual Machine). Java mode will appear as another state: instead of executing ARM or Thumb
instructions, it executes Java byte codes. The Java byte code decoder logic implemented in
ARM9EJ-S decodes 95% of executed byte codes and turns them into ARM instructions without
any overhead, while less frequently used byte codes are broken down into optimized sequences
of ARM instructions. The hardware/software split is invisible to the programmer, invisible to the
application and invisible to the operating system. All existing ARM registers are re-used in
Jazelle state and all registers then have particular functions in this mode.
41
6384E–ATARM–05-Feb-10
Minimum interrupt latency is maintained across both ARM state and Java state. Since byte
codes execution can be restarted, an interrupt automatically triggers the core to switch from
Java state to ARM state for the execution of the interrupt handler. This means that no special
provision has to be made for handling interrupts while executing byte codes, whether in hardware or in software.
11.3.6
ARM9EJ-S Operating Modes
In all states, there are seven operation modes:
• User mode is the usual ARM program execution state. It is used for executing most
application programs
• Fast Interrupt (FIQ) mode is used for handling fast interrupts. It is suitable for high-speed data
transfer or channel process
• Interrupt (IRQ) mode is used for general-purpose interrupt handling
• Supervisor mode is a protected mode for the operating system
• Abort mode is entered after a data or instruction prefetch abort
• System mode is a privileged user mode for the operating system
• Undefined mode is entered when an undefined instruction exception occurs
Mode changes may be made under software control, or may be brought about by external interrupts or exception processing. Most application programs execute in User Mode. The non-user
modes, known as privileged modes, are entered in order to service interrupts or exceptions or to
access protected resources.
11.3.7
ARM9EJ-S Registers
The ARM9EJ-S core has a total of 37 registers.
• 31 general-purpose 32-bit registers
• 6 32-bit status registers
Table 11-1 shows all the registers in all modes.
Table 11-1.
42
ARM9TDMI Modes and Registers Layout
User and
System Mode
Supervisor
Mode
Abort Mode
Undefined
Mode
Interrupt
Mode
Fast Interrupt
Mode
R0
R0
R0
R0
R0
R0
R1
R1
R1
R1
R1
R1
R2
R2
R2
R2
R2
R2
R3
R3
R3
R3
R3
R3
R4
R4
R4
R4
R4
R4
R5
R5
R5
R5
R5
R5
R6
R6
R6
R6
R6
R6
R7
R7
R7
R7
R7
R7
R8
R8
R8
R8
R8
R8_FIQ
R9
R9
R9
R9
R9
R9_FIQ
R10
R10
R10
R10
R10
R10_FIQ
R11
R11
R11
R11
R11
R11_FIQ
AT91SAM9G20
6384E–ATARM–05-Feb-10
AT91SAM9G20
Table 11-1.
ARM9TDMI Modes and Registers Layout (Continued)
User and
System Mode
Supervisor
Mode
Abort Mode
Undefined
Mode
Interrupt
Mode
Fast Interrupt
Mode
R12
R12
R12
R12
R12
R12_FIQ
R13
R13_SVC
R13_ABORT
R13_UNDEF
R13_IRQ
R13_FIQ
R14
R14_SVC
R14_ABORT
R14_UNDEF
R14_IRQ
R14_FIQ
PC
PC
PC
PC
PC
PC
CPSR
CPSR
CPSR
CPSR
CPSR
CPSR
SPSR_SVC
SPSR_ABOR
T
SPSR_UNDE
F
SPSR_IRQ
SPSR_FIQ
Mode-specific banked registers
The ARM state register set contains 16 directly-accessible registers, r0 to r15, and an additional
register, the Current Program Status Register (CPSR). Registers r0 to r13 are general-purpose
registers used to hold either data or address values. Register r14 is used as a Link register that
holds a value (return address) of r15 when BL or BLX is executed. Register r15 is used as a program counter (PC), whereas the Current Program Status Register (CPSR) contains condition
code flags and the current mode bits.
In privileged modes (FIQ, Supervisor, Abort, IRQ, Undefined), mode-specific banked registers
(r8 to r14 in FIQ mode or r13 to r14 in the other modes) become available. The corresponding
banked registers r14_fiq, r14_svc, r14_abt, r14_irq, r14_und are similarly used to hold the values (return address for each mode) of r15 (PC) when interrupts and exceptions arise, or when
BL or BLX instructions are executed within interrupt or exception routines. There is another register called Saved Program Status Register (SPSR) that becomes available in privileged modes
instead of CPSR. This register contains condition code flags and the current mode bits saved as
a result of the exception that caused entry to the current (privileged) mode.
In all modes and due to a software agreement, register r13 is used as stack pointer.
The use and the function of all the registers described above should obey ARM Procedure Call
Standard (APCS) which defines:
• constraints on the use of registers
• stack conventions
• argument passing and result return
For more details, refer to ARM Software Development Kit.
The Thumb state register set is a subset of the ARM state set. The programmer has direct
access to:
• Eight general-purpose registers r0-r7
• Stack pointer, SP
• Link register, LR (ARM r14)
• PC
• CPSR
43
6384E–ATARM–05-Feb-10
There are banked registers SPs, LRs and SPSRs for each privileged mode (for more details see
the ARM9EJ-S Technical Reference Manual, revision r1p2 page 2-12).
11.3.7.1
Status Registers
The ARM9EJ-S core contains one CPSR, and five SPSRs for exception handlers to use. The
program status registers:
• hold information about the most recently performed ALU operation
• control the enabling and disabling of interrupts
• set the processor operation mode
Figure 11-2. Status Register Format
31 30 29 28 27
24
N Z C V Q
J
7 6 5
Reserved
I F T
Jazelle state bit
Reserved
Sticky Overflow
Overflow
Carry/Borrow/Extend
Zero
Negative/Less than
0
Mode
Mode bits
Thumb state bit
FIQ disable
IRQ disable
Figure 11-2 shows the status register format, where:
• N: Negative, Z: Zero, C: Carry, and V: Overflow are the four ALU flags
• The Sticky Overflow (Q) flag can be set by certain multiply and fractional arithmetic
instructions like QADD, QDADD, QSUB, QDSUB, SMLAxy, and SMLAWy needed to achieve
DSP operations.
The Q flag is sticky in that, when set by an instruction, it remains set until explicitly cleared by
an MSR instruction writing to the CPSR. Instructions cannot execute conditionally on the
status of the Q flag.
• The J bit in the CPSR indicates when the ARM9EJ-S core is in Jazelle state, where:
– J = 0: The processor is in ARM or Thumb state, depending on the T bit
– J = 1: The processor is in Jazelle state.
• Mode: five bits to encode the current processor mode
11.3.7.2
Exceptions
Exception Types and Priorities
The ARM9EJ-S supports five types of exceptions. Each type drives the ARM9EJ-S in a privi-
leged mode. The types of exceptions are:
• Fast interrupt (FIQ)
• Normal interrupt (IRQ)
• Data and Prefetched aborts (Abort)
• Undefined instruction (Undefined)
• Software interrupt and Reset (Supervisor)
44
AT91SAM9G20
6384E–ATARM–05-Feb-10
AT91SAM9G20
When an exception occurs, the banked version of R14 and the SPSR for the exception mode
are used to save the state.
More than one exception can happen at a time, therefore the ARM9EJ-S takes the arisen exceptions according to the following priority order:
• Reset (highest priority)
• Data Abort
• FIQ
• IRQ
• Prefetch Abort
• BKPT, Undefined instruction, and Software Interrupt (SWI) (Lowest priority)
The BKPT, or Undefined instruction, and SWI exceptions are mutually exclusive.
Note that there is one exception in the priority scheme: when FIQs are enabled and a Data Abort
occurs at the same time as an FIQ, the ARM9EJ-S core enters the Data Abort handler, and proceeds immediately to FIQ vector. A normal return from the FIQ causes the Data Abort handler to
resume execution. Data Aborts must have higher priority than FIQs to ensure that the transfer
error does not escape detection.
Exception Modes and Handling
Exceptions arise whenever the normal flow of a program must be halted temporarily, for example, to service an interrupt from a peripheral.
When handling an ARM exception, the ARM9EJ-S core performs the following operations:
1. Preserves the address of the next instruction in the appropriate Link Register that corresponds to the new mode that has been entered. When the exception entry is from:
– ARM and Jazelle states, the ARM9EJ-S copies the address of the next instruction
into LR (current PC(r15) + 4 or PC + 8 depending on the exception).
– THUMB state, the ARM9EJ-S writes the value of the PC into LR, offset by a value
(current PC + 2, PC + 4 or PC + 8 depending on the exception) that causes the
program to resume from the correct place on return.
2. Copies the CPSR into the appropriate SPSR.
3. Forces the CPSR mode bits to a value that depends on the exception.
4. Forces the PC to fetch the next instruction from the relevant exception vector.
The register r13 is also banked across exception modes to provide each exception handler with
private stack pointer.
The ARM9EJ-S can also set the interrupt disable flags to prevent otherwise unmanageable
nesting of exceptions.
When an exception has completed, the exception handler must move both the return value in
the banked LR minus an offset to the PC and the SPSR to the CPSR. The offset value varies
according to the type of exception. This action restores both PC and the CPSR.
The fast interrupt mode has seven private registers r8 to r14 (banked registers) to reduce or
remove the requirement for register saving which minimizes the overhead of context switching.
The Prefetch Abort is one of the aborts that indicates that the current memory access cannot be
completed. When a Prefetch Abort occurs, the ARM9EJ-S marks the prefetched instruction as
invalid, but does not take the exception until the instruction reaches the Execute stage in the
45
6384E–ATARM–05-Feb-10
pipeline. If the instruction is not executed, for example because a branch occurs while it is in the
pipeline, the abort does not take place.
The breakpoint (BKPT) instruction is a new feature of ARM9EJ-S that is destined to solve the
problem of the Prefetch Abort. A breakpoint instruction operates as though the instruction
caused a Prefetch Abort.
A breakpoint instruction does not cause the ARM9EJ-S to take the Prefetch Abort exception until
the instruction reaches the Execute stage of the pipeline. If the instruction is not executed, for
example because a branch occurs while it is in the pipeline, the breakpoint does not take place.
11.3.8
ARM Instruction Set Overview
The ARM instruction set is divided into:
• Branch instructions
• Data processing instructions
• Status register transfer instructions
• Load and Store instructions
• Coprocessor instructions
• Exception-generating instructions
ARM instructions can be executed conditionally. Every instruction contains a 4-bit condition
code field (bits[31:28]).
For further details, see the ARM Technical Reference Manual, ARM ref. DDI0198B.
Table 11-2 gives the ARM instruction mnemonic list.
Table 11-2.
Mnemonic
Operation
Mnemonic
Operation
MOV
Move
MVN
Move Not
ADD
Add
ADC
Add with Carry
SUB
Subtract
SBC
Subtract with Carry
RSB
Reverse Subtract
RSC
Reverse Subtract with Carry
CMP
Compare
CMN
Compare Negated
TST
Test
TEQ
Test Equivalence
AND
Logical AND
BIC
Bit Clear
EOR
Logical Exclusive OR
ORR
Logical (inclusive) OR
MUL
Multiply
MLA
Multiply Accumulate
SMULL
Sign Long Multiply
UMULL
Unsigned Long Multiply
SMLAL
Signed Long Multiply Accumulate
UMLAL
Unsigned Long Multiply
Accumulate
MSR
B
BX
LDR
46
ARM Instruction Mnemonic List
Move to Status Register
Branch
MRS
BL
Move From Status Register
Branch and Link
Branch and Exchange
SWI
Software Interrupt
Load Word
STR
Store Word
LDRSH
Load Signed Halfword
LDRSB
Load Signed Byte
AT91SAM9G20
6384E–ATARM–05-Feb-10
AT91SAM9G20
Table 11-2.
Mnemonic
Mnemonic
Operation
Load Half Word
STRH
Store Half Word
LDRB
Load Byte
STRB
Store Byte
Load Register Byte with
Translation
STRBT
Store Register Byte with
Translation
LDRT
Load Register with Translation
STRT
Store Register with Translation
LDM
Load Multiple
STM
Store Multiple
SWP
Swap Word
MCR
Move To Coprocessor
MRC
Move From Coprocessor
LDC
Load To Coprocessor
STC
Store From Coprocessor
CDP
Coprocessor Data Processing
SWPB
Swap Byte
New ARM Instruction Set
.
Table 11-3.
Mnemonic
BXJ
New ARM Instruction Mnemonic List
Operation
Mnemonic
Operation
Branch and exchange to Java
MRRC
Move double from coprocessor
Branch, Link and exchange
MCR2
Alternative move of ARM reg to
coprocessor
SMLAxy
Signed Multiply Accumulate 16 *
16 bit
MCRR
Move double to coprocessor
SMLAL
Signed Multiply Accumulate Long
CDP2
Alternative Coprocessor Data
Processing
SMLAWy
Signed Multiply Accumulate 32 *
16 bit
BKPT
Breakpoint
SMULxy
Signed Multiply 16 * 16 bit
PLD
SMULWy
Signed Multiply 32 * 16 bit
STRD
Store Double
Saturated Add
STC2
Alternative Store from
Coprocessor
Saturated Add with Double
LDRD
Load Double
Saturated subtract
LDC2
Alternative Load to Coprocessor
BLX (1)
QADD
QDADD
QSUB
QDSUB
Note:
11.3.10
Operation
LDRH
LDRBT
11.3.9
ARM Instruction Mnemonic List (Continued)
Saturated Subtract with double
CLZ
Soft Preload, Memory prepare to
load from address
Count Leading Zeroes
1. A Thumb BLX contains two consecutive Thumb instructions, and takes four cycles.
Thumb Instruction Set Overview
The Thumb instruction set is a re-encoded subset of the ARM instruction set.
The Thumb instruction set is divided into:
• Branch instructions
• Data processing instructions
• Load and Store instructions
• Load and Store multiple instructions
47
6384E–ATARM–05-Feb-10
• Exception-generating instruction
Table 5 shows the Thumb instruction set, for further details, see the ARM Technical Reference
Manual, ARM ref. DDI0198B.
Table 11-4 gives the Thumb instruction mnemonic list.
Table 11-4.
Mnemonic
Operation
Mnemonic
Operation
MOV
Move
MVN
Move Not
ADD
Add
ADC
Add with Carry
SUB
Subtract
SBC
Subtract with Carry
CMP
Compare
CMN
Compare Negated
TST
Test
NEG
Negate
AND
Logical AND
BIC
Bit Clear
EOR
Logical Exclusive OR
ORR
Logical (inclusive) OR
LSL
Logical Shift Left
LSR
Logical Shift Right
ASR
Arithmetic Shift Right
ROR
Rotate Right
MUL
Multiply
BLX
Branch, Link, and Exchange
B
Branch
BL
BX
LDR
Branch and Link
Branch and Exchange
SWI
Software Interrupt
Load Word
STR
Store Word
LDRH
Load Half Word
STRH
Store Half Word
LDRB
Load Byte
STRB
Store Byte
LDRSH
Load Signed Halfword
LDRSB
Load Signed Byte
LDMIA
Load Multiple
STMIA
Store Multiple
PUSH
Push Register to stack
POP
Pop Register from stack
Conditional Branch
BKPT
Breakpoint
BCC
48
Thumb Instruction Mnemonic List
AT91SAM9G20
6384E–ATARM–05-Feb-10
AT91SAM9G20
11.4
CP15 Coprocessor
Coprocessor 15, or System Control Coprocessor CP15, is used to configure and control all the
items in the list below:
• ARM9EJ-S
• Caches (ICache, DCache and write buffer)
• TCM
• MMU
• Other system options
To control these features, CP15 provides 16 additional registers. See Table 11-5.
Table 11-5.
Register
0
Name
Read/Write
(1)
Read/Unpredictable
ID Code
0
Cache type
(1)
Read/Unpredictable
0
TCM status(1)
Read/Unpredictable
1
Control
Read/write
2
Translation Table Base
Read/write
3
Domain Access Control
Read/write
4
Reserved
None
5
Notes:
CP15 Registers
Data fault Status
(1)
Read/write
(1)
5
Instruction fault status
6
Fault Address
Read/write
7
Cache Operations
Read/Write
8
TLB operations
Unpredictable/Write
(2)
Read/write
9
cache lockdown
Read/write
9
TCM region
Read/write
10
TLB lockdown
Read/write
11
Reserved
None
12
Reserved
None
(1)
Read/write
13
FCSE PID
13
Context ID(1)
Read/Write
14
Reserved
None
15
Test configuration
Read/Write
1. Register locations 0,5, and 13 each provide access to more than one register. The register
accessed depends on the value of the opcode_2 field.
2. Register location 9 provides access to more than one register. The register accessed depends
on the value of the CRm field.
49
6384E–ATARM–05-Feb-10
11.4.1
CP15 Registers Access
CP15 registers can only be accessed in privileged mode by:
• MCR (Move to Coprocessor from ARM Register) instruction is used to write an ARM register
to CP15.
• MRC (Move to ARM Register from Coprocessor) instruction is used to read the value of
CP15 to an ARM register.
Other instructions like CDP, LDC, STC can cause an undefined instruction exception.
The assembler code for these instructions is:
MCR/MRC{cond} p15, opcode_1, Rd, CRn, CRm, opcode_2.
The MCR, MRC instructions bit pattern is shown below:
31
30
29
28
cond
23
22
21
opcode_1
15
20
13
12
Rd
6
26
25
24
1
1
1
0
19
18
17
16
L
14
7
27
5
opcode_2
4
CRn
11
10
9
8
1
1
1
1
3
2
1
0
1
CRm
• CRm[3:0]: Specified Coprocessor Action
Determines specific coprocessor action. Its value is dependent on the CP15 register used. For details, refer to CP15 specific register behavior.
• opcode_2[7:5]
Determines specific coprocessor operation code. By default, set to 0.
• Rd[15:12]: ARM Register
Defines the ARM register whose value is transferred to the coprocessor. If R15 is chosen, the result is unpredictable.
• CRn[19:16]: Coprocessor Register
Determines the destination coprocessor register.
• L: Instruction Bit
0 = MCR instruction
1 = MRC instruction
• opcode_1[23:20]: Coprocessor Code
Defines the coprocessor specific code. Value is c15 for CP15.
• cond [31:28]: Condition
For more details, see Chapter 2 in ARM926EJ-S TRM.
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AT91SAM9G20
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AT91SAM9G20
11.5
Memory Management Unit (MMU)
The ARM926EJ-S processor implements an enhanced ARM architecture v5 MMU to provide virtual memory features required by operating systems like Symbian OS®, Windows CE, and
Linux. These virtual memory features are memory access permission controls and virtual to
physical address translations.
The Virtual Address generated by the CPU core is converted to a Modified Virtual Address
(MVA) by the FCSE (Fast Context Switch Extension) using the value in CP15 register13. The
MMU translates modified virtual addresses to physical addresses by using a single, two-level
page table set stored in physical memory. Each entry in the set contains the access permissions
and the physical address that correspond to the virtual address.
The first level translation tables contain 4096 entries indexed by bits [31:20] of the MVA. These
entries contain a pointer to either a 1 MB section of physical memory along with attribute information (access permissions, domain, etc.) or an entry in the second level translation tables;
coarse table and fine table.
The second level translation tables contain two subtables, coarse table and fine table. An entry
in the coarse table contains a pointer to both large pages and small pages along with access
permissions. An entry in the fine table contains a pointer to large, small and tiny pages.
Table 7 shows the different attributes of each page in the physical memory.
Table 11-6.
Mapping Details
Mapping Name
Mapping Size
Access Permission By
Subpage Size
Section
1M byte
Section
-
Large Page
64K bytes
4 separated subpages
16K bytes
Small Page
4K bytes
4 separated subpages
1K byte
Tiny Page
1K byte
Tiny Page
-
The MMU consists of:
• Access control logic
• Translation Look-aside Buffer (TLB)
• Translation table walk hardware
11.5.1
Access Control Logic
The access control logic controls access information for every entry in the translation table. The
access control logic checks two pieces of access information: domain and access permissions.
The domain is the primary access control mechanism for a memory region; there are 16 of them.
It defines the conditions necessary for an access to proceed. The domain determines whether
the access permissions are used to qualify the access or whether they should be ignored.
The second access control mechanism is access permissions that are defined for sections and
for large, small and tiny pages. Sections and tiny pages have a single set of access permissions
whereas large and small pages can be associated with 4 sets of access permissions, one for
each subpage (quarter of a page).
11.5.2
Translation Look-aside Buffer (TLB)
The Translation Look-aside Buffer (TLB) caches translated entries and thus avoids going
through the translation process every time. When the TLB contains an entry for the MVA (Modi-
51
6384E–ATARM–05-Feb-10
fied Virtual Address), the access control logic determines if the access is permitted and outputs
the appropriate physical address corresponding to the MVA. If access is not permitted, the MMU
signals the CPU core to abort.
If the TLB does not contain an entry for the MVA, the translation table walk hardware is invoked
to retrieve the translation information from the translation table in physical memory.
11.5.3
Translation Table Walk Hardware
The translation table walk hardware is a logic that traverses the translation tables located in
physical memory, gets the physical address and access permissions and updates the TLB.
The number of stages in the hardware table walking is one or two depending whether the
address is marked as a section-mapped access or a page-mapped access.
There are three sizes of page-mapped accesses and one size of section-mapped access. Pagemapped accesses are for large pages, small pages and tiny pages. The translation process
always begins with a level one fetch. A section-mapped access requires only a level one fetch,
but a page-mapped access requires an additional level two fetch. For further details on the
MMU, please refer to chapter 3 in ARM926EJ-S Technical Reference Manual.
11.5.4
MMU Faults
The MMU generates an abort on the following types of faults:
• Alignment faults (for data accesses only)
• Translation faults
• Domain faults
• Permission faults
The access control mechanism of the MMU detects the conditions that produce these faults. If
the fault is a result of memory access, the MMU aborts the access and signals the fault to the
CPU core.The MMU retains status and address information about faults generated by the data
accesses in the data fault status register and fault address register. It also retains the status of
faults generated by instruction fetches in the instruction fault status register.
The fault status register (register 5 in CP15) indicates the cause of a data or prefetch abort, and
the domain number of the aborted access when it happens. The fault address register (register 6
in CP15) holds the MVA associated with the access that caused the Data Abort. For further
details on MMU faults, please refer to chapter 3 in ARM926EJ-S Technical Reference Manual.
52
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AT91SAM9G20
11.6
Caches and Write Buffer
The ARM926EJ-S contains a 32 KB Instruction Cache (ICache), a 32 KB Data Cache (DCache),
and a write buffer. Although the ICache and DCache share common features, each still has
some specific mechanisms.
The caches (ICache and DCache) are four-way set associative, addressed, indexed and tagged
using the Modified Virtual Address (MVA), with a cache line length of eight words with two dirty
bits for the DCache. The ICache and DCache provide mechanisms for cache lockdown, cache
pollution control, and line replacement.
A new feature is now supported by ARM926EJ-S caches called allocate on read-miss commonly
known as wrapping. This feature enables the caches to perform critical word first cache refilling.
This means that when a request for a word causes a read-miss, the cache performs an AHB
access. Instead of loading the whole line (eight words), the cache loads the critical word first, so
the processor can reach it quickly, and then the remaining words, no matter where the word is
located in the line.
The caches and the write buffer are controlled by the CP15 register 1 (Control), CP15 register 7
(cache operations) and CP15 register 9 (cache lockdown).
11.6.1
Instruction Cache (ICache)
The ICache caches fetched instructions to be executed by the processor. The ICache can be
enabled by writing 1 to I bit of the CP15 Register 1 and disabled by writing 0 to this same bit.
When the MMU is enabled, all instruction fetches are subject to translation and permission
checks. If the MMU is disabled, all instructions fetches are cachable, no protection checks are
made and the physical address is flat-mapped to the modified virtual address. With the MVA use
disabled, context switching incurs ICache cleaning and/or invalidating.
When the ICache is disabled, all instruction fetches appear on external memory (AHB) (see
Tables 4-1 and 4-2 in page 4-4 in ARM926EJ-S TRM).
On reset, the ICache entries are invalidated and the ICache is disabled. For best performance,
ICache should be enabled as soon as possible after reset.
11.6.2
11.6.2.1
Data Cache (DCache) and Write Buffer
ARM926EJ-S includes a DCache and a write buffer to reduce the effect of main memory bandwidth and latency on data access performance. The operations of DCache and write buffer are
closely connected.
DCache
The DCache needs the MMU to be enabled. All data accesses are subject to MMU permission
and translation checks. Data accesses that are aborted by the MMU do not cause linefills or data
accesses to appear on the AMBA ASB interface. If the MMU is disabled, all data accesses are
noncachable, nonbufferable, with no protection checks, and appear on the AHB bus. All
addresses are flat-mapped, VA = MVA = PA, which incurs DCache cleaning and/or invalidating
every time a context switch occurs.
The DCache stores the Physical Address Tag (PA Tag) from which every line was loaded and
uses it when writing modified lines back to external memory. This means that the MMU is not
involved in write-back operations.
Each line (8 words) in the DCache has two dirty bits, one for the first four words and the other
one for the second four words. These bits, if set, mark the associated half-lines as dirty. If the
53
6384E–ATARM–05-Feb-10
cache line is replaced due to a linefill or a cache clean operation, the dirty bits are used to decide
whether all, half or none is written back to memory.
DCache can be enabled or disabled by writing either 1 or 0 to bit C in register 1 of CP15 (see
Tables 4-3 and 4-4 on page 4-5 in ARM926EJ-S TRM).
The DCache supports write-through and write-back cache operations, selected by memory
region using the C and B bits in the MMU translation tables.
The DCache contains an eight data word entry, single address entry write-back buffer used to
hold write-back data for cache line eviction or cleaning of dirty cache lines.
The Write Buffer can hold up to 16 words of data and four separate addresses. DCache and
Write Buffer operations are closely connected as their configuration is set in each section by the
page descriptor in the MMU translation table.
11.6.2.2
Write Buffer
The ARM926EJ-S contains a write buffer that has a 16-word data buffer and a four- address
buffer. The write buffer is used for all writes to a bufferable region, write-through region and
write-back region. It also allows to avoid stalling the processor when writes to external memory
are performed. When a store occurs, data is written to the write buffer at core speed (high
speed). The write buffer then completes the store to external memory at bus speed (typically
slower than the core speed). During this time, the ARM9EJ-S processor can preform other
tasks.
DCache and Write Buffer support write-back and write-through memory regions, controlled by C
and B bits in each section and page descriptor within the MMU translation tables.
11.6.2.3
Write-though Operation
When a cache write hit occurs, the DCache line is updated. The updated data is then written to
the write buffer which transfers it to external memory.
When a cache write miss occurs, a line, chosen by round robin or another algorithm, is stored in
the write buffer which transfers it to external memory.
11.6.2.4
Write-back Operation
When a cache write hit occurs, the cache line or half line is marked as dirty, meaning that its
contents are not up-to-date with those in the external memory.
When a cache write miss occurs, a line, chosen by round robin or another algorithm, is stored in
the write buffer which transfers it to external memory.
54
AT91SAM9G20
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AT91SAM9G20
11.7
Bus Interface Unit
The ARM926EJ-S features a Bus Interface Unit (BIU) that arbitrates and schedules AHB
requests. The BIU implements a multi-layer AHB, based on the AHB-Lite protocol, that enables
parallel access paths between multiple AHB masters and slaves in a system. This is achieved by
using a more complex interconnection matrix and gives the benefit of increased overall bus
bandwidth, and a more flexible system architecture.
The multi-master bus architecture has a number of benefits:
• It allows the development of multi-master systems with an increased bus bandwidth and a
flexible architecture.
• Each AHB layer becomes simple because it only has one master, so no arbitration or masterto-slave muxing is required. AHB layers, implementing AHB-Lite protocol, do not have to
support request and grant, nor do they have to support retry and split transactions.
• The arbitration becomes effective when more than one master wants to access the same
slave simultaneously.
11.7.1
Supported Transfers
The ARM926EJ-S processor performs all AHB accesses as single word, bursts of four words, or
bursts of eight words. Any ARM9EJ-S core request that is not 1, 4, 8 words in size is split into
packets of these sizes. Note that the Atmel bus is AHB-Lite protocol compliant, hence it does not
support split and retry requests.
Table 8 gives an overview of the supported transfers and different kinds of transactions they are
used for.
Table 11-7.
HBurst[2:0]
Supported Transfers
Description
Single transfer of word, half word, or byte:
• data write (NCNB, NCB, WT, or WB that has missed in DCache)
SINGLE
Single transfer
• data read (NCNB or NCB)
• NC instruction fetch (prefetched and non-prefetched)
• page table walk read
INCR4
Four-word incrementing burst
Half-line cache write-back, Instruction prefetch, if enabled. Four-word burst NCNB,
NCB, WT, or WB write.
INCR8
Eight-word incrementing burst
Full-line cache write-back, eight-word burst NCNB, NCB, WT, or WB write.
WRAP8
Eight-word wrapping burst
Cache linefill
11.7.2
Thumb Instruction Fetches
All instructions fetches, regardless of the state of ARM9EJ-S core, are made as 32-bit accesses
on the AHB. If the ARM9EJ-S is in Thumb state, then two instructions can be fetched at a time.
11.7.3
Address Alignment
The ARM926EJ-S BIU performs address alignment checking and aligns AHB addresses to the
necessary boundary. 16-bit accesses are aligned to halfword boundaries, and 32-bit accesses
are aligned to word boundaries.
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6384E–ATARM–05-Feb-10
56
AT91SAM9G20
6384E–ATARM–05-Feb-10
AT91SAM9G20
12. AT91SAM9G20 Debug and Test
12.1
Overview
The AT91SAM9G20 features a number of complementary debug and test capabilities. A common JTAG/ICE (In-Circuit Emulator) port is used for standard debugging functions, such as
downloading code and single-stepping through programs. The Debug Unit provides a two-pin
UART that can be used to upload an application into internal SRAM. It manages the interrupt
handling of the internal COMMTX and COMMRX signals that trace the activity of the Debug
Communication Channel.
A set of dedicated debug and test input/output pins gives direct access to these capabilities from
a PC-based test environment.
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6384E–ATARM–05-Feb-10
12.2
Block Diagram
Figure 12-1. Debug and Test Block Diagram
TMS
TCK
TDI
NTRST
ICE/JTAG
TAP
Boundary
Port
JTAGSEL
TDO
RTCK
POR
Reset
and
Test
ARM9EJ-S
TST
ICE-RT
PDC
DBGU
PIO
ARM926EJ-S
DTXD
DRXD
TAP: Test Access Port
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AT91SAM9G20
6384E–ATARM–05-Feb-10
AT91SAM9G20
12.3
12.3.1
Application Examples
Debug Environment
Figure 12-2 on page 59 shows a complete debug environment example. The ICE/JTAG interface is used for standard debugging functions, such as downloading code and single-stepping
through the program. A software debugger running on a personal computer provides the user
interface for configuring a Trace Port interface utilizing the ICE/JTAG interface.
Figure 12-2. Application Debug and Trace Environment Example
Host Debugger
ICE/JTA
ICE/JTAG
AT91SAM9G20
RS232
Connector
Terminal
AT91SAM9G20-based Application
59
6384E–ATARM–05-Feb-10
12.3.2
Test Environment
Figure 12-3 on page 60 shows a test environment example. Test vectors are sent and interpreted by the tester. In this example, the “board in test” is designed using a number of JTAGcompliant devices. These devices can be connected to form a single scan chain.
Figure 12-3. Application Test Environment Example
Test Adaptor
Tester
JTAG
Interface
ICE/JTAG
Connector
Chip n
AT91SAM9G20
Chip 2
Chip 1
AT91SAM9G20-based Application Board In Test
12.4
Debug and Test Pin Description
Table 12-1.
Pin Name
Debug and Test Pin List
Function
Type
Active Level
Input/Output
Low
Input
High
Low
Reset/Test
NRST
Microcontroller Reset
TST
Test Mode Select
ICE and JTAG
NTRST
Test Reset Signal
Input
TCK
Test Clock
Input
TDI
Test Data In
Input
TDO
Test Data Out
TMS
Test Mode Select
RTCK
Returned Test Clock
JTAGSEL
JTAG Selection
Output
Input
Output
Input
Debug Unit
60
DRXD
Debug Receive Data
Input
DTXD
Debug Transmit Data
Output
AT91SAM9G20
6384E–ATARM–05-Feb-10
AT91SAM9G20
12.5
12.5.1
Functional Description
Test Pin
One dedicated pin, TST, is used to define the device operating mode. The user must make sure
that this pin is tied at low level to ensure normal operating conditions. Other values associated
with this pin are reserved for manufacturing test.
12.5.2
EmbeddedICE
The ARM9EJ-S EmbeddedICE-RT™ is supported via the ICE/JTAG port. It is connected to a
host computer via an ICE interface. Debug support is implemented using an ARM9EJ-S core
embedded within the ARM926EJ-S. The internal state of the ARM926EJ-S is examined through
an ICE/JTAG port which allows instructions to be serially inserted into the pipeline of the core
without using the external data bus. Therefore, when in debug state, a store-multiple (STM) can
be inserted into the instruction pipeline. This exports the contents of the ARM9EJ-S registers.
This data can be serially shifted out without affecting the rest of the system.
There are two scan chains inside the ARM9EJ-S processor which support testing, debugging,
and programming of the EmbeddedICE-RT. The scan chains are controlled by the ICE/JTAG
port.
EmbeddedICE mode is selected when JTAGSEL is low. It is not possible to switch directly
between ICE and JTAG operations. A chip reset must be performed after JTAGSEL is changed.
For further details on the EmbeddedICE-RT, see the ARM document:
ARM9EJ-S Technical Reference Manual (DDI 0222A).
12.5.3
JTAG Signal Description
TMS is the Test Mode Select input which controls the transitions of the test interface state
machine.
TDI is the Test Data Input line which supplies the data to the JTAG registers (Boundary Scan
Register, Instruction Register, or other data registers).
TDO is the Test Data Output line which is used to serially output the data from the JTAG registers to the equipment controlling the test. It carries the sampled values from the boundary scan
chain (or other JTAG registers) and propagates them to the next chip in the serial test circuit.
NTRST (optional in IEEE Standard 1149.1) is a Test-ReSeT input which is mandatory in ARM
cores and used to reset the debug logic. On Atmel ARM926EJ-S-based cores, NTRST is a
Power On Reset output. It is asserted on power on. If necessary, the user can also reset the
debug logic with the NTRST pin assertion during 2.5 MCK periods.
TCK is the Test ClocK input which enables the test interface. TCK is pulsed by the equipment
controlling the test and not by the tested device. It can be pulsed at any frequency. Note the
maximum JTAG clock rate on ARM926EJ-S cores is 1/6th the clock of the CPU. This gives 5.45
kHz maximum initial JTAG clock rate for an ARM9E™ running from the 32.768 kHz slow clock.
RTCK is the Return Test Clock. Not an IEEE Standard 1149.1 signal added for a better clock
handling by emulators. From some ICE Interface probes, this return signal can be used to synchronize the TCK clock and take not care about the given ratio between the ICE Interface clock
and system clock equal to 1/6th. This signal is only available in JTAG ICE Mode and not in
boundary scan mode.
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6384E–ATARM–05-Feb-10
12.5.4
Debug Unit
The Debug Unit provides a two-pin (DXRD and TXRD) USART that can be used for several
debug and trace purposes and offers an ideal means for in-situ programming solutions and
debug monitor communication. Moreover, the association with two peripheral data controller
channels permits packet handling of these tasks with processor time reduced to a minimum.
The Debug Unit also manages the interrupt handling of the COMMTX and COMMRX signals
that come from the ICE and that trace the activity of the Debug Communication Channel.The
Debug Unit allows blockage of access to the system through the ICE interface.
A specific register, the Debug Unit Chip ID Register, gives information about the product version
and its internal configuration.
The AT91SAM9G20 Debug Unit Chip ID value is 0x0199 05A1 on 32-bit width.
For further details on the Debug Unit, see the Debug Unit section.
12.5.5
IEEE 1149.1 JTAG Boundary Scan
IEEE 1149.1 JTAG Boundary Scan allows pin-level access independent of the device packaging
technology.
IEEE 1149.1 JTAG Boundary Scan is enabled when JTAGSEL is high. The SAMPLE, EXTEST
and BYPASS functions are implemented. In ICE debug mode, the ARM processor responds
with a non-JTAG chip ID that identifies the processor to the ICE system. This is not IEEE 1149.1
JTAG-compliant.
It is not possible to switch directly between JTAG and ICE operations. A chip reset must be performed after JTAGSEL is changed.
A Boundary-scan Descriptor Language (BSDL) file is provided to set up test.
12.5.5.1
JTAG Boundary-scan Register
The Boundary-scan Register (BSR) contains 308 bits that correspond to active pins and associated control signals.
Each AT91SAM9G20 input/output pin corresponds to a 3-bit register in the BSR. The OUTPUT
bit contains data that can be forced on the pad. The INPUT bit facilitates the observability of data
applied to the pad. The CONTROL bit selects the direction of the pad.
Table 12-2.
Bit Number
AT91SAM9G20 JTAG Boundary Scan Register
Pin Name
Pin Type
A0
IN/OUT
307
CONTROL
306
INPUT/OUTPUT
305
CONTROL
A1
IN/OUT
304
INPUT/OUTPUT
303
CONTROL
A10
IN/OUT
302
INPUT/OUTPUT
301
CONTROL
A11
IN/OUT
300
INPUT/OUTPUT
299
CONTROL
A12
298
62
Associated BSR Cells
IN/OUT
INPUT/OUTPUT
AT91SAM9G20
6384E–ATARM–05-Feb-10
AT91SAM9G20
Table 12-2.
AT91SAM9G20 JTAG Boundary Scan Register
297
CONTROL
A13
IN/OUT
296
INPUT/OUTPUT
295
CONTROL
A14
IN/OUT
294
INPUT/OUTPUT
293
CONTROL
A15
IN/OUT
292
INPUT/OUTPUT
291
CONTROL
A16
IN/OUT
290
INPUT/OUTPUT
289
CONTROL
A17
IN/OUT
288
INPUT/OUTPUT
287
CONTROL
A18
IN/OUT
286
INPUT/OUTPUT
285
CONTROL
A19
IN/OUT
284
INPUT/OUTPUT
283
CONTROL
A2
IN/OUT
282
INPUT/OUTPUT
281
CONTROL
A20
IN/OUT
280
INPUT/OUTPUT
279
CONTROL
A21
IN/OUT
278
INPUT/OUTPUT
277
CONTROL
A22
IN/OUT
276
INPUT/OUTPUT
275
CONTROL
A3
IN/OUT
274
INPUT/OUTPUT
273
CONTROL
A4
IN/OUT
272
INPUT/OUTPUT
271
CONTROL
A5
IN/OUT
270
INPUT/OUTPUT
269
CONTROL
A6
IN/OUT
268
INPUT/OUTPUT
267
CONTROL
A7
IN/OUT
266
INPUT/OUTPUT
265
CONTROL
A8
IN/OUT
264
INPUT/OUTPUT
263
CONTROL
A9
IN/OUT
262
261
INPUT/OUTPUT
BMS
INPUT
INPUT
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6384E–ATARM–05-Feb-10
Table 12-2.
AT91SAM9G20 JTAG Boundary Scan Register
260
CONTROL
CAS
IN/OUT
259
INPUT/OUTPUT
258
CONTROL
D0
IN/OUT
257
INPUT/OUTPUT
256
CONTROL
D1
IN/OUT
255
INPUT/OUTPUT
254
CONTROL
D10
IN/OUT
253
INPUT/OUTPUT
252
CONTROL
D11
IN/OUT
251
INPUT/OUTPUT
250
CONTROL
D12
IN/OUT
249
INPUT/OUTPUT
248
CONTROL
D13
IN/OUT
247
INPUT/OUTPUT
246
CONTROL
D14
IN/OUT
245
INPUT/OUTPUT
244
CONTROL
D15
IN/OUT
243
INPUT/OUTPUT
242
CONTROL
D2
IN/OUT
241
INPUT/OUTPUT
240
CONTROL
D3
IN/OUT
239
INPUT/OUTPUT
238
CONTROL
D4
IN/OUT
237
INPUT/OUTPUT
236
CONTROL
D5
IN/OUT
235
INPUT/OUTPUT
234
CONTROL
D6
IN/OUT
233
INPUT/OUTPUT
232
CONTROL
D7
IN/OUT
231
INPUT/OUTPUT
230
CONTROL
D8
IN/OUT
229
INPUT/OUTPUT
228
CONTROL
D9
IN/OUT
227
INPUT/OUTPUT
226
CONTROL
NANDOE
225
64
IN/OUT
INPUT/OUTPUT
AT91SAM9G20
6384E–ATARM–05-Feb-10
AT91SAM9G20
Table 12-2.
AT91SAM9G20 JTAG Boundary Scan Register
224
CONTROL
NANDWE
IN/OUT
223
INPUT/OUTPUT
222
CONTROL
NCS0
IN/OUT
221
INPUT/OUTPUT
220
CONTROL
NCS1
IN/OUT
219
INPUT/OUTPUT
218
CONTROL
NRD
IN/OUT
217
INPUT/OUTPUT
216
CONTROL
NRST
IN/OUT
215
INPUT/OUTPUT
214
CONTROL
NWR0
IN/OUT
213
INPUT/OUTPUT
212
CONTROL
NWR1
IN/OUT
211
INPUT/OUTPUT
210
CONTROL
NWR3
IN/OUT
209
208
INPUT/OUTPUT
OSCSEL
INPUT
PA0
IN/OUT
207
CONTROL
206
INPUT/OUTPUT
205
CONTROL
PA1
IN/OUT
204
INPUT/OUTPUT
203
CONTROL
PA10
IN/OUT
202
INPUT/OUTPUT
201
CONTROL
PA11
IN/OUT
200
INPUT/OUTPUT
199
CONTROL
PA12
IN/OUT
198
INPUT/OUTPUT
197
CONTROL
PA13
IN/OUT
196
INPUT/OUTPUT
195
CONTROL
PA14
IN/OUT
194
INPUT/OUTPUT
193
CONTROL
PA15
IN/OUT
192
INPUT/OUTPUT
191
CONTROL
PA16
IN/OUT
190
INPUT/OUTPUT
189
CONTROL
PA17
188
INPUT
IN/OUT
INPUT/OUTPUT
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6384E–ATARM–05-Feb-10
Table 12-2.
AT91SAM9G20 JTAG Boundary Scan Register
187
CONTROL
PA18
IN/OUT
186
INPUT/OUTPUT
185
CONTROL
PA19
IN/OUT
184
INPUT/OUTPUT
183
CONTROL
PA2
IN/OUT
182
INPUT/OUTPUT
181
CONTROL
PA20
IN/OUT
180
INPUT/OUTPUT
179
CONTROL
PA21
IN/OUT
178
INPUT/OUTPUT
177
CONTROL
PA22
IN/OUT
176
INPUT/OUTPUT
175
CONTROL
PA23
IN/OUT
174
INPUT/OUTPUT
173
CONTROL
PA24
IN/OUT
172
INPUT/OUTPUT
171
CONTROL
PA25
IN/OUT
170
INPUT/OUTPUT
169
CONTROL
PA26
IN/OUT
168
INPUT/OUTPUT
167
CONTROL
PA27
IN/OUT
166
INPUT/OUTPUT
165
CONTROL
PA28
IN/OUT
164
INPUT/OUTPUT
163
CONTROL
PA29
IN/OUT
162
INPUT/OUTPUT
161
CONTROL
PA3
IN/OUT
160
INPUT/OUTPUT
159
internal
158
internal
157
internal
156
internal
155
CONTROL
PA4
IN/OUT
154
INPUT/OUTPUT
153
CONTROL
PA5
152
66
IN/OUT
INPUT/OUTPUT
AT91SAM9G20
6384E–ATARM–05-Feb-10
AT91SAM9G20
Table 12-2.
AT91SAM9G20 JTAG Boundary Scan Register
151
CONTROL
PA6
IN/OUT
150
INPUT/OUTPUT
149
CONTROL
PA7
IN/OUT
148
INPUT/OUTPUT
147
CONTROL
PA8
IN/OUT
146
INPUT/OUTPUT
145
CONTROL
PA9
IN/OUT
144
INPUT/OUTPUT
143
CONTROL
PB0
IN/OUT
142
INPUT/OUTPUT
141
CONTROL
PB1
IN/OUT
140
INPUT/OUTPUT
139
CONTROL
PB10
IN/OUT
138
INPUT/OUTPUT
137
CONTROL
PB11
IN/OUT
136
INPUT/OUTPUT
135
internal
134
internal
133
internal
132
internal
131
CONTROL
PB14
IN/OUT
130
INPUT/OUTPUT
129
CONTROL
PB15
IN/OUT
128
INPUT/OUTPUT
127
CONTROL
PB16
IN/OUT
126
INPUT/OUTPUT
125
CONTROL
PB17
IN/OUT
124
INPUT/OUTPUT
123
CONTROL
PB18
IN/OUT
122
INPUT/OUTPUT
121
CONTROL
PB19
IN/OUT
120
INPUT/OUTPUT
119
CONTROL
PB2
IN/OUT
118
INPUT/OUTPUT
117
CONTROL
PB20
116
IN/OUT
INPUT/OUTPUT
67
6384E–ATARM–05-Feb-10
Table 12-2.
AT91SAM9G20 JTAG Boundary Scan Register
115
CONTROL
PB21
IN/OUT
114
INPUT/OUTPUT
113
CONTROL
PB22
IN/OUT
112
INPUT/OUTPUT
111
CONTROL
PB23
IN/OUT
110
INPUT/OUTPUT
109
CONTROL
PB24
IN/OUT
108
INPUT/OUTPUT
107
CONTROL
PB25
IN/OUT
106
INPUT/OUTPUT
105
CONTROL
PB26
IN/OUT
104
INPUT/OUTPUT
103
CONTROL
PB27
IN/OUT
102
INPUT/OUTPUT
101
CONTROL
PB28
IN/OUT
100
INPUT/OUTPUT
99
CONTROL
PB29
IN/OUT
98
INPUT/OUTPUT
97
CONTROL
PB3
IN/OUT
96
INPUT/OUTPUT
95
CONTROL
PB30
IN/OUT
94
INPUT/OUTPUT
93
CONTROL
PB31
IN/OUT
92
INPUT/OUTPUT
91
CONTROL
PB4
IN/OUT
90
INPUT/OUTPUT
89
CONTROL
PB5
IN/OUT
88
INPUT/OUTPUT
87
CONTROL
PB6
IN/OUT
86
INPUT/OUTPUT
85
CONTROL
PB7
IN/OUT
84
INPUT/OUTPUT
83
CONTROL
PB8
IN/OUT
82
INPUT/OUTPUT
81
CONTROL
PB9
80
68
IN/OUT
INPUT/OUTPUT
AT91SAM9G20
6384E–ATARM–05-Feb-10
AT91SAM9G20
Table 12-2.
AT91SAM9G20 JTAG Boundary Scan Register
79
CONTROL
PC0
IN/OUT
78
INPUT/OUTPUT
77
CONTROL
PC1
IN/OUT
76
INPUT/OUTPUT
75
CONTROL
PC10
IN/OUT
74
INPUT/OUTPUT
73
CONTROL
PC11
IN/OUT
72
INPUT/OUTPUT
71
internal
70
internal
69
CONTROL
PC13
IN/OUT
68
INPUT/OUTPUT
67
CONTROL
PC14
IN/OUT
66
INPUT/OUTPUT
65
CONTROL
PC15
IN/OUT
64
INPUT/OUTPUT
63
CONTROL
PC16
IN/OUT
62
INPUT/OUTPUT
61
CONTROL
PC17
IN/OUT
60
INPUT/OUTPUT
59
CONTROL
PC18
IN/OUT
58
INPUT/OUTPUT
57
CONTROL
PC19
IN/OUT
56
INPUT/OUTPUT
55
internal
54
internal
53
CONTROL
PC20
IN/OUT
52
INPUT/OUTPUT
51
CONTROL
PC21
IN/OUT
50
INPUT/OUTPUT
49
CONTROL
PC22
IN/OUT
48
INPUT/OUTPUT
47
CONTROL
PC23
IN/OUT
46
INPUT/OUTPUT
45
CONTROL
PC24
44
IN/OUT
INPUT/OUTPUT
69
6384E–ATARM–05-Feb-10
Table 12-2.
AT91SAM9G20 JTAG Boundary Scan Register
43
CONTROL
PC25
IN/OUT
42
INPUT/OUTPUT
41
CONTROL
PC26
IN/OUT
40
INPUT/OUTPUT
39
CONTROL
PC27
IN/OUT
38
INPUT/OUTPUT
37
CONTROL
PC28
IN/OUT
36
INPUT/OUTPUT
35
CONTROL
PC29
IN/OUT
34
INPUT/OUTPUT
33
internal
32
internal
31
CONTROL
PC30
IN/OUT
30
INPUT/OUTPUT
29
CONTROL
PC31
IN/OUT
28
INPUT/OUTPUT
27
CONTROL
PC4
IN/OUT
26
INPUT/OUTPUT
25
CONTROL
PC5
IN/OUT
24
INPUT/OUTPUT
23
CONTROL
PC6
IN/OUT
22
INPUT/OUTPUT
21
CONTROL
PC7
IN/OUT
20
INPUT/OUTPUT
19
CONTROL
PC8
IN/OUT
18
INPUT/OUTPUT
17
CONTROL
PC9
IN/OUT
16
INPUT/OUTPUT
15
CONTROL
RAS
IN/OUT
14
INPUT/OUTPUT
13
CONTROL
RTCK
OUT
12
OUTPUT
11
CONTROL
SDA10
IN/OUT
10
INPUT/OUTPUT
09
CONTROL
SDCK
08
70
IN/OUT
INPUT/OUTPUT
AT91SAM9G20
6384E–ATARM–05-Feb-10
AT91SAM9G20
Table 12-2.
AT91SAM9G20 JTAG Boundary Scan Register
07
CONTROL
SDCKE
IN/OUT
06
INPUT/OUTPUT
05
CONTROL
SDWE
IN/OUT
04
INPUT/OUTPUT
03
CONTROL
SHDN
OUT
02
OUTPUT
01
TST
INPUT
INPUT
00
WKUP
INPUT
INPUT
71
6384E–ATARM–05-Feb-10
12.5.6
JID Code Register
Access: Read-only
31
30
29
28
27
VERSION
23
22
26
25
24
PART NUMBER
21
20
19
18
17
16
10
9
8
PART NUMBER
15
14
13
12
11
PART NUMBER
7
6
MANUFACTURER IDENTITY
5
4
MANUFACTURER IDENTITY
3
2
1
0
1
• VERSION[31:28]: Product Version Number
Set to 0x0.
• PART NUMBER[27:12]: Product Part Number
Product part Number is 0x5B24
• MANUFACTURER IDENTITY[11:1]
Set to 0x01F.
Bit[0] required by IEEE Std. 1149.1.
Set to 0x1.
JTAG ID Code value is 0x05B2_403F.
72
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AT91SAM9G20
13. AT91SAM9G20 Boot Program
13.1
Overview
The Boot Program integrates different programs that manage download and/or upload into the
different memories of the product.
First, it initializes the Debug Unit serial port (DBGU) and the USB High Speed Device Port.
The Boot program tries to detect SPI flash memories. The Serial Flash Boot program and DataFlash® Boot program are executed. It looks for a sequence of seven valid ARM exception
vectors in a Serial Flash or DataFlash connected to the SPI. All these vectors must be B-branch
or LDR load register instructions except for the sixth vector. This vector is used to store the size
of the image to download.
If a valid sequence is found, code is downloaded into the internal SRAM. This is followed by a
remap and a jump to the first address of the SRAM.
If no valid ARM vector sequence is found, NAND Flash Boot program is then executed. The
NAND Flash Boot program looks for a sequence of seven valid ARM exception vectors. If such a
sequence is found, code is downloaded into the internal SRAM. This is followed by a remap and
a jump to the first address of the SRAM.
If no valid ARM exception vector is found, the SDCard Boot program is then executed. It looks
for a boot.bin file in the root directory of a FAT12/16/32 formatted SDCard on SlotA. If such a file
is found, code is downloaded into the internal SRAM. This is followed by a remap and a jump to
the first address of the SRAM.
If the SDCard is not formatted or if boot.bin file is not found, TWI Boot program is then executed.
The TWI Boot program searches for a valid application in an EEPROM memory. If such a file is
found, code is downloaded into the internal SRAM. This is followed by a remap and a jump to
the first address of the SRAM.
If no valid application is found, SAM-BA Boot is then executed. It waits for transactions either on
the USB device, or on the DBGU serial port.
13.2
Flow Diagram
The Boot Program implements the algorithm in Figure 13-1.
73
6384E–ATARM–05-Feb-10
Figure 13-1. Boot Program Algorithm Flow Diagram
Device
Setup
SPI Serialflash Boot
NPCS0
No
Run
Yes
Download from
Serial flash NPCS1
Run
Yes
Download from
Dataflash NPCS1
Run
Yes
Download from
NandFlash
Run
NandFlash Boot
Yes
Download from
SDCARD
Run
SD Card Boot
Yes
Download from
EEPROM
Run
TWI/EEPROM Boot
DataFlash Boot NPCS0
DataFlash Boot NPCS1
Timeout < 50ms
EEPROMBoot
No
Timeout 50ms.
Character(s) received
on DBGU
Run SAM-BA Boot
OR
SAM-BA Boot
USB Enumeration
Successful
74
Serial Flash Boot NPCS1
Timeout < 50ms
SD Card Boot
No
Download from
Dataflash NPCS0
Timeout < 25 ms
NandFlash Boot
No
Yes
Serial Flash Boot NPCS0
Timeout < 25 ms
SPI Dataflash Boot
NPCS1
No
Run
Timeout < 25 ms
SPI Serialflash Boot
NPCS1
No
Download from
Serial flash NPCS0
Timeout < 25 ms
SPI Dataflash Boot
NPCS0
No
Yes
Run SAM-BA Boot
AT91SAM9G20
6384E–ATARM–05-Feb-10
AT91SAM9G20
13.3
Device Initialization
Initialization follows the steps described below:
1. Stack setup for ARM supervisor mode
2. Main Oscillator Frequency Detection
3. C variable initialization
4. PLL setup: PLLB is initialized to generate a 48 MHz clock necessary to use the USB
Device. A register located in the Power Management Controller (PMC) determines the
frequency of the main oscillator and thus the correct factor for the PLLB.
– If internal RC Oscillator is used (OSCSEL = 0) and Main Oscillator is active, TTable
13-1 defines the crystals supported by the Boot Program when using the internal RC
oscillator. also supported by the Boot Program.
Table 13-1.
Crystals Supported by Software Auto-Detection (MHz)
3.0
8.0
18.432
Other
Boot in DBGU
Yes
Yes
Yes
Yes
Boot on USB
Yes
Yes
Yes
No
Note:
Any other crystal can be used but it prevents using the USB.
– If internal RC Oscillator is used (OSCSEL = 0) and Main Oscillator is bypassed,
Table 13-2 defines the frequencies supported by the Boot Program when bypassing
the main oscillator.
Table 13-2.
Crystals Supported by Software Auto-Detection (MHz)
3.0
8.0
20
50
Other
Boot in DBGU
Yes
Yes
Yes
Yes
Yes
Boot on USB
Yes
Yes
Yes
Yes
No
Note:
Any other crystal can be used but it prevents using the USB.
– If an external 32768 Hz Oscillator is used (OSCSEL = 1), defines the crystals
supported by the Boot Program. Table 13-3 defines the crystals supported by the
Boot Program.
Table 13-3.
Crystals Supported by Software Auto-Detection (MHz)
3.0
3.2768
3.6864
3.84
4.0
4.433619
4.608
4.9152
5.0
5.24288
6.0
6.144
6.4
6.5536
7.159090
7.3728
7.864320
8.0
9.8304
10.0
11.05920
12.0
12.288
13.56
14.31818
14.7456
16.0
17.734470
18.432
20.0
Note:
Booting either on USB or on DBGU is possible with any of these input frequencies.
75
6384E–ATARM–05-Feb-10
AT91SAM9G20
– If an external 32768 Hz Oscillator is used (OSCSEL = 1) and Main Oscillator is
bypassed. Table 13-4 defines the crystals supported by the Boot Program.
Table 13-4.
Input Frequencies Supported (OSCEL = 1)
3.0
3.2768
3.6864
3.84
4.0
4.433619
4.608
4.9152
5.0
5.24288
6.0
6.144
6.4
6.5536
7.159090
7.3728
7.864320
8.0
9.8304
10.0
11.05920
12.0
12.288
13.56
14.31818
14.7456
16.0
17.734470
18.432
20.0
24.0
24.576
25.0
28.224
32.0
33.0
40.0
48.0
50
Note:
Booting either on USB or on DBGU is possible with any of these input frequencies.
5. Initialization of the DBGU serial port (115200 bauds, 8, N, 1)
6. Jump to Serial Flash Boot sequence through NPCS0. If Serial Flash Boot succeeds,
perform a remap and jump to 0x0.
7. Jump to DataFlash Boot sequence through NPCS0. If DataFlash Boot succeeds, perform a remap and jump to 0x0.
8. Jump to Serial Flash Boot sequence through NPCS1. If Serial Flash Boot succeeds,
perform a remap and jump to 0x0.
9. Jump to DataFlash Boot sequence through NPCS1. If DataFlash Boot succeeds, perform a remap and jump to 0x0.
10. Jump to NAND Flash Boot sequence. If NAND Flash Boot succeeds, perform a remap
and jump to 0x0.
11. Jump to SDCard Boot sequence. If SDCard Boot succeeds, perform a remap and jump
to 0x0.
12. Jump to EEPROM Boot sequence. If EEPROM Boot succeeds, perform a remap and
jump to 0x0.
13. Activation of the Instruction Cache
14. Jump to SAM-BA Boot sequence
15. Disable the WatchDog
16. Initialization of the USB Device Port
76
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AT91SAM9G20
Figure 13-2. Remap Action after Download Completion
0x0000_0000
0x0000_0000
Internal
ROM
Internal
SRAM
REMAP
0x0020_0000
0x0010_0000
Internal
SRAM
13.4
Internal
ROM
Valid Image Detection
The DataFlash Boot software looks for a valid application by analyzing the first 28 bytes corresponding to the ARM exception vectors. These bytes must implement ARM instructions for
either branch or load PC with PC relative addressing.
The sixth vector, at offset 0x14, contains the size of the image to download. The user must
replace this vector with his/her own vector (see “Structure of ARM Vector 6” on page 77).
13.4.1
Valid ARM exception vectors
Figure 13-3. LDR Opcode
31
1
28 27
1
1
0
0
24 23
1
I
P
U
20 19
0
W
1
16 15
Rn
12 11
0
Rd
Figure 13-4. B Opcode
31
1
28 27
1
1
0
1
24 23
0
1
0
0
Offset (24 bits)
Unconditional instruction: 0xE for bits 31 to 28
Load PC with PC relative addressing instruction:
– Rn = Rd = PC = 0xF
– I==0
– P==1
– U offset added (U==1) or subtracted (U==0)
– W==1
13.4.2
Structure of ARM Vector 6
The ARM exception vector 6 is used to store information needed by the DataFlash boot program. This information is described below.
77
6384E–ATARM–05-Feb-10
AT91SAM9G20
Figure 13-5. Structure of the ARM Vector 6
31
0
Size of the code to download in bytes
13.4.2.1
Example
An example of valid vectors follows:
00
ea000006
B
0x20
04
eafffffe
B
0x04
08
ea00002f
B
_main
0c
eafffffe
B
0x0c
10
eafffffe
B
0x10
14
00001234
B
0x14
18
eafffffe
B
0x18
<- Code size = 4660 bytes
The size of the image to load into SRAM is contained in the location of the sixth ARM vector.
Thus the user must replace this vector by the correct size of his/her application.
13.5
Serial Flash Boot
The Serial Flash boot looks for a valid application in the SPI Serial Flash memory.
SPI0 is configured in master mode to generate a SPCK at 8 MHz. Serial Flash shall be connected to NPCS0 or NPCS1.
The Serial Flash boot reads the Serial Flash status register (Instruction code 0x05). The Serial
Flash is considered as ready if bit 0 of the returned status register is cleared.
If no Serial Flash is connected or if it does not answer, Serial Flash boot exits after 1000
attempts.
If the Serial Flash is ready, Serial Flash boot reads the first 8 words into SRAM (Instruction code
“Continuos read array” 0x0b) and checks if it corresponds to valid exception vectors according to
the Valid Image detection algorithm.
If a valid application is found, this application is loaded into internal SRAM and executed by
branching at address 0x0000_0000 after remap. This application may be the application code or
a second-level bootloader.
78
6384E–ATARM–05-Feb-10
AT91SAM9G20
Figure 13-6. Serial Flash Download
Start
Send status command (0x05)
Is status OK ?
No
Jump to next boot
solution
Yes
Read the first 8 instructions (0x0b).
Decode the sixth ARM vector
8 vectors
(except vector 6) are LDR
or Branch instruction
No
Yes
Read the SerialFlash into the internal SRAM.
(code size to read in vector 6)
Restore the reset value for the peripherals.
Set the PC to 0 and perform the REMAP
to jump to the downloaded application
End
13.6
DataFlash Boot Sequence
The DataFlash boot looks for a valid application in the SPI DataFlash memory.
SPI0 is configured in master mode to generate a SPCK at 8 MHz. DataFlash shall be connected
to NPCS0 or NPCS1.
The DataFlash boot reads the DataFlash flash status register (Instruction code 0xD7). The DataFlash is considered as ready if bit 7 of the returned status register is set.
If no DataFlash is connected or if it does not answer, DataFlash boot exits after 1000 attempts.
If the DataFlash is ready, DataFlash boot reads the first 8 words into SRAM (Instruction code
“Continuous Read Array” 0x0b) and checks if it corresponds to valid exception vectors according
to the Valid Image detection algorithm.
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AT91SAM9G20
If a valid application is found, this application is loaded into internal SRAM and executed by
branching at address 0x0000_0000 after remap. This application may be the application code or
a second-level bootloader.
The DataFlash boot is configured to be compatible with the future design of the DataFlash.
Figure 13-7. Serial DataFlash Download
Start
Send status command
Is status OK ?
No
Jump to next boot
solution
Yes
Read the first 8 instructions (32 bytes).
Decode the sixth ARM vector
8 vectors
(except vector 6) are LDR
or Branch instruction
No
Yes
Read the DataFlash into the internal SRAM.
(code size to read in vector 6)
Restore the reset value for the peripherals.
Set the PC to 0 and perform the REMAP
to jump to the downloaded application
End
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6384E–ATARM–05-Feb-10
AT91SAM9G20
13.7
NAND Flash Boot
The NAND Flash Boot program searches for a valid application in the NAND Flash memory.
If a valid application is found, this application is loaded into internal SRAM and executed by
branching at address 0x0000_0000 after remap. See “Valid Image Detection” on page 77 for
more information on Valid Image Detection.
13.7.1
13.8
Supported NAND Flash Devices
Any 8- or 16-bit NAND Flash Device.
SDCard Boot
The SDCard Boot program searches for a valid application in the SD Card memory.
(Boot ROM does not support high capacity SDCards.)
It looks for a boot.bin file in the root directory of a FAT12/16/32 formatted SD Card. If a valid file
is found, this application is loaded into internal SRAM and executed by branching at address
0x0000_0000 after remap. This application may be the application code or a second-level
bootloader.
13.9
EEPROM Boot
The EEPROM Boot program searches for a valid application in an EEPROM connected to the
TWI address: 0x0050_0000.
If a valid application is found, this application is loaded into internal SRAM and executed by
branching at address 0x0000_0000 after remap. See “Valid Image Detection” on page 77 for
more information on Valid Image Detection.
81
6384E–ATARM–05-Feb-10
13.10 SAM-BA Boot
If no valid DataFlash device has been found during the DataFlash boot sequence, the SAM-BA
boot program is performed.
The SAM-BA boot principle is to:
– Wait for USB Device enumeration.
– In parallel, wait for character(s) received on the DBGU.
– Once the communication interface is identified, the application runs in an infinite
loop waiting for different commands as in Table 13-5.
Table 13-5.
Commands Available through the SAM-BA Boot
Command
Action
Argument(s)
Example
O
write a byte
Address, Value#
O200001,CA#
o
read a byte
Address,#
o200001,#
H
write a half word
Address, Value#
H200002,CAFE#
h
read a half word
Address,#
h200002,#
W
write a word
Address, Value#
W200000,CAFEDECA#
w
read a word
Address,#
w200000,#
S
send a file
Address,#
S200000,#
R
receive a file
Address, NbOfBytes#
R200000,1234#
G
go
Address#
G200200#
V
display version
No argument
V#
• Write commands: Write a byte (O), a halfword (H) or a word (W) to the target.
– Address: Address in hexadecimal.
– Value: Byte, halfword or word to write in hexadecimal.
– Output: ‘>’.
• Read commands: Read a byte (o), a halfword (h) or a word (w) from the target.
– Address: Address in hexadecimal
– Output: The byte, halfword or word read in hexadecimal following by ‘>’
• Send a file (S): Send a file to a specified address
– Address: Address in hexadecimal
– Output: ‘>’.
Note:
There is a time-out on this command which is reached when the prompt ‘>’ appears before the
end of the command execution.
• Receive a file (R): Receive data into a file from a specified address
– Address: Address in hexadecimal
– NbOfBytes: Number of bytes in hexadecimal to receive
– Output: ‘>’
• Go (G): Jump to a specified address and execute the code
– Address: Address to jump in hexadecimal
– Output: ‘>’
• Get Version (V): Return the SAM-BA boot version
– Output: ‘>’
82
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AT91SAM9G20
13.10.1
DBGU Serial Port
Communication is performed through the DBGU serial port initialized to 115200 Baud, 8, n, 1.
The Send and Receive File commands use the Xmodem protocol to communicate. Any terminal
performing this protocol can be used to send the application file to the target. The size of the
binary file to send depends on the SRAM size embedded in the product. In all cases, the size of
the binary file must be lower than the SRAM size because the Xmodem protocol requires some
SRAM memory to work.
13.10.2
Xmodem Protocol
The Xmodem protocol supported is the 128-byte length block. This protocol uses a two-character CRC-16 to guarantee detection of a maximum bit error.
Xmodem protocol with CRC is accurate provided both sender and receiver report successful
transmission. Each block of the transfer looks like:
<SOH><blk #><255-blk #><--128 data bytes--><checksum> in which:
– <SOH> = 01 hex
– <blk #> = binary number, starts at 01, increments by 1, and wraps 0FFH to 00H (not
to 01)
– <255-blk #> = 1’s complement of the blk#.
– <checksum> = 2 bytes CRC16
Figure 13-8 shows a transmission using this protocol.
Figure 13-8. Xmodem Transfer Example
Host
Device
C
SOH 01 FE Data[128] CRC CRC
ACK
SOH 02 FD Data[128] CRC CRC
ACK
SOH 03 FC Data[100] CRC CRC
ACK
EOT
ACK
83
6384E–ATARM–05-Feb-10
13.10.3
USB Device Port
A 48 MHz USB clock is necessary to use the USB Device port. It has been programmed earlier
in the device initialization procedure with PLLB configuration.
The device uses the USB communication device class (CDC) drivers to take advantage of the
installed PC RS-232 software to talk over the USB. The CDC class is implemented in all
releases of Windows®, from Windows 98SE to Windows XP®. The CDC document, available at
www.usb.org, describes a way to implement devices such as ISDN modems and virtual COM
ports.
The Vendor ID is Atmel’s vendor ID 0x03EB. The product ID is 0x6124. These references are
used by the host operating system to mount the correct driver. On Windows systems, the INF
files contain the correspondence between vendor ID and product ID.
Atmel provides an INF example to see the device as a new serial port and also provides another
custom driver used by the SAM-BA application: atm6124.sys. Refer to the document “USB Basic
Application”, literature number 6123, for more details.
13.10.3.1
Enumeration Process
The USB protocol is a master/slave protocol. This is the host that starts the enumeration sending requests to the device through the control endpoint. The device handles standard requests
as defined in the USB Specification.
Table 13-6.
Handled Standard Requests
Request
Definition
GET_DESCRIPTOR
Returns the current device configuration value.
SET_ADDRESS
Sets the device address for all future device access.
SET_CONFIGURATION
Sets the device configuration.
GET_CONFIGURATION
Returns the current device configuration value.
GET_STATUS
Returns status for the specified recipient.
SET_FEATURE
Used to set or enable a specific feature.
CLEAR_FEATURE
Used to clear or disable a specific feature.
The device also handles some class requests defined in the CDC class.
Table 13-7.
Handled Class Requests
Request
Definition
SET_LINE_CODING
Configures DTE rate, stop bits, parity and number of
character bits.
GET_LINE_CODING
Requests current DTE rate, stop bits, parity and number of
character bits.
SET_CONTROL_LINE_STATE
RS-232 signal used to tell the DCE device the DTE device
is now present.
Unhandled requests are STALLed.
84
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AT91SAM9G20
13.10.3.2
Communication Endpoints
There are two communication endpoints and endpoint 0 is used for the enumeration process.
Endpoint 1 is a 64-byte Bulk OUT endpoint and endpoint 2 is a 64-byte Bulk IN endpoint. SAMBA Boot commands are sent by the host through the endpoint 1. If required, the message is split
by the host into several data payloads by the host driver.
If the command requires a response, the host can send IN transactions to pick up the response.
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13.11 Hardware and Software Constraints
• The DataFlash, Serial Flash, NAND Flash, SDCard(1), and EEPROM downloaded code size
must be inferior to 16K bytes.
• The code is always downloaded from the device address 0x0000_0000 to the address
0x0000_0000 of the internal SRAM (after remap).
• The downloaded code must be position-independent or linked at address 0x0000_0000.
• The DataFlash must be connected to NPCS0 of the SPI.
Note:
1. Boot ROM does not support high capacity SDCards.
The SPI and NAND Flash drivers use several PIOs in alternate functions to communicate with
devices. Care must be taken when these PIOs are used by the application. The devices connected could be unintentionally driven at boot time, and electrical conflicts between SPI output
pins and the connected devices may appear.
To assure correct functionality, it is recommended to plug in critical devices to other pins.
Table 13-8 contains a list of pins that are driven during the boot program execution. These pins
are driven during the boot sequence for a period of less than 1 second if no correct boot program
is found.
Before performing the jump to the application in internal SRAM, all the PIOs and peripherals
used in the boot program are set to their reset state.
Table 13-8.
86
Pins Driven during Boot Program Execution
Peripheral
Pin
PIO Line
SPI0
MOSI
PIOA1
SPI0
MISO
PIOA0
SPI0
SPCK
PIOA2
SPI0
NPCS0
PIOA3
SPI0
NPCS1
PIOC11
PIOC
NANDCS
PIOC14
Address Bus
NAND CLE
A22
Address Bus
NAND ALE
A21
MCI0
MCDA0
PIOA6
MCI0
MCCDA
PIOA7
MCI0
MCCK
PIOA8
MCI0
MCDA1
PIOA9
MCI0
MCDA2
PIOA10
MCI0
MCDA3
PIOA11
TWI
TWCK
PIOA24
TWI
TWD
PIOA23
DBGU
DRXD
PIOB14
DBGU
DTXD
PIOB15
AT91SAM9G20
6384E–ATARM–05-Feb-10
AT91SAM9G20
14. Reset Controller (RSTC)
14.1
Overview
The Reset Controller (RSTC), based on power-on reset cells, handles all the resets of the system without any external components. It reports which reset occurred last.
The Reset Controller also drives independently or simultaneously the external reset and the
peripheral and processor resets.
14.2
Block Diagram
Figure 14-1. Reset Controller Block Diagram
Reset Controller
Main Supply
POR
Backup Supply
POR
rstc_irq
Startup
Counter
Reset
State
Manager
proc_nreset
user_reset
NRST
nrst_out
NRST
Manager
periph_nreset
exter_nreset
backup_neset
WDRPROC
wd_fault
SLCK
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14.3
Functional Description
14.3.1
Reset Controller Overview
The Reset Controller is made up of an NRST Manager, a Startup Counter and a Reset State
Manager. It runs at Slow Clock and generates the following reset signals:
• proc_nreset: Processor reset line. It also resets the Watchdog Timer.
• backup_nreset: Affects all the peripherals powered by VDDBU.
• periph_nreset: Affects the whole set of embedded peripherals.
• nrst_out: Drives the NRST pin.
These reset signals are asserted by the Reset Controller, either on external events or on software action. The Reset State Manager controls the generation of reset signals and provides a
signal to the NRST Manager when an assertion of the NRST pin is required.
The NRST Manager shapes the NRST assertion during a programmable time, thus controlling
external device resets.
The startup counter waits for the complete crystal oscillator startup. The wait delay is given by
the crystal oscillator startup time maximum value that can be found in the section Crystal Oscillator Characteristics in the Electrical Characteristics section of the product documentation.
The Reset Controller Mode Register (RSTC_MR), allowing the configuration of the Reset Controller, is powered with VDDBU, so that its configuration is saved as long as VDDBU is on.
14.3.2
NRST Manager
The NRST Manager samples the NRST input pin and drives this pin low when required by the
Reset State Manager. Figure 14-2 shows the block diagram of the NRST Manager.
Figure 14-2. NRST Manager
RSTC_MR
URSTIEN
RSTC_SR
URSTS
NRSTL
rstc_irq
RSTC_MR
URSTEN
Other
interrupt
sources
user_reset
NRST
RSTC_MR
ERSTL
nrst_out
14.3.2.1
External Reset Timer
exter_nreset
NRST Signal or Interrupt
The NRST Manager samples the NRST pin at Slow Clock speed. When the line is detected low,
a User Reset is reported to the Reset State Manager.
However, the NRST Manager can be programmed to not trigger a reset when an assertion of
NRST occurs. Writing the bit URSTEN at 0 in RSTC_MR disables the User Reset trigger.
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The level of the pin NRST can be read at any time in the bit NRSTL (NRST level) in RSTC_SR.
As soon as the pin NRST is asserted, the bit URSTS in RSTC_SR is set. This bit clears only
when RSTC_SR is read.
The Reset Controller can also be programmed to generate an interrupt instead of generating a
reset. To do so, the bit URSTIEN in RSTC_MR must be written at 1.
14.3.2.2
NRST External Reset Control
The Reset State Manager asserts the signal ext_nreset to assert the NRST pin. When this
occurs, the “nrst_out” signal is driven low by the NRST Manager for a time programmed by the
field ERSTL in RSTC_MR. This assertion duration, named EXTERNAL_RESET_LENGTH, lasts
2(ERSTL+1) Slow Clock cycles. This gives the approximate duration of an assertion between 60 µs
and 2 seconds. Note that ERSTL at 0 defines a two-cycle duration for the NRST pulse.
This feature allows the Reset Controller to shape the NRST pin level, and thus to guarantee that
the NRST line is driven low for a time compliant with potential external devices connected on the
system reset.
As the field is within RSTC_MR, which is backed-up, this field can be used to shape the system
power-up reset for devices requiring a longer startup time than the Slow Clock Oscillator.
14.3.3
BMS Sampling
The product matrix manages a boot memory that depends on the level on the BMS pin at reset.
The BMS signal is sampled three slow clock cycles after the Core Power-On-Reset output rising
edge.
Figure 14-3. BMS Sampling
SLCK
Core Supply
POR output
BMS Signal
XXX
H or L
BMS sampling delay
= 3 cycles
proc_nreset
14.3.4
Reset States
The Reset State Manager handles the different reset sources and generates the internal reset
signals. It reports the reset status in the field RSTTYP of the Status Register (RSTC_SR). The
update of the field RSTTYP is performed when the processor reset is released.
14.3.4.1
General Reset
A general reset occurs when VDDBU and VDDCORE are powered on. The backup supply POR
cell output rises and is filtered with a Startup Counter, which operates at Slow Clock. The purpose of this counter is to make sure the Slow Clock oscillator is stable before starting up the
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device. The length of startup time is hardcoded to comply with the Slow Clock Oscillator startup
time.
After this time, the processor clock is released at Slow Clock and all the other signals remain
valid for 3 cycles for proper processor and logic reset. Then, all the reset signals are released
and the field RSTTYP in RSTC_SR reports a General Reset. As the RSTC_MR is reset, the
NRST line rises 2 cycles after the backup_nreset, as ERSTL defaults at value 0x0.
When VDDBU is detected low by the Backup Supply POR Cell, all resets signals are immediately asserted, even if the Main Supply POR Cell does not report a Main Supply shutdown.
VDDBU only activates the backup_nreset signal.
The backup_nreset must be released so that any other reset can be generated by VDDCORE
(Main Supply POR output).
Figure 14-4 shows how the General Reset affects the reset signals.
Figure 14-4. General Reset State
SLCK
Any
Freq.
MCK
Backup Supply
POR output
Startup Time
Main Supply
POR output
backup_nreset
Processor Startup
= 3 cycles
proc_nreset
RSTTYP
XXX
0x0 = General Reset
XXX
periph_nreset
NRST
(nrst_out)
BMS Sampling
EXTERNAL RESET LENGTH
= 2 cycles
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14.3.4.2
Wake-up Reset
The Wake-up Reset occurs when the Main Supply is down. When the Main Supply POR output
is active, all the reset signals are asserted except backup_nreset. When the Main Supply powers up, the POR output is resynchronized on Slow Clock. The processor clock is then re-enabled
during 3 Slow Clock cycles, depending on the requirements of the ARM processor.
At the end of this delay, the processor and other reset signals rise. The field RSTTYP in
RSTC_SR is updated to report a Wake-up Reset.
The “nrst_out” remains asserted for EXTERNAL_RESET_LENGTH cycles. As RSTC_MR is
backed-up, the programmed number of cycles is applicable.
When the Main Supply is detected falling, the reset signals are immediately asserted. This transition is synchronous with the output of the Main Supply POR.
Figure 14-5. Wake-up State
SLCK
Any
Freq.
MCK
Main Supply
POR output
backup_nreset
Resynch.
2 cycles
proc_nreset
RSTTYP
Processor Startup
= 3 cycles
XXX
0x1 = WakeUp Reset
XXX
periph_nreset
NRST
(nrst_out)
EXTERNAL RESET LENGTH
= 4 cycles (ERSTL = 1)
14.3.4.3
User Reset
The User Reset is entered when a low level is detected on the NRST pin and the bit URSTEN in
RSTC_MR is at 1. The NRST input signal is resynchronized with SLCK to insure proper behavior of the system.
The User Reset is entered as soon as a low level is detected on NRST. The Processor Reset
and the Peripheral Reset are asserted.
The User Reset is left when NRST rises, after a two-cycle resynchronization time and a 3-cycle
processor startup. The processor clock is re-enabled as soon as NRST is confirmed high.
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When the processor reset signal is released, the RSTTYP field of the Status Register
(RSTC_SR) is loaded with the value 0x4, indicating a User Reset.
The NRST Manager guarantees that the NRST line is asserted for
EXTERNAL_RESET_LENGTH Slow Clock cycles, as programmed in the field ERSTL. However, if NRST does not rise after EXTERNAL_RESET_LENGTH because it is driven low
externally, the internal reset lines remain asserted until NRST actually rises.
Figure 14-6. User Reset State
SLCK
MCK
Any
Freq.
NRST
Resynch.
2 cycles
Resynch.
2 cycles
Processor Startup
= 3 cycles
proc_nreset
RSTTYP
Any
XXX
0x4 = User Reset
periph_nreset
NRST
(nrst_out)
>= EXTERNAL RESET LENGTH
14.3.4.4
Software Reset
The Reset Controller offers several commands used to assert the different reset signals. These
commands are performed by writing the Control Register (RSTC_CR) with the following bits at
1:
• PROCRST: Writing PROCRST at 1 resets the processor and the watchdog timer.
• PERRST: Writing PERRST at 1 resets all the embedded peripherals, including the memory
system, and, in particular, the Remap Command. The Peripheral Reset is generally used for
debug purposes.
• EXTRST: Writing EXTRST at 1 asserts low the NRST pin during a time defined by the field
ERSTL in the Mode Register (RSTC_MR).
The software reset is entered if at least one of these bits is set by the software. All these commands can be performed independently or simultaneously. The software reset lasts 3 Slow
Clock cycles.
The internal reset signals are asserted as soon as the register write is performed. This is
detected on the Master Clock (MCK). They are released when the software reset is left, i.e.; synchronously to SLCK.
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If EXTRST is set, the nrst_out signal is asserted depending on the programming of the field
ERSTL. However, the resulting falling edge on NRST does not lead to a User Reset.
If and only if the PROCRST bit is set, the Reset Controller reports the software status in the field
RSTTYP of the Status Register (RSTC_SR). Other Software Resets are not reported in
RSTTYP.
As soon as a software operation is detected, the bit SRCMP (Software Reset Command in
Progress) is set in the Status Register (RSTC_SR). It is cleared as soon as the software reset is
left. No other software reset can be performed while the SRCMP bit is set, and writing any value
in RSTC_CR has no effect.
Figure 14-7. Software Reset
SLCK
MCK
Any
Freq.
Write RSTC_CR
Resynch.
1 cycle
Processor Startup
= 3 cycles
proc_nreset
if PROCRST=1
RSTTYP
Any
XXX
0x3 = Software Reset
periph_nreset
if PERRST=1
NRST
(nrst_out)
if EXTRST=1
EXTERNAL RESET LENGTH
8 cycles (ERSTL=2)
SRCMP in RSTC_SR
14.3.4.5
Watchdog Reset
The Watchdog Reset is entered when a watchdog fault occurs. This state lasts 3 Slow Clock
cycles.
When in Watchdog Reset, assertion of the reset signals depends on the WDRPROC bit in
WDT_MR:
• If WDRPROC is 0, the Processor Reset and the Peripheral Reset are asserted. The NRST
line is also asserted, depending on the programming of the field ERSTL. However, the
resulting low level on NRST does not result in a User Reset state.
• If WDRPROC = 1, only the processor reset is asserted.
The Watchdog Timer is reset by the proc_nreset signal. As the watchdog fault always causes a
processor reset if WDRSTEN is set, the Watchdog Timer is always reset after a Watchdog
Reset, and the Watchdog is enabled by default and with a period set to a maximum.
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When the WDRSTEN in WDT_MR bit is reset, the watchdog fault has no impact on the reset
controller.
Figure 14-8. Watchdog Reset
SLCK
MCK
Any
Freq.
wd_fault
Processor Startup
= 3 cycles
proc_nreset
RSTTYP
Any
XXX
0x2 = Watchdog Reset
periph_nreset
Only if
WDRPROC = 0
NRST
(nrst_out)
EXTERNAL RESET LENGTH
8 cycles (ERSTL=2)
14.3.5
Reset State Priorities
The Reset State Manager manages the following priorities between the different reset sources,
given in descending order:
• Backup Reset
• Wake-up Reset
• Watchdog Reset
• Software Reset
• User Reset
Particular cases are listed below:
• When in User Reset:
– A watchdog event is impossible because the Watchdog Timer is being reset by the
proc_nreset signal.
– A software reset is impossible, since the processor reset is being activated.
• When in Software Reset:
– A watchdog event has priority over the current state.
– The NRST has no effect.
• When in Watchdog Reset:
– The processor reset is active and so a Software Reset cannot be programmed.
– A User Reset cannot be entered.
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14.3.6
Reset Controller Status Register
The Reset Controller status register (RSTC_SR) provides several status fields:
• RSTTYP field: This field gives the type of the last reset, as explained in previous sections.
• SRCMP bit: This field indicates that a Software Reset Command is in progress and that no
further software reset should be performed until the end of the current one. This bit is
automatically cleared at the end of the current software reset.
• NRSTL bit: The NRSTL bit of the Status Register gives the level of the NRST pin sampled on
each MCK rising edge.
• URSTS bit: A high-to-low transition of the NRST pin sets the URSTS bit of the RSTC_SR
register. This transition is also detected on the Master Clock (MCK) rising edge (see Figure
14-9). If the User Reset is disabled (URSTEN = 0) and if the interruption is enabled by the
URSTIEN bit in the RSTC_MR register, the URSTS bit triggers an interrupt. Reading the
RSTC_SR status register resets the URSTS bit and clears the interrupt.
Figure 14-9.
Reset Controller Status and Interrupt
MCK
read
RSTC_SR
Peripheral Access
2 cycle
resynchronization
2 cycle
resynchronization
NRST
NRSTL
URSTS
rstc_irq
if (URSTEN = 0) and
(URSTIEN = 1)
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14.4
Reset Controller (RSTC) User Interface
Table 14-1.
Register Mapping
Offset
Register
Name
0x00
Control Register
0x04
0x08
Note:
96
Back-up Reset
Value
Access
Reset Value
RSTC_CR
Write-only
-
Status Register
RSTC_SR
Read-only
0x0000_0001
0x0000_0000
Mode Register
RSTC_MR
Read-write
-
0x0000_0000
1. The reset value of RSTC_SR either reports a General Reset or a Wake-up Reset depending on last rising power supply.
AT91SAM9G20
6384E–ATARM–05-Feb-10
AT91SAM9G20
14.4.1
Name:
Reset Controller Control Register
RSTC_CR
Access Type:Write-only
31
30
29
28
27
26
25
24
KEY
23
–
22
–
21
–
20
–
19
–
18
–
17
–
16
–
15
–
14
–
13
–
12
–
11
–
10
–
9
8
–
7
–
6
–
5
–
4
–
3
EXTRST
2
PERRST
1
–
0
PROCRST
• PROCRST: Processor Reset
0 = No effect.
1 = If KEY is correct, resets the processor.
• PERRST: Peripheral Reset
0 = No effect.
1 = If KEY is correct, resets the peripherals.
• EXTRST: External Reset
0 = No effect.
1 = If KEY is correct, asserts the NRST pin.
• KEY: Password
Should be written at value 0xA5. Writing any other value in this field aborts the write operation.
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14.4.2
Name:
Reset Controller Status Register
RSTC_SR
Access Type:Read-only
31
–
30
–
29
–
28
–
27
–
26
–
25
–
24
–
23
–
22
–
21
–
20
–
19
–
18
–
17
SRCMP
16
NRSTL
15
–
14
–
13
–
12
–
11
–
10
9
RSTTYP
8
7
–
6
–
5
–
4
–
3
–
2
–
1
–
0
URSTS
• URSTS: User Reset Status
0 = No high-to-low edge on NRST happened since the last read of RSTC_SR.
1 = At least one high-to-low transition of NRST has been detected since the last read of RSTC_SR.
• RSTTYP: Reset Type
Reports the cause of the last processor reset. Reading this RSTC_SR does not reset this field.
RSTTYP
Reset Type
Comments
0
0
0
General Reset
Both VDDCORE and VDDBU rising
0
0
1
Wake Up Reset
VDDCORE rising
0
1
0
Watchdog Reset
Watchdog fault occurred
0
1
1
Software Reset
Processor reset required by the software
1
0
0
User Reset
NRST pin detected low
• NRSTL: NRST Pin Level
Registers the NRST Pin Level at Master Clock (MCK).
• SRCMP: Software Reset Command in Progress
0 = No software command is being performed by the reset controller. The reset controller is ready for a software command.
1 = A software reset command is being performed by the reset controller. The reset controller is busy.
98
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14.4.3
Name:
Reset Controller Mode Register
RSTC_MR
Access Type:Read-write
31
30
29
28
27
26
25
24
KEY
23
–
22
–
21
–
20
–
19
–
18
–
17
–
16
15
–
14
–
13
–
12
–
11
10
9
8
7
–
6
–
5
4
URSTIEN
3
–
1
–
0
URSTEN
ERSTL
2
–
• URSTEN: User Reset Enable
0 = The detection of a low level on the pin NRST does not generate a User Reset.
1 = The detection of a low level on the pin NRST triggers a User Reset.
• URSTIEN: User Reset Interrupt Enable
0 = USRTS bit in RSTC_SR at 1 has no effect on rstc_irq.
1 = USRTS bit in RSTC_SR at 1 asserts rstc_irq if URSTEN = 0.
• ERSTL: External Reset Length
This field defines the external reset length. The external reset is asserted during a time of 2(ERSTL+1) Slow Clock cycles. This
allows assertion duration to be programmed between 60 µs and 2 seconds.
• KEY: Password
Should be written at value 0xA5. Writing any other value in this field aborts the write operation.
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15. Real-time Timer (RTT)
15.1
Overview
The Real-time Timer is built around a 32-bit counter and used to count elapsed seconds. It generates a periodic interrupt and/or triggers an alarm on a programmed value.
15.2
Block Diagram
Figure 15-1. Real-time Timer
RTT_MR
RTTRST
RTT_MR
RTPRES
RTT_MR
SLCK
RTTINCIEN
reload
16-bit
Divider
set
0
RTT_MR
RTTRST
RTTINC
RTT_SR
1
reset
0
rtt_int
32-bit
Counter
read
RTT_SR
RTT_MR
ALMIEN
RTT_VR
reset
CRTV
RTT_SR
ALMS
set
rtt_alarm
=
RTT_AR
15.3
ALMV
Functional Description
The Real-time Timer is used to count elapsed seconds. It is built around a 32-bit counter fed by
Slow Clock divided by a programmable 16-bit value. The value can be programmed in the field
RTPRES of the Real-time Mode Register (RTT_MR).
Programming RTPRES at 0x00008000 corresponds to feeding the real-time counter with a 1 Hz
signal (if the Slow Clock is 32.768 Hz). The 32-bit counter can count up to 232 seconds, corresponding to more than 136 years, then roll over to 0.
The Real-time Timer can also be used as a free-running timer with a lower time-base. The best
accuracy is achieved by writing RTPRES to 3. Programming RTPRES to 1 or 2 is possible, but
may result in losing status events because the status register is cleared two Slow Clock cycles
after read. Thus if the RTT is configured to trigger an interrupt, the interrupt occurs during 2 Slow
Clock cycles after reading RTT_SR. To prevent several executions of the interrupt handler, the
interrupt must be disabled in the interrupt handler and re-enabled when the status register is
clear.
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6384E–ATARM–05-Feb-10
The Real-time Timer value (CRTV) can be read at any time in the register RTT_VR (Real-time
Value Register). As this value can be updated asynchronously from the Master Clock, it is advisable to read this register twice at the same value to improve accuracy of the returned value.
The current value of the counter is compared with the value written in the alarm register
RTT_AR (Real-time Alarm Register). If the counter value matches the alarm, the bit ALMS in
RTT_SR is set. The alarm register is set to its maximum value, corresponding to 0xFFFF_FFFF,
after a reset.
The bit RTTINC in RTT_SR is set each time the Real-time Timer counter is incremented. This bit
can be used to start a periodic interrupt, the period being one second when the RTPRES is programmed with 0x8000 and Slow Clock equal to 32.768 Hz.
Reading the RTT_SR status register resets the RTTINC and ALMS fields.
Writing the bit RTTRST in RTT_MR immediately reloads and restarts the clock divider with the
new programmed value. This also resets the 32-bit counter.
Note:
Because of the asynchronism between the Slow Clock (SCLK) and the System Clock (MCK):
1) The restart of the counter and the reset of the RTT_VR current value register is effective only 2
slow clock cycles after the write of the RTTRST bit in the RTT_MR register.
2) The status register flags reset is taken into account only 2 slow clock cycles after the read of the
RTT_SR (Status Register).
Figure 15-2. RTT Counting
APB cycle
APB cycle
MCK
RTPRES - 1
Prescaler
0
RTT
0
...
ALMV-1
ALMV
ALMV+1
ALMV+2
ALMV+3
RTTINC (RTT_SR)
ALMS (RTT_SR)
APB Interface
read RTT_SR
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15.4
Real-time Timer (RTT) User Interface
Table 15-1.
Register Mapping
Offset
Register
Name
Access
Reset
0x00
Mode Register
RTT_MR
Read-write
0x0000_8000
0x04
Alarm Register
RTT_AR
Read-write
0xFFFF_FFFF
0x08
Value Register
RTT_VR
Read-only
0x0000_0000
0x0C
Status Register
RTT_SR
Read-only
0x0000_0000
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15.4.1
Real-time Timer Mode Register
Register Name: RTT_MR
Access Type: Read/Write
31
–
30
–
29
–
28
–
27
–
26
–
25
–
24
–
23
–
22
–
21
–
20
–
19
–
18
RTTRST
17
RTTINCIEN
16
ALMIEN
15
14
13
12
11
10
9
8
3
2
1
0
RTPRES
7
6
5
4
RTPRES
• RTPRES: Real-time Timer Prescaler Value
Defines the number of SLCK periods required to increment the Real-time timer. RTPRES is defined as follows:
RTPRES = 0: The prescaler period is equal to 216.
RTPRES ≠ 0: The prescaler period is equal to RTPRES.
• ALMIEN: Alarm Interrupt Enable
0 = The bit ALMS in RTT_SR has no effect on interrupt.
1 = The bit ALMS in RTT_SR asserts interrupt.
• RTTINCIEN: Real-time Timer Increment Interrupt Enable
0 = The bit RTTINC in RTT_SR has no effect on interrupt.
1 = The bit RTTINC in RTT_SR asserts interrupt.
• RTTRST: Real-time Timer Restart
1 = Reloads and restarts the clock divider with the new programmed value. This also resets the 32-bit counter.
104
AT91SAM9G20
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15.4.2
Real-time Timer Alarm Register
Register Name: RTT_AR
Access Type: Read/Write
31
30
29
28
27
26
25
24
19
18
17
16
11
10
9
8
3
2
1
0
27
26
25
24
19
18
17
16
11
10
9
8
3
2
1
0
ALMV
23
22
21
20
ALMV
15
14
13
12
ALMV
7
6
5
4
ALMV
• ALMV: Alarm Value
Defines the alarm value (ALMV+1) compared with the Real-time Timer.
15.4.3
Real-time Timer Value Register
Register Name: RTT_VR
Access Type: Read-only
31
30
29
28
CRTV
23
22
21
20
CRTV
15
14
13
12
CRTV
7
6
5
4
CRTV
• CRTV: Current Real-time Value
Returns the current value of the Real-time Timer.
105
6384E–ATARM–05-Feb-10
15.4.4
Real-time Timer Status Register
Register Name: RTT_SR
Access Type: Read-only
31
–
30
–
29
–
28
–
27
–
26
–
25
–
24
–
23
–
22
–
21
–
20
–
19
–
18
–
17
–
16
–
15
–
14
–
13
–
12
–
11
–
10
–
9
–
8
–
7
–
6
–
5
–
4
–
3
–
2
–
1
RTTINC
0
ALMS
• ALMS: Real-time Alarm Status
0 = The Real-time Alarm has not occurred since the last read of RTT_SR.
1 = The Real-time Alarm occurred since the last read of RTT_SR.
• RTTINC: Real-time Timer Increment
0 = The Real-time Timer has not been incremented since the last read of the RTT_SR.
1 = The Real-time Timer has been incremented since the last read of the RTT_SR.
106
AT91SAM9G20
6384E–ATARM–05-Feb-10
AT91SAM9G20
16. Periodic Interval Timer (PIT)
16.1
Overview
The Periodic Interval Timer (PIT) provides the operating system’s scheduler interrupt. It is
designed to offer maximum accuracy and efficient management, even for systems with long
response time.
16.2
Block Diagram
Figure 16-1. Periodic Interval Timer
PIT_MR
PIV
=?
PIT_MR
PITIEN
set
0
PIT_SR
PITS
pit_irq
reset
0
MCK
Prescaler
16.3
0
0
1
12-bit
Adder
1
read PIT_PIVR
20-bit
Counter
MCK/16
CPIV
PIT_PIVR
CPIV
PIT_PIIR
PICNT
PICNT
Functional Description
The Periodic Interval Timer aims at providing periodic interrupts for use by operating systems.
The PIT provides a programmable overflow counter and a reset-on-read feature. It is built
around two counters: a 20-bit CPIV counter and a 12-bit PICNT counter. Both counters work at
Master Clock /16.
The first 20-bit CPIV counter increments from 0 up to a programmable overflow value set in the
field PIV of the Mode Register (PIT_MR). When the counter CPIV reaches this value, it resets to
0 and increments the Periodic Interval Counter, PICNT. The status bit PITS in the Status Register (PIT_SR) rises and triggers an interrupt, provided the interrupt is enabled (PITIEN in
PIT_MR).
107
6384E–ATARM–05-Feb-10
Writing a new PIV value in PIT_MR does not reset/restart the counters.
When CPIV and PICNT values are obtained by reading the Periodic Interval Value Register
(PIT_PIVR), the overflow counter (PICNT) is reset and the PITS is cleared, thus acknowledging
the interrupt. The value of PICNT gives the number of periodic intervals elapsed since the last
read of PIT_PIVR.
When CPIV and PICNT values are obtained by reading the Periodic Interval Image Register
(PIT_PIIR), there is no effect on the counters CPIV and PICNT, nor on the bit PITS. For example, a profiler can read PIT_PIIR without clearing any pending interrupt, whereas a timer
interrupt clears the interrupt by reading PIT_PIVR.
The PIT may be enabled/disabled using the PITEN bit in the PIT_MR register (disabled on
reset). The PITEN bit only becomes effective when the CPIV value is 0. Figure 16-2 illustrates
the PIT counting. After the PIT Enable bit is reset (PITEN= 0), the CPIV goes on counting until
the PIV value is reached, and is then reset. PIT restarts counting, only if the PITEN is set again.
The PIT is stopped when the core enters debug state.
Figure 16-2. Enabling/Disabling PIT with PITEN
APB cycle
APB cycle
MCK
15
restarts MCK Prescaler
MCK Prescaler 0
PITEN
CPIV
0
1
PICNT
PIV - 1
0
PIV
1
0
1
0
PITS (PIT_SR)
APB Interface
read PIT_PIVR
108
AT91SAM9G20
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AT91SAM9G20
16.4
Periodic Interval Timer (PIT) User Interface
Table 16-1.
Register Mapping
Offset
Register
Name
Access
Reset
0x00
Mode Register
PIT_MR
Read-write
0x000F_FFFF
0x04
Status Register
PIT_SR
Read-only
0x0000_0000
0x08
Periodic Interval Value Register
PIT_PIVR
Read-only
0x0000_0000
0x0C
Periodic Interval Image Register
PIT_PIIR
Read-only
0x0000_0000
109
6384E–ATARM–05-Feb-10
16.4.1
Name:
Periodic Interval Timer Mode Register
PIT_MR
Access:
Read/Write
31
–
30
–
29
–
28
–
27
–
26
–
25
PITIEN
24
PITEN
23
–
22
–
21
–
20
–
19
18
17
16
15
14
13
12
11
10
9
8
3
2
1
0
PIV
PIV
7
6
5
4
PIV
• PIV: Periodic Interval Value
Defines the value compared with the primary 20-bit counter of the Periodic Interval Timer (CPIV). The period is equal to
(PIV + 1).
• PITEN: Period Interval Timer Enabled
0 = The Periodic Interval Timer is disabled when the PIV value is reached.
1 = The Periodic Interval Timer is enabled.
• PITIEN: Periodic Interval Timer Interrupt Enable
0 = The bit PITS in PIT_SR has no effect on interrupt.
1 = The bit PITS in PIT_SR asserts interrupt.
110
AT91SAM9G20
6384E–ATARM–05-Feb-10
AT91SAM9G20
16.4.2
Name:
Periodic Interval Timer Status Register
PIT_SR
Access:
Read-only
31
–
30
–
29
–
28
–
27
–
26
–
25
–
24
–
23
–
22
–
21
–
20
–
19
–
18
–
17
–
16
–
15
–
14
–
13
–
12
–
11
–
10
–
9
–
8
–
7
–
6
–
5
–
4
–
3
–
2
–
1
–
0
PITS
25
24
17
16
• PITS: Periodic Interval Timer Status
0 = The Periodic Interval timer has not reached PIV since the last read of PIT_PIVR.
1 = The Periodic Interval timer has reached PIV since the last read of PIT_PIVR.
16.4.3
Name:
Periodic Interval Timer Value Register
PIT_PIVR
Access:
Read-only
31
30
29
28
27
26
19
18
PICNT
23
22
21
20
PICNT
15
14
CPIV
13
12
11
10
9
8
3
2
1
0
CPIV
7
6
5
4
CPIV
Reading this register clears PITS in PIT_SR.
• CPIV: Current Periodic Interval Value
Returns the current value of the periodic interval timer.
• PICNT: Periodic Interval Counter
Returns the number of occurrences of periodic intervals since the last read of PIT_PIVR.
111
6384E–ATARM–05-Feb-10
AT91SAM9G20
16.4.4
Name:
Periodic Interval Timer Image Register
PIT_PIIR
Access:
Read-only
31
30
29
28
27
26
25
24
19
18
17
16
PICNT
23
22
21
20
PICNT
15
14
CPIV
13
12
11
10
9
8
3
2
1
0
CPIV
7
6
5
4
CPIV
• CPIV: Current Periodic Interval Value
Returns the current value of the periodic interval timer.
• PICNT: Periodic Interval Counter
Returns the number of occurrences of periodic intervals since the last read of PIT_PIVR.
112
6384E–ATARM–05-Feb-10
AT91SAM9G20
17. Watchdog Timer (WDT)
17.1
Overview
The Watchdog Timer can be used to prevent system lock-up if the software becomes trapped in
a deadlock. It features a 12-bit down counter that allows a watchdog period of up to 16 seconds
(slow clock at 32.768 kHz). It can generate a general reset or a processor reset only. In addition,
it can be stopped while the processor is in debug mode or idle mode.
17.2
Block Diagram
Figure 17-1. Watchdog Timer Block Diagram
write WDT_MR
WDT_MR
WDV
WDT_CR
WDRSTT
reload
1
0
12-bit Down
Counter
WDT_MR
WDD
reload
Current
Value
1/128
SLCK
<= WDD
WDT_MR
WDRSTEN
= 0
wdt_fault
(to Reset Controller)
set
set
read WDT_SR
or
reset
WDERR
reset
WDUNF
reset
wdt_int
WDFIEN
WDT_MR
113
6384E–ATARM–05-Feb-10
17.3
Functional Description
The Watchdog Timer can be used to prevent system lock-up if the software becomes trapped in
a deadlock. It is supplied with VDDCORE. It restarts with initial values on processor reset.
The Watchdog is built around a 12-bit down counter, which is loaded with the value defined in
the field WDV of the Mode Register (WDT_MR). The Watchdog Timer uses the Slow Clock
divided by 128 to establish the maximum Watchdog period to be 16 seconds (with a typical Slow
Clock of 32.768 kHz).
After a Processor Reset, the value of WDV is 0xFFF, corresponding to the maximum value of
the counter with the external reset generation enabled (field WDRSTEN at 1 after a Backup
Reset). This means that a default Watchdog is running at reset, i.e., at power-up. The user must
either disable it (by setting the WDDIS bit in WDT_MR) if he does not expect to use it or must
reprogram it to meet the maximum Watchdog period the application requires.
The Watchdog Mode Register (WDT_MR) can be written only once. Only a processor reset
resets it. Writing the WDT_MR register reloads the timer with the newly programmed mode
parameters.
In normal operation, the user reloads the Watchdog at regular intervals before the timer underflow occurs, by writing the Control Register (WDT_CR) with the bit WDRSTT to 1. The
Watchdog counter is then immediately reloaded from WDT_MR and restarted, and the Slow
Clock 128 divider is reset and restarted. The WDT_CR register is write-protected. As a result,
writing WDT_CR without the correct hard-coded key has no effect. If an underflow does occur,
the “wdt_fault” signal to the Reset Controller is asserted if the bit WDRSTEN is set in the Mode
Register (WDT_MR). Moreover, the bit WDUNF is set in the Watchdog Status Register
(WDT_SR).
To prevent a software deadlock that continuously triggers the Watchdog, the reload of the
Watchdog must occur while the Watchdog counter is within a window between 0 and WDD,
WDD is defined in the WatchDog Mode Register WDT_MR.
Any attempt to restart the Watchdog while the Watchdog counter is between WDV and WDD
results in a Watchdog error, even if the Watchdog is disabled. The bit WDERR is updated in the
WDT_SR and the “wdt_fault” signal to the Reset Controller is asserted.
Note that this feature can be disabled by programming a WDD value greater than or equal to the
WDV value. In such a configuration, restarting the Watchdog Timer is permitted in the whole
range [0; WDV] and does not generate an error. This is the default configuration on reset (the
WDD and WDV values are equal).
The status bits WDUNF (Watchdog Underflow) and WDERR (Watchdog Error) trigger an interrupt, provided the bit WDFIEN is set in the mode register. The signal “wdt_fault” to the reset
controller causes a Watchdog reset if the WDRSTEN bit is set as already explained in the reset
controller programmer Datasheet. In that case, the processor and the Watchdog Timer are
reset, and the WDERR and WDUNF flags are reset.
If a reset is generated or if WDT_SR is read, the status bits are reset, the interrupt is cleared,
and the “wdt_fault” signal to the reset controller is deasserted.
Writing the WDT_MR reloads and restarts the down counter.
While the processor is in debug state or in idle mode, the counter may be stopped depending on
the value programmed for the bits WDIDLEHLT and WDDBGHLT in the WDT_MR.
114
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6384E–ATARM–05-Feb-10
AT91SAM9G20
Figure 17-2. Watchdog Behavior
Watchdog Error
Watchdog Underflow
if WDRSTEN is 1
FFF
Normal behavior
if WDRSTEN is 0
WDV
Forbidden
Window
WDD
Permitted
Window
0
Watchdog
Fault
WDT_CR = WDRSTT
115
6384E–ATARM–05-Feb-10
17.4
Watchdog Timer (WDT) User Interface
Table 17-1.
Register Mapping
Offset
Register
Name
Access
Reset
0x00
Control Register
WDT_CR
Write-only
-
0x04
Mode Register
WDT_MR
Read-write Once
0x3FFF_2FFF
0x08
Status Register
WDT_SR
Read-only
0x0000_0000
17.4.1
Watchdog Timer Control Register
Register Name:WDT_CR
Access Type: Write-only
31
30
29
28
27
26
25
24
KEY
23
–
22
–
21
–
20
–
19
–
18
–
17
–
16
–
15
–
14
–
13
–
12
–
11
–
10
–
9
–
8
–
7
–
6
–
5
–
4
–
3
–
2
–
1
–
0
WDRSTT
• WDRSTT: Watchdog Restart
0: No effect.
1: Restarts the Watchdog.
• KEY: Password
Should be written at value 0xA5. Writing any other value in this field aborts the write operation.
116
AT91SAM9G20
6384E–ATARM–05-Feb-10
AT91SAM9G20
17.4.2
Watchdog Timer Mode Register
Register Name: WDT_MR
Access Type:
Read-write Once
31
30
23
29
WDIDLEHLT
28
WDDBGHLT
27
21
20
19
11
22
26
25
24
18
17
16
10
9
8
1
0
WDD
WDD
15
WDDIS
14
13
12
WDRPROC
WDRSTEN
WDFIEN
7
6
5
4
WDV
3
2
WDV
• WDV: Watchdog Counter Value
Defines the value loaded in the 12-bit Watchdog Counter.
• WDFIEN: Watchdog Fault Interrupt Enable
0: A Watchdog fault (underflow or error) has no effect on interrupt.
1: A Watchdog fault (underflow or error) asserts interrupt.
• WDRSTEN: Watchdog Reset Enable
0: A Watchdog fault (underflow or error) has no effect on the resets.
1: A Watchdog fault (underflow or error) triggers a Watchdog reset.
• WDRPROC: Watchdog Reset Processor
0: If WDRSTEN is 1, a Watchdog fault (underflow or error) activates all resets.
1: If WDRSTEN is 1, a Watchdog fault (underflow or error) activates the processor reset.
• WDD: Watchdog Delta Value
Defines the permitted range for reloading the Watchdog Timer.
If the Watchdog Timer value is less than or equal to WDD, writing WDT_CR with WDRSTT = 1 restarts the timer.
If the Watchdog Timer value is greater than WDD, writing WDT_CR with WDRSTT = 1 causes a Watchdog error.
• WDDBGHLT: Watchdog Debug Halt
0: The Watchdog runs when the processor is in debug state.
1: The Watchdog stops when the processor is in debug state.
• WDIDLEHLT: Watchdog Idle Halt
0: The Watchdog runs when the system is in idle mode.
1: The Watchdog stops when the system is in idle state.
• WDDIS: Watchdog Disable
0: Enables the Watchdog Timer.
1: Disables the Watchdog Timer.
117
6384E–ATARM–05-Feb-10
17.4.3
Watchdog Timer Status Register
Register Name: WDT_SR
Access Type: Read-only
31
–
30
–
29
–
28
–
27
–
26
–
25
–
24
–
23
–
22
–
21
–
20
–
19
–
18
–
17
–
16
–
15
–
14
–
13
–
12
–
11
–
10
–
9
–
8
–
7
–
6
–
5
–
4
–
3
–
2
–
1
WDERR
0
WDUNF
• WDUNF: Watchdog Underflow
0: No Watchdog underflow occurred since the last read of WDT_SR.
1: At least one Watchdog underflow occurred since the last read of WDT_SR.
• WDERR: Watchdog Error
0: No Watchdog error occurred since the last read of WDT_SR.
1: At least one Watchdog error occurred since the last read of WDT_SR.
118
AT91SAM9G20
6384E–ATARM–05-Feb-10
AT91SAM9G20
18. Shutdown Controller (SHDWC)
18.1
Overview
The Shutdown Controller controls the power supplies VDDIO and VDDCORE and the wake-up
detection on debounced input lines.
18.2
Block Diagram
Figure 18-1. Shutdown Controller Block Diagram
SLCK
Shutdown Controller
read SHDW_SR
SHDW_MR
CPTWK0
reset
WAKEUP0
WKMODE0
SHDW_SR
set
WKUP0
read SHDW_SR
Wake-up
reset
RTTWKEN
SHDW_MR
RTT Alarm
RTTWK
SHDW_SR
set
SHDW_CR
SHDW
18.3
SHDN
Shutdown
Output
Controller
Shutdown
I/O Lines Description
Table 18-1.
I/O Lines Description
Name
Description
Type
WKUP0
Wake-up 0 input
Input
SHDN
Shutdown output
Output
18.4
18.4.1
Product Dependencies
Power Management
The Shutdown Controller is continuously clocked by Slow Clock. The Power Management Controller has no effect on the behavior of the Shutdown Controller.
119
6384E–ATARM–05-Feb-10
18.5
Functional Description
The Shutdown Controller manages the main power supply. To do so, it is supplied with VDDBU
and manages wake-up input pins and one output pin, SHDN.
A typical application connects the pin SHDN to the shutdown input of the DC/DC Converter providing the main power supplies of the system, and especially VDDCORE and/or VDDIO. The
wake-up inputs (WKUP0) connect to any push-buttons or signal that wake up the system.
The software is able to control the pin SHDN by writing the Shutdown Control Register
(SHDW_CR) with the bit SHDW at 1. The shutdown is taken into account only 2 slow clock
cycles after the write of SHDW_CR. This register is password-protected and so the value written
should contain the correct key for the command to be taken into account. As a result, the system
should be powered down.
A level change on WKUP0 is used as wake-up. Wake-up is configured in the Shutdown Mode
Register (SHDW_MR). The transition detector can be programmed to detect either a positive or
negative transition or any level change on WKUP0. The detection can also be disabled. Programming is performed by defining WKMODE0.
Moreover, a debouncing circuit can be programmed for WKUP0. The debouncing circuit filters
pulses on WKUP0 shorter than the programmed number of 16 SLCK cycles in CPTWK0 of the
SHDW_MR register. If the programmed level change is detected on a pin, a counter starts.
When the counter reaches the value programmed in the corresponding field, CPTWK0, the
SHDN pin is released. If a new input change is detected before the counter reaches the corresponding value, the counter is stopped and cleared. WAKEUP0 of the Status Register
(SHDW_SR) reports the detection of the programmed events on WKUP0 with a reset after the
read of SHDW_SR.
The Shutdown Controller can be programmed so as to activate the wake-up using the RTT
alarm (the detection of the rising edge of the RTT alarm is synchronized with SLCK). This is
done by writing the SHDW_MR register using the RTTWKEN fields. When enabled, the detection of the RTT alarm is reported in the RTTWK bit of the SHDW_SR Status register. It is reset
after the read of SHDW_SR. When using the RTT alarm to wake up the system, the user must
ensure that the RTT alarm status flag is cleared before shutting down the system. Otherwise, no
rising edge of the status flag may be detected and the wake-up fails.
120
AT91SAM9G20
6384E–ATARM–05-Feb-10
AT91SAM9G20
18.6
Shutdown Controller (SHDWC) User Interface
Table 18-2.
Register Mapping
Offset
Register
Name
Access
Reset
0x00
Shutdown Control Register
SHDW_CR
Write-only
-
0x04
Shutdown Mode Register
SHDW_MR
Read-write
0x0000_0003
0x08
Shutdown Status Register
SHDW_SR
Read-only
0x0000_0000
121
6384E–ATARM–05-Feb-10
18.6.1
Shutdown Control Register
Register Name: SHDW_CR
Access Type: Write-only
31
30
29
28
27
26
25
24
KEY
23
–
22
–
21
–
20
–
19
–
18
–
17
–
16
–
15
–
14
–
13
–
12
–
11
–
10
–
9
–
8
–
7
–
6
–
5
–
4
–
3
–
2
–
1
–
0
SHDW
• SHDW: Shutdown Command
0 = No effect.
1 = If KEY is correct, asserts the SHDN pin.
• KEY: Password
Should be written at value 0xA5. Writing any other value in this field aborts the write operation.
122
AT91SAM9G20
6384E–ATARM–05-Feb-10
AT91SAM9G20
18.6.2
Shutdown Mode Register
Register Name: SHDW_MR
Access Type: Read/Write
31
–
30
–
29
–
28
–
27
–
26
–
25
–
24
–
23
–
22
–
21
–
20
–
19
–
18
–
17
–
16
RTTWKEN
15
14
13
12
11
–
10
–
9
8
3
–
2
–
1
CPTWK1
7
6
5
4
CPTWK0
–
0
WKMODE0
• WKMODE0: Wake-up Mode 0
WKMODE[1:0]
Wake-up Input Transition Selection
0
0
None. No detection is performed on the wake-up input
0
1
Low to high level
1
0
High to low level
1
1
Both levels change
• CPTWK0: Counter on Wake-up 0
Defines the number of 16 Slow Clock cycles, the level detection on the corresponding input pin shall last before the wakeup event occurs. Because of the internal synchronization of WKUP0, the SHDN pin is released
(CPTWK x 16 + 1) Slow Clock cycles after the event on WKUP.
• RTTWKEN: Real-time Timer Wake-up Enable
0 = The RTT Alarm signal has no effect on the Shutdown Controller.
1 = The RTT Alarm signal forces the de-assertion of the SHDN pin.
123
6384E–ATARM–05-Feb-10
18.6.3
Shutdown Status Register
Register Name: SHDW_SR
Access Type: Read-only
31
–
30
–
29
–
28
–
27
–
26
–
25
–
24
–
23
–
22
–
21
–
20
–
19
–
18
–
17
–
16
RTTWK
15
–
14
–
13
–
12
–
11
–
10
–
9
–
8
–
7
–
6
–
5
–
4
–
3
–
2
–
1
–
0
WAKEUP0
• WAKEUP0: Wake-up 0 Status
0 = No wake-up event occurred on the corresponding wake-up input since the last read of SHDW_SR.
1 = At least one wake-up event occurred on the corresponding wake-up input since the last read of SHDW_SR.
• RTTWK: Real-time Timer Wake-up
0 = No wake-up alarm from the RTT occurred since the last read of SHDW_SR.
1 = At least one wake-up alarm from the RTT occurred since the last read of SHDW_SR.
124
AT91SAM9G20
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AT91SAM9G20
19. AT91SAM9G20 Bus Matrix
19.1
Overview
The Bus Matrix implements a multi-layer AHB based on the AHB-Lite protocol that enables parallel access paths between multiple AHB masters and slaves in a system, thus increasing the
overall bandwidth. The Bus Matrix interconnects 6 AHB Masters to 5 AHB Slaves. The normal
latency to connect a master to a slave is one cycle except for the default master of the accessed
slave which is connected directly (zero cycle latency).
The Bus Matrix user interface is compliant with the ARM Advanced High-performance Bus and
provides a Chip Configuration User Interface with registers that allow the Bus Matrix to support
application specific features.
19.2
Memory Mapping
The Bus Matrix provides one decoder for every AHB Master Interface. The decoder offers each
AHB Master several memory mappings. In fact, depending on the product, each memory area
may be assigned to several slaves. Booting at the same address while using different AHB
slaves (i.e., external RAM, internal ROM or internal Flash, etc.) becomes possible.
The Bus Matrix user interface provides Master Remap Control Register (MATRIX_MRCR) that
performs remap action for every master independently.
19.3
Special Bus Granting Techniques
The Bus Matrix provides some speculative bus granting techniques in order to anticipate access
requests from some masters. This mechanism reduces latency at first accesses of a burst or single transfer. The bus granting mechanism sets a default master for every slave.
At the end of the current access, if no other request is pending, the slave remains connected to
its associated default master. A slave can be associated with three kinds of default masters: no
default master, last access master and fixed default master.
19.3.1
No Default Master
At the end of the current access, if no other request is pending, the slave is disconnected from
all masters. No Default Master suits Low Power mode.
19.3.2
Last Access Master
At the end of the current access, if no other request is pending, the slave remains connected to
the last master that performed an access request.
19.3.3
Fixed Default Master
At the end of the current access, if no other request is pending, the slave connects to its fixed
default master. Unlike last access master, the fixed master doesn’t change unless the user modifies it by a software action (field FIXED_DEFMSTR of the related MATRIX_SCFG).
To change from one kind of default master to another, the Bus Matrix user interface provides the
Slave Configuration Registers, one for each slave, that set a default master for each slave. The
Slave Configuration Register contains two fields, DEFMSTR_TYPE and FIXED_DEFMSTR. The
2-bit DEFMSTR_TYPE field is used to select the default master type (no default, last access
master, fixed default master) whereas the 4-bit FIXED_DEFMSTR field is used to select a fixed
default master provided that DEFMSTR_TYPE is set to fixed default master. Refer to Section
19.5 “Bus Matrix (MATRIX) User Interface” on page 128.
125
6384E–ATARM–05-Feb-10
19.4
Arbitration
The Bus Matrix provides an arbitration mechanism that reduces latency when conflicting cases
occur, in particular when two or more masters try to access the same slave at the same time.
One arbiter per AHB slave is provided, thus arbitrating each slave differently.
The Bus Matrix provides the user the possibility to choose between 2 arbitration types for each
slave:
1. Round-Robin Arbitration (the default)
2. Fixed Priority Arbitration
This choice is made through the field ARBT of the Slave Configuration Registers
(MATRIX_SCFG).
Each algorithm may be complemented by selecting a default master configuration for each
slave.
When a re-arbitration has to be done, it is realized only under specific conditions described in
Section 19.4.1 “Arbitration Rules” on page 126.
19.4.1
Arbitration Rules
Each arbiter has the ability to arbitrate between two or more different master’s requests. In order
to avoid burst breaking and also to provide the maximum throughput for slave interfaces, arbitration may only take place during the following cycles:
1. Idle Cycles: when a slave is not connected to any master or is connected to a master
which is not currently accessing it.
2. Single Cycles: when a slave is currently doing a single access.
3. End of Burst Cycles: when the current cycle is the last cycle of a burst transfer. For
defined length burst, predicted end of burst matches the size of the transfer but is managed differently for undefined length burst (see Section 19.4.1.1 “Undefined Length
Burst Arbitration” on page 126).
4. Slot Cycle Limit: when the slot cycle counter has reached the limit value indicating that
the current master access is too long and must be broken (see Section 19.4.1.2 “Slot
Cycle Limit Arbitration” on page 127).
19.4.1.1
Undefined Length Burst Arbitration
In order to avoid too long slave handling during undefined length bursts (INCR), the Bus Matrix
provides specific logic in order to re-arbitrate before the end of the INCR transfer.
A predicted end of burst is used as for defined length burst transfer, which is selected between
the following:
1. Infinite: no predicted end of burst is generated and therefore INCR burst transfer is
never broken.
2. Four beat bursts: predicted end of burst is generated at the end of each four beat
boundary inside INCR transfer.
3. Eight beat bursts: predicted end of burst is generated at the end of each eight beat
boundary inside INCR transfer.
4. Sixteen beat bursts: predicted end of burst is generated at the end of each sixteen beat
boundary inside INCR transfer.
This selection can be done through the field ULBT of the Master Configuration Registers
(MATRIX_MCFG).
126
AT91SAM9G20
6384E–ATARM–05-Feb-10
AT91SAM9G20
19.4.1.2
19.4.2
Slot Cycle Limit Arbitration
The Bus Matrix contains specific logic to break too long accesses such as very long bursts on a
very slow slave (e.g., an external low speed memory). At the beginning of the burst access, a
counter is loaded with the value previously written in the SLOT_CYCLE field of the related Slave
Configuration Register (MATRIX_SCFG) and decreased at each clock cycle. When the counter
reaches zero, the arbiter has the ability to re-arbitrate at the end of the current byte, half word or
word transfer.
Round-Robin Arbitration
This algorithm allows the Bus Matrix arbiters to dispatch the requests from different masters to
the same slave in a round-robin manner. If two or more master’s requests arise at the same
time, the master with the lowest number is first serviced then the others are serviced in a roundrobin manner.
There are three round-robin algorithms implemented:
• Round-Robin arbitration without default master
• Round-Robin arbitration with last access master
• Round-Robin arbitration with fixed default master
19.4.2.1
Round-Robin Arbitration without Default Master
This is the main algorithm used by Bus Matrix arbiters. It allows the Bus Matrix to dispatch
requests from different masters to the same slave in a pure round-robin manner. At the end of
the current access, if no other request is pending, the slave is disconnected from all masters.
This configuration incurs one latency cycle for the first access of a burst. Arbitration without
default master can be used for masters that perform significant bursts.
19.4.2.2
Round-Robin Arbitration with Last Access Master
This is a biased round-robin algorithm used by Bus Matrix arbiters. It allows the Bus Matrix to
remove the one latency cycle for the last master that accessed the slave. At the end of the current transfer, if no other master request is pending, the slave remains connected to the last
master that performs the access. Other non privileged masters still get one latency cycle if they
want to access the same slave. This technique can be used for masters that mainly perform single accesses.
19.4.2.3
Round-Robin Arbitration with Fixed Default Master
This is another biased round-robin algorithm, it allows the Bus Matrix arbiters to remove the one
latency cycle for the fixed default master per slave. At the end of the current access, the slave
remains connected to its fixed default master. Requests attempted by this fixed default master
do not cause any latency whereas other non privileged masters get one latency cycle. This technique can be used for masters that mainly perform single accesses.
19.4.3
Fixed Priority Arbitration
This algorithm allows the Bus Matrix arbiters to dispatch the requests from different masters to
the same slave by using the fixed priority defined by the user. If two or more master’s requests
are active at the same time, the master with the highest priority number is serviced first. If two or
more master’s requests with the same priority are active at the same time, the master with the
highest number is serviced first.
For each slave, the priority of each master may be defined through the Priority Registers for
Slaves (MATRIX_PRAS and MATRIX_PRBS).
127
6384E–ATARM–05-Feb-10
19.5
Bus Matrix (MATRIX) User Interface
Table 19-1.
Register Mapping
Offset
Register
Name
Access
Reset
0x0000
Master Configuration Register 0
MATRIX_MCFG0
Read-write
0x00000000
0x0004
Master Configuration Register 1
MATRIX_MCFG1
Read-write
0x00000002
0x0008
Master Configuration Register 2
MATRIX_MCFG2
Read-write
0x00000002
0x000C
Master Configuration Register 3
MATRIX_MCFG3
Read-write
0x00000002
0x0010
Master Configuration Register 4
MATRIX_MCFG4
Read-write
0x00000002
0x0014
Master Configuration Register 5
MATRIX_MCFG5
Write-only
0x00000002
–
–
–
0x0018 - 0x003C
0x0040
Slave Configuration Register 0
MATRIX_SCFG0
Read-write
0x00000010
0x0044
Slave Configuration Register 1
MATRIX_SCFG1
Read-write
0x00000010
0x0048
Slave Configuration Register 2
MATRIX_SCFG2
Read-write
0x00000010
0x004C
Slave Configuration Register 3
MATRIX_SCFG3
Read-write
0x00000010
0x0050
Slave Configuration Register 4
MATRIX_SCFG4
Read-write
0x00000010
–
–
–
MATRIX_PRAS0
Read-write
0x00000000
–
–
–
MATRIX_PRAS1
Read-write
0x00000000
–
–
–
MATRIX_PRAS2
Read-write
0x00000000
–
–
–
MATRIX_PRAS3
Read-write
0x00000000
–
–
–
MATRIX_PRAS4
Read-write
0x00000000
–
–
–
MATRIX_MRCR
Read-write
0x00000000
–
–
–
0x0054 - 0x007C
Reserved
0x0080
Priority Register A for Slave 0
0x0084
Reserved
0x0088
Priority Register A for Slave 1
0x008C
Reserved
0x0090
Priority Register A for Slave 2
0x0094
Reserved
0x0098
Priority Register A for Slave 3
0x009C
Reserved
0x00A0
Priority Register A for Slave 4
0x00A8 - 0x00FC
0x0100
0x0104 - 0x010C
128
Reserved
Reserved
Master Remap Control Register
Reserved
AT91SAM9G20
6384E–ATARM–05-Feb-10
AT91SAM9G20
19.5.1
Bus Matrix Master Configuration Registers
Register Name:MATRIX_MCFG0...MATRIX_MCFG5
Access Type:Read-write
(MATRIX_MCFG5 is Write-only)
31
30
29
28
27
26
25
24
–
–
–
–
–
–
–
–
23
22
21
20
19
18
17
16
–
–
–
–
–
–
–
–
15
14
13
12
11
10
9
8
–
–
–
–
–
–
–
–
7
6
5
4
3
2
1
0
–
–
–
–
–
ULBT
• ULBT: Undefined Length Burst Type
0: Infinite Length Burst
No predicted end of burst is generated and therefore INCR bursts coming from this master cannot be broken.
1: Single Access
The undefined length burst is treated as a succession of single accesses allowing rearbitration at each beat of the INCR
burst.
2: Four Beat Burst
The undefined length burst is split into 4-beat bursts allowing rearbitration at each 4-beat burst end.
3: Eight Beat Burst
The undefined length burst is split into 8-beat bursts allowing rearbitration at each 8-beat burst end.
4: Sixteen Beat Burst
The undefined length burst is split into 16-beat bursts allowing rearbitration at each 16-beat burst end.
129
6384E–ATARM–05-Feb-10
19.5.2
Bus Matrix Slave Configuration Registers
Register Name:MATRIX_SCFG0...MATRIX_SCFG4
Access Type:Read-write
31
30
29
28
27
26
–
–
–
–
–
–
23
22
21
20
19
18
–
FIXED_DEFMSTR
25
24
ARBT
17
16
DEFMSTR_TYPE
15
14
13
12
11
10
9
8
–
–
–
–
–
–
–
–
7
6
5
4
3
2
1
0
SLOT_CYCLE
• SLOT_CYCLE: Maximum Number of Allowed Cycles for a Burst
When the SLOT_CYCLE limit is reached for a burst, it may be broken by another master trying to access this slave.
This limit has been placed to avoid locking very slow slaves when very long bursts are used.
This limit should not be very small though. Unreasonably small values break every burst and the Bus Matrix arbitrates without performing any data transfer. 16 cycles is a reasonable value for SLOT_CYCLE.
• DEFMSTR_TYPE: Default Master Type
0: No Default Master
At the end of current slave access, if no other master request is pending, the slave is disconnected from all masters.
This results in one cycle latency for the first access of a burst transfer or for a single access.
1: Last Default Master
At the end of current slave access, if no other master request is pending, the slave stays connected with the last master
having accessed it.
This results in not having the one cycle latency when the last master tries to access the slave again.
2: Fixed Default Master
At the end of the current slave access, if no other master request is pending, the slave connects to the fixed master whose
number has been written in the FIXED_DEFMSTR field.
This results in not having the one cycle latency when the fixed master tries to access the slave again.
• FIXED_DEFMSTR: Fixed Default Master
This is the number of the Default Master for this slave. Only used if DEFMASTR_TYPE is 2. Specifying the number of a
master which is not connected to the selected slave is equivalent to setting DEFMASTR_TYPE to 0.
• ARBT: Arbitration Type
0: Round-Robin Arbitration
1: Fixed Priority Arbitration
2: Reserved
3: Reserved
130
AT91SAM9G20
6384E–ATARM–05-Feb-10
AT91SAM9G20
19.5.3
Bus Matrix Priority Registers For Slaves
Register Name:MATRIX_PRAS0...MATRIX_PRAS4
Access Type:Read-write
31
30
29
28
27
26
25
24
–
–
–
–
–
–
–
–
23
22
21
20
19
18
17
–
–
–
–
15
14
11
10
–
–
–
–
7
6
3
2
–
–
–
–
M5PR
13
12
M3PR
5
4
M1PR
16
M4PR
9
8
M2PR
1
0
M0PR
• MxPR: Master x Priority
Fixed priority of Master x for access to the selected slave. The higher the number, the higher the priority.
131
6384E–ATARM–05-Feb-10
19.5.4
Bus Matrix Master Remap Control Register
Register Name:MATRIX_MRCR
Access Type:Read-write
Reset:
0x0000_0000
31
30
29
28
27
26
25
24
–
–
–
–
–
–
–
–
23
22
21
20
19
18
17
16
–
–
–
–
–
–
–
–
15
14
13
12
11
10
9
8
–
–
–
–
–
–
–
–
7
6
5
4
3
2
1
0
–
–
–
–
–
–
RCB1
RCB0
• RCBx: Remap Command Bit for AHB Master x
0: Disable remapped address decoding for the selected Master
1: Enable remapped address decoding for the selected Master
132
AT91SAM9G20
6384E–ATARM–05-Feb-10
AT91SAM9G20
19.6
Chip Configuration User Interface
Table 19-2.
Register Mapping
Offset
Register
Name
Access
Reset
0x0110 - 0x0118
Reserved
–
–
–
EBI_CSA
Read-write
0x00010000
–
–
–
0x011C
EBI Chip Select Assignment Register
0x0130 - 0x01FC
Reserved
19.6.1
EBI Chip Select Assignment Register
Register Name:EBI_CSA
Access Type:Read-write
Reset:
0x0001_0000
31
30
29
28
27
26
25
24
–
–
–
–
–
–
–
–
23
22
21
20
19
18
17
16
–
–
–
–
–
–
IOSR
VDDIOMSEL
15
14
13
12
11
10
9
8
–
–
–
–
–
–
–
EBI_DBPUC
7
6
5
4
3
2
1
0
–
–
EBI_CS5A
EBI_CS4A
EBI_CS3A
–
EBI_CS1A
–
• EBI_CS1A: EBI Chip Select 1 Assignment
0 = EBI Chip Select 1 is assigned to the Static Memory Controller.
1 = EBI Chip Select 1 is assigned to the SDRAM Controller.
• EBI_CS3A: EBI Chip Select 3 Assignment
0 = EBI Chip Select 3 is only assigned to the Static Memory Controller and EBI_NCS3 behaves as defined by the SMC.
1 = EBI Chip Select 3 is assigned to the Static Memory Controller and the SmartMedia Logic is activated.
• EBI_CS4A: EBI Chip Select 4 Assignment
0 = EBI Chip Select 4 is only assigned to the Static Memory Controller and EBI_NCS4 behaves as defined by the SMC.
1 = EBI Chip Select 4 is assigned to the Static Memory Controller and the CompactFlash Logic (first slot) is activated.
• EBI_CS5A: EBI Chip Select 5 Assignment
0 = EBI Chip Select 5 is only assigned to the Static Memory Controller and EBI_NCS5 behaves as defined by the SMC.
1 = EBI Chip Select 5 is assigned to the Static Memory Controller and the CompactFlash Logic (second slot) is activated.
• EBI_DBPUC: EBI Data Bus Pull-Up Configuration
0 = EBI D0 - D15 Data Bus bits are internally pulled-up to the VDDIOM power supply.
1 = EBI D0 - D15 Data Bus bits are not internally pulled-up.
133
6384E–ATARM–05-Feb-10
• VDDIOMSEL: Memory voltage selection
0 = Memories are 1.8V powered.
1 = Memories are 3.3V powered.
• IOSR: I/O Slew Rate Selection
Refer to the” I/Os” sub-section of the “Clock Characteristics” in the product “Electrical Characteristics”.
134
AT91SAM9G20
6384E–ATARM–05-Feb-10
AT91SAM9G20
20. AT91SAM9G20 External Bus Interface
20.1
Overview
The External Bus Interface (EBI) is designed to ensure the successful data transfer between
several external devices and the embedded Memory Controller of an ARM-based device. The
Static Memory, SDRAM and ECC Controllers are all featured external Memory Controllers on
the EBI. These external Memory Controllers are capable of handling several types of external
memory and peripheral devices, such as SRAM, PROM, EPROM, EEPROM, Flash, and
SDRAM.
The EBI also supports the CompactFlash and the NAND Flash protocols via integrated circuitry
that greatly reduces the requirements for external components. Furthermore, the EBI handles
data transfers with up to six external devices, each assigned to six address spaces defined by
the embedded Memory Controller. Data transfers are performed through a 16-bit or 32-bit data
bus, an address bus of up to 26 bits, up to eight chip select lines (NCS[7:0]) and several control
pins that are generally multiplexed between the different external Memory Controllers.
135
6384E–ATARM–05-Feb-10
20.2
20.2.1
Block Diagram
External Bus Interface
Figure 20-1 shows the organization of the External Bus Interface.
Figure 20-1. Organization of the External Bus Interface
D[15:0]
External Bus Interface
Bus Matrix
A0/NBS0
AHB
A1/NWR2/NBS2
SDRAM
Controller
A[15:2], A[20:18]
A16/BA0
A17/BA1
MUX
Logic
Static
Memory
Controller
NCS0
NCS1/SDCS
NRD/CFOE
NWR0/NWE/CFWE
NWR1/NBS1/CFIOR
NWR3/NBS3/CFIOW
SDCK
SDCKE
CompactFlash
Logic
RAS
CAS
SDWE
SDA10
NAND Flash
Logic
A21/NANDALE
A22/NANDCLE
NANDOE
NANDWE
ECC
Controller
NCS3/NANDCS
D[31:16]
PIO
Address Decoders
Chip Select
Assignor
A[24:23]
A25/CFRNW
NCS4/CFCS0
NCS5/CFCS1
NCS2, NCS6, NCS7
User Interface
NWAIT
CFCE1
CFCE2
APB
136
AT91SAM9G20
6384E–ATARM–05-Feb-10
AT91SAM9G20
20.3
I/O Lines Description
Table 20-1.
EBI I/O Lines Description
Name
Function
Type
Active Level
EBI
EBI_D0 - EBI_D31
Data Bus
I/O
EBI_A0 - EBI_A25
Address Bus
EBI_NWAIT
External Wait Signal
Output
Input
Low
SMC
EBI_NCS0 - EBI_NCS7
Chip Select Lines
Output
Low
EBI_NWR0 - EBI_NWR3
Write Signals
Output
Low
EBI_NRD
Read Signal
Output
Low
EBI_NWE
Write Enable
Output
Low
EBI_NBS0 - EBI_NBS3
Byte Mask Signals
Output
Low
EBI for CompactFlash Support
EBI_CFCE1 - EBI_CFCE2
CompactFlash Chip Enable
Output
Low
EBI_CFOE
CompactFlash Output Enable
Output
Low
EBI_CFWE
CompactFlash Write Enable
Output
Low
EBI_CFIOR
CompactFlash I/O Read Signal
Output
Low
EBI_CFIOW
CompactFlash I/O Write Signal
Output
Low
EBI_CFRNW
CompactFlash Read Not Write Signal
Output
EBI_CFCS0 - EBI_CFCS1
CompactFlash Chip Select Lines
Output
Low
EBI for NAND Flash Support
EBI_NANDCS
NAND Flash Chip Select Line
Output
Low
EBI_NANDOE
NAND Flash Output Enable
Output
Low
EBI_NANDWE
NAND Flash Write Enable
Output
Low
SDRAM Controller
EBI_SDCK
SDRAM Clock
Output
EBI_SDCKE
SDRAM Clock Enable
Output
High
EBI_SDCS
SDRAM Controller Chip Select Line
Output
Low
EBI_BA0 - EBI_BA1
Bank Select
Output
EBI_SDWE
SDRAM Write Enable
Output
Low
EBI_RAS - EBI_CAS
Row and Column Signal
Output
Low
EBI_NWR0 - EBI_NWR3
Write Signals
Output
Low
EBI_NBS0 - EBI_NBS3
Byte Mask Signals
Output
Low
EBI_SDA10
SDRAM Address 10 Line
Output
137
6384E–ATARM–05-Feb-10
The connection of some signals through the MUX logic is not direct and depends on the Memory
Controller in use at the moment.
Table 20-2 on page 138 details the connections between the two Memory Controllers and the
EBI pins.
Table 20-2.
138
EBI Pins and Memory Controllers I/O Lines Connections
EBIx Pins
SDRAMC I/O Lines
SMC I/O Lines
EBI_NWR1/NBS1/CFIOR
NBS1
NWR1/NUB
EBI_A0/NBS0
Not Supported
SMC_A0/NLB
EBI_A1/NBS2/NWR2
Not Supported
SMC_A1
EBI_A[11:2]
SDRAMC_A[9:0]
SMC_A[11:2]
EBI_SDA10
SDRAMC_A10
Not Supported
EBI_A12
Not Supported
SMC_A12
EBI_A[14:13]
SDRAMC_A[12:11]
SMC_A[14:13]
EBI_A[22:15]
Not Supported
SMC_A[22:15]
EBI_A[25:23]
Not Supported
SMC_A[25:23]
EBI_D[31:0]
D[31:0]
D[31:0]
AT91SAM9G20
6384E–ATARM–05-Feb-10
AT91SAM9G20
20.4
Application Example
20.4.1
Hardware Interface
Table 20-3 on page 139 details the connections to be applied between the EBI pins and the
external devices for each Memory Controller.
Table 20-3.
EBI Pins and External Static Devices Connections
Pins of the Interfaced Device
Signals:
EBI_
8-bit Static
Device
2 x 8-bit
Static
Devices
16-bit Static
Device
Controller
4 x 8-bit
Static
Devices
2 x 16-bit
Static
Devices
32-bit Static
Device
SMC
D0 - D7
D0 - D7
D0 - D7
D0 - D7
D0 - D7
D0 - D7
D0 - D7
D8 - D15
–
D8 - D15
D8 - D15
D8 - D15
D8 - 15
D8 - 15
D16 - D23
–
–
–
D16 - D23
D16 - D23
D16 - D23
D24 - D31
–
–
–
D24 - D31
D24 - D31
D24 - D31
BE0(5)
A0/NBS0
A0
–
NLB
–
A1/NWR2/NBS2
A1
A0
A0
WE(2)
NLB(4)
BE2(5)
A2 - A22
A[2:22]
A[1:21]
A[1:21]
A[0:20]
A[0:20]
A[0:20]
A23 - A25
A[23:25]
A[22:24]
A[22:24]
A[21:23]
A[21:23]
A[21:23]
NCS0
CS
CS
CS
CS
CS
CS
NCS1/SDCS
CS
CS
CS
CS
CS
CS
NCS2
CS
CS
CS
CS
CS
CS
NCS3/NANDCS
CS
CS
CS
CS
CS
CS
NCS4/CFCS0
CS
CS
CS
CS
CS
CS
NCS5/CFCS1
CS
CS
CS
CS
CS
CS
NCS6
CS
CS
CS
CS
CS
CS
NCS7
CS
CS
CS
CS
CS
CS
NRD/CFOE
OE
OE
OE
OE
OE
OE
WE
WE
NWR0/NWE
WE
WE
(1)
(1)
NWR1/NBS1
–
WE
NWR3/NBS3
–
–
Notes:
WE
NUB
–
NLB
(3)
WE
(2)
WE
(2)
WE(2)
(3)
BE1(5)
NUB(4)
BE3(5)
NUB
1. NWR1 enables upper byte writes. NWR0 enables lower byte writes.
2. NWRx enables corresponding byte x writes (x = 0,1,2 or 3).
3. NBS0 and NBS1 enable respectively lower and upper bytes of the lower 16-bit word.
4. NBS2 and NBS3 enable respectively lower and upper bytes of the upper 16-bit word.
5. BEx: Byte x Enable (x = 0,1,2 or 3).
139
6384E–ATARM–05-Feb-10
Table 20-4.
EBI Pins and External Device Connections
Pins of the Interfaced Device
Signals:
EBI_
SDRAM
Controller
CompactFlash
(EBI only)
SDRAMC
CompactFlash
True IDE Mode
(EBI only)
NAND Flash
SMC
D0 - D7
D0 - D7
D0 - D7
D0 - D7
I/O0 - I/O7
D8 - D15
D8 - D15
D8 - 15
D8 - 15
I/O8 - I/O15
D16 - D31
D16 - D31
–
–
–
A0/NBS0
DQM0
A0
A0
–
A1/NWR2/NBS2
DQM2
A1
A1
–
A2 - A10
A[0:8]
A[2:10]
A[2:10]
–
A11
A9
–
–
–
SDA10
A10
–
–
–
–
–
–
–
A[11:12]
–
–
–
–
–
–
–
A16/BA0
BA0
–
–
–
A17/BA1
BA1
–
–
–
A18 - A20
–
–
–
–
A21/NANDALE
–
–
–
ALE
A22/NANDCLE
–
REG
REG
CLE
A23 - A24
–
–
A12
A13 - A14
A15
–
–
(1)
A25
–
NCS0
–
–
–
–
CS
–
–
–
NCS2
–
–
–
–
NCS3/NANDCS
–
–
–
CE(3)
NCS4/CFCS0
–
CFCS0(1)
CFCS0(1)
–
NCS5/CFCS1
–
(1)
(1)
–
NCS6
–
–
–
–
NCS7
–
–
–
–
NANDOE
–
–
–
RE
NANDWE
–
–
–
WE
NRD/CFOE
–
OE
–
–
NWR0/NWE/CFWE
–
WE
WE
–
NWR1/NBS1/CFIOR
DQM1
IOR
IOR
–
NWR3/NBS3/CFIOW
DQM3
IOW
IOW
–
–
CE1
CS0
–
NCS1/SDCS
CFCE1
140
CFRNW
(1)
CFCS1
CFRNW
CFCS1
–
AT91SAM9G20
6384E–ATARM–05-Feb-10
AT91SAM9G20
Table 20-4.
EBI Pins and External Device Connections (Continued)
Pins of the Interfaced Device
Signals:
EBI_
Controller
SDRAM
CompactFlash
(EBI only)
SDRAMC
CompactFlash
True IDE Mode
(EBI only)
NAND Flash
SMC
CFCE2
–
CE2
CS1
–
SDCK
CLK
–
–
–
SDCKE
CKE
–
–
–
RAS
RAS
–
–
–
CAS
CAS
–
–
–
SDWE
WE
–
–
–
NWAIT
–
WAIT
WAIT
–
Pxx
(2)
–
CD1 or CD2
CD1 or CD2
–
Pxx
(2)
–
–
–
CE(3)
–
–
–
RDY
Pxx(2)
Notes:
1. Not directly connected to the CompactFlash slot. Permits the control of the bidirectional buffer between the EBI data bus and
the CompactFlash slot.
2. Any PIO line.
3. CE connection depends on the NAND Flash. For standard NAND Flash devices, it must be connected to any free PIO line.
For “CE don't care” NAND Flash devices, it can be either connected to NCS3/NANDCS or to any free PIO line.
141
6384E–ATARM–05-Feb-10
20.4.2
Connection Examples
Figure 20-2 shows an example of connections between the EBI and external devices.
Figure 20-2. EBI Connections to Memory Devices
EBI
D0-D31
RAS
CAS
SDCK
SDCKE
SDWE
A0/NBS0
NWR1/NBS1
A1/NWR2/NBS2
NWR3/NBS3
NRD/NOE
NWR0/NWE
D0-D7
2M x 8
SDRAM
D8-D15
D0-D7
CS
CLK
CKE
SDWE WE
RAS
CAS
DQM
NBS0
A0-A9, A11
A10
BA0
BA1
2M x 8
SDRAM
D0-D7
CS
CLK
CKE
SDWE
WE
RAS
CAS
DQM
NBS1
A2-A11, A13
SDA10
A16/BA0
A17/BA1
A0-A9, A11
A10
BA0
BA1
A2-A11, A13
SDA10
A16/BA0
A17/BA1
SDA10
A2-A15
A16/BA0
A17/BA1
A18-A25
D16-D23 D0-D7
NCS0
NCS1/SDCS
NCS2
NCS3
NCS4
NCS5
CS
CLK
CKE
SDWE WE
RAS
CAS
DQM
2M x 8
SDRAM
A0-A9, A11
A10
BA0
BA1
D24-D31
2M x 8
SDRAM
D0-D7
CS
CLK
CKE
SDWE
WE
RAS
CAS
DQM
NBS3
A2-A11, A13
SDA10
A16/BA0
A17/BA1
A0-A9, A11
A10
BA0
BA1
A2-A11, A13
SDA10
A16/BA0
A17/BA1
NBS2
128K x 8
SRAM
D0-D7
D0-D7
CS
OE
NRD/NOE
WE
A0/NWR0/NBS0
20.5
20.5.1
A0-A16
128K x 8
SRAM
A1-A17
D8-D15
D0-D7
A0-A16
A1-A17
CS
OE
NRD/NOE
WE
NWR1/NBS1
Product Dependencies
I/O Lines
The pins used for interfacing the External Bus Interface may be multiplexed with the PIO lines.
The programmer must first program the PIO controller to assign the External Bus Interface pins
to their peripheral function. If I/O lines of the External Bus Interface are not used by the application, they can be used for other purposes by the PIO Controller.
20.6
Functional Description
The EBI transfers data between the internal AHB Bus (handled by the Bus Matrix) and the external memories or peripheral devices. It controls the waveforms and the parameters of the
external address, data and control buses and is composed of the following elements:
• the Static Memory Controller (SMC)
• the SDRAM Controller (SDRAMC)
142
AT91SAM9G20
6384E–ATARM–05-Feb-10
AT91SAM9G20
• the ECC Controller (ECC)
• a chip select assignment feature that assigns an AHB address space to the external devices
• a multiplex controller circuit that shares the pins between the different Memory Controllers
• programmable CompactFlash support logic
• programmable NAND Flash support logic
20.6.1
Bus Multiplexing
The EBI offers a complete set of control signals that share the 32-bit data lines, the address
lines of up to 26 bits and the control signals through a multiplex logic operating in function of the
memory area requests.
Multiplexing is specifically organized in order to guarantee the maintenance of the address and
output control lines at a stable state while no external access is being performed. Multiplexing is
also designed to respect the data float times defined in the Memory Controllers. Furthermore,
refresh cycles of the SDRAM are executed independently by the SDRAM Controller without
delaying the other external Memory Controller accesses.
20.6.2
Pull-up Control
The EBI_CSA Registers in the Chip Configuration User Interface permit enabling of on-chip pullup resistors on the data bus lines not multiplexed with the PIO Controller lines. The pull-up resistors are enabled after reset. Setting the EBI_DBPUC bit disables the pull-up resistors on the D0
to D15 lines. Enabling the pull-up resistor on the D16-D31 lines can be performed by programming the appropriate PIO controller.
20.6.3
Static Memory Controller
For information on the Static Memory Controller, refer to the section “Static Memory Controller”.
20.6.4
SDRAM Controller
For information on the SDRAM Controller, refer to the section “SDRAM Controller”.
20.6.5
ECC Controller
For information on the ECC Controller, refer to the section “ECC Controller”.
20.6.6
CompactFlash Support
The External Bus Interface integrates circuitry that interfaces to CompactFlash devices.
The CompactFlash logic is driven by the Static Memory Controller (SMC) on the NCS4 and/or
NCS5 address space. Programming the EBI_CS4A and/or EBI_CS5A bit of the EBI_CSA Register in the Chip Configuration User Interface to the appropriate value enables this logic. For
details on this register, refer to the in the Bus Matrix Section. Access to an external CompactFlash device is then made by accessing the address space reserved to NCS4 and/or NCS5 (i.e.,
between 0x5000 0000 and 0x5FFF FFFF for NCS4 and between 0x6000 0000 and 0x6FFF
FFFF for NCS5).
All CompactFlash modes (Attribute Memory, Common Memory, I/O and True IDE) are supported but the signals _IOIS16 (I/O and True IDE modes) and _ATA SEL (True IDE mode) are
not handled.
143
6384E–ATARM–05-Feb-10
20.6.6.1
I/O Mode, Common Memory Mode, Attribute Memory Mode and True IDE Mode
Within the NCS4 and/or NCS5 address space, the current transfer address is used to distinguish
I/O mode, common memory mode, attribute memory mode and True IDE mode.
The different modes are accessed through a specific memory mapping as illustrated on Figure
20-3. A[23:21] bits of the transfer address are used to select the desired mode as described in
Table 20-5 on page 144.
Figure 20-3. CompactFlash Memory Mapping
True IDE Alternate Mode Space
Offset 0x00E0 0000
True IDE Mode Space
Offset 0x00C0 0000
CF Address Space
I/O Mode Space
Offset 0x0080 0000
Common Memory Mode Space
Offset 0x0040 0000
Attribute Memory Mode Space
Offset 0x0000 0000
Note:
The A22 pin is used to drive the REG signal of the CompactFlash Device (except in True IDE
mode).
Table 20-5.
A[23:21]
20.6.6.2
CompactFlash Mode Selection
Mode Base Address
000
Attribute Memory
010
Common Memory
100
I/O Mode
110
True IDE Mode
111
Alternate True IDE Mode
CFCE1 and CFCE2 Signals
To cover all types of access, the SMC must be alternatively set to drive 8-bit data bus or 16-bit
data bus. The odd byte access on the D[7:0] bus is only possible when the SMC is configured to
drive 8-bit memory devices on the corresponding NCS pin (NCS4 or NCS5). The Chip Select
Register (DBW field in the corresponding Chip Select Register) of the NCS4 and/or NCS5
address space must be set as shown in Table 20-6 to enable the required access type.
NBS1 and NBS0 are the byte selection signals from SMC and are available when the SMC is set
in Byte Select mode on the corresponding Chip Select.
144
AT91SAM9G20
6384E–ATARM–05-Feb-10
AT91SAM9G20
The CFCE1 and CFCE2 waveforms are identical to the corresponding NCSx waveform. For
details on these waveforms and timings, refer to the Static Memory Controller section.
Table 20-6.
CFCE1 and CFCE2 Truth Table
Mode
CFCE2
CFCE1
DBW
Comment
SMC Access Mode
NBS1
NBS0
16 bits
Access to Even Byte on D[7:0]
Byte Select
NBS1
NBS0
16bits
Access to Even Byte on D[7:0]
Access to Odd Byte on D[15:8]
Byte Select
1
0
8 bits
Access to Odd Byte on D[7:0]
NBS1
NBS0
16 bits
Access to Even Byte on D[7:0]
Access to Odd Byte on D[15:8]
1
0
8 bits
Access to Odd Byte on D[7:0]
Task File
1
0
8 bits
Access to Even Byte on D[7:0]
Access to Odd Byte on D[7:0]
Data Register
1
0
16 bits
Access to Even Byte on D[7:0]
Access to Odd Byte on D[15:8]
Byte Select
Control Register
Alternate Status Read
0
1
Don’t
Care
Access to Even Byte on D[7:0]
Don’t Care
Drive Address
0
1
8 bits
Access to Odd Byte on D[7:0]
1
1
–
Attribute Memory
Common Memory
I/O Mode
Byte Select
True IDE Mode
Alternate True IDE Mode
Standby Mode or
Address Space is not
assigned to CF
20.6.6.3
–
–
Read/Write Signals
In I/O mode and True IDE mode, the CompactFlash logic drives the read and write command
signals of the SMC on CFIOR and CFIOW signals, while the CFOE and CFWE signals are deactivated. Likewise, in common memory mode and attribute memory mode, the SMC signals are
driven on the CFOE and CFWE signals, while the CFIOR and CFIOW are deactivated. Figure
20-4 on page 146 demonstrates a schematic representation of this logic.
Attribute memory mode, common memory mode and I/O mode are supported by setting the
address setup and hold time on the NCS4 (and/or NCS5) chip select to the appropriate values.
145
6384E–ATARM–05-Feb-10
Figure 20-4. CompactFlash Read/Write Control Signals
External Bus Interface
SMC
CompactFlash Logic
A23
1
1
0
1
0
0
CFOE
CFWE
1
1
A22
NRD_NOE
NWR0_NWE
0
1
1
Table 20-7.
CFIOR
CFIOW
1
CompactFlash Mode Selection
Mode Base Address
CFOE
CFWE
CFIOR
CFIOW
NRD
NWR0_NWE
1
1
I/O Mode
1
1
NRD
NWR0_NWE
True IDE Mode
0
1
NRD
NWR0_NWE
Attribute Memory
Common Memory
20.6.6.4
Multiplexing of CompactFlash Signals on EBI Pins
Table 20-8 on page 146 and Table 20-9 on page 147 illustrate the multiplexing of the CompactFlash logic signals with other EBI signals on the EBI pins. The EBI pins in Table 20-8 are strictly
dedicated to the CompactFlash interface as soon as the EBI_CS4A and/or EBI_CS5A field of
the EBI_CSA Register in the Chip Configuration User Interface is set. These pins must not be
used to drive any other memory devices.
The EBI pins in Table 20-9 on page 147 remain shared between all memory areas when the corresponding CompactFlash interface is enabled (EBI_CS4A = 1 and/or EBI_CS5A = 1).
Table 20-8.
Dedicated CompactFlash Interface Multiplexing
CompactFlash Signals
EBI Signals
Pins
CS4A = 1
NCS4/CFCS0
CFCS0
NCS5/CFCS1
146
CS5A = 1
CS4A = 0
CS5A = 0
NCS4
CFCS1
NCS5
AT91SAM9G20
6384E–ATARM–05-Feb-10
AT91SAM9G20
Table 20-9.
Shared CompactFlash Interface Multiplexing
Access to CompactFlash Device
Access to Other EBI Devices
Pins
CompactFlash Signals
EBI Signals
NRD/CFOE
CFOE
NRD
NWR0/NWE/CFWE
CFWE
NWR0/NWE
NWR1/NBS1/CFIOR
CFIOR
NWR1/NBS1
NWR3/NBS3/CFIOW
CFIOW
NWR3/NBS3
A25/CFRNW
CFRNW
A25
20.6.6.5
Application Example
Figure 20-5 on page 148 illustrates an example of a CompactFlash application. CFCS0 and
CFRNW signals are not directly connected to the CompactFlash slot 0, but do control the direction and the output enable of the buffers between the EBI and the CompactFlash Device. The
timing of the CFCS0 signal is identical to the NCS4 signal. Moreover, the CFRNW signal
remains valid throughout the transfer, as does the address bus. The CompactFlash _WAIT signal is connected to the NWAIT input of the Static Memory Controller. For details on these
waveforms and timings, refer to the section “Static Memory Controller (SMC)”.
147
6384E–ATARM–05-Feb-10
Figure 20-5. CompactFlash Application Example
EBI
CompactFlash Connector
D[15:0]
D[15:0]
DIR /OE
A25/CFRNW
NCS4/CFCS0
_CD1
CD (PIO)
_CD2
/OE
20.6.7
20.6.7.1
A[10:0]
A[10:0]
A22/REG
_REG
NOE/CFOE
_OE
NWE/CFWE
_WE
NWR1/CFIOR
_IORD
NWR3/CFIOW
_IOWR
CFCE1
_CE1
CFCE2
_CE2
NWAIT
_WAIT
NAND Flash Support
The External Bus Interface integrates circuitry that interfaces to NAND Flash devices.
External Bus Interface
The NAND Flash logic is driven by the Static Memory Controller on the NCS3 address space.
Programming the EBI_CS3A field in the EBI_CSA Register in the Chip Configuration User Interface to the appropriate value enables the NAND Flash logic. For details on this register, refer to
the section “AT91SAM9G20 Bus Matrix”. Access to an external NAND Flash device is then
made by accessing the address space reserved to NCS3 (i.e., between 0x4000 0000 and
0x4FFF FFFF).
The NAND Flash Logic drives the read and write command signals of the SMC on the NANDOE
and NANDWE signals when the NCS3 signal is active. NANDOE and NANDWE are invalidated
as soon as the transfer address fails to lie in the NCS3 address space. See Figure 20-6 on page
149 for more information. For details on the waveforms, refer to the section “Static Memory Controller (SMC)”.
148
AT91SAM9G20
6384E–ATARM–05-Feb-10
AT91SAM9G20
Figure 20-6. NAND Flash Signal Multiplexing on EBI Pins
SMC
NAND Flash Logic
NANDOE
NCSx
NRD_NOE
NANDWE
NANDOE
NANDWE
NWR0_NWE
20.6.7.2
NAND Flash Signals
The address latch enable and command latch enable signals on the NAND Flash device are
driven by address bits A22 and A21 of the EBI address bus. The command, address or data
words on the data bus of the NAND Flash device are distinguished by using their address within
the NCSx address space. The chip enable (CE) signal of the device and the ready/busy (R/B)
signals are connected to PIO lines. The CE signal then remains asserted even when NCSx is
not selected, preventing the device from returning to standby mode.
Figure 20-7. NAND Flash Application Example
D[7:0]
AD[7:0]
A[22:21]
ALE
CLE
NCSx/NANDCS
Not Connected
NAND Flash
EBI
NANDOE
NANDWE
Note:
NOE
NWE
PIO
CE
PIO
R/B
The External Bus Interface is also able to support 16-bit devices.
149
6384E–ATARM–05-Feb-10
20.7
Implementation Examples
The following hardware configurations are given for illustration only. The user should refer to the
memory manufacturer web site to check current device availability.
20.7.1
16-bit SDRAM
Hardware Configuration
D[0..15]
A[0..14]
(Not used A12)
U1
A2
A3
A4
A5
A6
A7
A8
A9
A10
A11
A13
SDA10
BA0
BA1
SDA10
BA0
BA1
A14
23
24
25
26
29
30
31
32
33
34
22
35
20
21
36
40
SDCKE
SDCK
A0
CFIOR_NBS1_NWR1
CAS
RAS
SDWE
SDCS_NCS1
SDCKE
37
SDCK
38
15
39
CAS
RAS
17
18
SDWE
16
19
A0 MT48LC16M16A2 DQ0
A1
DQ1
A2
DQ2
A3
DQ3
A4
DQ4
A5
DQ5
A6
DQ6
A7
DQ7
A8
DQ8
A9
DQ9
A10
DQ10
A11
DQ11
DQ12
BA0
DQ13
BA1
DQ14
DQ15
A12
N.C
VDD
VDD
CKE
VDD
VDDQ
CLK
VDDQ
VDDQ
DQML
VDDQ
DQMH
VSS
CAS
VSS
RAS
VSS
VSSQ
VSSQ
WE
VSSQ
CS
VSSQ
2
4
5
7
8
10
11
13
42
44
45
47
48
50
51
53
1
14
27
3
9
43
49
D0
D1
D2
D3
D4
D5
D6
D7
D8
D9
D10
D11
D12
D13
D14
D15
3V3
C1
C2
C3
C4
C5
C6
C7
1
1
1
1
1
1
1
28
41
54
6
12
46
52
256 Mbits
TSOP54 PACKAGE
20.7.1.1
Software Configuration
The following configuration has to be performed:
• Assign the EBI CS1 to the SDRAM controller by setting the bit EBI_CS1A in the EBI Chip
Select Assignment Register located in the bus matrix memory space.
• Initialize the SDRAM Controller depending on the SDRAM device and system bus frequency.
The Data Bus Width is to be programmed to 16 bits.
The SDRAM initialization sequence is described in the “SDRAM device initialization” part of the
SDRAM controller.
150
AT91SAM9G20
6384E–ATARM–05-Feb-10
AT91SAM9G20
20.7.2
20.7.2.1
32-bit SDRAM
Hardware Configuration
D[0..31]
A[0..14]
U1
(Not used A12)
A2
A3
A4
A5
A6
A7
A8
A9
A10
A11
A13
SDA10
BA0
BA1
SDA10
BA0
BA1
A14
23
24
25
26
29
30
31
32
33
34
22
35
20
21
36
40
SDCKE
SDCK
A0
CFIOR_NBS1_NWR1
CAS
RAS
SDWE
SDCS_NCS1
SDCKE
37
SDCK
38
15
39
CAS
RAS
17
18
SDWE
16
19
U2
A0 MT48LC16M16A2 DQ0
A1
DQ1
A2
DQ2
A3
DQ3
A4
DQ4
A5
DQ5
A6
DQ6
A7
DQ7
A8
DQ8
A9
DQ9
A10
DQ10
A11
DQ11
DQ12
BA0
DQ13
BA1
DQ14
DQ15
A12
N.C
VDD
VDD
CKE
VDD
VDDQ
CLK
VDDQ
VDDQ
DQML
VDDQ
DQMH
VSS
CAS
VSS
RAS
VSS
VSSQ
VSSQ
WE
VSSQ
CS
VSSQ
2
4
5
7
8
10
11
13
42
44
45
47
48
50
51
53
1
14
27
3
9
43
49
28
41
54
6
12
46
52
D0
D1
D2
D3
D4
D5
D6
D7
D8
D9
D10
D11
D12
D13
D14
D15
3V3
A2
A3
A4
A5
A6
A7
A8
A9
A10
A11
SDA10
A13
BA0
BA1
A14
C1
C2
C3
C4
C5
C6
C7
100NF
100NF
100NF
100NF
100NF
100NF
100NF
A1
CFIOW_NBS3_NWR3
256 Mbits
23
24
25
26
29
30
31
32
33
34
22
35
20
21
36
40
SDCKE
37
SDCK
38
15
39
CAS
RAS
17
18
SDWE
16
19
A0 MT48LC16M16A2 DQ0
A1
DQ1
A2
DQ2
A3
DQ3
A4
DQ4
A5
DQ5
A6
DQ6
A7
DQ7
A8
DQ8
A9
DQ9
A10
DQ10
A11
DQ11
DQ12
BA0
DQ13
BA1
DQ14
DQ15
A12
N.C
VDD
VDD
CKE
VDD
VDDQ
CLK
VDDQ
VDDQ
DQML
VDDQ
DQMH
VSS
CAS
VSS
RAS
VSS
VSSQ
VSSQ
WE
VSSQ
CS
VSSQ
2
4
5
7
8
10
11
13
42
44
45
47
48
50
51
53
1
14
27
3
9
43
49
D16
D17
D18
D19
D20
D21
D22
D23
D24
D25
D26
D27
D28
D29
D30
D31
3V3
C8
C9
C10
C11
C12
C13
C14
100NF
100NF
100NF
100NF
100NF
100NF
100NF
28
41
54
6
12
46
52
256 Mbits
TSOP54 PACKAGE
20.7.2.2
Software Configuration
The following configuration has to be performed:
• Assign the EBI CS1 to the SDRAM controller by setting the bit EBI_CS1A in the EBI Chip
Select Assignment Register located in the bus matrix memory space.
• Initialize the SDRAM Controller depending on the SDRAM device and system bus frequency.
The Data Bus Width is to be programmed to 32 bits. The data lines D[16..31] are multiplexed
with PIO lines and thus the dedicated PIOs must be programmed in peripheral mode in the PIO
controller.
The SDRAM initialization sequence is described in the “SDRAM device initialization” part of the
SDRAM controller.
151
6384E–ATARM–05-Feb-10
20.7.3
8-bit NAND Flash
Figure 20-8. Hardware Configuration
D[0..7]
U1
CLE
ALE
NANDOE
NANDWE
(ANY PIO)
(ANY PIO)
R1
3V3
R2
10K
16
17
8
18
9
CLE
ALE
RE
WE
CE
7
R/B
19
WP
10K
1
2
3
4
5
6
10
11
14
15
20
21
22
23
24
25
26
K9F2G08U0M
N.C
N.C
N.C
N.C
N.C
N.C
N.C
N.C
N.C
N.C
N.C
N.C
N.C
N.C
N.C
N.C
N.C
2 Gb
I/O0
I/O1
I/O2
I/O3
I/O4
I/O5
I/O6
I/O7
29
30
31
32
41
42
43
44
N.C
N.C
N.C
N.C
N.C
N.C
PRE
N.C
N.C
N.C
N.C
N.C
48
47
46
45
40
39
38
35
34
33
28
27
VCC
VCC
37
12
VSS
VSS
36
13
D0
D1
D2
D3
D4
D5
D6
D7
3V3
C2
100NF
C1
100NF
TSOP48 PACKAGE
20.7.3.1
Software Configuration
The following configuration has to be performed:
• Assign the EBI CS3 to the NAND Flash by setting the bit EBI_CS3A in the EBI Chip Select
Assignment Register located in the bus matrix memory space
• Reserve A21 / A22 for ALE / CLE functions. Address and Command Latches are controlled
respectively by setting to 1 the address bit A21 and A22 during accesses.
• Configure a PIO line as an input to manage the Ready/Busy signal.
• Configure Static Memory Controller CS3 Setup, Pulse, Cycle and Mode accordingly to NAND
Flash timings, the data bus width and the system bus frequency.
152
AT91SAM9G20
6384E–ATARM–05-Feb-10
AT91SAM9G20
20.7.4
16-bit NAND Flash
Figure 20-9. Hardware Configuration
D[0..15]
U1
CLE
ALE
NANDOE
NANDWE
(ANY PIO)
(ANY PIO)
R1
3V3
R2
10K
16
17
8
18
9
CLE
ALE
RE
WE
CE
7
R/B
19
WP
1
2
3
4
5
6
10
11
14
15
20
21
22
23
24
34
35
N.C
N.C
N.C
N.C
N.C
N.C
N.C
N.C
N.C
N.C
N.C
N.C
N.C
N.C
N.C
N.C
N.C
10K
MT29F2G16AABWP-ET
I/O0 26
I/O1 28
I/O2 30
I/O3 32
I/O4 40
I/O5 42
I/O6 44
I/O7 46
I/O8 27
I/O9 29
I/O10 31
I/O11 33
I/O12 41
I/O13 43
I/O14 45
I/O15 47
2 Gb
N.C
PRE
N.C
39
38
36
VCC
VCC
37
12
VSS
VSS
VSS
48
25
13
D0
D1
D2
D3
D4
D5
D6
D7
D8
D9
D10
D11
D12
D13
D14
D15
3V3
C2
100NF
C1
100NF
TSOP48 PACKAGE
20.7.4.1
Software Configuration
The software configuration is the same as for an 8-bit NAND Flash except the data bus width
programmed in the mode register of the Static Memory Controller.
153
6384E–ATARM–05-Feb-10
20.7.5
NOR Flash on NCS0
Figure 20-10. Hardware Configuration
D[0..15]
A[1..22]
U1
A1
A2
A3
A4
A5
A6
A7
A8
A9
A10
A11
A12
A13
A14
A15
A16
A17
A18
A19
A20
A21
A22
NRST
NWE
3V3
NCS0
NRD
25
24
23
22
21
20
19
18
8
7
6
5
4
3
2
1
48
17
16
15
10
9
A0
A1
A2
A3
A4
A5
A6
A7
A8
A9
A10
A11
A12
A13
A14
A15
A16
A17
A18
A19
A20
A21
12
11
14
13
26
28
RESET
WE
WP
VPP
CE
OE
DQ0
DQ1
DQ2
DQ3
DQ4
DQ5
DQ6
DQ7
DQ8
DQ9
DQ10
DQ11
DQ12
DQ13
DQ14
DQ15
D0
D1
D2
D3
D4
D5
D6
D7
D8
D9
D10
D11
D12
D13
D14
D15
AT49BV6416
3V3
VCCQ
47
VCC
37
VSS
VSS
46
27
TSOP48 PACKAGE
20.7.5.1
29
31
33
35
38
40
42
44
30
32
34
36
39
41
43
45
C2
100NF
C1
100NF
Software Configuration
The default configuration for the Static Memory Controller, byte select mode, 16-bit data bus,
Read/Write controlled by Chip Select, allows boot on 16-bit non-volatile memory at slow clock.
For another configuration, configure the Static Memory Controller CS0 Setup, Pulse, Cycle and
Mode depending on Flash timings and system bus frequency.
154
AT91SAM9G20
6384E–ATARM–05-Feb-10
AT91SAM9G20
20.7.6
20.7.6.1
Compact Flash
Hardware Configuration
MEMORY & I/O MODE
D[0..15]
MN1A
D15
D14
D13
D12
D11
D10
D9
D8
A2
A1
B2
B1
C2
C1
D2
D1
1B1
1B2
1B3
1B4
1B5
1B6
1B7
1B8
A3
A4
1DIR
1OE
J1
1A1
1A2
1A3
1A4
1A5
1A6
1A7
1A8
A5
A6
B5
B6
C5
C6
D5
D6
CF_D15
CF_D14
CF_D13
CF_D12
CF_D11
CF_D10
CF_D9
CF_D8
E5
E6
F5
F6
G5
G6
H5
H6
CF_D7
CF_D6
CF_D5
CF_D4
CF_D3
CF_D2
CF_D1
CF_D0
74ALVCH32245
MN1B
D7
D6
D5
D4
D3
D2
D1
D0
A25/CFRNW
4
CFCSx
(CFCS0 or CFCS1)
6
5
E2
E1
F2
F1
G2
G1
H2
H1
2B1
2B2
2B3
2B4
2B5
2B6
2B7
2B8
H3
H4
2DIR
2OE
2A1
2A2
2A3
2A4
2A5
2A6
2A7
2A8
3V3
R1
MN2A
47K
SN74ALVC32
74ALVCH32245
MN2B
SN74ALVC32
R2
47K
CD2
1
3
(ANY PIO)
CD1
2
CF_D15
CF_D14
CF_D13
CF_D12
CF_D11
CF_D10
CF_D9
CF_D8
CF_D7
CF_D6
CF_D5
CF_D4
CF_D3
CF_D2
CF_D1
CF_D0
31
30
29
28
27
49
48
47
6
5
4
3
2
23
22
21
D15
D14
D13
D12
D11
D10
D9
D8
D7
D6
D5
D4
D3
D2
D1
D0
CD2
CD1
25
26
CD2#
CD1#
CF_A10
CF_A9
CF_A8
CF_A7
CF_A6
CF_A5
CF_A4
CF_A3
CF_A2
CF_A1
CF_A0
8
10
11
12
14
15
16
17
18
19
20
A10
A9
A8
A7
A6
A5
A4
A3
A2
A1
A0
REG
44
REG#
WE
OE
IOWR
IORD
36
9
35
34
WE#
OE#
IOWR#
IORD#
MN1C
A[0..10]
A10
A9
A8
A7
A6
A5
A4
A3
J5
J6
K5
K6
L5
L6
M5
M6
J3
J4
3V3
3A1
3A2
3A3
3A4
3A5
3A6
3A7
3A8
3B1
3B2
3B3
3B4
3B5
3B6
3B7
3B8
J2
J1
K2
K1
L2
L1
M2
M1
CF_A10
CF_A9
CF_A8
CF_A7
CF_A6
CF_A5
CF_A4
CF_A3
CE2
CE1
3DIR
3OE
74ALVCH32245
MN1D
A2
A1
A0
A22/REG
CFWE
CFOE
CFIOW
CFIOR
N5
N6
P5
P6
R5
R6
T6
T5
4A1
4A2
4A3
4A4
4A5
4A6
4A7
4A8
T3
T4
4DIR
4OE
4B1
4B2
4B3
4B4
4B5
4B6
4B7
4B8
N2
N1
P2
P1
R2
R1
T1
T2
CF_A2
CF_A1
CF_A0
REG
WE
OE
IOWR
IORD
VCC
38
VCC
13
GND
GND
50
1
CSEL#
39
INPACK#
43
BVD2
BVD1
45
46
32
7
CE2#
CE1#
24
WP
WAIT#
42
WAIT#
VS2#
VS1#
40
33
RESET
41
RESET
RDY/BSY
37
3V3
C1
100NF
C2
100NF
RDY/BSY
N7E50-7516VY-20
1
74ALVCH32245
2
CFCE1
5
10
4
CFCE2
9
(ANY PIO)
CFIRQ
11
13
(ANY PIO)
CFRST
MN3A
SN74ALVC125
3
CE2
MN3B
SN74ALVC125
6
CE1
MN3C
SN74ALVC125
RESET
8
MN3D
R3
SN74ALVC125
10K
RDY/BSY
12
3V3
MN4
3V3
NWAIT
5 VCC
1
4
2
GND
R4
10K
WAIT#
3V3
3
SN74LVC1G125-Q1
155
6384E–ATARM–05-Feb-10
20.7.6.2
Software Configuration
The following configuration has to be performed:
• Assign the EBI CS4 and/or EBI_CS5 to the CompactFlash Slot 0 or/and Slot 1 by setting the
bit EBI_CS4A or/and EBI_CS5A in the EBI Chip Select Assignment Register located in the
bus matrix memory space.
• The address line A23 is to select I/O (A23=1) or Memory mode (A23=0) and the address line
A22 for REG function.
• A23, CFRNW, CFS0, CFCS1, CFCE1 and CFCE2 signals are multiplexed with PIO lines and
thus the dedicated PIOs must be programmed in peripheral mode in the PIO controller.
• Configure a PIO line as an output for CFRST and two others as an input for CFIRQ and
CARD DETECT functions respectively.
• Configure SMC CS4 and/or SMC_CS5 (for Slot 0 or 1) Setup, Pulse, Cycle and Mode
accordingly to Compact Flash timings and system bus frequency.
156
AT91SAM9G20
6384E–ATARM–05-Feb-10
AT91SAM9G20
20.7.7
20.7.7.1
Compact Flash True IDE
Hardware Configuration
TRUE IDE MODE
D[0..15]
MN1A
D15
D14
D13
D12
D11
D10
D9
D8
A2
A1
B2
B1
C2
C1
D2
D1
A3
A4
1B1
1B2
1B3
1B4
1B5
1B6
1B7
1B8
CF_D15
CF_D14
CF_D13
CF_D12
CF_D11
CF_D10
CF_D9
CF_D8
E5
E6
F5
F6
G5
G6
H5
H6
CF_D7
CF_D6
CF_D5
CF_D4
CF_D3
CF_D2
CF_D1
CF_D0
1DIR
1OE
74ALVCH32245
MN1B
D7
D6
D5
D4
D3
D2
D1
D0
A25/CFRNW
CFCSx
(CFCS0 or CFCS1)
4
6
5
E2
E1
F2
F1
G2
G1
H2
H1
2B1
2B2
2B3
2B4
2B5
2B6
2B7
2B8
H3
H4
2DIR
2OE
2A1
2A2
2A3
2A4
2A5
2A6
2A7
2A8
3V3
R1
MN2A
47K
SN74ALVC32
74ALVCH32245
MN2B
SN74ALVC32
CD2
1
CD1
2
J5
J6
K5
K6
L5
L6
M5
M6
3A1
3A2
3A3
3A4
3A5
3A6
3A7
3A8
J3
J4
3DIR
3OE
3V3
3B1
3B2
3B3
3B4
3B5
3B6
3B7
3B8
J2
J1
K2
K1
L2
L1
M2
M1
CF_A10
CF_A9
CF_A8
CF_A7
CF_A6
CF_A5
CF_A4
CF_A3
74ALVCH32245
MN1D
A2
A1
A0
A22/REG
CFWE
CFOE
CFIOW
CFIOR
N5
N6
P5
P6
R5
R6
T6
T5
4A1
4A2
4A3
4A4
4A5
4A6
4A7
4A8
T3
T4
4DIR
4OE
31
30
29
28
27
49
48
47
6
5
4
3
2
23
22
21
D15
D14
D13
D12
D11
D10
D9
D8
D7
D6
D5
D4
D3
D2
D1
D0
CD2
CD1
25
26
CD2#
CD1#
CF_A2
CF_A1
CF_A0
8
10
11
12
14
15
16
17
18
19
20
A10
A9
A8
A7
A6
A5
A4
A3
A2
A1
A0
44
REG#
IOWR
IORD
36
9
35
34
WE#
ATA SEL#
IOWR#
IORD#
CE2
CE1
32
7
CS1#
CS0#
3V3
MN1C
A10
A9
A8
A7
A6
A5
A4
A3
CF_D15
CF_D14
CF_D13
CF_D12
CF_D11
CF_D10
CF_D9
CF_D8
CF_D7
CF_D6
CF_D5
CF_D4
CF_D3
CF_D2
CF_D1
CF_D0
R2
47K
3
(ANY PIO)
A[0..10]
3V3
J1
1A1
1A2
1A3
1A4
1A5
1A6
1A7
1A8
A5
A6
B5
B6
C5
C6
D5
D6
4B1
4B2
4B3
4B4
4B5
4B6
4B7
4B8
N2
N1
P2
P1
R2
R1
T1
T2
CF_A2
CF_A1
CF_A0
REG
WE
OE
IOWR
IORD
24
IOIS16#
IORDY
42
IORDY
RESET#
41
VCC
38
VCC
13
GND
GND
50
1
CSEL#
39
INPACK#
43
DASP#
PDIAG#
45
46
VS2#
VS1#
40
33
INTRQ
37
RESET#
C1
100NF
C2
100NF
INTRQ
N7E50-7516VY-20
1
74ALVCH32245
2
CFCE1
5
10
4
CFCE2
9
(ANY PIO)
CFIRQ
11
13
(ANY PIO)
CFRST
MN3A
SN74ALVC125
3
CE2
MN3B
SN74ALVC125
6
CE1
MN3C
SN74ALVC125
RESET#
8
MN3D
SN74ALVC125
INTRQ
12
R3
10K
3V3
MN4
3V3
NWAIT
5 VCC
1
4
2
GND
R4
10K
IORDY
3V3
3
SN74LVC1G125-Q1
157
6384E–ATARM–05-Feb-10
20.7.7.2
Software Configuration
The following configuration has to be performed:
• Assign the EBI CS4 and/or EBI_CS5 to the CompactFlash Slot 0 or/and Slot 1 by setting the
bit EBI_CS4A or/and EBI_CS5A in the EBI Chip Select Assignment Register located in the
bus matrix memory space.
• The address line A21 is to select Alternate True IDE (A21=1) or True IDE (A21=0) modes.
• CFRNW, CFS0, CFCS1, CFCE1 and CFCE2 signals are multiplexed with PIO lines and thus
the dedicated PIOs must be programmed in peripheral mode in the PIO controller.
• Configure a PIO line as an output for CFRST and two others as an input for CFIRQ and
CARD DETECT functions respectively.
• Configure SMC CS4 and/or SMC_CS5 (for Slot 0 or 1) Setup, Pulse, Cycle and Mode
accordingly to Compact Flash timings and system bus frequency.
158
AT91SAM9G20
6384E–ATARM–05-Feb-10
AT91SAM9G20
21. Static Memory Controller (SMC)
21.1
Overview
The Static Memory Controller (SMC) generates the signals that control the access to the external memory devices or peripheral devices. It has 8 Chip Selects and a 26-bit address bus. The
32-bit data bus can be configured to interface with 8-, 16-, or 32-bit external devices. Separate
read and write control signals allow for direct memory and peripheral interfacing. Read and write
signal waveforms are fully parametrizable.
The SMC can manage wait requests from external devices to extend the current access. The
SMC is provided with an automatic slow clock mode. In slow clock mode, it switches from userprogrammed waveforms to slow-rate specific waveforms on read and write signals. The SMC
supports asynchronous burst read in page mode access for page size up to 32 bytes.
21.2
I/O Lines Description
Table 21-1.
I/O Line Description
Name
Description
Type
Active Level
NCS[7:0]
Static Memory Controller Chip Select Lines
Output
Low
NRD
Read Signal
Output
Low
NWR0/NWE
Write 0/Write Enable Signal
Output
Low
A0/NBS0
Address Bit 0/Byte 0 Select Signal
Output
Low
NWR1/NBS1
Write 1/Byte 1 Select Signal
Output
Low
A1/NWR2/NBS2
Address Bit 1/Write 2/Byte 2 Select Signal
Output
Low
NWR3/NBS3
Write 3/Byte 3 Select Signal
Output
Low
A[25:2]
Address Bus
Output
D[31:0]
Data Bus
NWAIT
External Wait Signal
21.3
I/O
Input
Low
Multiplexed Signals
Table 21-2.
Static Memory Controller (SMC) Multiplexed Signals
Multiplexed Signals
Related Function
NWR0
NWE
Byte-write or byte-select access, see “Byte Write or Byte Select Access” on page 161
A0
NBS0
8-bit or 16-/32-bit data bus, see “Data Bus Width” on page 161
NWR1
NBS1
Byte-write or byte-select access see “Byte Write or Byte Select Access” on page 161
A1
NWR2
NWR3
NBS3
NBS2
8-/16-bit or 32-bit data bus, see “Data Bus Width” on page 161.
Byte-write or byte-select access, see “Byte Write or Byte Select Access” on page 161
Byte-write or byte-select access see “Byte Write or Byte Select Access” on page 161
159
6384E–ATARM–05-Feb-10
21.4
21.4.1
Application Example
Hardware Interface
Figure 21-1. SMC Connections to Static Memory Devices
D0-D31
A0/NBS0
NWR0/NWE
NWR1/NBS1
A1/NWR2/NBS2
NWR3/NBS3
D0 - D7
128K x 8
SRAM
D8-D15
D0 - D7
CS
NRD
NWR0/NWE
A2 - A25
A2 - A18
A0 - A16
NRD
OE
NWR1/NBS1
WE
128K x 8
SRAM
D16 - D23
D24-D31
D0 - D7
A0 - A16
NRD
Static Memory
Controller
21.5
21.5.1
A2 - A18
OE
WE
128K x 8
SRAM
D0-D7
CS
CS
A1/NWR2/NBS2
D0-D7
CS
A0 - A16
NCS0
NCS1
NCS2
NCS3
NCS4
NCS5
NCS6
NCS7
128K x 8
SRAM
A2 - A18
A2 - A18
A0 - A16
NRD
OE
WE
OE
NWR3/NBS3
WE
Product Dependencies
I/O Lines
The pins used for interfacing the Static Memory Controller may be multiplexed with the PIO
lines. The programmer must first program the PIO controller to assign the Static Memory Controller pins to their peripheral function. If I/O Lines of the SMC are not used by the application,
they can be used for other purposes by the PIO Controller.
160
AT91SAM9G20
6384E–ATARM–05-Feb-10
AT91SAM9G20
21.6
External Memory Mapping
The SMC provides up to 26 address lines, A[25:0]. This allows each chip select line to address
up to 64 Mbytes of memory.
If the physical memory device connected on one chip select is smaller than 64 Mbytes, it wraps
around and appears to be repeated within this space. The SMC correctly handles any valid
access to the memory device within the page (see Figure 21-2).
A[25:0] is only significant for 8-bit memory, A[25:1] is used for 16-bit memory, A[25:2] is used for
32-bit memory.
Figure 21-2.
Memory Connections for Eight External Devices
NCS[0] - NCS[7]
NCS7
NRD
SMC
NCS6
NWE
NCS5
A[25:0]
NCS4
D[31:0]
NCS3
NCS2
NCS1
NCS0
Memory Enable
Memory Enable
Memory Enable
Memory Enable
Memory Enable
Memory Enable
Memory Enable
Memory Enable
Output Enable
Write Enable
A[25:0]
8 or 16 or 32
21.7
21.7.1
D[31:0] or D[15:0] or
D[7:0]
Connection to External Devices
Data Bus Width
A data bus width of 8, 16, or 32 bits can be selected for each chip select. This option is controlled by the field DBW in SMC_MODE (Mode Register) for the corresponding chip select.
Figure 21-3 shows how to connect a 512K x 8-bit memory on NCS2. Figure 21-4 shows how to
connect a 512K x 16-bit memory on NCS2. Figure 21-5 shows two 16-bit memories connected
as a single 32-bit memory
21.7.2
Byte Write or Byte Select Access
Each chip select with a 16-bit or 32-bit data bus can operate with one of two different types of
write access: byte write or byte select access. This is controlled by the BAT field of the
SMC_MODE register for the corresponding chip select.
161
6384E–ATARM–05-Feb-10
Figure 21-3.
Memory Connection for an 8-bit Data Bus
D[7:0]
D[7:0]
A[18:2]
A[18:2]
SMC
A0
A0
A1
A1
NWE
Write Enable
NRD
Output Enable
NCS[2]
Figure 21-4.
Memory Enable
Memory Connection for a 16-bit Data Bus
D[15:0]
D[15:0]
A[19:2]
A[18:1]
A1
SMC
A[0]
NBS0
Low Byte Enable
NBS1
High Byte Enable
NWE
Write Enable
NRD
Output Enable
NCS[2]
Memory Enable
Figure 21-5. Memory Connection for a 32-bit Data Bus
D[31:16]
SMC
D[15:0]
D[15:0]
A[20:2]
A[18:0]
NBS0
Byte 0 Enable
NBS1
Byte 1 Enable
NBS2
Byte 2 Enable
NBS3
Byte 3 Enable
NWE
Write Enable
NRD
Output Enable
NCS[2]
162
D[31:16]
Memory Enable
AT91SAM9G20
6384E–ATARM–05-Feb-10
AT91SAM9G20
21.7.2.1
Byte Write Access
Byte write access supports one byte write signal per byte of the data bus and a single read
signal.
Note that the SMC does not allow boot in Byte Write Access mode.
• For 16-bit devices: the SMC provides NWR0 and NWR1 write signals for respectively byte0
(lower byte) and byte1 (upper byte) of a 16-bit bus. One single read signal (NRD) is provided.
Byte Write Access is used to connect 2 x 8-bit devices as a 16-bit memory.
• For 32-bit devices: NWR0, NWR1, NWR2 and NWR3, are the write signals of byte0 (lower
byte), byte1, byte2 and byte 3 (upper byte) respectively. One single read signal (NRD) is
provided.
Byte Write Access is used to connect 4 x 8-bit devices as a 32-bit memory.
Byte Write option is illustrated on Figure 21-6.
21.7.2.2
Byte Select Access
In this mode, read/write operations can be enabled/disabled at a byte level. One byte-select line
per byte of the data bus is provided. One NRD and one NWE signal control read and write.
• For 16-bit devices: the SMC provides NBS0 and NBS1 selection signals for respectively
byte0 (lower byte) and byte1 (upper byte) of a 16-bit bus.
Byte Select Access is used to connect one 16-bit device.
• For 32-bit devices: NBS0, NBS1, NBS2 and NBS3, are the selection signals of byte0 (lower
byte), byte1, byte2 and byte 3 (upper byte) respectively. Byte Select Access is used to
connect two 16-bit devices.
Figure 21-7 shows how to connect two 16-bit devices on a 32-bit data bus in Byte Select Access
mode, on NCS3 (BAT = Byte Select Access).
163
6384E–ATARM–05-Feb-10
Figure 21-6.
Connection of 2 x 8-bit Devices on a 16-bit Bus: Byte Write Option
D[7:0]
D[7:0]
D[15:8]
A[24:2]
SMC
A1
NWR0
A[23:1]
A[0]
Write Enable
NWR1
NRD
NCS[3]
Read Enable
Memory Enable
D[15:8]
A[23:1]
A[0]
Write Enable
Read Enable
Memory Enable
21.7.2.3
Signal Multiplexing
Depending on the BAT, only the write signals or the byte select signals are used. To save IOs at
the external bus interface, control signals at the SMC interface are multiplexed. Table 21-3
shows signal multiplexing depending on the data bus width and the byte access type.
For 32-bit devices, bits A0 and A1 are unused. For 16-bit devices, bit A0 of address is unused.
When Byte Select Option is selected, NWR1 to NWR3 are unused. When Byte Write option is
selected, NBS0 to NBS3 are unused.
164
AT91SAM9G20
6384E–ATARM–05-Feb-10
AT91SAM9G20
Figure 21-7. Connection of 2x16-bit Data Bus on a 32-bit Data Bus (Byte Select Option)
D[15:0]
D[15:0]
D[31:16]
A[25:2]
A[23:0]
NWE
Write Enable
NBS0
Low Byte Enable
NBS1
High Byte Enable
NBS2
SMC
NBS3
Read Enable
NRD
Memory Enable
NCS[3]
D[31:16]
A[23:0]
Write Enable
Low Byte Enable
High Byte Enable
Read Enable
Memory Enable
Table 21-3.
SMC Multiplexed Signal Translation
Signal Name
Device Type
32-bit Bus
16-bit Bus
8-bit Bus
1x32-bit
2x16-bit
4 x 8-bit
1x16-bit
2 x 8-bit
Byte Select
Byte Select
Byte Write
Byte Select
Byte Write
NBS0_A0
NBS0
NBS0
NWE_NWR0
NWE
NWE
NWR0
NWE
NWR0
NBS1_NWR1
NBS1
NBS1
NWR1
NBS1
NWR1
NBS2_NWR2_A1
NBS2
NBS2
NWR2
A1
A1
NBS3_NWR3
NBS3
NBS3
NWR3
Byte Access Type (BAT)
21.8
NBS0
1 x 8-bit
A0
NWE
A1
Standard Read and Write Protocols
In the following sections, the byte access type is not considered. Byte select lines (NBS0 to
NBS3) always have the same timing as the A address bus. NWE represents either the NWE signal in byte select access type or one of the byte write lines (NWR0 to NWR3) in byte write
access type. NWR0 to NWR3 have the same timings and protocol as NWE. In the same way,
NCS represents one of the NCS[0..7] chip select lines.
165
6384E–ATARM–05-Feb-10
21.8.1
Read Waveforms
The read cycle is shown on Figure 21-8.
The read cycle starts with the address setting on the memory address bus, i.e.:
{A[25:2], A1, A0} for 8-bit devices
{A[25:2], A1} for 16-bit devices
A[25:2] for 32-bit devices.
Figure 21-8. Standard Read Cycle
MCK
A[25:2]
NBS0,NBS1,
NBS2,NBS3,
A0, A1
NRD
NCS
D[31:0]
NRD_SETUP
NCS_RD_SETUP
NRD_PULSE
NCS_RD_PULSE
NRD_HOLD
NCS_RD_HOLD
NRD_CYCLE
21.8.1.1
NRD Waveform
The NRD signal is characterized by a setup timing, a pulse width and a hold timing.
1. NRD_SETUP: the NRD setup time is defined as the setup of address before the NRD
falling edge;
2. NRD_PULSE: the NRD pulse length is the time between NRD falling edge and NRD
rising edge;
3. NRD_HOLD: the NRD hold time is defined as the hold time of address after the NRD
rising edge.
166
AT91SAM9G20
6384E–ATARM–05-Feb-10
AT91SAM9G20
21.8.1.2
NCS Waveform
Similarly, the NCS signal can be divided into a setup time, pulse length and hold time:
1. NCS_RD_SETUP: the NCS setup time is defined as the setup time of address before
the NCS falling edge.
2. NCS_RD_PULSE: the NCS pulse length is the time between NCS falling edge and
NCS rising edge;
3. NCS_RD_HOLD: the NCS hold time is defined as the hold time of address after the
NCS rising edge.
21.8.1.3
Read Cycle
The NRD_CYCLE time is defined as the total duration of the read cycle, i.e., from the time where
address is set on the address bus to the point where address may change. The total read cycle
time is equal to:
NRD_CYCLE = NRD_SETUP + NRD_PULSE + NRD_HOLD
= NCS_RD_SETUP + NCS_RD_PULSE + NCS_RD_HOLD
All NRD and NCS timings are defined separately for each chip select as an integer number of
Master Clock cycles. To ensure that the NRD and NCS timings are coherent, user must define
the total read cycle instead of the hold timing. NRD_CYCLE implicitly defines the NRD hold time
and NCS hold time as:
NRD_HOLD = NRD_CYCLE - NRD SETUP - NRD PULSE
NCS_RD_HOLD = NRD_CYCLE - NCS_RD_SETUP - NCS_RD_PULSE
21.8.1.4
Null Delay Setup and Hold
If null setup and hold parameters are programmed for NRD and/or NCS, NRD and NCS remain
active continuously in case of consecutive read cycles in the same memory (see Figure 21-9).
167
6384E–ATARM–05-Feb-10
Figure 21-9. No Setup, No Hold On NRD and NCS Read Signals
MCK
A[25:2]
NBS0,NBS1,
NBS2,NBS3,
A0, A1
NRD
NCS
D[31:0]
NRD_PULSE
NCS_RD_PULSE
NRD_CYCLE
21.8.1.5
NRD_PULSE
NCS_RD_PULSE
NRD_CYCLE
NRD_PULSE
NCS_RD_PULSE
NRD_CYCLE
Null Pulse
Programming null pulse is not permitted. Pulse must be at least set to 1. A null value leads to
unpredictable behavior.
21.8.2
Read Mode
As NCS and NRD waveforms are defined independently of one other, the SMC needs to know
when the read data is available on the data bus. The SMC does not compare NCS and NRD timings to know which signal rises first. The READ_MODE parameter in the SMC_MODE register
of the corresponding chip select indicates which signal of NRD and NCS controls the read
operation.
21.8.2.1
168
Read is Controlled by NRD (READ_MODE = 1):
Figure 21-10 shows the waveforms of a read operation of a typical asynchronous RAM. The
read data is available tPACC after the falling edge of NRD, and turns to ‘Z’ after the rising edge of
NRD. In this case, the READ_MODE must be set to 1 (read is controlled by NRD), to indicate
that data is available with the rising edge of NRD. The SMC samples the read data internally on
the rising edge of Master Clock that generates the rising edge of NRD, whatever the programmed waveform of NCS may be.
AT91SAM9G20
6384E–ATARM–05-Feb-10
AT91SAM9G20
Figure 21-10. READ_MODE = 1: Data is sampled by SMC before the rising edge of NRD
MCK
A[25:2]
NBS0,NBS1,
NBS2,NBS3,
A0, A1
NRD
NCS
tPACC
D[31:0]
Data Sampling
21.8.2.2
Read is Controlled by NCS (READ_MODE = 0)
Figure 21-11 shows the typical read cycle of an LCD module. The read data is valid tPACC after
the falling edge of the NCS signal and remains valid until the rising edge of NCS. Data must be
sampled when NCS is raised. In that case, the READ_MODE must be set to 0 (read is controlled
by NCS): the SMC internally samples the data on the rising edge of Master Clock that generates
the rising edge of NCS, whatever the programmed waveform of NRD may be.
Figure 21-11. READ_MODE = 0: Data is sampled by SMC before the rising edge of NCS
MCK
A[25:2]
NBS0,NBS1,
NBS2,NBS3,
A0, A1
NRD
NCS
tPACC
D[31:0]
Data Sampling
169
6384E–ATARM–05-Feb-10
21.8.3
21.8.3.1
Write Waveforms
The write protocol is similar to the read protocol. It is depicted in Figure 21-12. The write cycle
starts with the address setting on the memory address bus.
NWE Waveforms
The NWE signal is characterized by a setup timing, a pulse width and a hold timing.
1. NWE_SETUP: the NWE setup time is defined as the setup of address and data before
the NWE falling edge;
2. NWE_PULSE: The NWE pulse length is the time between NWE falling edge and NWE
rising edge;
3. NWE_HOLD: The NWE hold time is defined as the hold time of address and data after
the NWE rising edge.
The NWE waveforms apply to all byte-write lines in Byte Write access mode: NWR0 to NWR3.
21.8.3.2
NCS Waveforms
The NCS signal waveforms in write operation are not the same that those applied in read operations, but are separately defined:
1. NCS_WR_SETUP: the NCS setup time is defined as the setup time of address before
the NCS falling edge.
2. NCS_WR_PULSE: the NCS pulse length is the time between NCS falling edge and
NCS rising edge;
3. NCS_WR_HOLD: the NCS hold time is defined as the hold time of address after the
NCS rising edge.
Figure 21-12. Write Cycle
MCK
A[25:2]
NBS0, NBS1,
NBS2, NBS3,
A0, A1
NWE
NCS
NWE_SETUP
NCS_WR_SETUP
NWE_PULSE
NCS_WR_PULSE
NWE_HOLD
NCS_WR_HOLD
NWE_CYCLE
170
AT91SAM9G20
6384E–ATARM–05-Feb-10
AT91SAM9G20
21.8.3.3
Write Cycle
The write-cycle time is defined as the total duration of the write cycle, that is, from the time
where address is set on the address bus to the point where address may change. The total write
cycle time is equal to:
NWE_CYCLE = NWE_SETUP + NWE_PULSE + NWE_HOLD
= NCS_WR_SETUP + NCS_WR_PULSE + NCS_WR_HOLD
All NWE and NCS (write) timings are defined separately for each chip select as an integer number of Master Clock cycles. To ensure that the NWE and NCS timings are coherent, the user
must define the total write cycle instead of the hold timing. This implicitly defines the NWE hold
time and NCS (write) hold times as:
NWE_HOLD = NWE_CYCLE - NWE_SETUP - NWE_PULSE
NCS_WR_HOLD = NWE_CYCLE - NCS_WR_SETUP - NCS_WR_PULSE
21.8.3.4
Null Delay Setup and Hold
If null setup parameters are programmed for NWE and/or NCS, NWE and/or NCS remain active
continuously in case of consecutive write cycles in the same memory (see Figure 21-13). However, for devices that perform write operations on the rising edge of NWE or NCS, such as
SRAM, either a setup or a hold must be programmed.
Figure 21-13. Null Setup and Hold Values of NCS and NWE in Write Cycle
MCK
A[25:2]
NBS0, NBS1,
NBS2, NBS3,
A0, A1
NWE,
NWR0, NWR1,
NWR2, NWR3
NCS
D[31:0]
NWE_PULSE
21.8.3.5
NWE_PULSE
NWE_PULSE
NCS_WR_PULSE
NCS_WR_PULSE
NCS_WR_PULSE
NWE_CYCLE
NWE_CYCLE
NWE_CYCLE
Null Pulse
Programming null pulse is not permitted. Pulse must be at least set to 1. A null value leads to
unpredictable behavior.
171
6384E–ATARM–05-Feb-10
21.8.4
Write Mode
The WRITE_MODE parameter in the SMC_MODE register of the corresponding chip select indicates which signal controls the write operation.
21.8.4.1
Write is Controlled by NWE (WRITE_MODE = 1):
Figure 21-14 shows the waveforms of a write operation with WRITE_MODE set to 1. The data is
put on the bus during the pulse and hold steps of the NWE signal. The internal data buffers are
turned out after the NWE_SETUP time, and until the end of the write cycle, regardless of the
programmed waveform on NCS.
Figure 21-14. WRITE_MODE = 1. The write operation is controlled by NWE
MCK
A[25:2]
NBS0, NBS1,
NBS2, NBS3,
A0, A1
NWE,
NWR0, NWR1,
NWR2, NWR3
NCS
D[31:0]
21.8.4.2
172
Write is Controlled by NCS (WRITE_MODE = 0)
Figure 21-15 shows the waveforms of a write operation with WRITE_MODE set to 0. The data is
put on the bus during the pulse and hold steps of the NCS signal. The internal data buffers are
turned out after the NCS_WR_SETUP time, and until the end of the write cycle, regardless of
the programmed waveform on NWE.
AT91SAM9G20
6384E–ATARM–05-Feb-10
AT91SAM9G20
Figure 21-15. WRITE_MODE = 0. The write operation is controlled by NCS
MCK
A[25:2]
NBS0, NBS1,
NBS2, NBS3,
A0, A1
NWE,
NWR0, NWR1,
NWR2, NWR3
NCS
D[31:0]
21.8.5
Coding Timing Parameters
All timing parameters are defined for one chip select and are grouped together in one
SMC_REGISTER according to their type.
The SMC_SETUP register groups the definition of all setup parameters:
• NRD_SETUP, NCS_RD_SETUP, NWE_SETUP, NCS_WR_SETUP
The SMC_PULSE register groups the definition of all pulse parameters:
• NRD_PULSE, NCS_RD_PULSE, NWE_PULSE, NCS_WR_PULSE
The SMC_CYCLE register groups the definition of all cycle parameters:
• NRD_CYCLE, NWE_CYCLE
Table 21-4 shows how the timing parameters are coded and their permitted range.
Table 21-4.
Coding and Range of Timing Parameters
Permitted Range
Coded Value
Number of Bits
Effective Value
Coded Value
Effective Value
setup [5:0]
6
128 x setup[5] + setup[4:0]
0 ≤≤31
128 ≤≤128+31
pulse [6:0]
7
256 x pulse[6] + pulse[5:0]
0 ≤≤63
256 ≤≤256+63
cycle [8:0]
9
256 x cycle[8:7] + cycle[6:0]
0 ≤≤127
256 ≤≤256+127
512 ≤≤512+127
768 ≤≤768+127
173
6384E–ATARM–05-Feb-10
21.8.6
Reset Values of Timing Parameters
Table 21-8, “Register Mapping” gives the default value of timing parameters at reset.
21.8.7
Usage Restriction
The SMC does not check the validity of the user-programmed parameters. If the sum of SETUP
and PULSE parameters is larger than the corresponding CYCLE parameter, this leads to unpredictable behavior of the SMC.
For read operations:
Null but positive setup and hold of address and NRD and/or NCS can not be guaranteed at the
memory interface because of the propagation delay of theses signals through external logic and
pads. If positive setup and hold values must be verified, then it is strictly recommended to program non-null values so as to cover possible skews between address, NCS and NRD signals.
For write operations:
If a null hold value is programmed on NWE, the SMC can guarantee a positive hold of address,
byte select lines, and NCS signal after the rising edge of NWE. This is true for WRITE_MODE =
1 only. See “Early Read Wait State” on page 175.
For read and write operations: a null value for pulse parameters is forbidden and may lead to
unpredictable behavior.
In read and write cycles, the setup and hold time parameters are defined in reference to the
address bus. For external devices that require setup and hold time between NCS and NRD signals (read), or between NCS and NWE signals (write), these setup and hold times must be
converted into setup and hold times in reference to the address bus.
21.9
Automatic Wait States
Under certain circumstances, the SMC automatically inserts idle cycles between accesses to
avoid bus contention or operation conflict.
21.9.1
Chip Select Wait States
The SMC always inserts an idle cycle between 2 transfers on separate chip selects. This idle
cycle ensures that there is no bus contention between the de-activation of one device and the
activation of the next one.
During chip select wait state, all control lines are turned inactive: NBS0 to NBS3, NWR0 to
NWR3, NCS[0..7], NRD lines are all set to 1.
Figure 21-16 illustrates a chip select wait state between access on Chip Select 0 and Chip
Select 2.
174
AT91SAM9G20
6384E–ATARM–05-Feb-10
AT91SAM9G20
Figure 21-16. Chip Select Wait State between a Read Access on NCS0 and a Write Access on
NCS2
MCK
A[25:2]
NBS0, NBS1,
NBS2, NBS3,
A0,A1
NRD
NWE
NCS0
NCS2
NRD_CYCLE
NWE_CYCLE
D[31:0]
Read to Write Chip Select
Wait State
Wait State
21.9.2
Early Read Wait State
In some cases, the SMC inserts a wait state cycle between a write access and a read access to
allow time for the write cycle to end before the subsequent read cycle begins. This wait state is
not generated in addition to a chip select wait state. The early read cycle thus only occurs
between a write and read access to the same memory device (same chip select).
An early read wait state is automatically inserted if at least one of the following conditions is
valid:
• if the write controlling signal has no hold time and the read controlling signal has no setup
time (Figure 21-18).
• in NCS write controlled mode (WRITE_MODE = 0), if there is no hold timing on the NCS
signal and the NCS_RD_SETUP parameter is set to 0, regardless of the read mode (Figure
21-19). The write operation must end with a NCS rising edge. Without an Early Read Wait
State, the write operation could not complete properly.
• in NWE controlled mode (WRITE_MODE = 1) and if there is no hold timing (NWE_HOLD =
0), the feedback of the write control signal is used to control address, data, chip select and
byte select lines. If the external write control signal is not inactivated as expected due to load
capacitances, an Early Read Wait State is inserted and address, data and control signals are
maintained one more cycle. See Figure 21-20.
Figure 21-17.
175
6384E–ATARM–05-Feb-10
Figure 21-18. Early Read Wait State: Write with No Hold Followed by Read with No Setup
MCK
A[25:2]
NBS0, NBS1,
NBS2, NBS3,
A0, A1
NWE
NRD
no hold
no setup
D[31:0]
write cycle
Early Read
wait state
read cycle
Figure 21-19. Early Read Wait State: NCS Controlled Write with No Hold Followed by a Read with No NCS Setup
MCK
A[25:2]
NBS0, NBS1,
NBS2, NBS3,
A0,A1
NCS
NRD
no hold
no setup
D[31:0]
write cycle
(WRITE_MODE = 0)
176
Early Read
wait state
read cycle
(READ_MODE = 0 or READ_MODE = 1)
AT91SAM9G20
6384E–ATARM–05-Feb-10
AT91SAM9G20
Figure 21-20. Early Read Wait State: NWE-controlled Write with No Hold Followed by a Read with one Set-up Cycle
MCK
A[25:2]
NBS0, NBS1,
NBS2, NBS3,
A0, A1
internal write controlling signal
external write controlling signal
(NWE)
no hold
read setup = 1
NRD
D[31:0]
write cycle
(WRITE_MODE = 1)
21.9.3
Early Read
wait state
read cycle
(READ_MODE = 0 or READ_MODE = 1)
Reload User Configuration Wait State
The user may change any of the configuration parameters by writing the SMC user interface.
When detecting that a new user configuration has been written in the user interface, the SMC
inserts a wait state before starting the next access. The so called “Reload User Configuration
Wait State” is used by the SMC to load the new set of parameters to apply to next accesses.
The Reload Configuration Wait State is not applied in addition to the Chip Select Wait State. If
accesses before and after re-programming the user interface are made to different devices
(Chip Selects), then one single Chip Select Wait State is applied.
On the other hand, if accesses before and after writing the user interface are made to the same
device, a Reload Configuration Wait State is inserted, even if the change does not concern the
current Chip Select.
21.9.3.1
User Procedure
To insert a Reload Configuration Wait State, the SMC detects a write access to any
SMC_MODE register of the user interface. If the user only modifies timing registers
(SMC_SETUP, SMC_PULSE, SMC_CYCLE registers) in the user interface, he must validate
the modification by writing the SMC_MODE, even if no change was made on the mode
parameters.
21.9.3.2
Slow Clock Mode Transition
A Reload Configuration Wait State is also inserted when the Slow Clock Mode is entered or
exited, after the end of the current transfer (see “Slow Clock Mode” on page 189).
177
6384E–ATARM–05-Feb-10
21.9.4
Read to Write Wait State
Due to an internal mechanism, a wait cycle is always inserted between consecutive read and
write SMC accesses.
This wait cycle is referred to as a read to write wait state in this document.
This wait cycle is applied in addition to chip select and reload user configuration wait states
when they are to be inserted. See Figure 21-16 on page 175.
178
AT91SAM9G20
6384E–ATARM–05-Feb-10
AT91SAM9G20
21.10 Data Float Wait States
Some memory devices are slow to release the external bus. For such devices, it is necessary to
add wait states (data float wait states) after a read access:
• before starting a read access to a different external memory
• before starting a write access to the same device or to a different external one.
The Data Float Output Time (t DF ) for each external memory device is programmed in the
TDF_CYCLES field of the SMC_MODE register for the corresponding chip select. The value of
TDF_CYCLES indicates the number of data float wait cycles (between 0 and 15) before the
external device releases the bus, and represents the time allowed for the data output to go to
high impedance after the memory is disabled.
Data float wait states do not delay internal memory accesses. Hence, a single access to an
external memory with long t DF will not slow down the execution of a program from internal
memory.
The data float wait states management depends on the READ_MODE and the TDF_MODE
fields of the SMC_MODE register for the corresponding chip select.
21.10.1
READ_MODE
Setting the READ_MODE to 1 indicates to the SMC that the NRD signal is responsible for turning off the tri-state buffers of the external memory device. The Data Float Period then begins
after the rising edge of the NRD signal and lasts TDF_CYCLES MCK cycles.
When the read operation is controlled by the NCS signal (READ_MODE = 0), the TDF field gives
the number of MCK cycles during which the data bus remains busy after the rising edge of NCS.
Figure 21-21 illustrates the Data Float Period in NRD-controlled mode (READ_MODE =1),
assuming a data float period of 2 cycles (TDF_CYCLES = 2). Figure 21-22 shows the read operation when controlled by NCS (READ_MODE = 0) and the TDF_CYCLES parameter equals 3.
179
6384E–ATARM–05-Feb-10
Figure 21-21. TDF Period in NRD Controlled Read Access (TDF = 2)
MCK
A[25:2]
NBS0, NBS1,
NBS2, NBS3,
A0, A1
NRD
NCS
tpacc
D[31:0]
TDF = 2 clock cycles
NRD controlled read operation
Figure 21-22. TDF Period in NCS Controlled Read Operation (TDF = 3)
MCK
A[25:2]
NBS0, NBS1,
NBS2, NBS3,
A0,A1
NRD
NCS
tpacc
D[31:0]
TDF = 3 clock cycles
NCS controlled read operation
180
AT91SAM9G20
6384E–ATARM–05-Feb-10
AT91SAM9G20
21.10.2
TDF Optimization Enabled (TDF_MODE = 1)
When the TDF_MODE of the SMC_MODE register is set to 1 (TDF optimization is enabled), the
SMC takes advantage of the setup period of the next access to optimize the number of wait
states cycle to insert.
Figure 21-23 shows a read access controlled by NRD, followed by a write access controlled by
NWE, on Chip Select 0. Chip Select 0 has been programmed with:
NRD_HOLD = 4; READ_MODE = 1 (NRD controlled)
NWE_SETUP = 3; WRITE_MODE = 1 (NWE controlled)
TDF_CYCLES = 6; TDF_MODE = 1 (optimization enabled).
Figure 21-23. TDF Optimization: No TDF wait states are inserted if the TDF period is over when the next access begins
MCK
A[25:2]
NRD
NRD_HOLD= 4
NWE
NWE_SETUP= 3
NCS0
TDF_CYCLES = 6
D[31:0]
read access on NCS0 (NRD controlled)
21.10.3
Read to Write
Wait State
write access on NCS0 (NWE controlled)
TDF Optimization Disabled (TDF_MODE = 0)
When optimization is disabled, tdf wait states are inserted at the end of the read transfer, so that
the data float period is ended when the second access begins. If the hold period of the read1
controlling signal overlaps the data float period, no additional tdf wait states will be inserted.
Figure 21-24, Figure 21-25 and Figure 21-26 illustrate the cases:
• read access followed by a read access on another chip select,
• read access followed by a write access on another chip select,
• read access followed by a write access on the same chip select,
with no TDF optimization.
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Figure 21-24. TDF Optimization Disabled (TDF Mode = 0). TDF wait states between 2 read accesses on different chip
selects
MCK
A[25:2]
NBS0, NBS1,
NBS2, NBS3,
A0, A1
read1 controlling signal
(NRD)
read1 hold = 1
read2 controlling signal
(NRD)
read2 setup = 1
TDF_CYCLES = 6
D[31:0]
5 TDF WAIT STATES
read 2 cycle
TDF_MODE = 0
(optimization disabled)
read1 cycle
TDF_CYCLES = 6
Chip Select Wait State
Figure 21-25. TDF Mode = 0: TDF wait states between a read and a write access on different chip selects
MCK
A[25:2]
NBS0, NBS1,
NBS2, NBS3,
A0, A1
read1 controlling signal
(NRD)
read1 hold = 1
write2 controlling signal
(NWE)
write2 setup = 1
TDF_CYCLES = 4
D[31:0]
2 TDF WAIT STATES
read1 cycle
TDF_CYCLES = 4
Read to Write Chip Select
Wait State Wait State
182
write2 cycle
TDF_MODE = 0
(optimization disabled)
AT91SAM9G20
6384E–ATARM–05-Feb-10
AT91SAM9G20
Figure 21-26. TDF Mode = 0: TDF wait states between read and write accesses on the same chip select
MCK
A[25:2]
NBS0, NBS1,
NBS2, NBS3,
A0, A1
read1 controlling signal
(NRD)
write2 setup = 1
read1 hold = 1
write2 controlling signal
(NWE)
TDF_CYCLES = 5
D[31:0]
4 TDF WAIT STATES
read1 cycle
TDF_CYCLES = 5
Read to Write
Wait State
write2 cycle
TDF_MODE = 0
(optimization disabled)
21.11 External Wait
Any access can be extended by an external device using the NWAIT input signal of the SMC.
The EXNW_MODE field of the SMC_MODE register on the corresponding chip select must be
set to either to “10” (frozen mode) or “11” (ready mode). When the EXNW_MODE is set to “00”
(disabled), the NWAIT signal is simply ignored on the corresponding chip select. The NWAIT
signal delays the read or write operation in regards to the read or write controlling signal,
depending on the read and write modes of the corresponding chip select.
21.11.1
Restriction
When one of the EXNW_MODE is enabled, it is mandatory to program at least one hold cycle
for the read/write controlling signal. For that reason, the NWAIT signal cannot be used in Page
Mode (“Asynchronous Page Mode” on page 192), or in Slow Clock Mode (“Slow Clock Mode” on
page 189).
The NWAIT signal is assumed to be a response of the external device to the read/write request
of the SMC. Then NWAIT is examined by the SMC only in the pulse state of the read or write
controlling signal. The assertion of the NWAIT signal outside the expected period has no impact
on SMC behavior.
183
6384E–ATARM–05-Feb-10
21.11.2
Frozen Mode
When the external device asserts the NWAIT signal (active low), and after internal synchronization of this signal, the SMC state is frozen, i.e., SMC internal counters are frozen, and all control
signals remain unchanged. When the resynchronized NWAIT signal is deasserted, the SMC
completes the access, resuming the access from the point where it was stopped. See Figure 2127. This mode must be selected when the external device uses the NWAIT signal to delay the
access and to freeze the SMC.
The assertion of the NWAIT signal outside the expected period is ignored as illustrated in Figure
21-28.
Figure 21-27. Write Access with NWAIT Assertion in Frozen Mode (EXNW_MODE = 10)
MCK
A[25:2]
NBS0, NBS1,
NBS2, NBS3,
A0,A1
FROZEN STATE
4
3
2
1
1
1
1
0
3
2
2
2
2
1
NWE
6
5
4
0
NCS
D[31:0]
NWAIT
internally synchronized
NWAIT signal
Write cycle
EXNW_MODE = 10 (Frozen)
WRITE_MODE = 1 (NWE_controlled)
NWE_PULSE = 5
NCS_WR_PULSE = 7
184
AT91SAM9G20
6384E–ATARM–05-Feb-10
AT91SAM9G20
Figure 21-28. Read Access with NWAIT Assertion in Frozen Mode (EXNW_MODE = 10)
MCK
A[25:2]
NBS0, NBS1,
NBS2, NBS3,
A0,A1
NCS
FROZEN STATE
4
1
NRD
3
2
2
2
1
0
2
1
0
2
1
0
0
5
5
5
4
3
NWAIT
internally synchronized
NWAIT signal
Read cycle
EXNW_MODE = 10 (Frozen)
READ_MODE = 0 (NCS_controlled)
NRD_PULSE = 2, NRD_HOLD = 6
NCS_RD_PULSE =5, NCS_RD_HOLD =3
Assertion is ignored
185
6384E–ATARM–05-Feb-10
21.11.3
Ready Mode
In Ready mode (EXNW_MODE = 11), the SMC behaves differently. Normally, the SMC begins
the access by down counting the setup and pulse counters of the read/write controlling signal. In
the last cycle of the pulse phase, the resynchronized NWAIT signal is examined.
If asserted, the SMC suspends the access as shown in Figure 21-29 and Figure 21-30. After
deassertion, the access is completed: the hold step of the access is performed.
This mode must be selected when the external device uses deassertion of the NWAIT signal to
indicate its ability to complete the read or write operation.
If the NWAIT signal is deasserted before the end of the pulse, or asserted after the end of the
pulse of the controlling read/write signal, it has no impact on the access length as shown in Figure 21-30.
Figure 21-29. NWAIT Assertion in Write Access: Ready Mode (EXNW_MODE = 11)
MCK
A[25:2]
NBS0, NBS1,
NBS2, NBS3,
A0,A1
Wait STATE
4
3
2
1
0
0
0
3
2
1
1
1
NWE
6
5
4
0
NCS
D[31:0]
NWAIT
internally synchronized
NWAIT signal
Write cycle
EXNW_MODE = 11 (Ready mode)
WRITE_MODE = 1 (NWE_controlled)
NWE_PULSE = 5
NCS_WR_PULSE = 7
186
AT91SAM9G20
6384E–ATARM–05-Feb-10
AT91SAM9G20
Figure 21-30. NWAIT Assertion in Read Access: Ready Mode (EXNW_MODE = 11)
MCK
A[25:2]
NBS0, NBS1,
NBS2, NBS3,
A0,A1
Wait STATE
6
5
4
3
2
1
0
0
6
5
4
3
2
1
1
NCS
NRD
0
NWAIT
internally synchronized
NWAIT signal
Read cycle
EXNW_MODE = 11(Ready mode)
READ_MODE = 0 (NCS_controlled)
Assertion is ignored
Assertion is ignored
NRD_PULSE = 7
NCS_RD_PULSE =7
187
6384E–ATARM–05-Feb-10
21.11.4
NWAIT Latency and Read/write Timings
There may be a latency between the assertion of the read/write controlling signal and the assertion of the NWAIT signal by the device. The programmed pulse length of the read/write
controlling signal must be at least equal to this latency plus the 2 cycles of resynchronization + 1
cycle. Otherwise, the SMC may enter the hold state of the access without detecting the NWAIT
signal assertion. This is true in frozen mode as well as in ready mode. This is illustrated on Figure 21-31.
When EXNW_MODE is enabled (ready or frozen), the user must program a pulse length of the
read and write controlling signal of at least:
minimal pulse length = NWAIT latency + 2 resynchronization cycles + 1 cycle
Figure 21-31. NWAIT Latency
MCK
A[25:2]
NBS0, NBS1,
NBS2, NBS3,
A0,A1
WAIT STATE
4
3
2
1
0
0
0
NRD
minimal pulse length
NWAIT
intenally synchronized
NWAIT signal
NWAIT latency 2 cycle resynchronization
Read cycle
EXNW_MODE = 10 or 11
READ_MODE = 1 (NRD_controlled)
NRD_PULSE = 5
188
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6384E–ATARM–05-Feb-10
AT91SAM9G20
21.12 Slow Clock Mode
The SMC is able to automatically apply a set of “slow clock mode” read/write waveforms when
an internal signal driven by the Power Management Controller is asserted because MCK has
been turned to a very slow clock rate (typically 32kHz clock rate). In this mode, the user-programmed waveforms are ignored and the slow clock mode waveforms are applied. This mode is
provided so as to avoid reprogramming the User Interface with appropriate waveforms at very
slow clock rate. When activated, the slow mode is active on all chip selects.
21.12.1
Slow Clock Mode Waveforms
Figure 21-32 illustrates the read and write operations in slow clock mode. They are valid on all
chip selects. Table 21-5 indicates the value of read and write parameters in slow clock mode.
Figure 21-32. Read/write Cycles in Slow Clock Mode
MCK
MCK
A[25:2]
A[25:2]
NBS0, NBS1,
NBS2, NBS3,
A0,A1
NBS0, NBS1,
NBS2, NBS3,
A0,A1
NWE
NRD
1
1
1
1
1
NCS
NCS
NRD_CYCLE = 2
NWE_CYCLE = 3
SLOW CLOCK MODE WRITE
Table 21-5.
SLOW CLOCK MODE READ
Read and Write Timing Parameters in Slow Clock Mode
Read Parameters
Duration (cycles)
Write Parameters
Duration (cycles)
NRD_SETUP
1
NWE_SETUP
1
NRD_PULSE
1
NWE_PULSE
1
NCS_RD_SETUP
0
NCS_WR_SETUP
0
NCS_RD_PULSE
2
NCS_WR_PULSE
3
NRD_CYCLE
2
NWE_CYCLE
3
189
6384E–ATARM–05-Feb-10
21.12.2
Switching from (to) Slow Clock Mode to (from) Normal Mode
When switching from slow clock mode to the normal mode, the current slow clock mode transfer
is completed at high clock rate, with the set of slow clock mode parameters.See Figure 21-33 on
page 190. The external device may not be fast enough to support such timings.
Figure 21-34 illustrates the recommended procedure to properly switch from one mode to the
other.
Figure 21-33. Clock Rate Transition Occurs while the SMC is Performing a Write Operation
Slow Clock Mode
internal signal from PMC
MCK
A[25:2]
NBS0, NBS1,
NBS2, NBS3,
A0,A1
NWE
1
1
1
1
1
1
2
3
2
NCS
NWE_CYCLE = 3
NWE_CYCLE = 7
SLOW CLOCK MODE WRITE SLOW CLOCK MODE WRITE
This write cycle finishes with the slow clock mode set
of parameters after the clock rate transition
190
NORMAL MODE WRITE
Slow clock mode transition is detected:
Reload Configuration Wait State
AT91SAM9G20
6384E–ATARM–05-Feb-10
AT91SAM9G20
Figure 21-34. Recommended Procedure to Switch from Slow Clock Mode to Normal Mode or from Normal Mode to Slow
Clock Mode
Slow Clock Mode
internal signal from PMC
MCK
A[25:2]
NBS0, NBS1,
NBS2, NBS3,
A0,A1
NWE
1
1
1
2
3
2
NCS
SLOW CLOCK MODE WRITE
IDLE STATE
NORMAL MODE WRITE
Reload Configuration
Wait State
191
6384E–ATARM–05-Feb-10
21.13 Asynchronous Page Mode
The SMC supports asynchronous burst reads in page mode, providing that the page mode is
enabled in the SMC_MODE register (PMEN field). The page size must be configured in the
SMC_MODE register (PS field) to 4, 8, 16 or 32 bytes.
The page defines a set of consecutive bytes into memory. A 4-byte page (resp. 8-, 16-, 32-byte
page) is always aligned to 4-byte boundaries (resp. 8-, 16-, 32-byte boundaries) of memory. The
MSB of data address defines the address of the page in memory, the LSB of address define the
address of the data in the page as detailed in Table 21-6.
With page mode memory devices, the first access to one page (tpa) takes longer than the subsequent accesses to the page (tsa ) as shown in Figure 21-35. When in page mode, the SMC
enables the user to define different read timings for the first access within one page, and next
accesses within the page.
Table 21-6.
Page Address and Data Address within a Page
Page Size
Page Address(1)
Data Address in the Page(2)
4 bytes
A[25:2]
A[1:0]
8 bytes
A[25:3]
A[2:0]
16 bytes
A[25:4]
A[3:0]
32 bytes
A[25:5]
A[4:0]
Notes:
1. A denotes the address bus of the memory device
2. For 16-bit devices, the bit 0 of address is ignored. For 32-bit devices, bits [1:0] are ignored.
21.13.1
Protocol and Timings in Page Mode
Figure 21-35 shows the NRD and NCS timings in page mode access.
Figure 21-35. Page Mode Read Protocol (Address MSB and LSB are defined in Table 21-6)
MCK
A[MSB]
A[LSB]
NRD
tpa
NCS
tsa
tsa
D[31:0]
NCS_RD_PULSE
NRD_PULSE
NRD_PULSE
The NRD and NCS signals are held low during all read transfers, whatever the programmed values of the setup and hold timings in the User Interface may be. Moreover, the NRD and NCS
192
AT91SAM9G20
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AT91SAM9G20
timings are identical. The pulse length of the first access to the page is defined with the
NCS_RD_PULSE field of the SMC_PULSE register. The pulse length of subsequent accesses
within the page are defined using the NRD_PULSE parameter.
In page mode, the programming of the read timings is described in Table 21-7:
Table 21-7.
Programming of Read Timings in Page Mode
Parameter
Value
Definition
READ_MODE
‘x’
No impact
NCS_RD_SETUP
‘x’
No impact
NCS_RD_PULSE
tpa
Access time of first access to the page
NRD_SETUP
‘x’
No impact
NRD_PULSE
tsa
Access time of subsequent accesses in the page
NRD_CYCLE
‘x’
No impact
The SMC does not check the coherency of timings. It will always apply the NCS_RD_PULSE
timings as page access timing (tpa) and the NRD_PULSE for accesses to the page (tsa), even if
the programmed value for tpa is shorter than the programmed value for tsa.
21.13.2
Byte Access Type in Page Mode
The Byte Access Type configuration remains active in page mode. For 16-bit or 32-bit page
mode devices that require byte selection signals, configure the BAT field of the
SMC_REGISTER to 0 (byte select access type).
21.13.3
Page Mode Restriction
The page mode is not compatible with the use of the NWAIT signal. Using the page mode and
the NWAIT signal may lead to unpredictable behavior.
21.13.4
Sequential and Non-sequential Accesses
If the chip select and the MSB of addresses as defined in Table 21-6 are identical, then the current access lies in the same page as the previous one, and no page break occurs.
Using this information, all data within the same page, sequential or not sequential, are accessed
with a minimum access time (tsa). Figure 21-36 illustrates access to an 8-bit memory device in
page mode, with 8-byte pages. Access to D1 causes a page access with a long access time
(tpa). Accesses to D3 and D7, though they are not sequential accesses, only require a short
access time (tsa).
If the MSB of addresses are different, the SMC performs the access of a new page. In the same
way, if the chip select is different from the previous access, a page break occurs. If two sequential accesses are made to the page mode memory, but separated by an other internal or external
peripheral access, a page break occurs on the second access because the chip select of the
device was deasserted between both accesses.
193
6384E–ATARM–05-Feb-10
Figure 21-36. Access to Non-sequential Data within the Same Page
MCK
Page address
A[25:3]
A[2], A1, A0
A1
A3
A7
NRD
NCS
D[7:0]
D1
NCS_RD_PULSE
194
D3
NRD_PULSE
D7
NRD_PULSE
AT91SAM9G20
6384E–ATARM–05-Feb-10
AT91SAM9G20
21.14 Static Memory Controller (SMC) User Interface
The SMC is programmed using the registers listed in Table 21-8. For each chip select, a set of 4 registers is used to program the parameters of the external device connected on it. In Table 21-8, “CS_number” denotes the chip select number.
16 bytes (0x10) are required per chip select.
The user must complete writing the configuration by writing any one of the SMC_MODE registers.
Table 21-8.
Register Mapping
Offset
Register
Name
Access
Reset
0x10 x CS_number + 0x00
SMC Setup Register
SMC_SETUP
Read-write
0x00000000
0x10 x CS_number + 0x04
SMC Pulse Register
SMC_PULSE
Read-write
0x01010101
0x10 x CS_number + 0x08
SMC Cycle Register
SMC_CYCLE
Read-write
0x00030003
0x10 x CS_number + 0x0C
SMC Mode Register
SMC_MODE
Read-write
0x10001000
195
6384E–ATARM–05-Feb-10
21.14.1 SMC Setup Register
Register Name:SMC_SETUP[0 ..7]
Access Type:Read-write
31
30
–
–
23
22
–
–
15
14
–
–
7
6
–
–
29
28
27
26
25
24
18
17
16
10
9
8
1
0
NCS_RD_SETUP
21
20
19
NRD_SETUP
13
12
11
NCS_WR_SETUP
5
4
3
2
NWE_SETUP
• NWE_SETUP: NWE Setup Length
The NWE signal setup length is defined as:
NWE setup length = (128* NWE_SETUP[5] + NWE_SETUP[4:0]) clock cycles
• NCS_WR_SETUP: NCS Setup Length in WRITE Access
In write access, the NCS signal setup length is defined as:
NCS setup length = (128* NCS_WR_SETUP[5] + NCS_WR_SETUP[4:0]) clock cycles
• NRD_SETUP: NRD Setup Length
The NRD signal setup length is defined in clock cycles as:
NRD setup length = (128* NRD_SETUP[5] + NRD_SETUP[4:0]) clock cycles
• NCS_RD_SETUP: NCS Setup Length in READ Access
In read access, the NCS signal setup length is defined as:
NCS setup length = (128* NCS_RD_SETUP[5] + NCS_RD_SETUP[4:0]) clock cycles
196
AT91SAM9G20
6384E–ATARM–05-Feb-10
AT91SAM9G20
21.14.2 SMC Pulse Register
Register Name:SMC_PULSE[0..7]
Access Type:Read-write
31
30
29
28
–
23
22
21
20
–
15
26
25
24
19
18
17
16
10
9
8
2
1
0
NRD_PULSE
14
13
12
–
7
27
NCS_RD_PULSE
11
NCS_WR_PULSE
6
5
4
–
3
NWE_PULSE
• NWE_PULSE: NWE Pulse Length
The NWE signal pulse length is defined as:
NWE pulse length = (256* NWE_PULSE[6] + NWE_PULSE[5:0]) clock cycles
The NWE pulse length must be at least 1 clock cycle.
• NCS_WR_PULSE: NCS Pulse Length in WRITE Access
In write access, the NCS signal pulse length is defined as:
NCS pulse length = (256* NCS_WR_PULSE[6] + NCS_WR_PULSE[5:0]) clock cycles
The NCS pulse length must be at least 1 clock cycle.
• NRD_PULSE: NRD Pulse Length
In standard read access, the NRD signal pulse length is defined in clock cycles as:
NRD pulse length = (256* NRD_PULSE[6] + NRD_PULSE[5:0]) clock cycles
The NRD pulse length must be at least 1 clock cycle.
In page mode read access, the NRD_PULSE parameter defines the duration of the subsequent accesses in the page.
• NCS_RD_PULSE: NCS Pulse Length in READ Access
In standard read access, the NCS signal pulse length is defined as:
NCS pulse length = (256* NCS_RD_PULSE[6] + NCS_RD_PULSE[5:0]) clock cycles
The NCS pulse length must be at least 1 clock cycle.
In page mode read access, the NCS_RD_PULSE parameter defines the duration of the first access to one page.
197
6384E–ATARM–05-Feb-10
21.14.3 SMC Cycle Register
Register Name:SMC_CYCLE[0..7]
Access Type:Read-write
31
30
29
28
27
26
25
24
–
–
–
–
–
–
–
NRD_CYCLE
23
22
21
20
19
18
17
16
NRD_CYCLE
15
14
13
12
11
10
9
8
–
–
–
–
–
–
–
NWE_CYCLE
7
6
5
4
3
2
1
0
NWE_CYCLE
• NWE_CYCLE: Total Write Cycle Length
The total write cycle length is the total duration in clock cycles of the write cycle. It is equal to the sum of the setup, pulse
and hold steps of the NWE and NCS signals. It is defined as:
Write cycle length = (NWE_CYCLE[8:7]*256 + NWE_CYCLE[6:0]) clock cycles
• NRD_CYCLE: Total Read Cycle Length
The total read cycle length is the total duration in clock cycles of the read cycle. It is equal to the sum of the setup, pulse
and hold steps of the NRD and NCS signals. It is defined as:
Read cycle length = (NRD_CYCLE[8:7]*256 + NRD_CYCLE[6:0]) clock cycles
198
AT91SAM9G20
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AT91SAM9G20
21.14.4 SMC MODE Register
Register Name:SMC_MODE[0..7]
Access Type:Read-write
31
30
–
–
29
28
23
22
21
20
–
–
–
TDF_MODE
15
14
13
–
–
7
6
–
–
PS
12
DBW
5
4
EXNW_MODE
27
26
25
24
–
–
–
PMEN
19
18
17
16
TDF_CYCLES
11
10
9
8
–
–
–
BAT
3
2
1
0
–
–
WRITE_MODE
READ_MODE
• READ_MODE:
1: The read operation is controlled by the NRD signal.
– If TDF cycles are programmed, the external bus is marked busy after the rising edge of NRD.
– If TDF optimization is enabled (TDF_MODE =1), TDF wait states are inserted after the setup of NRD.
0: The read operation is controlled by the NCS signal.
– If TDF cycles are programmed, the external bus is marked busy after the rising edge of NCS.
– If TDF optimization is enabled (TDF_MODE =1), TDF wait states are inserted after the setup of NCS.
• WRITE_MODE
1: The write operation is controlled by the NWE signal.
– If TDF optimization is enabled (TDF_MODE =1), TDF wait states will be inserted after the setup of NWE.
0: The write operation is controlled by the NCS signal.
– If TDF optimization is enabled (TDF_MODE =1), TDF wait states will be inserted after the setup of NCS.
• EXNW_MODE: NWAIT Mode
The NWAIT signal is used to extend the current read or write signal. It is only taken into account during the pulse phase of
the read and write controlling signal. When the use of NWAIT is enabled, at least one cycle hold duration must be programmed for the read and write controlling signal.
EXNW_MODE
NWAIT Mode
0
0
Disabled
0
1
Reserved
1
0
Frozen Mode
1
1
Ready Mode
• Disabled Mode: The NWAIT input signal is ignored on the corresponding Chip Select.
• Frozen Mode: If asserted, the NWAIT signal freezes the current read or write cycle. After deassertion, the read/write
cycle is resumed from the point where it was stopped.
• Ready Mode: The NWAIT signal indicates the availability of the external device at the end of the pulse of the controlling
read or write signal, to complete the access. If high, the access normally completes. If low, the access is extended until
NWAIT returns high.
199
6384E–ATARM–05-Feb-10
• BAT: Byte Access Type
This field is used only if DBW defines a 16- or 32-bit data bus.
• 1: Byte write access type:
– Write operation is controlled using NCS, NWR0, NWR1, NWR2, NWR3.
– Read operation is controlled using NCS and NRD.
• 0: Byte select access type:
– Write operation is controlled using NCS, NWE, NBS0, NBS1, NBS2 and NBS3
– Read operation is controlled using NCS, NRD, NBS0, NBS1, NBS2 and NBS3
• DBW: Data Bus Width
DBW
Data Bus Width
0
0
8-bit bus
0
1
16-bit bus
1
0
32-bit bus
1
1
Reserved
• TDF_CYCLES: Data Float Time
This field gives the integer number of clock cycles required by the external device to release the data after the rising edge
of the read controlling signal. The SMC always provide one full cycle of bus turnaround after the TDF_CYCLES period. The
external bus cannot be used by another chip select during TDF_CYCLES + 1 cycles. From 0 up to 15 TDF_CYCLES can
be set.
• TDF_MODE: TDF Optimization
1: TDF optimization is enabled.
– The number of TDF wait states is optimized using the setup period of the next read/write access.
0: TDF optimization is disabled.
– The number of TDF wait states is inserted before the next access begins.
• PMEN: Page Mode Enabled
1: Asynchronous burst read in page mode is applied on the corresponding chip select.
0: Standard read is applied.
• PS: Page Size
If page mode is enabled, this field indicates the size of the page in bytes.
PS
200
Page Size
0
0
4-byte page
0
1
8-byte page
1
0
16-byte page
1
1
32-byte page
AT91SAM9G20
6384E–ATARM–05-Feb-10
AT91SAM9G20
22. SDRAM Controller (SDRAMC)
22.1
Overview
The SDRAM Controller (SDRAMC) extends the memory capabilities of a chip by providing the
interface to an external 16-bit or 32-bit SDRAM device. The page size supports ranges from
2048 to 8192 and the number of columns from 256 to 2048. It supports byte (8-bit), half-word
(16-bit) and word (32-bit) accesses.
The SDRAM Controller supports a read or write burst length of one location. It keeps track of the
active row in each bank, thus maximizing SDRAM performance, e.g., the application may be
placed in one bank and data in the other banks. So as to optimize performance, it is advisable to
avoid accessing different rows in the same bank.
The SDRAM controller supports a CAS latency of 1, 2 or 3 and optimizes the read access
depending on the frequency.
The different modes available - self-refresh, power-down and deep power-down modes - minimize power consumption on the SDRAM device.
22.2
I/O Lines Description
Table 22-1.
I/O Line Description
Name
Description
Type
Active Level
SDCK
SDRAM Clock
Output
SDCKE
SDRAM Clock Enable
Output
High
SDCS
SDRAM Controller Chip Select
Output
Low
BA[1:0]
Bank Select Signals
Output
RAS
Row Signal
Output
Low
CAS
Column Signal
Output
Low
SDWE
SDRAM Write Enable
Output
Low
NBS[3:0]
Data Mask Enable Signals
Output
Low
SDRAMC_A[12:0]
Address Bus
Output
D[31:0]
Data Bus
I/O
201
6384E–ATARM–05-Feb-10
22.3
Application Example
22.3.1
Software Interface
The SDRAM address space is organized into banks, rows, and columns. The SDRAM controller
allows mapping different memory types according to the values set in the SDRAMC configuration register.
The SDRAM Controller’s function is to make the SDRAM device access protocol transparent to
the user. Table 22-2 to Table 22-7 illustrate the SDRAM device memory mapping seen by the
user in correlation with the device structure. Various configurations are illustrated.
22.3.1.1
32-bit Memory Data Bus Width
Table 22-2.
SDRAM Configuration Mapping: 2K Rows, 256/512/1024/2048 Columns
CPU Address Line
27
26
25
24
23
22
21
20
19
18
17
16
Bk[1:0]
14
13
12
11
10
9
8
7
Row[10:0]
Bk[1:0]
Bk[1:0]
6
5
4
3
2
Column[7:0]
Row[10:0]
0
M[1:0]
Column[9:0]
Row[10:0]
1
M[1:0]
Column[8:0]
Row[10:0]
Bk[1:0]
Table 22-3.
15
M[1:0]
Column[10:0]
M[1:0]
SDRAM Configuration Mapping: 4K Rows, 256/512/1024/2048 Columns
CPU Address Line
27
26
25
24
23
22
21
20
19
18
17
Bk[1:0]
15
14
13
12
11
10
9
8
7
Row[11:0]
Bk[1:0]
Bk[1:0]
6
5
4
3
2
Column[7:0]
Row[11:0]
0
M[1:0]
Column[9:0]
Row[11:0]
1
M[1:0]
Column[8:0]
Row[11:0]
Bk[1:0]
Table 22-4.
16
M[1:0]
Column[10:0]
M[1:0]
SDRAM Configuration Mapping: 8K Rows, 256/512/1024/2048 Columns
CPU Address Line
27
26
25
24
23
22
21
20
19
18
17
Bk[1:0]
Row[12:0]
Bk[1:0]
Notes:
15
Row[12:0]
Bk[1:0]
Bk[1:0]
16
Row[12:0]
Row[12:0]
14
13
12
11
10
9
8
7
6
5
Column[7:0]
Column[8:0]
Column[9:0]
Column[10:0]
4
3
2
1
0
M[1:0]
M[1:0]
M[1:0]
M[1:0]
1. M[1:0] is the byte address inside a 32-bit word.
2. Bk[1] = BA1, Bk[0] = BA0.
202
AT91SAM9G20
6384E–ATARM–05-Feb-10
AT91SAM9G20
22.3.1.2
16-bit Memory Data Bus Width
Table 22-5.
SDRAM Configuration Mapping: 2K Rows, 256/512/1024/2048 Columns
CPU Address Line
27
26
25
24
23
22
21
20
19
18
17
16
15
Bk[1:0]
13
12
11
10
9
8
7
6
Row[10:0]
Bk[1:0]
4
3
2
1
M0
M0
Column[9:0]
Row[10:0]
0
M0
Column[8:0]
Row[10:0]
Bk[1:0]
5
Column[7:0]
Row[10:0]
Bk[1:0]
Table 22-6.
14
M0
Column[10:0]
SDRAM Configuration Mapping: 4K Rows, 256/512/1024/2048 Columns
CPU Address Line
27
26
25
24
23
22
21
20
19
18
17
16
Bk[1:0]
14
13
12
11
10
9
8
7
6
Row[11:0]
Bk[1:0]
4
3
2
1
M0
M0
Column[9:0]
Row[11:0]
0
M0
Column[8:0]
Row[11:0]
Bk[1:0]
5
Column[7:0]
Row[11:0]
Bk[1:0]
Table 22-7.
15
M0
Column[10:0]
SDRAM Configuration Mapping: 8K Rows, 256/512/1024/2048 Columns
CPU Address Line
27
26
25
24
23
22
21
20
19
18
17
16
Bk[1:0]
Bk[1:0]
Notes:
14
Row[12:0]
Bk[1:0]
Bk[1:0]
15
Row[12:0]
Row[12:0]
Row[12:0]
13
12
11
10
9
8
7
6
5
4
Column[7:0]
Column[8:0]
Column[9:0]
Column[10:0]
3
2
1
0
M0
M0
M0
M0
1. M0 is the byte address inside a 16-bit half-word.
2. Bk[1] = BA1, Bk[0] = BA0.
203
6384E–ATARM–05-Feb-10
22.4
22.4.1
Product Dependencies
SDRAM Device Initialization
The initialization sequence is generated by software. The SDRAM devices are initialized by the
following sequence:
1. SDRAM features must be set in the configuration register: asynchronous timings (TRC,
TRAS, etc.), number of columns, rows, CAS latency, and the data bus width.
2. For mobile SDRAM, temperature-compensated self refresh (TCSR), drive strength
(DS) and partial array self refresh (PASR) must be set in the Low Power Register.
3. The SDRAM memory type must be set in the Memory Device Register.
4. A minimum pause of 200 µs is provided to precede any signal toggle.
5.
(1)
A NOP command is issued to the SDRAM devices. The application must set Mode to
1 in the Mode Register and perform a write access to any SDRAM address.
6. An All Banks Precharge command is issued to the SDRAM devices. The application
must set Mode to 2 in the Mode Register and perform a write access to any SDRAM
address.
7. Eight auto-refresh (CBR) cycles are provided. The application must set the Mode to 4 in
the Mode Register and perform a write access to any SDRAM location eight times.
8. A Mode Register set (MRS) cycle is issued to program the parameters of the SDRAM
devices, in particular CAS latency and burst length. The application must set Mode to 3
in the Mode Register and perform a write access to the SDRAM. The write address
must be chosen so that BA[1:0] are set to 0. For example, with a 16-bit 128 MB SDRAM
(12 rows, 9 columns, 4 banks) bank address, the SDRAM write access should be done
at the address 0x20000000.
9. For mobile SDRAM initialization, an Extended Mode Register set (EMRS) cycle is
issued to program the SDRAM parameters (TCSR, PASR, DS). The application must
set Mode to 5 in the Mode Register and perform a write access to the SDRAM. The
write address must be chosen so that BA[1] or BA[0] are set to 1. For example, with a
16-bit 128 MB SDRAM, (12 rows, 9 columns, 4 banks) bank address the SDRAM write
access should be done at the address 0x20800000 or 0x20400000.
10. The application must go into Normal Mode, setting Mode to 0 in the Mode Register and
performing a write access at any location in the SDRAM.
11. Write the refresh rate into the count field in the SDRAMC Refresh Timer register.
(Refresh rate = delay between refresh cycles). The SDRAM device requires a refresh
every 15.625 µs or 7.81 µs. With a 100 MHz frequency, the Refresh Timer Counter
Register must be set with the value 1562(15.652 µs x 100 MHz) or 781(7.81 µs x 100
MHz).
After initialization, the SDRAM devices are fully functional.
Note:
204
1. It is strongly recommended to respect the instructions stated in Step 5 of the initialization process in order to be certain that the subsequent commands issued by the SDRAMC will be
taken into account.
AT91SAM9G20
6384E–ATARM–05-Feb-10
AT91SAM9G20
Figure 22-1. SDRAM Device Initialization Sequence
SDCKE
tRP
tRC
tMRD
SDCK
SDRAMC_A[9:0]
A10
SDRAMC_A[12:11]
SDCS
RAS
CAS
SDWE
NBS
Inputs Stable for
200 μsec
22.4.2
Precharge All Banks
1st Auto-refresh
8th Auto-refresh
MRS Command
Valid Command
I/O Lines
The pins used for interfacing the SDRAM Controller may be multiplexed with the PIO lines. The
programmer must first program the PIO controller to assign the SDRAM Controller pins to their
peripheral function. If I/O lines of the SDRAM Controller are not used by the application, they
can be used for other purposes by the PIO Controller.
22.4.3
Interrupt
The SDRAM Controller interrupt (Refresh Error notification) is connected to the Memory Controller. This interrupt may be ORed with other System Peripheral interrupt lines and is finally
provided as the System Interrupt Source (Source 1) to the AIC (Advanced Interrupt Controller).
Using the SDRAM Controller interrupt requires the AIC to be programmed first.
205
6384E–ATARM–05-Feb-10
22.5
22.5.1
Functional Description
SDRAM Controller Write Cycle
The SDRAM Controller allows burst access or single access. In both cases, the SDRAM controller keeps track of the active row in each bank, thus maximizing performance. To initiate a burst
access, the SDRAM Controller uses the transfer type signal provided by the master requesting
the access. If the next access is a sequential write access, writing to the SDRAM device is carried out. If the next access is a write-sequential access, but the current access is to a boundary
page, or if the next access is in another row, then the SDRAM Controller generates a precharge
command, activates the new row and initiates a write command. To comply with SDRAM timing
parameters, additional clock cycles are inserted between precharge/active (tRP) commands and
active/write (tRCD) commands. For definition of these timing parameters, refer to the “SDRAMC
Configuration Register” on page 216. This is described in Figure 22-2 below.
Figure 22-2. Write Burst, 32-bit SDRAM Access
tRCD = 3
SDCS
SDCK
SDRAMC_A[12:0]
Row n
col a
col b
col c
col d
col e
col f
col g
col h
col i
col j
col k
col l
Dnb
Dnc
Dnd
Dne
Dnf
Dng
Dnh
Dni
Dnj
Dnk
Dnl
RAS
CAS
SDWE
D[31:0]
22.5.2
206
Dna
SDRAM Controller Read Cycle
The SDRAM Controller allows burst access, incremental burst of unspecified length or single
access. In all cases, the SDRAM Controller keeps track of the active row in each bank, thus
maximizing performance of the SDRAM. If row and bank addresses do not match the previous
row/bank address, then the SDRAM controller automatically generates a precharge command,
activates the new row and starts the read command. To comply with the SDRAM timing parameters, additional clock cycles on SDCK are inserted between precharge and active commands
(tRP) and between active and read command (tRCD). These two parameters are set in the configuration register of the SDRAM Controller. After a read command, additional wait states are
generated to comply with the CAS latency (1, 2 or 3 clock delays specified in the configuration
register).
AT91SAM9G20
6384E–ATARM–05-Feb-10
AT91SAM9G20
For a single access or an incremented burst of unspecified length, the SDRAM Controller anticipates the next access. While the last value of the column is returned by the SDRAM Controller
on the bus, the SDRAM Controller anticipates the read to the next column and thus anticipates
the CAS latency. This reduces the effect of the CAS latency on the internal bus.
For burst access of specified length (4, 8, 16 words), access is not anticipated. This case leads
to the best performance. If the burst is broken (border, busy mode, etc.), the next access is handled as an incrementing burst of unspecified length.
Figure 22-3. Read Burst, 32-bit SDRAM Access
tRCD = 3
CAS = 2
SDCS
SDCK
SDRAMC_A[12:0]
Row n
col a
col b
col c
col d
col e
col f
RAS
CAS
SDWE
D[31:0]
(Input)
Dna
Dnb
Dnc
Dnd
Dne
Dnf
207
6384E–ATARM–05-Feb-10
22.5.3
Border Management
When the memory row boundary has been reached, an automatic page break is inserted. In this
case, the SDRAM controller generates a precharge command, activates the new row and initiates a read or write command. To comply with SDRAM timing parameters, an additional clock
cycle is inserted between the precharge/active (tRP) command and the active/read (tRCD) command. This is described in Figure 22-4 below.
Figure 22-4. Read Burst with Boundary Row Access
TRP = 3
TRCD = 3
CAS = 2
SDCS
SDCK
Row n
SDRAMC_A[12:0]
col a
col b
col c
col d
Row m
col a
col b
col c
col d
col e
RAS
CAS
SDWE
D[31:0]
208
Dna
Dnb
Dnc
Dnd
Dma
Dmb
Dmc
Dmd
Dme
AT91SAM9G20
6384E–ATARM–05-Feb-10
AT91SAM9G20
22.5.4
SDRAM Controller Refresh Cycles
An auto-refresh command is used to refresh the SDRAM device. Refresh addresses are generated internally by the SDRAM device and incremented after each auto-refresh automatically.
The SDRAM Controller generates these auto-refresh commands periodically. An internal timer is
loaded with the value in the register SDRAMC_TR that indicates the number of clock cycles
between refresh cycles.
A refresh error interrupt is generated when the previous auto-refresh command did not perform.
It is acknowledged by reading the Interrupt Status Register (SDRAMC_ISR).
When the SDRAM Controller initiates a refresh of the SDRAM device, internal memory accesses
are not delayed. However, if the CPU tries to access the SDRAM, the slave indicates that the
device is busy and the master is held by a wait signal. See Figure 22-5.
Figure 22-5. Refresh Cycle Followed by a Read Access
tRP = 3
tRC = 8
tRCD = 3
CAS = 2
SDCS
SDCK
Row n
SDRAMC_A[12:0]
Row m
col c col d
col a
RAS
CAS
SDWE
D[31:0]
(input)
22.5.5
Dnb
Dnc
Dnd
Dma
Power Management
Three low-power modes are available:
• Self-refresh Mode: The SDRAM executes its own Auto-refresh cycle without control of the
SDRAM Controller. Current drained by the SDRAM is very low.
• Power-down Mode: Auto-refresh cycles are controlled by the SDRAM Controller. Between
auto-refresh cycles, the SDRAM is in power-down. Current drained in Power-down mode is
higher than in Self-refresh Mode.
• Deep Power-down Mode: (Only available with Mobile SDRAM) The SDRAM contents are
lost, but the SDRAM does not drain any current.
The SDRAM Controller activates one low-power mode as soon as the SDRAM device is not
selected. It is possible to delay the entry in self-refresh and power-down mode after the last
access by programming a timeout value in the Low Power Register.
209
6384E–ATARM–05-Feb-10
22.5.5.1
Self-refresh Mode
This mode is selected by programming the LPCB field to 1 in the SDRAMC Low Power Register.
In self-refresh mode, the SDRAM device retains data without external clocking and provides its
own internal clocking, thus performing its own auto-refresh cycles. All the inputs to the SDRAM
device become “don’t care” except SDCKE, which remains low. As soon as the SDRAM device
is selected, the SDRAM Controller provides a sequence of commands and exits self-refresh
mode.
Some low-power SDRAMs (e.g., mobile SDRAM) can refresh only one quarter or a half quarter
or all banks of the SDRAM array. This feature reduces the self-refresh current. To configure this
feature, Temperature Compensated Self Refresh (TCSR), Partial Array Self Refresh (PASR)
and Drive Strength (DS) parameters must be set in the Low Power Register and transmitted to
the low-power SDRAM during initialization.
The SDRAM device must remain in self-refresh mode for a minimum period of tRAS and may
remain in self-refresh mode for an indefinite period. This is described in Figure 22-6.
Figure 22-6. Self-refresh Mode Behavior
Self Refresh Mode
TXSR = 3
SRCB = 1
Write
SDRAMC_SRR
Row
SDRAMC_A[12:0]
SDCK
SDCKE
SDCS
RAS
CAS
SDWE
Access Request
to the SDRAM Controller
210
AT91SAM9G20
6384E–ATARM–05-Feb-10
AT91SAM9G20
22.5.5.2
Low-power Mode
This mode is selected by programming the LPCB field to 2 in the SDRAMC Low Power Register.
Power consumption is greater than in self-refresh mode. All the input and output buffers of the
SDRAM device are deactivated except SDCKE, which remains low. In contrast to self-refresh
mode, the SDRAM device cannot remain in low-power mode longer than the refresh period (64
ms for a whole device refresh operation). As no auto-refresh operations are performed by the
SDRAM itself, the SDRAM Controller carries out the refresh operation. The exit procedure is
faster than in self-refresh mode.
This is described in Figure 22-7.
Figure 22-7. Low-power Mode Behavior
TRCD = 3
CAS = 2
Low Power Mode
SDCS
SDCK
SDRAMC_A[12:0]
Row n
col a
col b
col c
col d
col e
col f
RAS
CAS
SDCKE
D[31:0]
(input)
Dna
Dnb
Dnc
Dnd
Dne
Dnf
211
6384E–ATARM–05-Feb-10
22.5.5.3
Deep Power-down Mode
This mode is selected by programming the LPCB field to 3 in the SDRAMC Low Power Register.
When this mode is activated, all internal voltage generators inside the SDRAM are stopped and
all data is lost.
When this mode is enabled, the application must not access to the SDRAM until a new initialization sequence is done (See “SDRAM Device Initialization” on page 204).
This is described in Figure 22-8.
Figure 22-8. Deep Power-down Mode Behavior
tRP = 3
SDCS
SDCK
Row n
SDRAMC_A[12:0]
col c
col d
RAS
CAS
SDWE
CKE
D[31:0]
(input)
212
Dnb
Dnc
Dnd
AT91SAM9G20
6384E–ATARM–05-Feb-10
AT91SAM9G20
22.6
SDRAM Controller (SDRAMC) User Interface
Table 22-8.
Offset
Register Mapping
Register
Name
Access
Reset
0x00
SDRAMC Mode Register
SDRAMC_MR
Read-write
0x00000000
0x04
SDRAMC Refresh Timer Register
SDRAMC_TR
Read-write
0x00000000
0x08
SDRAMC Configuration Register
SDRAMC_CR
Read-write
0x852372C0
0x10
SDRAMC Low Power Register
SDRAMC_LPR
Read-write
0x0
0x14
SDRAMC Interrupt Enable Register
SDRAMC_IER
Write-only
–
0x18
SDRAMC Interrupt Disable Register
SDRAMC_IDR
Write-only
–
0x1C
SDRAMC Interrupt Mask Register
SDRAMC_IMR
Read-only
0x0
0x20
SDRAMC Interrupt Status Register
SDRAMC_ISR
Read-only
0x0
0x24
SDRAMC Memory Device Register
SDRAMC_MDR
Read
0x0
–
–
–
0x28 - 0xFC
Reserved
213
6384E–ATARM–05-Feb-10
22.6.1
SDRAMC Mode Register
Register Name:SDRAMC_MR
Access Type:Read-write
Reset Value: 0x00000000
31
–
30
–
29
–
28
–
27
–
26
–
25
–
24
–
23
–
22
–
21
–
20
–
19
–
18
–
17
–
16
–
15
–
14
–
13
–
12
–
11
–
10
–
9
–
8
–
7
–
6
–
5
–
4
–
3
–
2
1
0
MODE
• MODE: SDRAMC Command Mode
This field defines the command issued by the SDRAM Controller when the SDRAM device is accessed.
MODE
Description
0
0
0
Normal mode. Any access to the SDRAM is decoded normally. To activate this mode, command must be
followed by a write to the SDRAM.
0
0
1
The SDRAM Controller issues a NOP command when the SDRAM device is accessed regardless of the cycle.
To activate this mode, command must be followed by a write to the SDRAM.
0
1
0
The SDRAM Controller issues an “All Banks Precharge” command when the SDRAM device is accessed
regardless of the cycle. To activate this mode, command must be followed by a write to the SDRAM.
0
1
1
The SDRAM Controller issues a “Load Mode Register” command when the SDRAM device is accessed
regardless of the cycle. To activate this mode, command must be followed by a write to the SDRAM.
1
0
0
The SDRAM Controller issues an “Auto-Refresh” Command when the SDRAM device is accessed regardless of
the cycle. Previously, an “All Banks Precharge” command must be issued. To activate this mode, command must
be followed by a write to the SDRAM.
1
0
1
The SDRAM Controller issues an “Extended Load Mode Register” command when the SDRAM device is
accessed regardless of the cycle. To activate this mode, the “Extended Load Mode Register” command must be
followed by a write to the SDRAM. The write in the SDRAM must be done in the appropriate bank; most lowpower SDRAM devices use the bank 1.
1
1
0
Deep power-down mode. Enters deep power-down mode.
214
AT91SAM9G20
6384E–ATARM–05-Feb-10
AT91SAM9G20
22.6.2
SDRAMC Refresh Timer Register
Register Name:SDRAMC_TR
Access Type:Read-write
Reset Value: 0x00000000
31
–
30
–
29
–
28
–
27
–
26
–
25
–
24
–
23
–
22
–
21
–
20
–
19
–
18
–
17
–
16
–
15
–
14
–
13
–
12
–
11
10
9
8
7
6
5
4
1
0
COUNT
3
2
COUNT
• COUNT: SDRAMC Refresh Timer Count
This 12-bit field is loaded into a timer that generates the refresh pulse. Each time the refresh pulse is generated, a refresh
burst is initiated. The value to be loaded depends on the SDRAMC clock frequency (MCK: Master Clock), the refresh rate
of the SDRAM device and the refresh burst length where 15.6 µs per row is a typical value for a burst of length one.
To refresh the SDRAM device, this 12-bit field must be written. If this condition is not satisfied, no refresh command is
issued and no refresh of the SDRAM device is carried out.
215
6384E–ATARM–05-Feb-10
22.6.3
SDRAMC Configuration Register
Register Name:SDRAMC_CR
Access Type:Read-write
Reset Value: 0x852372C0
31
30
29
28
27
26
TXSR
23
21
20
19
18
TRCD
17
16
9
8
TRP
14
13
12
11
10
TRC
7
DBW
24
TRAS
22
15
25
TWR
6
5
CAS
4
NB
3
2
NR
1
0
NC
• NC: Number of Column Bits
Reset value is 8 column bits.
NC
Column Bits
0
0
8
0
1
9
1
0
10
1
1
11
• NR: Number of Row Bits
Reset value is 11 row bits.
NR
Row Bits
0
0
11
0
1
12
1
0
13
1
1
Reserved
• NB: Number of Banks
Reset value is two banks.
216
NB
Number of Banks
0
2
1
4
AT91SAM9G20
6384E–ATARM–05-Feb-10
AT91SAM9G20
• CAS: CAS Latency
Reset value is two cycles.
In the SDRAMC, only a CAS latency of one, two and three cycles are managed.
CAS
CAS Latency (Cycles)
0
0
Reserved
0
1
1
1
0
2
1
1
3
• DBW: Data Bus Width
Reset value is 16 bits
0: Data bus width is 32 bits.
1: Data bus width is 16 bits.
• TWR: Write Recovery Delay
Reset value is two cycles.
This field defines the Write Recovery Time in number of cycles. Number of cycles is between 0 and 15.
• TRC: Row Cycle Delay
Reset value is seven cycles.
This field defines the delay between a Refresh and an Activate Command in number of cycles. Number of cycles is
between 0 and 15.
• TRP: Row Precharge Delay
Reset value is three cycles.
This field defines the delay between a Precharge Command and another Command in number of cycles. Number of cycles
is between 0 and 15.
• TRCD: Row to Column Delay
Reset value is two cycles.
This field defines the delay between an Activate Command and a Read/Write Command in number of cycles. Number of
cycles is between 0 and 15.
• TRAS: Active to Precharge Delay
Reset value is five cycles.
This field defines the delay between an Activate Command and a Precharge Command in number of cycles. Number of
cycles is between 0 and 15.
• TXSR: Exit Self Refresh to Active Delay
Reset value is eight cycles.
This field defines the delay between SCKE set high and an Activate Command in number of cycles. Number of cycles is
between 0 and 15.
217
6384E–ATARM–05-Feb-10
22.6.4
SDRAMC Low Power Register
Register Name:SDRAMC_LPR
Access Type:Read-write
Reset Value: 0x0
31
–
30
–
29
–
28
–
27
–
26
–
25
–
24
–
23
–
22
–
21
–
20
–
19
–
18
–
17
–
16
–
15
–
14
–
13
12
11
10
9
7
–
6
5
PASR
TIMEOUT
DS
4
3
–
8
TCSR
2
–
1
0
LPCB
• LPCB: Low-power Configuration Bits
00
Low Power Feature is inhibited: no Power-down, Self-refresh or Deep Power-down command is issued to the SDRAM
device.
01
The SDRAM Controller issues a Self-refresh command to the SDRAM device, the SDCLK clock is deactivated and the
SDCKE signal is set low. The SDRAM device leaves the Self Refresh Mode when accessed and enters it after the
access.
10
The SDRAM Controller issues a Power-down Command to the SDRAM device after each access, the SDCKE signal is
set to low. The SDRAM device leaves the Power-down Mode when accessed and enters it after the access.
11
The SDRAM Controller issues a Deep Power-down command to the SDRAM device. This mode is unique to lowpower SDRAM.
• PASR: Partial Array Self-refresh (only for low-power SDRAM)
PASR parameter is transmitted to the SDRAM during initialization to specify whether only one quarter, one half or all banks
of the SDRAM array are enabled. Disabled banks are not refreshed in self-refresh mode. This parameter must be set
according to the SDRAM device specification.
• TCSR: Temperature Compensated Self-Refresh (only for low-power SDRAM)
TCSR parameter is transmitted to the SDRAM during initialization to set the refresh interval during self-refresh mode
depending on the temperature of the low-power SDRAM. This parameter must be set according to the SDRAM device
specification.
• DS: Drive Strength (only for low-power SDRAM)
DS parameter is transmitted to the SDRAM during initialization to select the SDRAM strength of data output. This parameter must be set according to the SDRAM device specification.
218
AT91SAM9G20
6384E–ATARM–05-Feb-10
AT91SAM9G20
• TIMEOUT: Time to define when low-power mode is enabled
00
The SDRAM controller activates the SDRAM low-power mode immediately after the end of the last transfer.
01
The SDRAM controller activates the SDRAM low-power mode 64 clock cycles after the end of the last
transfer.
10
The SDRAM controller activates the SDRAM low-power mode 128 clock cycles after the end of the last
transfer.
11
Reserved.
219
6384E–ATARM–05-Feb-10
22.6.5
SDRAMC Interrupt Enable Register
Register Name:SDRAMC_IER
Access Type:Write-only
31
–
30
–
29
–
28
–
27
–
26
–
25
–
24
–
23
–
22
–
21
–
20
–
19
–
18
–
17
–
16
–
15
–
14
–
13
–
12
–
11
–
10
–
9
–
8
–
7
–
6
–
5
–
4
–
3
–
2
–
1
–
0
RES
• RES: Refresh Error Status
0: No effect.
1: Enables the refresh error interrupt.
22.6.6
SDRAMC Interrupt Disable Register
Register Name:SDRAMC_IDR
Access Type:Write-only
31
–
30
–
29
–
28
–
27
–
26
–
25
–
24
–
23
–
22
–
21
–
20
–
19
–
18
–
17
–
16
–
15
–
14
–
13
–
12
–
11
–
10
–
9
–
8
–
7
–
6
–
5
–
4
–
3
–
2
–
1
–
0
RES
• RES: Refresh Error Status
0: No effect.
1: Disables the refresh error interrupt.
220
AT91SAM9G20
6384E–ATARM–05-Feb-10
AT91SAM9G20
22.6.7
SDRAMC Interrupt Mask Register
Register Name:SDRAMC_IMR
Access Type:Read-only
31
–
30
–
29
–
28
–
27
–
26
–
25
–
24
–
23
–
22
–
21
–
20
–
19
–
18
–
17
–
16
–
15
–
14
–
13
–
12
–
11
–
10
–
9
–
8
–
7
–
6
–
5
–
4
–
3
–
2
–
1
–
0
RES
• RES: Refresh Error Status
0: The refresh error interrupt is disabled.
1: The refresh error interrupt is enabled.
22.6.8
SDRAMC Interrupt Status Register
Register Name:SDRAMC_ISR
Access Type:Read-only
31
–
30
–
29
–
28
–
27
–
26
–
25
–
24
–
23
–
22
–
21
–
20
–
19
–
18
–
17
–
16
–
15
–
14
–
13
–
12
–
11
–
10
–
9
–
8
–
7
–
6
–
5
–
4
–
3
–
2
–
1
–
0
RES
• RES: Refresh Error Status
0: No refresh error has been detected since the register was last read.
1: A refresh error has been detected since the register was last read.
221
6384E–ATARM–05-Feb-10
22.6.9
SDRAMC Memory Device Register
Register Name:SDRAMC_MDR
Access Type:Read-write
31
–
30
–
29
–
28
–
27
–
26
–
25
–
24
–
23
–
22
–
21
–
20
–
19
–
18
–
17
–
16
–
15
–
14
–
13
–
12
–
11
–
10
–
9
–
8
–
7
–
6
–
5
–
4
–
3
–
2
–
1
0
MD
• MD: Memory Device Type
222
00
SDRAM
01
Low-power SDRAM
10
Reserved
11
Reserved.
AT91SAM9G20
6384E–ATARM–05-Feb-10
AT91SAM9G20
23. Error Corrected Code Controller (ECC)
23.1
Overview
NAND Flash/SmartMedia devices contain by default invalid blocks which have one or more
invalid bits. Over the NAND Flash/SmartMedia lifetime, additional invalid blocks may occur
which can be detected/corrected by ECC code.
The ECC Controller is a mechanism that encodes data in a manner that makes possible the
identification and correction of certain errors in data. The ECC controller is capable of single bit
error correction and 2-bit random detection. When NAND Flash/SmartMedia have more than 2
bits of errors, the data cannot be corrected.
The ECC user interface is compliant with the ARM® Advanced Peripheral Bus (APB rev2).
23.2
Block Diagram
Figure 23-1. Block Diagram
NAND Flash
Static
Memory
Controller
SmartMedia
Logic
ECC
Controller
Ctrl/ECC Algorithm
User Interface
APB
223
6384E–ATARM–05-Feb-10
23.3
Functional Description
A page in NAND Flash and SmartMedia memories contains an area for main data and an additional area used for redundancy (ECC). The page is organized in 8-bit or 16-bit words. The page
size corresponds to the number of words in the main area plus the number of words in the extra
area used for redundancy.
Over time, some memory locations may fail to program or erase properly. In order to ensure that
data is stored properly over the life of the NAND Flash device, NAND Flash providers recommend to utilize either 1 ECC per 256 bytes of data, 1 ECC per 512 bytes of data or 1 ECC for all
of the page.
The only configurations required for ECC are the NAND Flash or the SmartMedia page size
(528/2112/4224) and the type of correction wanted (1 ECC for all the page/1 ECC per 256 bytes
of data /1 ECC per 512 bytes of data). Page size is configured setting the PAGESIZE field in the
ECC Mode Register (ECC_MR). Type of correction is configured setting the TYPCORRECT
field in the ECC Mode Register (ECC_MR).
ECC is automatically computed as soon as a read (00h)/write (80h) command to the NAND
Flash or the SmartMedia is detected. Read and write access must start at a page boundary.
ECC results are available as soon as the counter reaches the end of the main area. Values in
the ECC Parity Registers (ECC_PR0 to ECC_PR15) are then valid and locked until a new start
condition occurs (read/write command followed by address cycles).
23.3.1
Write Access
Once the Flash memory page is written, the computed ECC codes are available in the ECC Parity (ECC_PR0 to ECC_PR15) registers. The ECC code values must be written by the software
application in the extra area used for redundancy. The number of write accesses in the extra
area is a function of the value of the type of correction field. For example, for 1 ECC per 256
bytes of data for a page of 512 bytes, only the values of ECC_PR0 and ECC_PR1 must be written by the software application. Other registers are meaningless.
23.3.2
Read Access
After reading the whole data in the main area, the application must perform read accesses to the
extra area where ECC code has been previously stored. Error detection is automatically performed by the ECC controller. Please note that it is mandatory to read consecutively the entire
main area and the locations where Parity and NParity values have been previously stored to let
the ECC controller perform error detection.
The application can check the ECC Status Registers (ECC_SR1/ECC_SR2) for any detected
errors. It is up to the application to correct any detected error. ECC computation can detect four
different circumstances:
• No error: XOR between the ECC computation and the ECC code stored at the end of the
NAND Flash or SmartMedia page is equal to 0. No error flags in the ECC Status Registers
(ECC_SR1/ECC_SR2).
• Recoverable error: Only the RECERR flags in the ECC Status registers
(ECC_SR1/ECC_SR2) are set. The corrupted word offset in the read page is defined by the
WORDADDR field in the ECC Parity Registers (ECC_PR0 to ECC_PR15). The corrupted bit
position in the concerned word is defined in the BITADDR field in the ECC Parity Registers
(ECC_PR0 to ECC_PR15).
224
AT91SAM9G20
6384E–ATARM–05-Feb-10
AT91SAM9G20
• ECC error: The ECCERR flag in the ECC Status Registers (ECC_SR1/ECC_SR2) are set.
An error has been detected in the ECC code stored in the Flash memory. The position of the
corrupted bit can be found by the application performing an XOR between the Parity and the
NParity contained in the ECC code stored in the Flash memory.
• Non correctable error: The MULERR flag in the ECC Status Registers
(ECC_SR1/ECC_SR2) are set. Several unrecoverable errors have been detected in the
Flash memory page.
ECC Status Registers, ECC Parity Registers are cleared when a read/write command is
detected or a software reset is performed.
For Single-bit Error Correction and Double-bit Error Detection (SEC-DED) hsiao code is used.
24-bit ECC is generated in order to perform one bit correction per 256 or 512 bytes for pages of
512/2048/4096 8-bit words. 32-bit ECC is generated in order to perform one bit correction per
512/1024/2048/4096 8- or 16-bit words.They are generated according to the schemes shown in
Figure 23-2 and Figure 23-3.
Figure 23-2. Parity Generation for 512/1024/2048/4096 8-bit Words
1st byte
2nd byte
3rd byte
4 th byte
(page size -3 )th byte
(page size -2 )th byte
(page size -1 )th byte
Page size th byte
Bit7
Bit6
Bit5
Bit4
Bit3
Bit2
Bit1
Bit0
Bit7
Bit6
Bit5
Bit4
Bit3
Bit2
Bit1
Bit7
Bit7
Bit6
Bit6
Bit5
Bit5
Bit4
Bit4
Bit3
Bit3
Bit2
Bit2
Bit7
Bit7
Bit6
Bit6
Bit5
Bit5
Bit4
Bit3
Bit4
Bit7
Bit7
Bit6
Bit6
Bit5
Bit5
Bit4
Bit4
P1
P1'
P1
P2
P1'
P2'
P4
Page size
Page size
Page size
Page size
= 512
= 1024
= 2048
= 4096
Px = 2048
Px = 4096
Px = 8192
Px = 16384
P16
Bit0
P8
P8'
Bit1
Bit1
Bit0
Bit0
P8
P8'
P16'
Bit2
Bit1
Bit0
P16
Bit3
Bit2
Bit1
Bit0
P8
P8'
Bit3
Bit3
Bit2
Bit0
P8
P8'
P16'
Bit2
Bit1
Bit1
P1
P1'
P1
P1'
P2
Bit0
P32
PX
P32
PX'
P2'
P4'
P1=bit7(+)bit5(+)bit3(+)bit1(+)P1
P2=bit7(+)bit6(+)bit3(+)bit2(+)P2
P4=bit7(+)bit6(+)bit5(+)bit4(+)P4
P1'=bit6(+)bit4(+)bit2(+)bit0(+)P1'
P2'=bit5(+)bit4(+)bit1(+)bit0(+)P2'
P4'=bit7(+)bit6(+)bit5(+)bit4(+)P4'
To calculate P8’ to PX’ and P8 to PX, apply the algorithm that follows.
Page size = 2n
for i =0 to n
225
6384E–ATARM–05-Feb-10
begin
for (j = 0 to page_size_byte)
begin
if(j[i] ==1)
P[2i+3]=bit7(+)bit6(+)bit5(+)bit4(+)bit3(+)
bit2(+)bit1(+)bit0(+)P[2i+3]
else
P[2i+3]’=bit7(+)bit6(+)bit5(+)bit4(+)bit3(+)
bit2(+)bit1(+)bit0(+)P[2i+3]'
end
end
226
AT91SAM9G20
6384E–ATARM–05-Feb-10
6384E–ATARM–05-Feb-10
(Page size -3 )th word
(Page size -2 )th word
(Page size -1 )th word
Page size th word
3rd word
4th word
1st word
2nd word
(+)
AT91SAM9G20
Figure 23-3. Parity Generation for 512/1024/2048/4096 16-bit Words
227
To calculate P8’ to PX’ and P8 to PX, apply the algorithm that follows.
Page size = 2n
for i =0 to n
begin
for (j = 0 to page_size_word)
begin
if(j[i] ==1)
P[2i+3]= bit15(+)bit14(+)bit13(+)bit12(+)
bit11(+)bit10(+)bit9(+)bit8(+)
bit7(+)bit6(+)bit5(+)bit4(+)bit3(+)
bit2(+)bit1(+)bit0(+)P[2n+3]
else
P[2i+3]’=bit15(+)bit14(+)bit13(+)bit12(+)
bit11(+)bit10(+)bit9(+)bit8(+)
bit7(+)bit6(+)bit5(+)bit4(+)bit3(+)
bit2(+)bit1(+)bit0(+)P[2i+3]'
end
end
228
AT91SAM9G20
6384E–ATARM–05-Feb-10
AT91SAM9G20
23.4
Error Corrected Code Controller (ECC) User Interface
Table 23-1.
Register Mapping
Offset
Register
Name
Access
Reset
0x00
ECC Control Register
ECC_CTRL
Write-only
0x0
0x04
ECC Mode Register
ECC_MD
Read-write
0x0
0x08
ECC Status1 Register
ECC_SR1
Read-only
0x0
0x0C
ECC Parity Register 0
ECC_PR0
Read-only
0x0
0x10
ECC Parity Register 1
ECC_PR1
Read-only
0x0
0x14
ECC Status2 Register
ECC_SR2
Read-only
0x0
0x18
ECC Parity 2
ECC_PR2
Read-only
0x0
0x1C
ECC Parity 3
ECC_PR3
Read-only
0x0
0x20
ECC Parity 4
ECC_PR4
Read-only
0x0
0x24
ECC Parity 5
ECC_PR5
Read-only
0x0
0x28
ECC Parity 6
ECC_PR6
Read-only
0x0
0x2C
ECC Parity 7
ECC_PR7
Read-only
0x0
0x30
ECC Parity 8
ECC_PR8
Read-only
0x0
0x34
ECC Parity 9
ECC_PR9
Read-only
0x0
0x38
ECC Parity 10
ECC_PR10
Read-only
0x0
0x3C
ECC Parity 11
ECC_PR11
Read-only
0x0
0x40
ECC Parity 12
ECC_PR12
Read-only
0x0
0x44
ECC Parity 13
ECC_PR13
Read-only
0x0
0x48
ECC Parity 14
ECC_PR14
Read-only
0x0
0x4C
ECC Parity 15
ECC_PR15
Read-only
0x0
Reserved
–
–
–
0x14 - 0xFC
229
6384E–ATARM–05-Feb-10
23.4.1
Name:
ECC Control Register
ECC_CR
Access Type:Write-only
31
–
23
–
15
–
7
–
30
–
22
–
14
–
6
–
29
–
21
–
13
–
5
–
28
–
20
–
12
–
4
–
27
–
19
–
11
–
3
–
26
–
18
–
10
–
2
–
25
–
17
–
9
–
1
–
24
–
16
–
8
–
0
RST
• RST: RESET Parity
Provides reset to current ECC by software.
1: Reset ECC Parity registers
0: No effect
230
AT91SAM9G20
6384E–ATARM–05-Feb-10
AT91SAM9G20
23.4.2
ECC Mode Register
Register Name:ECC_MR
Access Type:Read-write
31
–
23
–
15
–
7
–
30
–
22
–
14
–
6
–
29
–
21
–
13
–
5
28
–
20
–
12
–
4
TYPCORREC
27
–
19
–
11
–
3
–
26
–
18
–
10
–
2
–
25
–
17
–
9
–
1
24
–
16
–
8
–
0
PAGESIZE
• PAGESIZE: Page Size
This field defines the page size of the NAND Flash device.
Page Size
Description
00
528 words
01
1056 words
10
2112 words
11
4224 words
A word has a value of 8 bits or 16 bits, depending on the NAND Flash or SmartMedia memory organization.
• TYPECORREC: Type of Correction
00: 1 bit correction for a page size of 512/1024/2048/4096 bytes.
01: 1 bit correction for 256 bytes of data for a page size of 512/2048/4096 bytes.
10: 1 bit correction for 512 bytes of data for a page size of 512/2048/4096 bytes.
231
6384E–ATARM–05-Feb-10
23.4.3
ECC Status Register 1
Register Name:ECC_SR1
Access Type:Read-only
31
–
23
–
15
–
7
–
30
ECCERR7
22
ECCERR5
14
MULERR3
6
MULERR1
29
ECCERR7
21
ECCERR5
13
ECCERR3
5
ECCERR1
28
RECERR7
20
RECERR5
12
RECERR3
4
RECERR1
27
–
19
–
11
–
3
–
26
ECCERR6
18
ECCERR4
10
MULERR2
2
ECCERR0
25
ECCERR6
17
ECCERR4
9
ECCERR2
1
ECCERR0
24
RECERR6
16
RECERR4
8
RECERR2
0
RECERR0
• RECERR0: Recoverable Error
0 = No Errors Detected.
1 = Errors Detected. If MUL_ERROR is 0, a single correctable error was detected. Otherwise multiple uncorrected errors
were detected.
• ECCERR0: ECC Error
0 = No Errors Detected.
1 = A single bit error occurred in the ECC bytes.
If TYPECORRECT = 0, read both ECC Parity 0 and ECC Parity 1 registers, the error occurred at the location which contains a 1 in the least significant 16 bits; else read ECC Parity 0 register, the error occurred at the location which contains a
1 in the least significant 24 bits.
• MULERR0: Multiple Error
0 = No Multiple Errors Detected.
1 = Multiple Errors Detected.
• RECERR1: Recoverable Error in the page between the 256th and the 511th bytes or the 512th and the 1023rd
bytes
Fixed to 0 if TYPECORREC = 0.
0 = No Errors Detected.
1 = Errors Detected. If MUL_ERROR is 0, a single correctable error was detected. Otherwise multiple uncorrected errors
were detected.
• ECCERR1: ECC Error in the page between the 256th and the 511th bytes or the 512th and the 1023rd bytes
Fixed to 0 if TYPECORREC = 0
0 = No Errors Detected.
1 = A single bit error occurred in the ECC bytes.
Read ECC Parity 1 register, the error occurred at the location which contains a 1 in the least significant 24 bits.
• MULERR1: Multiple Error in the page between the 256th and the 511th bytes or the 512th and the 1023rd bytes
Fixed to 0 if TYPECORREC = 0.
0 = No Multiple Errors Detected.
232
AT91SAM9G20
6384E–ATARM–05-Feb-10
AT91SAM9G20
1 = Multiple Errors Detected.
• RECERR2: Recoverable Error in the page between the 512th and the 767th bytes or the 1024th and the 1535th
bytes
Fixed to 0 if TYPECORREC = 0.
0 = No Errors Detected.
1 = Errors Detected. If MUL_ERROR is 0, a single correctable error was detected. Otherwise, multiple uncorrected errors
were detected.
• ECCERR2: ECC Error in the page between the 512th and the 767th bytes or the 1024th and the 1535th bytes
Fixed to 0 if TYPECORREC = 0.
0 = No Errors Detected.
1 = A single bit error occurred in the ECC bytes.
Read ECC Parity 2 register, the error occurred at the location which contains a 1 in the least significant 24 bits.
• MULERR2: Multiple Error in the page between the 512th and the 767th bytes or the 1024th and the 1535th bytes
Fixed to 0 if TYPECORREC = 0.
0 = No Multiple Errors Detected.
1 = Multiple Errors Detected.
• RECERR3: Recoverable Error in the page between the 768th and the 1023rd bytes or the 1536th and the 2047th
bytes
Fixed to 0 if TYPECORREC = 0.
0 = No Errors Detected.
1 = Errors Detected. If MUL_ERROR is 0, a single correctable error was detected. Otherwise multiple uncorrected errors
were detected.
• ECCERR3: ECC Error in the page between the 768th and the 1023rd bytes or the 1536th and the 2047th bytes
Fixed to 0 if TYPECORREC = 0.
0 = No Errors Detected.
1 = A single bit error occurred in the ECC bytes.
Read ECC Parity 3 register, the error occurred at the location which contains a 1 in the least significant 24 bits.
• MULERR3: Multiple Error in the page between the 768th and the 1023rd bytes or the 1536th and the 2047th bytes
Fixed to 0 if TYPECORREC = 0.
0 = No Multiple Errors Detected.
1 = Multiple Errors Detected.
• RECERR4: Recoverable Error in the page between the 1024th and the 1279th bytes or the 2048th and the 2559th
bytes
Fixed to 0 if TYPECORREC = 0.
0 = No Errors Detected.
233
6384E–ATARM–05-Feb-10
1 = Errors Detected. If MUL_ERROR is 0, a single correctable error was detected. Otherwise multiple uncorrected errors
were detected.
• ECCERR4: ECC Error in the page between the 1024th and the 1279th bytes or the 2048th and the 2559th bytes
Fixed to 0 if TYPECORREC = 0.
0 = No Errors Detected.
1 = A single bit error occurred in the ECC bytes.
Read ECC Parity 4 register, the error occurred at the location which contains a 1 in the least significant 24 bits.
• MULERR4: Multiple Error in the page between the 1024th and the 1279th bytes or the 2048th and the 2559th
bytes
Fixed to 0 if TYPECORREC = 0.
0 = No Multiple Errors Detected.
1 = Multiple Errors Detected.
• RECERR5: Recoverable Error in the page between the 1280th and the 1535th bytes or the 2560th and the 3071st
bytes
Fixed to 0 if TYPECORREC = 0.
0 = No Errors Detected.
1 = Errors Detected. If MUL_ERROR is 0, a single correctable error was detected. Otherwise multiple uncorrected errors
were detected
• ECCERR5: ECC Error in the page between the 1280th and the 1535th bytes or the 2560th and the 3071st bytes
Fixed to 0 if TYPECORREC = 0.
0 = No Errors Detected.
1 = A single bit error occurred in the ECC bytes.
Read ECC Parity 5 register, the error occurred at the location which contains a 1 in the least significant 24 bits.
• MULERR5: Multiple Error in the page between the 1280th and the 1535th bytes or the 2560th and the 3071st
bytes
Fixed to 0 if TYPECORREC = 0.
0 = No Multiple Errors Detected.
1 = Multiple Errors Detected.
• RECERR6: Recoverable Error in the page between the 1536th and the 1791st bytes or the 3072nd and the 3583rd
bytes
Fixed to 0 if TYPECORREC = 0.
0 = No Errors Detected.
1 = Errors Detected. If MUL_ERROR is 0, a single correctable error was detected. Otherwise multiple uncorrected errors
were detected.
• ECCERR6: ECC Error in the page between the 1536th and the 1791st bytes or the 3072nd and the 3583rd bytes
Fixed to 0 if TYPECORREC = 0.
234
AT91SAM9G20
6384E–ATARM–05-Feb-10
AT91SAM9G20
0 = No Errors Detected.
1 = A single bit error occurred in the ECC bytes.
Read ECC Parity 6 register, the error occurred at the location which contains a 1 in the least significant 24 bits.
• MULERR6: Multiple Error in the page between the 1536th and the 1791st bytes or the 3072nd and the 3583rd
bytes
Fixed to 0 if TYPECORREC = 0.
0 = No Multiple Errors Detected.
1 = Multiple Errors Detected.
• RECERR7: Recoverable Error in the page between the 1792nd and the 2047th bytes or the 3584th and the 4095th
bytes
Fixed to 0 if TYPECORREC = 0.
0 = No Errors Detected.
1 = Errors Detected. If MUL_ERROR is 0, a single correctable error was detected. Otherwise, multiple uncorrected errors
were detected.
• ECCERR7: ECC Error in the page between the 1792nd and the 2047th bytes or the 3584th and the 4095th bytes
Fixed to 0 if TYPECORREC = 0.
0 = No Errors Detected.
1 = A single bit error occurred in the ECC bytes.
Read ECC Parity 7 register, the error occurred at the location which contains a 1 in the least significant 24 bits.
• MULERR7: Multiple Error in the page between the 1792nd and the 2047th bytes or the 3584th and the 4095th
bytes
Fixed to 0 if TYPECORREC = 0.
0 = No Multiple Errors Detected.
1 = Multiple Errors Detected.
235
6384E–ATARM–05-Feb-10
23.4.4
ECC Status Register 2
Register Name:ECC_SR2
Access Type:Read-only
31
–
23
–
15
–
7
–
30
ECCERR15
22
ECCERR13
14
MULERR11
6
MULERR9
29
ECCERR15
21
ECCERR13
13
ECCERR11
5
ECCERR9
28
RECERR15
20
RECERR13
12
RECERR11
4
RECERR9
27
–
19
–
11
–
3
–
26
ECCERR14
18
ECCERR12
10
MULERR10
2
ECCERR8
25
ECCERR14
17
ECCERR12
9
ECCERR10
1
ECCERR8
24
–RECERR14
16
RECERR12
8
RECERR10
0
RECERR8
• RECERR8: Recoverable Error in the page between the 2048th and the 2303rd bytes
Fixed to 0 if TYPECORREC = 0.
0 = No Errors Detected.
1 = Errors Detected. If MUL_ERROR is 0, a single correctable error was detected. Otherwise multiple uncorrected errors
were detected
• ECCERR8: ECC Error in the page between the 2048th and the 2303rd bytes
Fixed to 0 if TYPECORREC = 0.
0 = No Errors Detected.
1 = A single bit error occurred in the ECC bytes.
Read ECC Parity 8 register, the error occurred at the location which contains a 1 in the least significant 24 bits.
• MULERR8: Multiple Error in the page between the 2048th and the 2303rd bytes
Fixed to 0 if TYPECORREC = 0.
0 = No Multiple Errors Detected.
1 = Multiple Errors Detected.
• RECERR9: Recoverable Error in the page between the 2304th and the 2559th bytes
Fixed to 0 if TYPECORREC = 0.
0 = No Errors Detected.
1 = Errors Detected. If MUL_ERROR is 0, a single correctable error was detected. Otherwise multiple uncorrected errors
were detected.
• ECCERR9: ECC Error in the page between the 2304th and the 2559th bytes
Fixed to 0 if TYPECORREC = 0.
0 = No Errors Detected.
1 = A single bit error occurred in the ECC bytes.
Read ECC Parity 9 register, the error occurred at the location which contains a 1 in the least significant 24 bits.
• MULERR9: Multiple Error in the page between the 2304th and the 2559th bytes
Fixed to 0 if TYPECORREC = 0.
236
AT91SAM9G20
6384E–ATARM–05-Feb-10
AT91SAM9G20
0 = No Multiple Errors Detected.
1 = Multiple Errors Detected.
• RECERR10: Recoverable Error in the page between the 2560th and the 2815th bytes
Fixed to 0 if TYPECORREC = 0.
0 = No Errors Detected.
1 = Errors Detected. If MUL_ERROR is 0, a single correctable error was detected. Otherwise, multiple uncorrected errors
were detected.
• ECCERR10: ECC Error in the page between the 2560th and the 2815th bytes
Fixed to 0 if TYPECORREC = 0.
0 = No Errors Detected.
1 = A single bit error occurred in the ECC bytes.
Read ECC Parity 10 register, the error occurred at the location which contains a 1 in the least significant 24 bits.
• MULERR10: Multiple Error in the page between the 2560th and the 2815th bytes
Fixed to 0 if TYPECORREC = 0.
0 = No Multiple Errors Detected.
1 = Multiple Errors Detected.
• RECERR11: Recoverable Error in the page between the 2816th and the 3071st bytes
Fixed to 0 if TYPECORREC = 0.
0 = No Errors Detected.
1 = Errors Detected.. If MUL_ERROR is 0, a single correctable error was detected. Otherwise, multiple uncorrected errors
were detected
• ECCERR11: ECC Error in the page between the 2816th and the 3071st bytes
Fixed to 0 if TYPECORREC = 0.
0 = No Errors Detected.
1 = A single bit error occurred in the ECC bytes.
Read ECC Parity 11 register, the error occurred at the location which contains a 1 in the least significant 24 bits.
• MULERR11: Multiple Error in the page between the 2816th and the 3071st bytes
Fixed to 0 if TYPECORREC = 0.
0 = No Multiple Errors Detected.
1 = Multiple Errors Detected.
• RECERR12: Recoverable Error in the page between the 3072nd and the 3327th bytes
Fixed to 0 if TYPECORREC = 0
0 = No Errors Detected
1 = Errors Detected. If MUL_ERROR is 0, a single correctable error was detected. Otherwise multiple uncorrected errors
were detected
237
6384E–ATARM–05-Feb-10
• ECCERR12: ECC Error in the page between the 3072nd and the 3327th bytes
Fixed to 0 if TYPECORREC = 0
0 = No Errors Detected
1 = A single bit error occurred in the ECC bytes.
Read ECC Parity 12 register, the error occurred at the location which contains a 1 in the least significant 24 bits.
• MULERR12: Multiple Error in the page between the 3072nd and the 3327th bytes
Fixed to 0 if TYPECORREC = 0.
0 = No Multiple Errors Detected.
1 = Multiple Errors Detected.
• RECERR13: Recoverable Error in the page between the 3328th and the 3583rd bytes
Fixed to 0 if TYPECORREC = 0.
0 = No Errors Detected.
1 = Errors Detected. If MUL_ERROR is 0, a single correctable error was detected. Otherwise multiple uncorrected errors
were detected.
• ECCERR13: ECC Error in the page between the 3328th and the 3583rd bytes
Fixed to 0 if TYPECORREC = 0.
0 = No Errors Detected.
1 = A single bit error occurred in the ECC bytes.
Read ECC Parity 13 register, the error occurred at the location which contains a 1 in the least significant 24 bits.
• MULERR13: Multiple Error in the page between the 3328th and the 3583rd bytes
Fixed to 0 if TYPECORREC = 0.
0 = No Multiple Errors Detected.
1 = Multiple Errors Detected.
• RECERR14: Recoverable Error in the page between the 3584th and the 3839th bytes
Fixed to 0 if TYPECORREC = 0.
0 = No Errors Detected.
1 = Errors Detected. If MUL_ERROR is 0, a single correctable error was detected. Otherwise, multiple uncorrected errors
were detected.
• ECCERR14: ECC Error in the page between the 3584th and the 3839th bytes
Fixed to 0 if TYPECORREC = 0.
0 = No Errors Detected.
1 = A single bit error occurred in the ECC bytes.
Read ECC Parity 14 register, the error occurred at the location which contains a 1 in the least significant 24 bits.
• MULERR14: Multiple Error in the page between the 3584th and the 3839th bytes
Fixed to 0 if TYPECORREC = 0.
238
AT91SAM9G20
6384E–ATARM–05-Feb-10
AT91SAM9G20
0 = No Multiple Errors Detected.
1 = Multiple Errors Detected.
• RECERR15: Recoverable Error in the page between the 3840th and the 4095th bytes
Fixed to 0 if TYPECORREC = 0.
0 = No Errors Detected.
1 = Errors Detected. If MUL_ERROR is 0, a single correctable error was detected. Otherwise, multiple uncorrected errors
were detected
• ECCERR15: ECC Error in the page between the 3840th and the 4095th bytes
Fixed to 0 if TYPECORREC = 0
0 = No Errors Detected.
1 = A single bit error occurred in the ECC bytes.
Read ECC Parity 15 register, the error occurred at the location which contains a 1 in the least significant 24 bits.
• MULERR15: Multiple Error in the page between the 3840th and the 4095th bytes
Fixed to 0 if TYPECORREC = 0.
0 = No Multiple Errors Detected.
1 = Multiple Errors Detected.
239
6384E–ATARM–05-Feb-10
23.5
Registers for 1 ECC for a page of 512/1024/2048/4096 bytes
23.5.1
ECC Parity Register 0
Register Name:ECC_PR0
Access Type:Read-only
31
–
23
–
15
30
–
22
–
14
29
–
21
–
13
28
–
20
–
12
7
6
5
4
27
–
19
–
11
26
–
18
–
10
3
2
25
–
17
–
9
24
–
16
–
8
1
0
WORDADDR
WORDADDR
BITADDR
Once the entire main area of a page is written with data, the register content must be stored at any free location of the
spare area.
• BITADDR: Bit Address
During a page read, this value contains the corrupted bit offset where an error occurred, if a single error was detected. If
multiple errors were detected, this value is meaningless.
• WORDADDR: Word Address
During a page read, this value contains the word address (8-bit or 16-bit word depending on the memory plane organization) where an error occurred, if a single error was detected. If multiple errors were detected, this value is meaningless.
240
AT91SAM9G20
6384E–ATARM–05-Feb-10
AT91SAM9G20
23.5.2
ECC Parity Register 1
Register Name:ECC_PR1
Access Type:Read-only
31
–
23
–
15
30
–
22
–
14
29
–
21
–
13
28
–
20
–
12
7
6
5
4
27
–
19
–
11
26
–
18
–
10
25
–
17
–
9
24
–
16
–
8
3
2
1
0
NPARITY
NPARITY
• NPARITY:
Parity N
241
6384E–ATARM–05-Feb-10
23.6
Registers for 1 ECC per 512 bytes for a page of 512/2048/4096 bytes, 8-bit word
23.6.1
ECC Parity Register 0
Register Name:ECC_PR0
Access Type:Read-only
31
30
29
28
27
26
25
24
23
22
21
19
18
17
16
15
14
13
20
NPARITY0
12
11
10
9
8
7
6
4
3
2
1
BITADDR0
0
NPARITY0
5
WORDADDR0
WORDADD0
Once the entire main area of a page is written with data, the register content must be stored at any free location of the
spare area.
• BITADDR0: corrupted Bit Address in the page between the first byte and the 511th bytes
During a page read, this value contains the corrupted bit offset where an error occurred, if a single error was detected. If
multiple errors were detected, this value is meaningless.
• WORDADDR0: corrupted Word Address in the page between the first byte and the 511th bytes
During a page read, this value contains the word address (8-bit word) where an error occurred, if a single error was
detected. If multiple errors were detected, this value is meaningless.
• NPARITY0:
Parity N
242
AT91SAM9G20
6384E–ATARM–05-Feb-10
AT91SAM9G20
23.6.2
ECC Parity Register 1
Register Name:ECC_PR1
Access Type:Read-only
31
30
29
28
27
26
25
24
23
22
21
19
18
17
16
15
14
20
NPARITY1
12
11
10
9
8
1
BITADDR1
0
13
NPARITY1
7
6
5
WORDADDR1
WORDADD1
4
3
2
Once the entire main area of a page is written with data, the register content must be stored at any free location of the
spare area.
• BITADDR1: corrupted Bit Address in the page between the 512th and the 1023rd bytes
During a page read, this value contains the corrupted bit offset where an error occurred, if a single error was detected. If
multiple errors were detected, this value is meaningless.
• WORDADDR1: corrupted Word Address in the page between the 512th and the 1023rd bytes
During a page read, this value contains the word address (8-bit word) where an error occurred, if a single error was
detected. If multiple errors were detected, this value is meaningless.
• NPARITY1:
Parity N
243
6384E–ATARM–05-Feb-10
23.6.3
ECC Parity Register 2
Register Name:ECC_PR2
Access Type:Read-only
31
30
29
28
27
26
25
24
23
22
21
19
18
17
16
15
14
20
NPARITY2
12
11
10
9
8
1
BITADDR2
0
13
NPARITY2
7
6
5
WORDADDR2
WORDADD2
4
3
2
Once the entire main area of a page is written with data, the register content must be stored at any free location of the
spare area.
• BITADDR2: corrupted Bit Address in the page between the 1023rd and the 1535th bytes
During a page read, this value contains the corrupted bit offset where an error occurred, if a single error was detected. If
multiple errors were detected, this value is meaningless.
• WORDADDR2: corrupted Word Address in the page in the page between the 1023rd and the 1535th bytes
During a page read, this value contains the word address (8-bit word) where an error occurred, if a single error was
detected. If multiple errors were detected, this value is meaningless.
• NPARITY2:
Parity N
244
AT91SAM9G20
6384E–ATARM–05-Feb-10
AT91SAM9G20
23.6.4
ECC Parity Register 3
Register Name:ECC_PR3
Access Type:Read-only
31
30
29
28
27
26
25
24
23
22
21
19
18
17
16
15
14
20
NPARITY3
12
11
10
9
8
1
BITADDR3
0
13
NPARITY3
7
6
5
WORDADDR3
WORDADD3
4
3
2
Once the entire main area of a page is written with data, the register content must be stored at any free location of the
spare area.
• BITADDR3: corrupted Bit Address in the page between the1536th and the 2047th bytes
During a page read, this value contains the corrupted bit offset where an error occurred, if a single error was detected. If
multiple errors were detected, this value is meaningless.
• WORDADDR3 corrupted Word Address in the page between the 1536th and the 2047th bytes
During a page read, this value contains the word address (8-bit word) where an error occurred, if a single error was
detected. If multiple errors were detected, this value is meaningless.
• NPARITY3
Parity N
245
6384E–ATARM–05-Feb-10
23.6.5
ECC Parity Register 4
Register Name:ECC_PR4
Access Type:Read-only
31
30
29
28
27
26
25
24
23
22
21
19
18
17
16
15
14
20
NPARITY4
12
11
10
9
8
1
BITADDR4
0
13
NPARITY4
7
6
5
WORDADDR4
WORDADD4
4
3
2
Once the entire main area of a page is written with data, the register content must be stored at any free location of the
spare area.
• BITADDR4: corrupted Bit Address in the page between the 2048th and the 2559th bytes
During a page read, this value contains the corrupted bit offset where an error occurred, if a single error was detected. If
multiple errors were detected, this value is meaningless.
• WORDADDR4: corrupted Word Address in the page between the 2048th and the 2559th bytes
During a page read, this value contains the word address (8-bit word) where an error occurred, if a single error was
detected. If multiple errors were detected, this value is meaningless.
• NPARITY4:
Parity N
246
AT91SAM9G20
6384E–ATARM–05-Feb-10
AT91SAM9G20
23.6.6
ECC Parity Register 5
Register Name:ECC_PR5
Access Type:Read-only
31
30
29
28
27
26
25
24
23
22
21
19
18
17
16
15
14
20
NPARITY5
12
11
10
9
8
1
BITADDR5
0
13
NPARITY5
7
6
5
WORDADDR5
WORDADD5
4
3
2
Once the entire main area of a page is written with data, the register content must be stored at any free location of the
spare area.
• BITADDR5: corrupted Bit Address in the page between the 2560th and the 3071st bytes
During a page read, this value contains the corrupted bit offset where an error occurred, if a single error was detected. If
multiple errors were detected, this value is meaningless.
• WORDADDR5: corrupted Word Address in the page between the 2560th and the 3071st bytes
During a page read, this value contains the word address (8-bit word) where an error occurred, if a single error was
detected. If multiple errors were detected, this value is meaningless.
• NPARITY5:
Parity N
247
6384E–ATARM–05-Feb-10
23.6.7
ECC Parity Register 6
Register Name:ECC_PR6
Access Type:Read-only
31
30
29
28
27
26
25
24
23
22
21
19
18
17
16
15
14
20
NPARITY6
12
11
10
9
8
1
BITADDR6
0
13
NPARITY6
7
6
5
WORDADDR6
WORDADD6
4
3
2
Once the entire main area of a page is written with data, the register content must be stored at any free location of the
spare area.
• BITADDR6: corrupted Bit Address in the page between the 3072nd and the 3583rd bytes
During a page read, this value contains the corrupted bit offset where an error occurred, if a single error was detected. If
multiple errors were detected, this value is meaningless.
• WORDADDR6: corrupted Word Address in the page between the 3072nd and the 3583rd bytes
During a page read, this value contains the word address (8-bit word) where an error occurred, if a single error was
detected. If multiple errors were detected, this value is meaningless.
• NPARITY6:
Parity N
248
AT91SAM9G20
6384E–ATARM–05-Feb-10
AT91SAM9G20
23.6.8
ECC Parity Register 7
Register Name:ECC_PR7
Access Type:Read-only
31
30
29
28
27
26
25
24
23
22
21
19
18
17
16
15
14
20
NPARITY7
12
11
10
9
8
1
BITADDR7
0
13
NPARITY7
7
6
5
WORDADDR7
WORDADD7
4
3
2
Once the entire main area of a page is written with data, the register content must be stored at any free location of the
spare area.
• BITADDR7: corrupted Bit Address in the page between the 3584h and the 4095th bytes
During a page read, this value contains the corrupted bit offset where an error occurred, if a single error was detected. If
multiple errors were detected, this value is meaningless.
• WORDADDR7: corrupted Word Address in the page between the 3584th and the 4095th bytes
During a page read, this value contains the word address (8-bit word) where an error occurred, if a single error was
detected. If multiple errors were detected, this value is meaningless.
• NPARITY7:
Parity N
249
6384E–ATARM–05-Feb-10
23.7
Registers for 1 ECC per 256 bytes for a page of 512/2048/4096 bytes, 8-bit word
23.7.1
ECC Parity Register 0
Register Name:ECC_PR0
Access Type:Read-only
31
30
29
28
23
0
15
22
21
20
14
13
12
7
6
NPARITY0
5
WORDADDR0
4
27
19
NPARITY0
11
0
3
26
25
24
18
17
16
10
9
WORDADD0
1
BITADDR0
8
2
0
Once the entire main area of a page is written with data, the register content must be stored at any free location of the
spare area.
• BITADDR0: corrupted Bit Address in the page between the first byte and the 255th bytes
During a page read, this value contains the corrupted bit offset where an error occurred, if a single error was detected. If
multiple errors were detected, this value is meaningless.
• WORDADDR0: corrupted Word Address in the page between the first byte and the 255th bytes
During a page read, this value contains the word address (8-bit word) where an error occurred, if a single error was
detected. If multiple errors were detected, this value is meaningless.
• NPARITY0:
Parity N
250
AT91SAM9G20
6384E–ATARM–05-Feb-10
AT91SAM9G20
23.7.2
ECC Parity Register 1
Register Name:ECC_PR1
Access Type:Read-only
31
30
29
28
23
0
15
22
21
20
13
12
14
NPARITY1
7
6
5
WORDADDR1
4
27
19
NPARITY1
11
0
3
26
25
24
18
17
16
10
9
WORDADD1
1
BITADDR1
8
2
0
Once the entire main area of a page is written with data, the register content must be stored at any free location of the
spare area
• BITADDR1: corrupted Bit Address in the page between the 256th and the 511th bytes
During a page read, this value contains the corrupted bit offset where an error occurred, if a single error was detected. If
multiple errors were detected, this value is meaningless.
• WORDADDR1: corrupted Word Address in the page between the 256th and the 511th bytes
During a page read, this value contains the word address (8-bit word) where an error occurred, if a single error was
detected. If multiple errors were detected, this value is meaningless.
• NPARITY1:
Parity N
251
6384E–ATARM–05-Feb-10
23.7.3
ECC Parity Register 2
Register Name:ECC_PR2
Access Type:Read-only
31
30
29
28
23
0
15
22
21
20
13
12
14
NPARITY2
7
6
5
WORDADDR2
4
27
19
NPARITY2
11
0
3
26
25
24
18
17
16
10
9
WORDADD2
1
BITADDR2
8
2
0
Once the entire main area of a page is written with data, the register content must be stored at any free location of the
spare area.
• BITADDR2: corrupted Bit Address in the page between the 512th and the 767th bytes
During a page read, this value contains the corrupted bit offset where an error occurred, if a single error was detected. If
multiple errors were detected, this value is meaningless.
• WORDADDR2: corrupted Word Address in the page between the 512th and the 767th bytes
During a page read, this value contains the word address (8-bit word) where an error occurred, if a single error was
detected. If multiple errors were detected, this value is meaningless.
• NPARITY2:
Parity N
252
AT91SAM9G20
6384E–ATARM–05-Feb-10
AT91SAM9G20
23.7.4
ECC Parity Register 3
Register Name:ECC_PR3
Access Type:Read-only
31
30
29
28
23
0
15
22
21
20
13
12
14
NPARITY3
7
6
5
WORDADDR3
4
27
19
NPARITY3
11
0
3
26
25
24
18
17
16
10
9
WORDADD3
1
BITADDR3
8
2
0
Once the entire main area of a page is written with data, the register content must be stored at any free location of the
spare area.
• BITADDR3: corrupted Bit Address in the page between the 768th and the 1023rd bytes
During a page read, this value contains the corrupted bit offset where an error occurred, if a single error was detected. If
multiple errors were detected, this value is meaningless.
• WORDADDR3: corrupted Word Address in the page between the 768th and the 1023rd bytes
During a page read, this value contains the word address (8-bit word) where an error occurred, if a single error was
detected. If multiple errors were detected, this value is meaningless
• NPARITY3:
Parity N
253
6384E–ATARM–05-Feb-10
23.7.5
ECC Parity Register 4
Register Name:ECC_PR4
Access Type:Read-only
31
30
29
28
27
26
25
24
23
0
15
22
21
20
18
17
16
13
12
19
NPARITY4
11
0
3
14
NPARITY4
7
6
5
WORDADDR4
4
10
2
9
WORDADD4
1
BITADDR4
8
0
Once the entire main area of a page is written with data, the register content must be stored at any free location of the
spare area
• BITADDR4: corrupted bit address in the page between the 1024th and the 1279th bytes
During a page read, this value contains the corrupted bit offset where an error occurred, if a single error was detected. If
multiple errors were detected, this value is meaningless.
• WORDADDR4: corrupted word address in the page between the 1024th and the 1279th bytes
During a page read, this value contains the word address (8-bit word) where an error occurred, if a single error was
detected. If multiple errors were detected, this value is meaningless.
• NPARITY4
Parity N
254
AT91SAM9G20
6384E–ATARM–05-Feb-10
AT91SAM9G20
23.7.6
ECC Parity Register 5
Register Name:ECC_PR5
Access Type:Read-only
31
30
29
28
27
26
25
24
23
0
15
22
21
20
18
17
16
13
12
19
NPARITY5
11
0
3
14
NPARITY5
7
6
5
WORDADDR5
4
10
2
9
WORDADD5
1
BITADDR5
8
0
Once the entire main area of a page is written with data, the register content must be stored at any free location of the
spare area.
• BITADDR5: corrupted Bit Address in the page between the 1280th and the 1535th bytes
During a page read, this value contains the corrupted bit offset where an error occurred, if a single error was detected. If
multiple errors were detected, this value is meaningless.
• WORDADDR5: corrupted Word Address in the page between the 1280th and the 1535th bytes
During a page read, this value contains the word address (8-bit word) where an error occurred, if a single error was
detected. If multiple errors were detected, this value is meaningless.
• NPARITY5:
Parity N
255
6384E–ATARM–05-Feb-10
23.7.7
ECC Parity Register 6
Register Name:ECC_PR6
Access Type:Read-only
31
30
29
28
23
0
15
22
21
20
13
12
14
NPARITY6
7
6
5
WORDADDR6
4
27
19
NPARITY6
11
0
3
26
25
24
18
17
16
10
9
WORDADDR6
1
BITADDR6
8
2
0
Once the entire main area of a page is written with data, the register content must be stored at any free location of the
spare area.
• BITADDR6: corrupted bit address in the page between the 1536th and the 1791st bytes
During a page read, this value contains the corrupted bit offset where an error occurred, if a single error was detected. If
multiple errors were detected, this value is meaningless.
• WORDADDR6: corrupted word address in the page between the 1536th and the 1791st bytes
During a page read, this value contains the word address (8-bit word) where an error occurred, if a single error was
detected. If multiple errors were detected, this value is meaningless.
• NPARITY6:
Parity N
256
AT91SAM9G20
6384E–ATARM–05-Feb-10
AT91SAM9G20
23.7.8
ECC Parity Register 7
Register Name:ECC_PR7
Access Type:Read-only
31
30
29
28
23
0
15
22
21
20
13
12
14
NPARITY7
7
6
5
WORDADDR7
4
27
19
NPARITY7
11
0
3
26
25
24
18
17
16
10
9
WORDADDR7
1
BITADDR7
8
2
0
Once the entire main area of a page is written with data, the register content must be stored at any free location of the
spare area.
• BITADDR7: corrupted Bit Address in the page between the 1792nd and the 2047th bytes
During a page read, this value contains the corrupted bit offset where an error occurred, if a single error was detected. If
multiple errors were detected, this value is meaningless.
• WORDADDR7: corrupted Word Address in the page between the 1792nd and the 2047th bytes
During a page read, this value contains the word address (8-bit word) where an error occurred, if a single error was
detected. If multiple errors were detected, this value is meaningless.
• NPARITY7:
Parity N
257
6384E–ATARM–05-Feb-10
23.7.9
ECC Parity Register 8
Register Name:ECC_PR8
Access Type:Read-only
31
30
29
28
23
0
15
22
21
20
13
12
14
NPARITY8
7
6
5
WORDADDR8
4
27
19
NPARITY8
11
0
3
26
25
24
18
17
16
10
9
WORDADDR8
1
BITADDR8
8
2
0
Once the entire main area of a page is written with data, the register content must be stored at any free location of the
spare area.
• BITADDR8: corrupted Bit Address in the page between the 2048th and the2303rd bytes
During a page read, this value contains the corrupted bit offset where an error occurred, if a single error was detected. If
multiple errors were detected, this value is meaningless.
• WORDADDR8: corrupted Word Address in the page between the 2048th and the 2303rd bytes
During a page read, this value contains the word address (8-bit word) where an error occurred, if a single error was
detected. If multiple errors were detected, this value is meaningless.
• NPARITY8:
Parity N.
258
AT91SAM9G20
6384E–ATARM–05-Feb-10
AT91SAM9G20
23.7.10 ECC Parity Register 9
Register Name:ECC_PR9
Access Type:Read-only
31
30
29
28
23
0
15
22
21
20
13
12
14
NPARITY9
7
6
5
WORDADDR9
4
27
19
NPARITY9
11
0
3
26
25
24
18
17
16
10
9
WORDADDR9
1
BITADDR9
8
2
0
Once the entire main area of a page is written with data, the register content must be stored at any free location of the
spare area
• BITADDR9: corrupted bit address in the page between the 2304th and the 2559th bytes
During a page read, this value contains the corrupted bit offset where an error occurred, if a single error was detected. If
multiple errors were detected, this value is meaningless.
• WORDADDR9: corrupted word address in the page between the 2304th and the 2559th bytes
During a page read, this value contains the word address (8-bit word) where an error occurred, if a single error was
detected. If multiple errors were detected, this value is meaningless
• NPARITY9
Parity N
259
6384E–ATARM–05-Feb-10
23.7.11 ECC Parity Register 10
Register Name:ECC_PR10
Access Type:Read-only
31
30
29
28
23
0
15
22
21
20
14
13
NPARITY10
6
5
WORDADDR10
7
12
4
27
19
NPARITY10
11
0
3
26
25
24
18
17
16
10
9
WORDADDR10
1
BITADDR10
8
2
0
Once the entire main area of a page is written with data, the register content must be stored at any free location of the
spare area.
• BITADDR10: corrupted Bit Address in the page between the 2560th and the 2815th bytes
During a page read, this value contains the corrupted bit offset where an error occurred, if a single error was detected. If
multiple errors were detected, this value is meaningless.
• WORDADDR10: corrupted Word Address in the page between the 2560th and the 2815th bytes
During a page read, this value contains the word address (8-bit word) where an error occurred, if a single error was
detected. If multiple errors were detected, this value is meaningless.
• NPARITY10:
Parity N
260
AT91SAM9G20
6384E–ATARM–05-Feb-10
AT91SAM9G20
23.7.12 ECC Parity Register 11
Register Name:ECC_PR11
Access Type:Read-only
31
30
29
28
23
0
15
22
21
20
7
14
13
NPARITY11
6
5
WORDADDR11
12
4
27
19
NPARITY11
11
0
3
26
25
24
18
17
16
10
9
WORDADDR11
1
BITADDR11
8
2
0
Once the entire main area of a page is written with data, the register content must be stored at any free location of the
spare area.
• BITADDR11: corrupted Bit Address in the page between the 2816th and the 3071st bytes
During a page read, this value contains the corrupted bit offset where an error occurred, if a single error was detected. If
multiple errors were detected, this value is meaningless.
• WORDADDR11: corrupted Word Address in the page between the 2816th and the 3071st bytes
During a page read, this value contains the word address (8-bit word) where an error occurred, if a single error was
detected. If multiple errors were detected, this value is meaningless.
• NPARITY11:
Parity N
261
6384E–ATARM–05-Feb-10
23.7.13 ECC Parity Register 12
Register Name:ECC_PR12
Access Type:Read-only
31
30
29
28
23
0
15
22
21
20
14
13
NPARITY12
6
5
WORDADDR12
7
12
4
27
19
NPARITY12
11
0
3
26
25
24
18
17
16
10
9
WORDADDR12
1
BITADDR12
8
2
0
Once the entire main area of a page is written with data, the register content must be stored at any free location of the
spare area.
• BITADDR12; corrupted Bit Address in the page between the 3072nd and the 3327th bytes
During a page read, this value contains the corrupted bit offset where an error occurred, if a single error was detected. If
multiple errors were detected, this value is meaningless.
• WORDADDR12: corrupted Word Address in the page between the 3072nd and the 3327th bytes
During a page read, this value contains the word address (8-bit word) where an error occurred, if a single error was
detected. If multiple errors were detected, this value is meaningless.
• NPARITY12:
Parity N
262
AT91SAM9G20
6384E–ATARM–05-Feb-10
AT91SAM9G20
23.7.14 ECC Parity Register 13
Register Name:ECC_PR13
Access Type:Read-only
31
30
29
28
23
0
15
22
21
20
7
14
13
NPARITY13
6
5
WORDADDR13
12
4
27
19
NPARITY13
11
0
3
26
25
24
18
17
16
10
9
WORDADDR13
1
BITADDR13
8
2
0
Once the entire main area of a page is written with data, the register content must be stored at any free location of the
spare area.
• BITADDR13: corrupted Bit Address in the page between the 3328th and the 3583rd bytes
During a page read, this value contains the corrupted bit offset where an error occurred, if a single error was detected. If
multiple errors were detected, this value is meaningless.
• WORDADDR13: corrupted Word Address in the page between the 3328th and the 3583rd bytes
During a page read, this value contains the word address (8-bit word) where an error occurred, if a single error was
detected. If multiple errors were detected, this value is meaningless.
• NPARITY13:
Parity N
263
6384E–ATARM–05-Feb-10
23.7.15 ECC Parity Register 14
Register Name:ECC_PR14
Access Type:Read-only
31
30
29
28
23
0
15
22
21
20
14
13
NPARITY14
6
5
WORDADDR14
7
12
4
27
19
NPARITY14
11
0
3
26
25
24
18
17
16
10
9
WORDADDR14
1
BITADDR14
8
2
0
Once the entire main area of a page is written with data, the register content must be stored at any free location of the
spare area.
• BITADDR14: corrupted Bit Address in the page between the 3584th and the 3839th bytes
During a page read, this value contains the corrupted bit offset where an error occurred, if a single error was detected. If
multiple errors were detected, this value is meaningless.
• WORDADDR14: corrupted Word Address in the page between the 3584th and the 3839th bytes
During a page read, this value contains the word address (8-bit word) where an error occurred, if a single error was
detected. If multiple errors were detected, this value is meaningless.
• NPARITY14:
Parity N
264
AT91SAM9G20
6384E–ATARM–05-Feb-10
AT91SAM9G20
23.7.16 ECC Parity Register 15
Register Name:ECC_PR15
Access Type:Read-only
31
30
29
28
23
0
15
22
21
20
7
14
13
NPARITY15
6
5
WORDADDR15
12
4
27
19
NPARITY15
11
0
3
26
25
24
18
17
16
10
9
WORDADDR15
1
BITADDR15
8
2
0
Once the entire main area of a page is written with data, the register content must be stored at any free location of the
spare area
• BITADDR15: corrupted Bit Address in the page between the 3840th and the 4095th bytes
During a page read, this value contains the corrupted bit offset where an error occurred, if a single error was detected. If
multiple errors were detected, this value is meaningless.
• WORDADDR15: corrupted Word Address in the page between the 3840th and the 4095th bytes
During a page read, this value contains the word address (8-bit word) where an error occurred, if a single error was
detected. If multiple errors were detected, this value is meaningless.
• NPARITY15
Parity N
265
6384E–ATARM–05-Feb-10
266
AT91SAM9G20
6384E–ATARM–05-Feb-10
AT91SAM9G20
24. Peripheral DMA Controller (PDC)
24.1
Overview
The Peripheral DMA Controller (PDC) transfers data between on-chip serial peripherals and the
on- and/or off-chip memories. The link between the PDC and a serial peripheral is operated by
the AHB to ABP bridge.
The PDC contains 24 channels. The full-duplex peripherals feature 21 mono directional channels used in pairs (transmit only or receive only). The half-duplex peripherals feature 1 bidirectional channel.
The user interface of each PDC channel is integrated into the user interface of the peripheral it
serves. The user interface of mono directional channels (receive only or transmit only), contains
two 32-bit memory pointers and two 16-bit counters, one set (pointer, counter) for current transfer and one set (pointer, counter) for next transfer. The bi-directional channel user interface
contains four 32-bit memory pointers and four 16-bit counters. Each set (pointer, counter) is
used by current transmit, next transmit, current receive and next receive.
Using the PDC removes processor overhead by reducing its intervention during the transfer.
This significantly reduces the number of clock cycles required for a data transfer, which
improves microcontroller performance.
To launch a transfer, the peripheral triggers its associated PDC channels by using transmit and
receive signals. When the programmed data is transferred, an end of transfer interrupt is generated by the peripheral itself.
267
6384E–ATARM–05-Feb-10
24.2
Block Diagram
Figure 24-1. Block Diagram
FULL DUPLEX
PERIPHERAL
PDC
THR
PDC Channel A
RHR
PDC Channel B
Control
Status & Control
HALF DUPLEX
PERIPHERAL
Control
THR
PDC Channel C
RHR
Control
Status & Control
RECEIVE or TRANSMIT
PERIPHERAL
RHR or THR
Control
24.3
24.3.1
PDC Channel D
Status & Control
Functional Description
Configuration
The PDC channel user interface enables the user to configure and control data transfers for
each channel. The user interface of each PDC channel is integrated into the associated peripheral user interface.
The user interface of a serial peripheral, whether it is full or half duplex, contains four 32-bit
pointers (RPR, RNPR, TPR, TNPR) and four 16-bit counter registers (RCR, RNCR, TCR,
TNCR). However, the transmit and receive parts of each type are programmed differently: the
268
AT91SAM9G20
6384E–ATARM–05-Feb-10
AT91SAM9G20
transmit and receive parts of a full duplex peripheral can be programmed at the same time,
whereas only one part (transmit or receive) of a half duplex peripheral can be programmed at a
time.
32-bit pointers define the access location in memory for current and next transfer, whether it is
for read (transmit) or write (receive). 16-bit counters define the size of current and next transfers.
It is possible, at any moment, to read the number of transfers left for each channel.
The PDC has dedicated status registers which indicate if the transfer is enabled or disabled for
each channel. The status for each channel is located in the associated peripheral status register.
Transfers can be enabled and/or disabled by setting TXTEN/TXTDIS and RXTEN/RXTDIS in
the peripheral’s Transfer Control Register.
At the end of a transfer, the PDC channel sends status flags to its associated peripheral. These
flags are visible in the peripheral status register (ENDRX, ENDTX, RXBUFF, and TXBUFE).
Refer to Section 24.3.3 and to the associated peripheral user interface.
24.3.2
Memory Pointers
Each full duplex peripheral is connected to the PDC by a receive channel and a transmit channel. Both channels have 32-bit memory pointers that point respectively to a receive area and to
a transmit area in on- and/or off-chip memory.
Each half duplex peripheral is connected to the PDC by a bidirectional channel. This channel
has two 32-bit memory pointers, one for current transfer and the other for next transfer. These
pointers point to transmit or receive data depending on the operating mode of the peripheral.
Depending on the type of transfer (byte, half-word or word), the memory pointer is incremented
respectively by 1, 2 or 4 bytes.
If a memory pointer address changes in the middle of a transfer, the PDC channel continues
operating using the new address.
24.3.3
Transfer Counters
Each channel has two 16-bit counters, one for current transfer and the other one for next transfer. These counters define the size of data to be transferred by the channel. The current transfer
counter is decremented first as the data addressed by current memory pointer starts to be transferred. When the current transfer counter reaches zero, the channel checks its next transfer
counter. If the value of next counter is zero, the channel stops transferring data and sets the
appropriate flag. But if the next counter value is greater then zero, the values of the next
pointer/next counter are copied into the current pointer/current counter and the channel resumes
the transfer whereas next pointer/next counter get zero/zero as values. At the end of this transfer the PDC channel sets the appropriate flags in the Peripheral Status Register.
The following list gives an overview of how status register flags behave depending on the
counters’ values:
• ENDRX flag is set when the PERIPH_RCR register reaches zero.
• RXBUFF flag is set when both PERIPH_RCR and PERIPH_RNCR reach zero.
• ENDTX flag is set when the PERIPH_TCR register reaches zero.
• TXBUFE flag is set when both PERIPH_TCR and PERIPH_TNCR reach zero.
These status flags are described in the Peripheral Status Register.
269
6384E–ATARM–05-Feb-10
24.3.4
Data Transfers
The serial peripheral triggers its associated PDC channels’ transfers using transmit enable
(TXEN) and receive enable (RXEN) flags in the transfer control register integrated in the peripheral’s user interface.
When the peripheral receives an external data, it sends a Receive Ready signal to its PDC
receive channel which then requests access to the Matrix. When access is granted, the PDC
receive channel starts reading the peripheral Receive Holding Register (RHR). The read data
are stored in an internal buffer and then written to memory.
When the peripheral is about to send data, it sends a Transmit Ready to its PDC transmit channel which then requests access to the Matrix. When access is granted, the PDC transmit
channel reads data from memory and puts them to Transmit Holding Register (THR) of its associated peripheral. The same peripheral sends data according to its mechanism.
24.3.5
PDC Flags and Peripheral Status Register
Each peripheral connected to the PDC sends out receive ready and transmit ready flags and the
PDC sends back flags to the peripheral. All these flags are only visible in the Peripheral Status
Register.
Depending on the type of peripheral, half or full duplex, the flags belong to either one single
channel or two different channels.
24.3.5.1
Receive Transfer End
This flag is set when PERIPH_RCR register reaches zero and the last data has been transferred
to memory.
It is reset by writing a non zero value in PERIPH_RCR or PERIPH_RNCR.
24.3.5.2
Transmit Transfer End
This flag is set when PERIPH_TCR register reaches zero and the last data has been written into
peripheral THR.
It is reset by writing a non zero value in PERIPH_TCR or PERIPH_TNCR.
24.3.5.3
Receive Buffer Full
This flag is set when PERIPH_RCR register reaches zero with PERIPH_RNCR also set to zero
and the last data has been transferred to memory.
It is reset by writing a non zero value in PERIPH_TCR or PERIPH_TNCR.
24.3.5.4
Transmit Buffer Empty
This flag is set when PERIPH_TCR register reaches zero with PERIPH_TNCR also set to zero
and the last data has been written into peripheral THR.
It is reset by writing a non zero value in PERIPH_TCR or PERIPH_TNCR.
270
AT91SAM9G20
6384E–ATARM–05-Feb-10
AT91SAM9G20
24.4
Peripheral DMA Controller (PDC) User Interface
Table 24-1.
Register Mapping
Offset
Register
Name
(1)
Access
Reset
0x100
Receive Pointer Register
PERIPH _RPR
Read-write
0
0x104
Receive Counter Register
PERIPH_RCR
Read-write
0
0x108
Transmit Pointer Register
PERIPH_TPR
Read-write
0
0x10C
Transmit Counter Register
PERIPH_TCR
Read-write
0
0x110
Receive Next Pointer Register
PERIPH_RNPR
Read-write
0
0x114
Receive Next Counter Register
PERIPH_RNCR
Read-write
0
0x118
Transmit Next Pointer Register
PERIPH_TNPR
Read-write
0
0x11C
Transmit Next Counter Register
PERIPH_TNCR
Read-write
0
0x120
Transfer Control Register
PERIPH_PTCR
Write-only
0
0x124
Transfer Status Register
PERIPH_PTSR
Read-only
0
Note:
1. PERIPH: Ten registers are mapped in the peripheral memory space at the same offset. These can be defined by the user
according to the function and the peripheral desired (DBGU, USART, SSC, SPI, MCI, etc.)
271
6384E–ATARM–05-Feb-10
24.4.1
Receive Pointer Register
Register Name:
PERIPH_RPR
Access Type:
31
Read-write
30
29
28
27
26
25
24
19
18
17
16
11
10
9
8
3
2
1
0
RXPTR
23
22
21
20
RXPTR
15
14
13
12
RXPTR
7
6
5
4
RXPTR
• RXPTR: Receive Pointer Register
RXPTR must be set to receive buffer address.
When a half duplex peripheral is connected to the PDC, RXPTR = TXPTR.
272
AT91SAM9G20
6384E–ATARM–05-Feb-10
AT91SAM9G20
24.4.2
Receive Counter Register
Register Name:
PERIPH_RCR
Access Type:
Read-write
31
–
30
–
29
–
28
–
27
–
26
–
25
–
24
–
23
–
22
–
21
–
20
–
19
–
18
–
17
–
16
–
15
14
13
12
11
10
9
8
3
2
1
0
RXCTR
7
6
5
4
RXCTR
• RXCTR: Receive Counter Register
RXCTR must be set to receive buffer size.
When a half duplex peripheral is connected to the PDC, RXCTR = TXCTR.
0 = Stops peripheral data transfer to the receiver
1 - 65535 = Starts peripheral data transfer if corresponding channel is active
273
6384E–ATARM–05-Feb-10
24.4.3
Transmit Pointer Register
Register Name:
PERIPH_TPR
Access Type:
31
Read-write
30
29
28
27
26
25
24
19
18
17
16
11
10
9
8
3
2
1
0
TXPTR
23
22
21
20
TXPTR
15
14
13
12
TXPTR
7
6
5
4
TXPTR
• TXPTR: Transmit Counter Register
TXPTR must be set to transmit buffer address.
When a half duplex peripheral is connected to the PDC, RXPTR = TXPTR.
24.4.4
Transmit Counter Register
Register Name:
PERIPH_TCR
Access Type:
Read-write
31
–
30
–
29
–
28
–
27
–
26
–
25
–
24
–
23
–
22
–
21
–
20
–
19
–
18
–
17
–
16
–
15
14
13
12
11
10
9
8
3
2
1
0
TXCTR
7
6
5
4
TXCTR
• TXCTR: Transmit Counter Register
TXCTR must be set to transmit buffer size.
When a half duplex peripheral is connected to the PDC, RXCTR = TXCTR.
0 = Stops peripheral data transfer to the transmitter
1- 65535 = Starts peripheral data transfer if corresponding channel is active
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24.4.5
Receive Next Pointer Register
Register Name:
PERIPH_RNPR
Access Type:
31
Read-write
30
29
28
27
26
25
24
19
18
17
16
11
10
9
8
3
2
1
0
RXNPTR
23
22
21
20
RXNPTR
15
14
13
12
RXNPTR
7
6
5
4
RXNPTR
• RXNPTR: Receive Next Pointer
RXNPTR contains next receive buffer address.
When a half duplex peripheral is connected to the PDC, RXNPTR = TXNPTR.
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24.4.6
Receive Next Counter Register
Register Name:
PERIPH_RNCR
Access Type:
Read-write
31
–
30
–
29
–
28
–
27
–
26
–
25
–
24
–
23
–
22
–
21
–
20
–
19
–
18
–
17
–
16
–
15
14
13
12
11
10
9
8
3
2
1
0
RXNCTR
7
6
5
4
RXNCTR
• RXNCTR: Receive Next Counter
RXNCTR contains next receive buffer size.
When a half duplex peripheral is connected to the PDC, RXNCTR = TXNCTR.
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24.4.7
Transmit Next Pointer Register
Register Name:
PERIPH_TNPR
Access Type:
31
Read-write
30
29
28
27
26
25
24
19
18
17
16
11
10
9
8
3
2
1
0
TXNPTR
23
22
21
20
TXNPTR
15
14
13
12
TXNPTR
7
6
5
4
TXNPTR
• TXNPTR: Transmit Next Pointer
TXNPTR contains next transmit buffer address.
When a half duplex peripheral is connected to the PDC, RXNPTR = TXNPTR.
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24.4.8
Transmit Next Counter Register
Register Name:
PERIPH_TNCR
Access Type:
Read-write
31
–
30
–
29
–
28
–
27
–
26
–
25
–
24
–
23
–
22
–
21
–
20
–
19
–
18
–
17
–
16
–
15
14
13
12
11
10
9
8
3
2
1
0
TXNCTR
7
6
5
4
TXNCTR
• TXNCTR: Transmit Counter Next
TXNCTR contains next transmit buffer size.
When a half duplex peripheral is connected to the PDC, RXNCTR = TXNCTR.
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24.4.9
Transfer Control Register
Register Name:
PERIPH_PTCR
Access Type:
Write-only
31
–
30
–
29
–
28
–
27
–
26
–
25
–
24
–
23
–
22
–
21
–
20
–
19
–
18
–
17
–
16
–
15
–
14
–
13
–
12
–
11
–
10
–
9
TXTDIS
8
TXTEN
7
–
6
–
5
–
4
–
3
–
2
–
1
RXTDIS
0
RXTEN
• RXTEN: Receiver Transfer Enable
0 = No effect.
1 = Enables PDC receiver channel requests if RXTDIS is not set.
When a half duplex peripheral is connected to the PDC, enabling the receiver channel requests automatically disables the
transmitter channel requests. It is forbidden to set both TXTEN and RXTEN for a half duplex peripheral.
• RXTDIS: Receiver Transfer Disable
0 = No effect.
1 = Disables the PDC receiver channel requests.
When a half duplex peripheral is connected to the PDC, disabling the receiver channel requests also disables the transmitter channel requests.
• TXTEN: Transmitter Transfer Enable
0 = No effect.
1 = Enables the PDC transmitter channel requests.
When a half duplex peripheral is connected to the PDC, it enables the transmitter channel requests only if RXTEN is not
set. It is forbidden to set both TXTEN and RXTEN for a half duplex peripheral.
• TXTDIS: Transmitter Transfer Disable
0 = No effect.
1 = Disables the PDC transmitter channel requests.
When a half duplex peripheral is connected to the PDC, disabling the transmitter channel requests disables the receiver
channel requests.
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24.4.10 Transfer Status Register
Register Name:
PERIPH_PTSR
Access Type:
Read-only
31
–
30
–
29
–
28
–
27
–
26
–
25
–
24
–
23
–
22
–
21
–
20
–
19
–
18
–
17
–
16
–
15
–
14
–
13
–
12
–
11
–
10
–
9
–
8
TXTEN
7
–
6
–
5
–
4
–
3
–
2
–
1
–
0
RXTEN
• RXTEN: Receiver Transfer Enable
0 = PDC Receiver channel requests are disabled.
1 = PDC Receiver channel requests are enabled.
• TXTEN: Transmitter Transfer Enable
0 = PDC Transmitter channel requests are disabled.
1 = PDC Transmitter channel requests are enabled.
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25. Clock Generator
25.1
Overview
The Clock Generator is made up of 2 PLLs, a Main Oscillator, as well as an RC Oscillator and a
32,768 Hz low-power Oscillator.
It provides the following clocks:
• SLCK, the Slow Clock, which is the only permanent clock within the system
• MAINCK is the output of the Main Oscillator
The Clock Generator User Interface is embedded within the Power Management Controller one
and is described in Section 26.9. However, the Clock Generator registers are named CKGR_.
• PLLACK is the output of the Divider and PLL A block
• PLLBCK is the output of the Divider and PLL B block
25.2
Slow Clock Crystal Oscillator
The Clock Generator integrates a 32,768 Hz low-power oscillator. The XIN32 and XOUT32 pins
must be connected to a 32,768 Hz crystal. Two external capacitors must be wired as shown in
Figure 25-1.
Figure 25-1. Typical Slow Clock Crystal Oscillator Connection
XIN32
XOUT32
GNDPLL
32,768 Hz
Crystal
25.3
Slow Clock RC Oscillator
The user has to take into account the possible drifts of the RC Oscillator. More details are given
in the section “DC Characteristics” of the product datasheet.
25.4
Main Oscillator
Figure 25-2 shows the Main Oscillator block diagram.
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Figure 25-2. Main Oscillator Block Diagram
MOSCEN
XIN
Main
Oscillator
MAINCK
Main Clock
XOUT
OSCOUNT
Main
Oscillator
Counter
SLCK
Slow Clock
MOSCS
MAINF
Main Clock
Frequency
Counter
25.4.1
MAINRDY
Main Oscillator Connections
The Clock Generator integrates a Main Oscillator that is designed for a 3 to 20 MHz fundamental
crystal. The typical crystal connection is illustrated in Figure 25-3. For further details on the electrical characteristics of the Main Oscillator, see the section “DC Characteristics” of the product
datasheet.
Figure 25-3. Typical Crystal Connection
AT91 Microcontroller
XIN
XOUT
GND
1K
25.4.2
Main Oscillator Startup Time
The startup time of the Main Oscillator is given in the DC Characteristics section of the product
datasheet. The startup time depends on the crystal frequency and decreases when the frequency rises.
25.4.3
Main Oscillator Control
To minimize the power required to start up the system, the main oscillator is disabled after reset
and slow clock is selected.
The software enables or disables the main oscillator so as to reduce power consumption by
clearing the MOSCEN bit in the Main Oscillator Register (CKGR_MOR).
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When disabling the main oscillator by clearing the MOSCEN bit in CKGR_MOR, the MOSCS bit
in PMC_SR is automatically cleared, indicating the main clock is off.
When enabling the main oscillator, the user must initiate the main oscillator counter with a value
corresponding to the startup time of the oscillator. This startup time depends on the crystal frequency connected to the main oscillator.
When the MOSCEN bit and the OSCOUNT are written in CKGR_MOR to enable the main oscillator, the MOSCS bit in PMC_SR (Status Register) is cleared and the counter starts counting
down on the slow clock divided by 8 from the OSCOUNT value. Since the OSCOUNT value is
coded with 8 bits, the maximum startup time is about 62 ms.
When the counter reaches 0, the MOSCS bit is set, indicating that the main clock is valid. Setting the MOSCS bit in PMC_IMR can trigger an interrupt to the processor.
25.4.4
Main Clock Frequency Counter
The Main Oscillator features a Main Clock frequency counter that provides the quartz frequency
connected to the Main Oscillator. Generally, this value is known by the system designer; however, it is useful for the boot program to configure the device with the correct clock speed,
independently of the application.
The Main Clock frequency counter starts incrementing at the Main Clock speed after the next rising edge of the Slow Clock as soon as the Main Oscillator is stable, i.e., as soon as the MOSCS
bit is set. Then, at the 16th falling edge of Slow Clock, the MAINRDY bit in CKGR_MCFR (Main
Clock Frequency Register) is set and the counter stops counting. Its value can be read in the
MAINF field of CKGR_MCFR and gives the number of Main Clock cycles during 16 periods of
Slow Clock, so that the frequency of the crystal connected on the Main Oscillator can be
determined.
25.4.5
25.5
Main Oscillator Bypass
The user can input a clock on the device instead of connecting a crystal. In this case, the user
has to provide the external clock signal on the XIN pin. The input characteristics of the XIN pin
under these conditions are given in the product electrical characteristics section. The programmer has to be sure to set the OSCBYPASS bit to 1 and the MOSCEN bit to 0 in the Main OSC
register (CKGR_MOR) for the external clock to operate properly.
Divider and PLL Block
The PLL embeds an input divider to increase the accuracy of the resulting clock signals. However, the user must respect the PLL minimum input frequency when programming the divider.
Figure 25-4 shows the block diagram of the divider and PLL block.
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Figure 25-4. Divider and PLL Block Diagram
DIVB
Divider B
MAINCK
DIVA
Divider A
MULB
OUTB
PLL B
MULA
PLLBCK
OUTA
PLL A
PLLACK
PLLBCOUNT
PLL B
Counter
LOCKB
PLLACOUNT
SLCK
25.5.1
PLL A
Counter
LOCKA
Divider and Phase Lock Loop Programming
The divider can be set between 1 and 255 in steps of 1. When a divider field (DIV) is set to 0, the
output of the corresponding divider and the PLL output is a continuous signal at level 1. On
reset, each DIV field is set to 0, thus the corresponding PLL input clock is set to 0.
The PLL allows multiplication of the divider’s outputs. The PLL clock signal has a frequency that
depends on the respective source signal frequency and on the parameters DIV and MUL. The
factor applied to the source signal frequency is (MUL + 1)/DIV. When MUL is written to 0, the
corresponding PLL is disabled and its power consumption is saved. Re-enabling the PLL can be
performed by writing a value higher than 0 in the MUL field.
Whenever the PLL is re-enabled or one of its parameters is changed, the LOCK bit (LOCKA or
LOCKB) in PMC_SR is automatically cleared. The values written in the PLLCOUNT field (PLLACOUNT or PLLBCOUNT) in CKGR_PLLR (CKGR_PLLAR or CKGR_PLLBR), are loaded in the
PLL counter. The PLL counter then decrements at the speed of the Slow Clock until it reaches 0.
At this time, the LOCK bit is set in PMC_SR and can trigger an interrupt to the processor. The
user has to load the number of Slow Clock cycles required to cover the PLL transient time into
the PLLCOUNT field. The transient time depends on the PLL filter. Refer to the PLL Characteristics sub section of the Product Electrical Characteristics.
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26. Power Management Controller (PMC)
26.1
Overview
The Power Management Controller (PMC) optimizes power consumption by controlling all system and user peripheral clocks. The PMC enables/disables the clock inputs to many of the
peripherals and the ARM Processor.
The Power Management Controller provides the following clocks:
• MCK, the Master Clock, programmable from a few hundred Hz to the maximum operating
frequency of the device. It is available to the modules running permanently, such as the AIC
and the Memory Controller.
• Processor Clock (PCK), switched off when entering processor in idle mode.
• Peripheral Clocks, typically MCK, provided to the embedded peripherals (USART, SSC, SPI,
TWI, TC, MCI, etc.) and independently controllable. In order to reduce the number of clock
names in a product, the Peripheral Clocks are named MCK in the product datasheet.
• UHP Clock (UHPCK), required by USB Host Port operations.
• Programmable Clock Outputs can be selected from the clocks provided by the clock
generator and driven on the PCKx pins.
26.2
Master Clock Controller
The Master Clock Controller provides selection and division of the Master Clock (MCK). MCK is
the clock provided to all the peripherals and the memory controller.
The Master Clock is selected from one of the clocks provided by the Clock Generator. Selecting
the Slow Clock provides a Slow Clock signal to the whole device. Selecting the Main Clock
saves power consumption of the PLLs.
The Master Clock Controller is made up of a clock selector and a prescaler. It also contains a
Master Clock divider which allows the processor clock to be faster than the Master Clock.
The Master Clock selection is made by writing the CSS field (Clock Source Selection) in
PMC_MCKR (Master Clock Register). The prescaler supports the division by a power of 2 of the
selected clock between 1 and 64. The PRES field in PMC_MCKR programs the prescaler. The
Master Clock divider can be programmed through the MDIV field in PMC_MCKR.
Each time PMC_MCKR is written to define a new Master Clock, the MCKRDY bit is cleared in
PMC_SR. It reads 0 until the Master Clock is established. Then, the MCKRDY bit is set and can
trigger an interrupt to the processor. This feature is useful when switching from a high-speed
clock to a lower one to inform the software when the change is actually done.
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Figure 26-1. Master Clock Controller
PMC_MCKR
CSS
PMC_MCKR
PRES
PMC_MCKR
MDIV
SLCK
MAINCK
PLLACK
Master Clock
Prescaler
Master
Clock
Divider
MCK
PLLBCK
Processor
Clock
Divider
To the Processor
Clock Controller (PCK)
PDIV
PMC_MCKR
26.3
Processor Clock Controller
The PMC features a Processor Clock Controller (PCK) that implements the Processor Idle
Mode. The Processor Clock can be disabled by writing the System Clock Disable Register
(PMC_SCDR).The status of this clock (at least for debug purpose) can be read in the System
Clock Status Register (PMC_SCSR).
The Processor Clock PCK is enabled after a reset and is automatically re-enabled by any
enabled interrupt. The Processor Idle Mode is achieved by disabling the Processor Clock, which
is automatically re-enabled by any enabled fast or normal interrupt, or by the reset of the
product.
When the Processor Clock is disabled, the current instruction is finished before the clock is
stopped, but this does not prevent data transfers from other masters of the system bus.
The PMC contains a Processor Clock divider which allows the processor clock to be divided
independently of the Master Clock divider setting. The Processor Clock divider can be programmed through the PDIV field in PMC_MCKR.
26.4
USB Clock Controller
The USB Source Clock is always generated from the PLL B output. If using the USB, the user
must program the PLL to generate a 48 MHz or a 96 MHz signal with an accuracy of ± 0.25%
depending on the USBDIV bit in CKGR_PLLBR (see Figure 26-2).
When the PLL B output is stable, i.e., the LOCKB is set:
• The USB host clock can be enabled by setting the UHP bit in PMC_SCER. To save power on
this peripheral when it is not used, the user can set the UHP bit in PMC_SCDR. The UHP bit
in PMC_SCSR gives the activity of this clock. The USB host port require both the 12/48 MHz
signal and the Master Clock. The Master Clock may be controlled via the Master Clock
Controller.
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Figure 26-2. USB Clock Controller
USBDIV
USB
Source
Clock
UDP Clock (UDPCK)
Divider
/1,/2,/4
UDP
UHP Clock (UHPCK)
UHP
26.5
Peripheral Clock Controller
The Power Management Controller controls the clocks of each embedded peripheral by the way
of the Peripheral Clock Controller. The user can individually enable and disable the Master
Clock on the peripherals by writing into the Peripheral Clock Enable (PMC_PCER) and Peripheral Clock Disable (PMC_PCDR) registers. The status of the peripheral clock activity can be
read in the Peripheral Clock Status Register (PMC_PCSR).
When a peripheral clock is disabled, the clock is immediately stopped. The peripheral clocks are
automatically disabled after a reset.
In order to stop a peripheral, it is recommended that the system software wait until the peripheral
has executed its last programmed operation before disabling the clock. This is to avoid data corruption or erroneous behavior of the system.
The bit number within the Peripheral Clock Control registers (PMC_PCER, PMC_PCDR, and
PMC_PCSR) is the Peripheral Identifier defined at the product level. Generally, the bit number
corresponds to the interrupt source number assigned to the peripheral.
26.6
Programmable Clock Output Controller
The PMC controls 2 signals to be output on external pins PCKx. Each signal can be independently programmed via the PMC_PCKx registers.
PCKx can be independently selected between the Slow clock, the PLL A output, the PLL B output and the main clock by writing the CSS field in PMC_PCKx. Each output signal can also be
divided by a power of 2 between 1 and 64 by writing the PRES (Prescaler) field in PMC_PCKx.
Each output signal can be enabled and disabled by writing 1 in the corresponding bit, PCKx of
PMC_SCER and PMC_SCDR, respectively. Status of the active programmable output clocks
are given in the PCKx bits of PMC_SCSR (System Clock Status Register).
Moreover, like the PCK, a status bit in PMC_SR indicates that the Programmable Clock is actually what has been programmed in the Programmable Clock registers.
As the Programmable Clock Controller does not manage with glitch prevention when switching
clocks, it is strongly recommended to disable the Programmable Clock before any configuration
change and to re-enable it after the change is actually performed.
26.7
Programming Sequence
1. Enabling the Main Oscillator:
The main oscillator is enabled by setting the MOSCEN field in the CKGR_MOR register. In
some cases it may be advantageous to define a start-up time. This can be achieved by writing a value in the OSCOUNT field in the CKGR_MOR register.
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Once this register has been correctly configured, the user must wait for MOSCS field in the
PMC_SR register to be set. This can be done either by polling the status register or by waiting the interrupt line to be raised if the associated interrupt to MOSCS has been enabled in
the PMC_IER register.
Code Example:
write_register(CKGR_MOR,0x00000701)
Start Up Time = 8 * OSCOUNT / SLCK = 56 Slow Clock Cycles.
So, the main oscillator will be enabled (MOSCS bit set) after 56 Slow Clock Cycles.
2. Checking the Main Oscillator Frequency (Optional):
In some situations the user may need an accurate measure of the main oscillator frequency.
This measure can be accomplished via the CKGR_MCFR register.
Once the MAINRDY field is set in CKGR_MCFR register, the user may read the MAINF field
in CKGR_MCFR register. This provides the number of main clock cycles within sixteen slow
clock cycles.
3. Setting PLL A and divider A:
All parameters necessary to configure PLL A and divider A are located in the CKGR_PLLAR
register.
It is important to note that Bit 29 must always be set to 1 when programming the
CKGR_PLLAR register.
The DIVA field is used to control the divider A itself. The user can program a value between
0 and 255. Divider A output is divider A input divided by DIVA. By default, DIVA parameter is
set to 0 which means that divider A is turned off.
The OUTA field is used to select the PLL A output frequency range.
The MULA field is the PLL A multiplier factor. This parameter can be programmed between
0 and 254. If MULA is set to 0, PLL A will be turned off. Otherwise PLL A output frequency is
PLL A input frequency multiplied by (MULA + 1).
The PLLACOUNT field specifies the number of slow clock cycles before LOCKA bit is set in
the PMC_SR register after CKGR_PLLAR register has been written.
Once CKGR_PLLAR register has been written, the user is obliged to wait for the LOCKA bit
to be set in the PMC_SR register. This can be done either by polling the status register or by
waiting the interrupt line to be raised if the associated interrupt to LOCKA has been enabled
in the PMC_IER register.
All parameters in CKGR_PLLAR can be programmed in a single write operation. If at some
stage one of the following parameters, MULA, DIVA is modified, LOCKA bit will go low to
indicate that PLL A is not ready yet. When PLL A is locked, LOCKA will be set again. User
has to wait for LOCKA bit to be set before using the PLL A output clock.
Code Example:
write_register(CKGR_PLLAR,0x20030602)
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PLL A input clock is main clock divided by 2. PLL An output clock is PLL A input clock multiplied by 4. Once CKGR_PLLAR has been written, LOCKA bit will be set after six slow clock
cycles.
4. Setting PLL B and divider B:
All parameters needed to configure PLL B and divider B are located in the CKGR_PLLBR
register.
The DIVB field is used to control divider B itself. A value between 0 and 255 can be programmed. Divider B output is divider B input divided by DIVB parameter. By default DIVB
parameter is set to 0 which means that divider B is turned off.
The OUTB field is used to select the PLL B output frequency range.
The MULB field is the PLL B multiplier factor. This parameter can be programmed between
0 and 62. If MULB is set to 0, PLL B will be turned off, otherwise the PLL B output frequency
is PLL B input frequency multiplied by (MULB + 1).
The PLLBCOUNT field specifies the number of slow clock cycles before LOCKB bit is set in
the PMC_SR register after CKGR_PLLBR register has been written.
Once the PMC_PLLB register has been written, the user must wait for the LOCKB bit to be
set in the PMC_SR register. This can be done either by polling the status register or by waiting the interrupt line to be raised if the associated interrupt to LOCKB has been enabled in
the PMC_IER register. All parameters in CKGR_PLLBR can be programmed in a single
write operation. If at some stage one of the following parameters, MULB, DIVB is modified,
LOCKB bit will go low to indicate that PLL B is not ready yet. When PLL B is locked, LOCKB
will be set again. The user is constrained to wait for LOCKB bit to be set before using the
PLL A output clock.
The USBDIV field is used to control the additional divider by 1, 2 or 4, which generates the
USB clock(s).
Code Example:
write_register(CKGR_PLLBR,0x20030602)
PLL B input clock is main clock divided by 2. PLL B output clock is PLL B input clock multiplied by 4. Once CKGR_PLLBR has been written, LOCKB bit will be set after six slow clock
cycles.
5. Selection of Master Clock and Processor Clock
The Master Clock and the Processor Clock are configurable via the PMC_MCKR register.
The CSS field is used to select the clock source of the Master Clock and Processor Clock
dividers. By default, the selected clock source is slow clock.
The PRES field is used to control the Master/Processor Clock prescaler. The user can
choose between different values (1, 2, 4, 8, 16, 32, 64). Prescaler output is the selected
clock source divided by PRES parameter. By default, PRES parameter is set to 1 which
means that the input clock of the Master Clock and Processor Clock dividers is equal to slow
clock.
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The MDIV field is used to control the Master Clock divider. It is possible to choose between
different values (0, 1, 2, 3). The Master Clock output is Master/Processor Clock Prescaler
output divided by 1, 2, 4 or 6, depending on the value programmed in MDIV.
The PDIV field is used to control the Processor Clock divider. It is possible to choose
between different values (0, 1). The Processor Clock output is Master/Processor Clock
Prescaler output divided by 1 or 2, depending on the value programmed in PDIV.
By default, MDIV and PDIV are set to 0, which indicates that Processor Clock is equal to the
Master Clock.
Once the PMC_MCKR register has been written, the user must wait for the MCKRDY bit to
be set in the PMC_SR register. This can be done either by polling the status register or by
waiting for the interrupt line to be raised if the associated interrupt to MCKRDY has been
enabled in the PMC_IER register.
The PMC_MCKR register must not be programmed in a single write operation. The preferred programming sequence for the PMC_MCKR register is as follows:
• If a new value for CSS field corresponds to PLL Clock,
– Program the PRES field in the PMC_MCKR register.
– Wait for the MCKRDY bit to be set in the PMC_SR register.
– Program the CSS field in the PMC_MCKR register.
– Wait for the MCKRDY bit to be set in the PMC_SR register.
• If a new value for CSS field corresponds to Main Clock or Slow Clock,
– Program the CSS field in the PMC_MCKR register.
– Wait for the MCKRDY bit to be set in the PMC_SR register.
– Program the PRES field in the PMC_MCKR register.
– Wait for the MCKRDY bit to be set in the PMC_SR register.
If at some stage one of the following parameters, CSS or PRES, is modified, the MCKRDY
bit will go low to indicate that the Master Clock and the Processor Clock are not ready yet.
The user must wait for MCKRDY bit to be set again before using the Master and Processor
Clocks.
Note:
IF PLLx clock was selected as the Master Clock and the user decides to modify it by writing in
CKGR_PLLR (CKGR_PLLAR or CKGR_PLLBR), the MCKRDY flag will go low while PLL is
unlocked. Once PLL is locked again, LOCK (LOCKA or LOCKB) goes high and MCKRDY is set.
While PLLA is unlocked, the Master Clock selection is automatically changed to Slow Clock. While
PLLB is unlocked, the Master Clock selection is automatically changed to Main Clock. For further
information, see Section 26.8.2. “Clock Switching Waveforms” on page 294.
Code Example:
write_register(PMC_MCKR,0x00000001)
wait (MCKRDY=1)
write_register(PMC_MCKR,0x00000011)
wait (MCKRDY=1)
The Master Clock is main clock divided by 16.
The Processor Clock is the Master Clock.
290
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AT91SAM9G20
6. Selection of Programmable clocks
Programmable clocks are controlled via registers; PMC_SCER, PMC_SCDR and
PMC_SCSR.
Programmable clocks can be enabled and/or disabled via the PMC_SCER and PMC_SCDR
registers. Depending on the system used, 2 Programmable clocks can be enabled or disabled. The PMC_SCSR provides a clear indication as to which Programmable clock is
enabled. By default all Programmable clocks are disabled.
PMC_PCKx registers are used to configure Programmable clocks.
The CSS field is used to select the Programmable clock divider source. Four clock options
are available: main clock, slow clock PLLACK, PLLBCK. By default, the clock source
selected is slow clock.
The PRES field is used to control the Programmable clock prescaler. It is possible to choose
between different values (1, 2, 4, 8, 16, 32, 64). Programmable clock output is prescaler
input divided by PRES parameter. By default, the PRES parameter is set to 1 which means
that master clock is equal to slow clock.
Once the PMC_PCKx register has been programmed, The corresponding Programmable
clock must be enabled and the user is constrained to wait for the PCKRDYx bit to be set in
the PMC_SR register. This can be done either by polling the status register or by waiting the
interrupt line to be raised if the associated interrupt to PCKRDYx has been enabled in the
PMC_IER register. All parameters in PMC_PCKx can be programmed in a single write
operation.
If the CSS and PRES parameters are to be modified, the corresponding Programmable
clock must be disabled first. The parameters can then be modified. Once this has been
done, the user must re-enable the Programmable clock and wait for the PCKRDYx bit to be
set.
Code Example:
write_register(PMC_PCK0,0x00000015)
Programmable clock 0 is main clock divided by 32.
7. Enabling Peripheral Clocks
Once all of the previous steps have been completed, the peripheral clocks can be enabled
and/or disabled via registers PMC_PCER and PMC_PCDR.
Depending on the system used, 13 peripheral clocks can be enabled or disabled. The
PMC_PCSR provides a clear view as to which peripheral clock is enabled.
Note:
Each enabled peripheral clock corresponds to Master Clock.
Code Examples:
write_register(PMC_PCER,0x00000110)
291
6384E–ATARM–05-Feb-10
Peripheral clocks 4 and 8 are enabled.
write_register(PMC_PCDR,0x00000010)
Peripheral clock 4 is disabled.
292
AT91SAM9G20
6384E–ATARM–05-Feb-10
AT91SAM9G20
26.8
26.8.1
Clock Switching Details
Master Clock Switching Timings
Table 26-1and Table 26-2 give the worst case timings required for the Master Clock to switch
from one selected clock to another one. This is in the event that the prescaler is de-activated.
When the prescaler is activated, an additional time of 64 clock cycles of the new selected clock
has to be added.
Table 26-1.
Clock Switching Timings (Worst Case)
From
Main Clock
SLCK
PLL Clock
–
4 x SLCK +
2.5 x Main Clock
3 x PLL Clock +
4 x SLCK +
1 x Main Clock
0.5 x Main Clock +
4.5 x SLCK
–
3 x PLL Clock +
5 x SLCK
0.5 x Main Clock +
4 x SLCK +
PLLCOUNT x SLCK +
2.5 x PLLx Clock
2.5 x PLL Clock +
5 x SLCK +
PLLCOUNT x SLCK
2.5 x PLL Clock +
4 x SLCK +
PLLCOUNT x SLCK
To
Main Clock
SLCK
PLL Clock
Notes:
1. PLL designates either the PLL A or the PLL B Clock.
2. PLLCOUNT designates either PLLACOUNT or PLLBCOUNT.
Table 26-2.
Clock Switching Timings (Worst Case)
From
PLLA Clock
PLLB Clock
PLLA Clock
2.5 x PLLA Clock +
4 x SLCK +
PLLACOUNT x SLCK
3 x PLLA Clock +
4 x SLCK +
1.5 x PLLA Clock
PLLB Clock
3 x PLLB Clock +
4 x SLCK +
1.5 x PLLB Clock
2.5 x PLLB Clock +
4 x SLCK +
PLLBCOUNT x SLCK
To
293
6384E–ATARM–05-Feb-10
26.8.2
Clock Switching Waveforms
Figure 26-3. Switch Master Clock from Slow Clock to PLL Clock
Slow Clock
PLL Clock
LOCK
MCKRDY
Master Clock
Write PMC_MCKR
Figure 26-4. Switch Master Clock from Main Clock to Slow Clock
Slow Clock
Main Clock
MCKRDY
Master Clock
Write PMC_MCKR
294
AT91SAM9G20
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AT91SAM9G20
Figure 26-5. Change PLLA Programming
Slow Clock
PLLA Clock
LOCK
MCKRDY
Master Clock
Slow Clock
Write CKGR_PLLAR
Figure 26-6. Change PLLB Programming
Main Clock
PLLB Clock
LOCK
MCKRDY
Master Clock
Main Clock
Write CKGR_PLLBR
295
6384E–ATARM–05-Feb-10
Figure 26-7. Programmable Clock Output Programming
PLL Clock
PCKRDY
PCKx Output
Write PMC_PCKx
Write PMC_SCER
Write PMC_SCDR
296
PLL Clock is selected
PCKx is enabled
PCKx is disabled
AT91SAM9G20
6384E–ATARM–05-Feb-10
AT91SAM9G20
26.9
Power Management Controller (PMC) User Interface
Table 26-3.
Register Mapping
Offset
Register
Name
Access
Reset
0x0000
System Clock Enable Register
PMC_SCER
Write-only
–
0x0004
System Clock Disable Register
PMC_SCDR
Write-only
–
0x0008
System Clock Status Register
PMC _SCSR
Read-only
0x03
0x000C
Reserved
–
–
0x0010
Peripheral Clock Enable Register
PMC _PCER
Write-only
–
0x0014
Peripheral Clock Disable Register
PMC_PCDR
Write-only
–
0x0018
Peripheral Clock Status Register
PMC_PCSR
Read-only
0x0
0x001C
Reserved
–
–
0x0020
Main Oscillator Register
CKGR_MOR
Read-write
0x0
0x0024
Main Clock Frequency Register
CKGR_MCFR
Read-only
0x0
0x0028
PLL A Register
CKGR_PLLAR
Read-write
0x3F00
0x002C
PLL B Register
CKGR_PLLBR
Read-write
0x3F00
0x0030
Master Clock Register
PMC_MCKR
Read-write
0x0
0x0038
Reserved
–
–
–
0x003C
Reserved
–
–
–
0x0040
Programmable Clock 0 Register
PMC_PCK0
Read-write
0x0
0x0044
Programmable Clock 1 Register
PMC_PCK1
Read-write
0x0
–
–
0x0048 - 0x005C
–
–
Reserved
–
0x0060
Interrupt Enable Register
PMC_IER
Write-only
--
0x0064
Interrupt Disable Register
PMC_IDR
Write-only
--
0x0068
Status Register
PMC_SR
Read-only
0x08
0x006C
Interrupt Mask Register
PMC_IMR
Read-only
0x0
–
–
Write-only
0x0
0x0070 - 0x007C
0x0080
Reserved
PLL Charge Pump Current Register
–
PMC_PLLICPR
297
6384E–ATARM–05-Feb-10
26.9.1
PMC System Clock Enable Register
Register Name:PMC_SCER
Access Type:Write-only
31
30
29
28
27
26
25
24
–
–
–
–
–
–
–
–
23
22
21
20
19
18
17
16
-
-
-
-
-
-
-
-
15
14
13
12
11
10
9
8
-
-
-
-
-
-
PCK1
PCK0
7
6
5
4
3
2
1
0
UDP
UHP
–
–
–
–
-
-
• UHP: USB Host Port Clock Enable
0 = No effect.
1 = Enables the 12 and 48 MHz clock of the USB Host Port.
• UDP: USB Device Port Clock Enable
0 = No effect.
1 = Enables the 48 MHz clock of the USB Device Port.
• PCKx: Programmable Clock x Output Enable
0 = No effect.
1 = Enables the corresponding Programmable Clock output.
298
AT91SAM9G20
6384E–ATARM–05-Feb-10
AT91SAM9G20
26.9.2
PMC System Clock Disable Register
Register Name:PMC_SCDR
Access Type:Write-only
31
30
29
28
27
26
25
24
–
–
–
–
–
–
–
–
23
22
21
20
19
18
17
16
-
-
-
-
-
-
-
-
15
14
13
12
11
10
9
8
-
-
-
-
-
-
PCK1
PCK0
7
6
5
4
3
2
1
0
UDP
UHP
–
–
–
–
-
PCK
• PCK: Processor Clock Disable
0 = No effect.
1 = Disables the Processor clock. This is used to enter the processor in Idle Mode.
• UHP: USB Host Port Clock Disable
0 = No effect.
1 = Disables the 12 and 48 MHz clock of the USB Host Port.
• UDP: USB Device Port Clock Disable
0 = No effect.
1 = Disables the 48 MHz clock of the USB Device Port.
• PCKx: Programmable Clock x Output Disable
0 = No effect.
1 = Disables the corresponding Programmable Clock output.
299
6384E–ATARM–05-Feb-10
26.9.3
PMC System Clock Status Register
Register Name:PMC_SCSR
Access Type:Read-only
31
30
29
28
27
26
25
24
–
–
–
–
–
–
–
–
23
22
21
20
19
18
17
16
-
-
-
-
-
-
-
-
15
14
13
12
11
10
9
8
-
-
-
-
-
-
PCK1
PCK0
7
6
5
4
3
2
1
0
UDP
UHP
–
–
–
–
-
PCK
• PCK: Processor Clock Status
0 = The Processor clock is disabled.
1 = The Processor clock is enabled.
• UHP: USB Host Port Clock Status
0 = The 12 and 48 MHz clock (UHPCK) of the USB Host Port is disabled.
1 = The 12 and 48 MHz clock (UHPCK) of the USB Host Port is enabled.
• UDP: USB Device Port Clock Status
0 = The 48 MHz clock (UDPCK) of the USB Device Port is disabled.
1 = The 48 MHz clock (UDPCK) of the USB Device Port is enabled.
• PCKx: Programmable Clock x Output Status
0 = The corresponding Programmable Clock output is disabled.
1 = The corresponding Programmable Clock output is enabled.
300
AT91SAM9G20
6384E–ATARM–05-Feb-10
AT91SAM9G20
26.9.4
PMC Peripheral Clock Enable Register
Register Name:PMC_PCER
Access Type:Write-only
31
30
29
28
27
26
25
24
PID31
PID30
PID29
PID28
PID27
PID26
PID25
PID24
23
22
21
20
19
18
17
16
PID23
PID22
PID21
PID20
PID19
PID18
PID17
PID16
15
14
13
12
11
10
9
8
PID15
PID14
PID13
PID12
PID11
PID10
PID9
PID8
7
6
5
4
3
2
1
0
PID7
PID6
PID5
PID4
PID3
PID2
-
-
• PIDx: Peripheral Clock x Enable
0 = No effect.
1 = Enables the corresponding peripheral clock.
Note:
PID2 to PID31 refer to identifiers as defined in the section “Peripheral Identifiers” in the product datasheet.
Note:
Programming the control bits of the Peripheral ID that are not implemented has no effect on the behavior of the PMC.
26.9.5
PMC Peripheral Clock Disable Register
Register Name:PMC_PCDR
Access Type:Write-only
31
30
29
28
27
26
25
24
PID31
PID30
PID29
PID28
PID27
PID26
PID25
PID24
23
22
21
20
19
18
17
16
PID23
PID22
PID21
PID20
PID19
PID18
PID17
PID16
15
14
13
12
11
10
9
8
PID15
PID14
PID13
PID12
PID11
PID10
PID9
PID8
7
6
5
4
3
2
1
0
PID7
PID6
PID5
PID4
PID3
PID2
-
-
• PIDx: Peripheral Clock x Disable
0 = No effect.
1 = Disables the corresponding peripheral clock.
Note:
PID2 to PID31 refer to identifiers as defined in the section “Peripheral Identifiers” in the product datasheet.
301
6384E–ATARM–05-Feb-10
26.9.6
PMC Peripheral Clock Status Register
Register Name:PMC_PCSR
Access Type:Read-only
31
30
29
28
27
26
25
24
PID31
PID30
PID29
PID28
PID27
PID26
PID25
PID24
23
22
21
20
19
18
17
16
PID23
PID22
PID21
PID20
PID19
PID18
PID17
PID16
15
14
13
12
11
10
9
8
PID15
PID14
PID13
PID12
PID11
PID10
PID9
PID8
7
6
5
4
3
2
1
0
PID7
PID6
PID5
PID4
PID3
PID2
–
–
• PIDx: Peripheral Clock x Status
0 = The corresponding peripheral clock is disabled.
1 = The corresponding peripheral clock is enabled.
Note:
302
PID2 to PID31 refer to identifiers as defined in the section “Peripheral Identifiers” in the product datasheet.
AT91SAM9G20
6384E–ATARM–05-Feb-10
AT91SAM9G20
26.9.7
PMC Clock Generator Main Oscillator Register
Register Name:CKGR_MOR
Access Type:Read-write
31
–
30
–
29
–
28
–
27
–
26
–
25
–
24
–
23
–
22
–
21
–
20
–
19
–
18
–
17
–
16
–
15
14
13
12
11
10
9
8
3
–
2
–
1
OSCBYPASS
0
MOSCEN
OSCOUNT
7
–
6
–
5
–
4
–
• MOSCEN: Main Oscillator Enable
A crystal must be connected between XIN and XOUT.
0 = The Main Oscillator is disabled.
1 = The Main Oscillator is enabled. OSCBYPASS must be set to 0.
When MOSCEN is set, the MOSCS flag is set once the Main Oscillator startup time is achieved.
• OSCBYPASS: Oscillator Bypass
0 = No effect.
1 = The Main Oscillator is bypassed. MOSCEN must be set to 0. An external clock must be connected on XIN.
When OSCBYPASS is set, the MOSCS flag in PMC_SR is automatically set.
Clearing MOSCEN and OSCBYPASS bits allows resetting the MOSCS flag.
• OSCOUNT: Main Oscillator Start-up Time
Specifies the number of Slow Clock cycles multiplied by 8 for the Main Oscillator start-up time.
303
6384E–ATARM–05-Feb-10
26.9.8
PMC Clock Generator Main Clock Frequency Register
Register Name:CKGR_MCFR
Access Type:Read-only
31
–
30
–
29
–
28
–
27
–
26
–
25
–
24
–
23
–
22
–
21
–
20
–
19
–
18
–
17
–
16
MAINRDY
15
14
13
12
11
10
9
8
3
2
1
0
MAINF
7
6
5
4
MAINF
• MAINF: Main Clock Frequency
Gives the number of Main Clock cycles within 16 Slow Clock periods.
• MAINRDY: Main Clock Ready
0 = MAINF value is not valid or the Main Oscillator is disabled.
1 = The Main Oscillator has been enabled previously and MAINF value is available.
304
AT91SAM9G20
6384E–ATARM–05-Feb-10
AT91SAM9G20
26.9.9
PMC Clock Generator PLL A Register
Register Name:CKGR_PLLAR
Access Type:Read-write
31
–
30
–
29
1
28
–
27
–
26
–
25
–
24
–
23
22
21
20
19
18
17
16
11
10
9
8
2
1
0
MULA
15
14
13
12
OUTA
7
PLLACOUNT
6
5
4
3
DIVA
Possible limitations on PLL A input frequencies and multiplier factors should be checked before using the PMC.
Warning: Bit 29 must always be set to 1 when programming the CKGR_PLLAR register.
• DIVA: Divider A
DIVA
Divider Selected
0
Divider output is 0
1
Divider is bypassed
2 - 255
Divider output is the Main Clock divided by DIVA.
• PLLACOUNT: PLL A Counter
Specifies the number of Slow Clock cycles before the LOCKA bit is set in PMC_SR after CKGR_PLLAR is written.
• OUTA: PLL A Clock Frequency Range
To optimize clock performance, this field must be programmed as specified in “PLL Characteristics” in the Electrical Characteristics section of the product datasheet.
• MULA: PLL A Multiplier
0 = The PLL A is deactivated.
1 up to 254 = The PLL A Clock frequency is the PLL A input frequency multiplied by MULA + 1.
305
6384E–ATARM–05-Feb-10
26.9.10 PMC Clock Generator PLL B Register
Register Name:CKGR_PLLBR
Access Type:Read-write
31
–
30
–
29
23
–
22
–
21
15
14
13
28
27
–
26
–
25
–
24
–
20
19
18
17
16
10
9
8
2
1
0
USBDIV
MULB
12
11
OUTB
7
PLLBCOUNT
6
5
4
3
DIVB
Possible limitations on PLL B input frequencies and multiplier factors should be checked before using the PMC.
• DIVB: Divider B
DIVB
Divider Selected
0
Divider output is 0
1
Divider is bypassed
2 - 255
Divider output is the selected clock divided by DIVB.
• PLLBCOUNT: PLL B Counter
Specifies the number of slow clock cycles before the LOCKB bit is set in PMC_SR after CKGR_PLLBR is written.
• OUTB: PLL B Clock Frequency Range
To optimize clock performance, this field must be programmed as specified in “PLL Characteristics” in the Electrical Characteristics section of the product datasheet.
• MULB: PLL B Multiplier
0 = The PLL B is deactivated.
1 up to 62 = The PLL B Clock frequency is the PLL B input frequency multiplied by MULB + 1.
• USBDIV: Divider for USB Clock.
USBDIV
Divider Selected
0
0
Divider output is PLL B clock output
0
1
Divider output is PLL B clock output divided by 2
1
0
Divider output is PLL B clock output divided by 4
1
1
Reserved
306
AT91SAM9G20
6384E–ATARM–05-Feb-10
AT91SAM9G20
26.9.11 PMC Master Clock Register
Register Name:PMC_MCKR
Access Type:Read-write
31
30
29
28
27
26
25
24
–
–
–
–
–
–
–
–
23
22
21
20
19
18
17
16
–
–
–
–
–
–
–
–
15
14
13
12
11
10
9
–
–
–
PDIV
–
–
4
3
2
7
6
5
–
–
–
8
MDIV
1
PRES
0
CSS
• CSS: Master/Processor Clock Source Selection
CSS
Clock Source Selection
0
0
Slow Clock is selected
0
1
Main Clock is selected
1
0
PLLA Clock is selected
1
1
PLLB Clock is selected
• PRES: Master/Processor Clock Prescaler
Master/Processor Clock Dividers
Input Clock
PRES
0
0
0
Selected clock
0
0
1
Selected clock divided by 2
0
1
0
Selected clock divided by 4
0
1
1
Selected clock divided by 8
1
0
0
Selected clock divided by 16
1
0
1
Selected clock divided by 32
1
1
0
Selected clock divided by 64
1
1
1
Reserved
• MDIV: Master Clock Division
MDIV
Master Clock Division
0
0
Master Clock is Prescaler Output Clock divided by 1.
0
1
Master Clock is Prescaler Output Clock divided by 2.
1
0
Master Clock is Prescaler Output Clock divided by 4.
1
1
Master Clock is Prescaler Output Clock divided by 6.
307
6384E–ATARM–05-Feb-10
• PDIV: Processor Clock Division
PDIV
Processor Clock Division
0
Processor Clock is Prescaler Output Clock divided by 1.
1
Processor Clock is Prescaler Output Clock divided by 2.
Warning: If MDIV is written to 0, the write in PDIV is not taken in account and PDIV is forced to 0 (The Master Clock frequency cannot be superior to the Processor Clock frequency).
308
AT91SAM9G20
6384E–ATARM–05-Feb-10
AT91SAM9G20
26.9.12 PMC Programmable Clock Register
Register Name:PMC_PCKx
Access Type:Read-write
31
30
29
28
27
26
25
24
–
–
–
–
–
–
–
–
23
22
21
20
19
18
17
16
–
–
–
–
–
–
–
–
15
14
13
12
11
10
9
8
–
–
–
–
–
–
–
–
4
3
2
1
7
6
5
–
–
–
PRES
0
CSS
• CSS: Master Clock Selection
CSS
Clock Source Selection
0
0
Slow Clock is selected
0
1
Main Clock is selected
1
0
PLL A Clock is selected
1
1
PLL B Clock is selected
• PRES: Programmable Clock Prescaler
PRES
Programmable Clock
0
0
0
Selected clock
0
0
1
Selected clock divided by 2
0
1
0
Selected clock divided by 4
0
1
1
Selected clock divided by 8
1
0
0
Selected clock divided by 16
1
0
1
Selected clock divided by 32
1
1
0
Selected clock divided by 64
1
1
1
Reserved
309
6384E–ATARM–05-Feb-10
26.9.13 PMC Interrupt Enable Register
Register Name:PMC_IER
Access Type:Write-only
31
30
29
28
27
26
25
24
–
–
–
–
–
–
–
–
23
22
21
20
19
18
17
16
–
–
–
–
–
–
–
–
15
14
13
12
11
10
9
8
-
-
-
-
-
-
PCKRDY1
PCKRDY0
7
6
5
4
3
2
1
0
–
-
-
-
MCKRDY
LOCKB
LOCKA
MOSCS
• MOSCS: Main Oscillator Status Interrupt Enable
• LOCKA: PLL A Lock Interrupt Enable
• LOCKB: PLL B Lock Interrupt Enable
• MCKRDY: Master Clock Ready Interrupt Enable
• PCKRDYx: Programmable Clock Ready x Interrupt Enable
0 = No effect.
1 = Enables the corresponding interrupt.
310
AT91SAM9G20
6384E–ATARM–05-Feb-10
AT91SAM9G20
26.9.14 PMC Interrupt Disable Register
Register Name:PMC_IDR
Access Type:Write-only
31
30
29
28
27
26
25
24
–
–
–
–
–
–
–
–
23
22
21
20
19
18
17
16
–
–
–
–
–
–
–
–
15
14
13
12
11
10
9
8
-
-
-
-
-
-
PCKRDY1
PCKRDY0
7
6
5
4
3
2
1
0
–
-
-
-
MCKRDY
LOCKB
LOCKA
MOSCS
• MOSCS: Main Oscillator Status Interrupt Disable
• LOCKA: PLL A Lock Interrupt Disable
• LOCKB: PLL B Lock Interrupt Disable
• MCKRDY: Master Clock Ready Interrupt Disable
• PCKRDYx: Programmable Clock Ready x Interrupt Disable
0 = No effect.
1 = Disables the corresponding interrupt.
311
6384E–ATARM–05-Feb-10
26.9.15 PMC Status Register
Register Name:PMC_SR
Access Type:Read-only
31
30
29
28
27
26
25
24
–
–
–
–
–
–
–
–
23
22
21
20
19
18
17
16
–
–
–
–
–
–
–
–
15
14
13
12
11
10
9
8
-
-
-
-
-
-
PCKRDY1
PCKRDY0
7
6
5
4
3
2
1
0
OSC_SEL
-
-
-
MCKRDY
LOCKB
LOCKA
MOSCS
• MOSCS: Main Oscillator Status
0 = Main oscillator is not stabilized.
1 = Main oscillator is stabilized.
• LOCKA: PLL A Lock Status
0 = PLL A is not locked
1 = PLL A is locked.
• LOCKB: PLL B Lock Status
0 = PLL B is not locked.
1 = PLL B is locked.
• MCKRDY: Master Clock Status
0 = Master Clock is not ready.
1 = Master Clock is ready.
• OSC_SEL: Slow Clock Oscillator Selection
0 = Internal slow clock RC oscillator.
1 = External slow clock 32 kHz oscillator.
• PCKRDYx: Programmable Clock Ready Status
0 = Programmable Clock x is not ready.
1 = Programmable Clock x is ready.
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26.9.16 PMC Interrupt Mask Register
Register Name:PMC_IMR
Access Type:Read-only
31
30
29
28
27
26
25
24
–
–
–
–
–
–
–
–
23
22
21
20
19
18
17
16
–
–
–
–
–
–
–
–
15
14
13
12
11
10
9
8
-
-
-
-
-
-
PCKRDY1
PCKRDY0
7
6
5
4
3
2
1
0
–
-
-
-
MCKRDY
LOCKB
LOCKA
MOSCS
• MOSCS: Main Oscillator Status Interrupt Mask
• LOCKA: PLL A Lock Interrupt Mask
• LOCKB: PLL B Lock Interrupt Mask
• MCKRDY: Master Clock Ready Interrupt Mask
• PCKRDYx: Programmable Clock Ready Interrupt Mask
0 = The corresponding interrupt is disabled.
1 = The corresponding interrupt is enabled.
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26.9.17 PLL Charge Pump Current Register
Register Name:PMC_PLLICPR
Access Type:Write-only
31
30
29
28
27
26
25
24
–
–
–
–
–
–
–
–
23
22
21
20
19
18
17
16
–
–
–
–
–
–
–
ICPLLB
15
14
13
12
11
10
9
8
–
–
–
–
–
–
–
–
7
6
5
4
3
2
1
0
–
–
–
–
–
–
–
ICPLLA
• ICPLLA: Charge Pump Current
To optimize clock performance, this field must be programmed as specified in “PLL A Characteristics” in the Electrical Characteristics section of the product datasheet.
• ICPLLB: Charge Pump Current
Must be set to 0.
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27. Advanced Interrupt Controller (AIC)
27.1
Overview
The Advanced Interrupt Controller (AIC) is an 8-level priority, individually maskable, vectored
interrupt controller, providing handling of up to thirty-two interrupt sources. It is designed to substantially reduce the software and real-time overhead in handling internal and external
interrupts.
The AIC drives the nFIQ (fast interrupt request) and the nIRQ (standard interrupt request) inputs
of an ARM processor. Inputs of the AIC are either internal peripheral interrupts or external interrupts coming from the product's pins.
The 8-level Priority Controller allows the user to define the priority for each interrupt source, thus
permitting higher priority interrupts to be serviced even if a lower priority interrupt is being
treated.
Internal interrupt sources can be programmed to be level sensitive or edge triggered. External
interrupt sources can be programmed to be positive-edge or negative-edge triggered or highlevel or low-level sensitive.
The fast forcing feature redirects any internal or external interrupt source to provide a fast interrupt rather than a normal interrupt.
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27.2
Block Diagram
Figure 27-1. Block Diagram
FIQ
AIC
ARM
Processor
IRQ0-IRQn
Up to
Thirty-two
Sources
Embedded
PeripheralEE
Embedded
nFIQ
nIRQ
Peripheral
Embedded
Peripheral
APB
27.3
Application Block Diagram
Figure 27-2. Description of the Application Block
OS-based Applications
Standalone
Applications
OS Drivers
RTOS Drivers
Hard Real Time Tasks
General OS Interrupt Handler
Advanced Interrupt Controller
External Peripherals
(External Interrupts)
Embedded Peripherals
27.4
AIC Detailed Block Diagram
Figure 27-3. AIC Detailed Block Diagram
Advanced Interrupt Controller
FIQ
PIO
Controller
Fast
Interrupt
Controller
External
Source
Input
Stage
ARM
Processor
nFIQ
nIRQ
IRQ0-IRQn
Embedded
Peripherals
Interrupt
Priority
Controller
Fast
Forcing
PIOIRQ
Internal
Source
Input
Stage
Processor
Clock
Power
Management
Controller
User Interface
Wake Up
APB
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27.5
I/O Line Description
Table 27-1.
I/O Line Description
Pin Name
Pin Description
Type
FIQ
Fast Interrupt
Input
IRQ0 - IRQn
Interrupt 0 - Interrupt n
Input
27.6
27.6.1
Product Dependencies
I/O Lines
The interrupt signals FIQ and IRQ0 to IRQn are normally multiplexed through the PIO controllers. Depending on the features of the PIO controller used in the product, the pins must be
programmed in accordance with their assigned interrupt function. This is not applicable when
the PIO controller used in the product is transparent on the input path.
27.6.2
Power Management
The Advanced Interrupt Controller is continuously clocked. The Power Management Controller
has no effect on the Advanced Interrupt Controller behavior.
The assertion of the Advanced Interrupt Controller outputs, either nIRQ or nFIQ, wakes up the
ARM processor while it is in Idle Mode. The General Interrupt Mask feature enables the AIC to
wake up the processor without asserting the interrupt line of the processor, thus providing synchronization of the processor on an event.
27.6.3
Interrupt Sources
The Interrupt Source 0 is always located at FIQ. If the product does not feature an FIQ pin, the
Interrupt Source 0 cannot be used.
The Interrupt Source 1 is always located at System Interrupt. This is the result of the OR-wiring
of the system peripheral interrupt lines. When a system interrupt occurs, the service routine
must first distinguish the cause of the interrupt. This is performed by reading successively the
status registers of the above mentioned system peripherals.
The interrupt sources 2 to 31 can either be connected to the interrupt outputs of an embedded
user peripheral or to external interrupt lines. The external interrupt lines can be connected
directly, or through the PIO Controller.
The PIO Controllers are considered as user peripherals in the scope of interrupt handling.
Accordingly, the PIO Controller interrupt lines are connected to the Interrupt Sources 2 to 31.
The peripheral identification defined at the product level corresponds to the interrupt source
number (as well as the bit number controlling the clock of the peripheral). Consequently, to simplify the description of the functional operations and the user interface, the interrupt sources are
named FIQ, SYS, and PID2 to PID31.
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27.7
Functional Description
27.7.1
27.7.1.1
Interrupt Source Control
Interrupt Source Mode
The Advanced Interrupt Controller independently programs each interrupt source. The SRCTYPE field of the corresponding AIC_SMR (Source Mode Register) selects the interrupt
condition of each source.
The internal interrupt sources wired on the interrupt outputs of the embedded peripherals can be
programmed either in level-sensitive mode or in edge-triggered mode. The active level of the
internal interrupts is not important for the user.
The external interrupt sources can be programmed either in high level-sensitive or low level-sensitive modes, or in positive edge-triggered or negative edge-triggered modes.
27.7.1.2
Interrupt Source Enabling
Each interrupt source, including the FIQ in source 0, can be enabled or disabled by using the
command registers; AIC_IECR (Interrupt Enable Command Register) and AIC_IDCR (Interrupt
Disable Command Register). This set of registers conducts enabling or disabling in one instruction. The interrupt mask can be read in the AIC_IMR register. A disabled interrupt does not affect
servicing of other interrupts.
27.7.1.3
Interrupt Clearing and Setting
All interrupt sources programmed to be edge-triggered (including the FIQ in source 0) can be
individually set or cleared by writing respectively the AIC_ISCR and AIC_ICCR registers. Clearing or setting interrupt sources programmed in level-sensitive mode has no effect.
The clear operation is perfunctory, as the software must perform an action to reinitialize the
“memorization” circuitry activated when the source is programmed in edge-triggered mode.
However, the set operation is available for auto-test or software debug purposes. It can also be
used to execute an AIC-implementation of a software interrupt.
The AIC features an automatic clear of the current interrupt when the AIC_IVR (Interrupt Vector
Register) is read. Only the interrupt source being detected by the AIC as the current interrupt is
affected by this operation. (See “Priority Controller” on page 321.) The automatic clear reduces
the operations required by the interrupt service routine entry code to reading the AIC_IVR. Note
that the automatic interrupt clear is disabled if the interrupt source has the Fast Forcing feature
enabled as it is considered uniquely as a FIQ source. (For further details, See “Fast Forcing” on
page 325.)
The automatic clear of the interrupt source 0 is performed when AIC_FVR is read.
27.7.1.4
Interrupt Status
For each interrupt, the AIC operation originates in AIC_IPR (Interrupt Pending Register) and its
mask in AIC_IMR (Interrupt Mask Register). AIC_IPR enables the actual activity of the sources,
whether masked or not.
The AIC_ISR register reads the number of the current interrupt (see “Priority Controller” on page
321) and the register AIC_CISR gives an image of the signals nIRQ and nFIQ driven on the
processor.
Each status referred to above can be used to optimize the interrupt handling of the systems.
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27.7.1.5
Internal Interrupt Source Input Stage
Figure 27-4.
Internal Interrupt Source Input Stage
AIC_SMRI
(SRCTYPE)
Level/
Edge
Source i
AIC_IPR
AIC_IMR
Fast Interrupt Controller
or
Priority Controller
Edge
AIC_IECR
Detector
Set Clear
FF
AIC_ISCR
AIC_ICCR
AIC_IDCR
27.7.1.6
External Interrupt Source Input Stage
Figure 27-5. External Interrupt Source Input Stage
High/Low
AIC_SMRi
SRCTYPE
Level/
Edge
AIC_IPR
AIC_IMR
Source i
Fast Interrupt Controller
or
Priority Controller
AIC_IECR
Pos./Neg.
Edge
Detector
Set
AIC_ISCR
FF
Clear
AIC_IDCR
AIC_ICCR
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27.7.2
Interrupt Latencies
Global interrupt latencies depend on several parameters, including:
• The time the software masks the interrupts.
• Occurrence, either at the processor level or at the AIC level.
• The execution time of the instruction in progress when the interrupt occurs.
• The treatment of higher priority interrupts and the resynchronization of the hardware signals.
This section addresses only the hardware resynchronizations. It gives details of the latency
times between the event on an external interrupt leading in a valid interrupt (edge or level) or the
assertion of an internal interrupt source and the assertion of the nIRQ or nFIQ line on the processor. The resynchronization time depends on the programming of the interrupt source and on
its type (internal or external). For the standard interrupt, resynchronization times are given
assuming there is no higher priority in progress.
The PIO Controller multiplexing has no effect on the interrupt latencies of the external interrupt
sources.
27.7.2.1
External Interrupt Edge Triggered Source
Figure 27-6.
External Interrupt Edge Triggered Source
MCK
IRQ or FIQ
(Positive Edge)
IRQ or FIQ
(Negative Edge)
nIRQ
Maximum IRQ Latency = 4 Cycles
nFIQ
Maximum FIQ Latency = 4 Cycles
27.7.2.2
External Interrupt Level Sensitive Source
Figure 27-7.
External Interrupt Level Sensitive Source
MCK
IRQ or FIQ
(High Level)
IRQ or FIQ
(Low Level)
nIRQ
Maximum IRQ
Latency = 3 Cycles
nFIQ
Maximum FIQ
Latency = 3 cycles
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27.7.2.3
Internal Interrupt Edge Triggered Source
Figure 27-8.
Internal Interrupt Edge Triggered Source
MCK
nIRQ
Maximum IRQ Latency = 4.5 Cycles
Peripheral Interrupt
Becomes Active
27.7.2.4
Internal Interrupt Level Sensitive Source
Figure 27-9.
Internal Interrupt Level Sensitive Source
MCK
nIRQ
Maximum IRQ Latency = 3.5 Cycles
Peripheral Interrupt
Becomes Active
27.7.3
27.7.3.1
Normal Interrupt
Priority Controller
An 8-level priority controller drives the nIRQ line of the processor, depending on the interrupt
conditions occurring on the interrupt sources 1 to 31 (except for those programmed in Fast
Forcing).
Each interrupt source has a programmable priority level of 7 to 0, which is user-definable by writing the PRIOR field of the corresponding AIC_SMR (Source Mode Register). Level 7 is the
highest priority and level 0 the lowest.
As soon as an interrupt condition occurs, as defined by the SRCTYPE field of the AIC_SMR
(Source Mode Register), the nIRQ line is asserted. As a new interrupt condition might have happened on other interrupt sources since the nIRQ has been asserted, the priority controller
determines the current interrupt at the time the AIC_IVR (Interrupt Vector Register) is read. The
read of AIC_IVR is the entry point of the interrupt handling which allows the AIC to consider
that the interrupt has been taken into account by the software.
The current priority level is defined as the priority level of the current interrupt.
If several interrupt sources of equal priority are pending and enabled when the AIC_IVR is read,
the interrupt with the lowest interrupt source number is serviced first.
The nIRQ line can be asserted only if an interrupt condition occurs on an interrupt source with a
higher priority. If an interrupt condition happens (or is pending) during the interrupt treatment in
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progress, it is delayed until the software indicates to the AIC the end of the current service by
writing the AIC_EOICR (End of Interrupt Command Register). The write of AIC_EOICR is the
exit point of the interrupt handling.
27.7.3.2
Interrupt Nesting
The priority controller utilizes interrupt nesting in order for the high priority interrupt to be handled
during the service of lower priority interrupts. This requires the interrupt service routines of the
lower interrupts to re-enable the interrupt at the processor level.
When an interrupt of a higher priority happens during an already occurring interrupt service routine, the nIRQ line is re-asserted. If the interrupt is enabled at the core level, the current
execution is interrupted and the new interrupt service routine should read the AIC_IVR. At this
time, the current interrupt number and its priority level are pushed into an embedded hardware
stack, so that they are saved and restored when the higher priority interrupt servicing is finished
and the AIC_EOICR is written.
The AIC is equipped with an 8-level wide hardware stack in order to support up to eight interrupt
nestings pursuant to having eight priority levels.
27.7.3.3
Interrupt Vectoring
The interrupt handler addresses corresponding to each interrupt source can be stored in the registers AIC_SVR1 to AIC_SVR31 (Source Vector Register 1 to 31). When the processor reads
AIC_IVR (Interrupt Vector Register), the value written into AIC_SVR corresponding to the current interrupt is returned.
This feature offers a way to branch in one single instruction to the handler corresponding to the
current interrupt, as AIC_IVR is mapped at the absolute address 0xFFFF F100 and thus accessible from the ARM interrupt vector at address 0x0000 0018 through the following instruction:
LDR
PC,[PC,# -&F20]
When the processor executes this instruction, it loads the read value in AIC_IVR in its program
counter, thus branching the execution on the correct interrupt handler.
This feature is often not used when the application is based on an operating system (either real
time or not). Operating systems often have a single entry point for all the interrupts and the first
task performed is to discern the source of the interrupt.
However, it is strongly recommended to port the operating system on AT91 products by supporting the interrupt vectoring. This can be performed by defining all the AIC_SVR of the interrupt
source to be handled by the operating system at the address of its interrupt handler. When doing
so, the interrupt vectoring permits a critical interrupt to transfer the execution on a specific very
fast handler and not onto the operating system’s general interrupt handler. This facilitates the
support of hard real-time tasks (input/outputs of voice/audio buffers and software peripheral handling) to be handled efficiently and independently of the application running under an operating
system.
27.7.3.4
Interrupt Handlers
This section gives an overview of the fast interrupt handling sequence when using the AIC. It is
assumed that the programmer understands the architecture of the ARM processor, and especially the processor interrupt modes and the associated status bits.
It is assumed that:
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1. The Advanced Interrupt Controller has been programmed, AIC_SVR registers are
loaded with corresponding interrupt service routine addresses and interrupts are
enabled.
2. The instruction at the ARM interrupt exception vector address is required to work with
the vectoring
LDR PC, [PC, # -&F20]
When nIRQ is asserted, if the bit “I” of CPSR is 0, the sequence is as follows:
1. The CPSR is stored in SPSR_irq, the current value of the Program Counter is loaded in
the Interrupt link register (R14_irq) and the Program Counter (R15) is loaded with 0x18.
In the following cycle during fetch at address 0x1C, the ARM core adjusts R14_irq, decrementing it by four.
2. The ARM core enters Interrupt mode, if it has not already done so.
3. When the instruction loaded at address 0x18 is executed, the program counter is
loaded with the value read in AIC_IVR. Reading the AIC_IVR has the following effects:
– Sets the current interrupt to be the pending and enabled interrupt with the highest
priority. The current level is the priority level of the current interrupt.
– De-asserts the nIRQ line on the processor. Even if vectoring is not used, AIC_IVR
must be read in order to de-assert nIRQ.
– Automatically clears the interrupt, if it has been programmed to be edge-triggered.
– Pushes the current level and the current interrupt number on to the stack.
– Returns the value written in the AIC_SVR corresponding to the current interrupt.
4. The previous step has the effect of branching to the corresponding interrupt service
routine. This should start by saving the link register (R14_irq) and SPSR_IRQ. The link
register must be decremented by four when it is saved if it is to be restored directly into
the program counter at the end of the interrupt. For example, the instruction SUB PC,
LR, #4 may be used.
5. Further interrupts can then be unmasked by clearing the “I” bit in CPSR, allowing reassertion of the nIRQ to be taken into account by the core. This can happen if an interrupt with a higher priority than the current interrupt occurs.
6. The interrupt handler can then proceed as required, saving the registers that will be
used and restoring them at the end. During this phase, an interrupt of higher priority
than the current level will restart the sequence from step 1.
Note:
If the interrupt is programmed to be level sensitive, the source of the interrupt must be cleared during this phase.
7. The “I” bit in CPSR must be set in order to mask interrupts before exiting to ensure that
the interrupt is completed in an orderly manner.
8. The End of Interrupt Command Register (AIC_EOICR) must be written in order to indicate to the AIC that the current interrupt is finished. This causes the current level to be
popped from the stack, restoring the previous current level if one exists on the stack. If
another interrupt is pending, with lower or equal priority than the old current level but
with higher priority than the new current level, the nIRQ line is re-asserted, but the interrupt sequence does not immediately start because the “I” bit is set in the core.
SPSR_irq is restored. Finally, the saved value of the link register is restored directly into
the PC. This has the effect of returning from the interrupt to whatever was being executed before, and of loading the CPSR with the stored SPSR, masking or unmasking
the interrupts depending on the state saved in SPSR_irq.
Note:
The “I” bit in SPSR is significant. If it is set, it indicates that the ARM core was on the verge of
masking an interrupt when the mask instruction was interrupted. Hence, when SPSR is restored,
the mask instruction is completed (interrupt is masked).
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27.7.4
Fast Interrupt
27.7.4.1
Fast Interrupt Source
The interrupt source 0 is the only source which can raise a fast interrupt request to the processor
except if fast forcing is used. The interrupt source 0 is generally connected to a FIQ pin of the
product, either directly or through a PIO Controller.
27.7.4.2
Fast Interrupt Control
The fast interrupt logic of the AIC has no priority controller. The mode of interrupt source 0 is
programmed with the AIC_SMR0 and the field PRIOR of this register is not used even if it reads
what has been written. The field SRCTYPE of AIC_SMR0 enables programming the fast interrupt source to be positive-edge triggered or negative-edge triggered or high-level sensitive or
low-level sensitive
Writing 0x1 in the AIC_IECR (Interrupt Enable Command Register) and AIC_IDCR (Interrupt
Disable Command Register) respectively enables and disables the fast interrupt. The bit 0 of
AIC_IMR (Interrupt Mask Register) indicates whether the fast interrupt is enabled or disabled.
27.7.4.3
Fast Interrupt Vectoring
The fast interrupt handler address can be stored in AIC_SVR0 (Source Vector Register 0). The
value written into this register is returned when the processor reads AIC_FVR (Fast Vector Register). This offers a way to branch in one single instruction to the interrupt handler, as AIC_FVR
is mapped at the absolute address 0xFFFF F104 and thus accessible from the ARM fast interrupt vector at address 0x0000 001C through the following instruction:
LDR
PC,[PC,# -&F20]
When the processor executes this instruction it loads the value read in AIC_FVR in its program
counter, thus branching the execution on the fast interrupt handler. It also automatically performs the clear of the fast interrupt source if it is programmed in edge-triggered mode.
27.7.4.4
Fast Interrupt Handlers
This section gives an overview of the fast interrupt handling sequence when using the AIC. It is
assumed that the programmer understands the architecture of the ARM processor, and especially the processor interrupt modes and associated status bits.
Assuming that:
1. The Advanced Interrupt Controller has been programmed, AIC_SVR0 is loaded with
the fast interrupt service routine address, and the interrupt source 0 is enabled.
2. The Instruction at address 0x1C (FIQ exception vector address) is required to vector
the fast interrupt:
LDR PC, [PC, # -&F20]
3. The user does not need nested fast interrupts.
When nFIQ is asserted, if the bit “F” of CPSR is 0, the sequence is:
1. The CPSR is stored in SPSR_fiq, the current value of the program counter is loaded in
the FIQ link register (R14_FIQ) and the program counter (R15) is loaded with 0x1C. In
the following cycle, during fetch at address 0x20, the ARM core adjusts R14_fiq, decrementing it by four.
2. The ARM core enters FIQ mode.
3. When the instruction loaded at address 0x1C is executed, the program counter is
loaded with the value read in AIC_FVR. Reading the AIC_FVR has effect of automati-
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cally clearing the fast interrupt, if it has been programmed to be edge triggered. In this
case only, it de-asserts the nFIQ line on the processor.
4. The previous step enables branching to the corresponding interrupt service routine. It is
not necessary to save the link register R14_fiq and SPSR_fiq if nested fast interrupts
are not needed.
5. The Interrupt Handler can then proceed as required. It is not necessary to save registers R8 to R13 because FIQ mode has its own dedicated registers and the user R8 to
R13 are banked. The other registers, R0 to R7, must be saved before being used, and
restored at the end (before the next step). Note that if the fast interrupt is programmed
to be level sensitive, the source of the interrupt must be cleared during this phase in
order to de-assert the interrupt source 0.
6. Finally, the Link Register R14_fiq is restored into the PC after decrementing it by four
(with instruction SUB PC, LR, #4 for example). This has the effect of returning from
the interrupt to whatever was being executed before, loading the CPSR with the SPSR
and masking or unmasking the fast interrupt depending on the state saved in the
SPSR.
Note:
The “F” bit in SPSR is significant. If it is set, it indicates that the ARM core was just about to mask
FIQ interrupts when the mask instruction was interrupted. Hence when the SPSR is restored, the
interrupted instruction is completed (FIQ is masked).
Another way to handle the fast interrupt is to map the interrupt service routine at the address of
the ARM vector 0x1C. This method does not use the vectoring, so that reading AIC_FVR must
be performed at the very beginning of the handler operation. However, this method saves the
execution of a branch instruction.
27.7.4.5
Fast Forcing
The Fast Forcing feature of the advanced interrupt controller provides redirection of any normal
Interrupt source on the fast interrupt controller.
Fast Forcing is enabled or disabled by writing to the Fast Forcing Enable Register (AIC_FFER)
and the Fast Forcing Disable Register (AIC_FFDR). Writing to these registers results in an
update of the Fast Forcing Status Register (AIC_FFSR) that controls the feature for each internal or external interrupt source.
When Fast Forcing is disabled, the interrupt sources are handled as described in the previous
pages.
When Fast Forcing is enabled, the edge/level programming and, in certain cases, edge detection of the interrupt source is still active but the source cannot trigger a normal interrupt to the
processor and is not seen by the priority handler.
If the interrupt source is programmed in level-sensitive mode and an active level is sampled,
Fast Forcing results in the assertion of the nFIQ line to the core.
If the interrupt source is programmed in edge-triggered mode and an active edge is detected,
Fast Forcing results in the assertion of the nFIQ line to the core.
The Fast Forcing feature does not affect the Source 0 pending bit in the Interrupt Pending Register (AIC_IPR).
The FIQ Vector Register (AIC_FVR) reads the contents of the Source Vector Register 0
(AIC_SVR0), whatever the source of the fast interrupt may be. The read of the FVR does not
clear the Source 0 when the fast forcing feature is used and the interrupt source should be
cleared by writing to the Interrupt Clear Command Register (AIC_ICCR).
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All enabled and pending interrupt sources that have the fast forcing feature enabled and that are
programmed in edge-triggered mode must be cleared by writing to the Interrupt Clear Command
Register. In doing so, they are cleared independently and thus lost interrupts are prevented.
The read of AIC_IVR does not clear the source that has the fast forcing feature enabled.
The source 0, reserved to the fast interrupt, continues operating normally and becomes one of
the Fast Interrupt sources.
Figure 27-10. Fast Forcing
Source 0 _ FIQ
AIC_IPR
Input Stage
Automatic Clear
AIC_IMR
nFIQ
Read FVR if Fast Forcing is
disabled on Sources 1 to 31.
AIC_FFSR
Source n
AIC_IPR
Input Stage
Priority
Manager
Automatic Clear
AIC_IMR
nIRQ
Read IVR if Source n is the current interrupt
and if Fast Forcing is disabled on Source n.
27.7.5
Protect Mode
The Protect Mode permits reading the Interrupt Vector Register without performing the associated automatic operations. This is necessary when working with a debug system. When a
debugger, working either with a Debug Monitor or the ARM processor's ICE, stops the applications and updates the opened windows, it might read the AIC User Interface and thus the IVR.
This has undesirable consequences:
• If an enabled interrupt with a higher priority than the current one is pending, it is stacked.
• If there is no enabled pending interrupt, the spurious vector is returned.
In either case, an End of Interrupt command is necessary to acknowledge and to restore the
context of the AIC. This operation is generally not performed by the debug system as the debug
system would become strongly intrusive and cause the application to enter an undesired state.
This is avoided by using the Protect Mode. Writing PROT in AIC_DCR (Debug Control Register)
at 0x1 enables the Protect Mode.
When the Protect Mode is enabled, the AIC performs interrupt stacking only when a write access
is performed on the AIC_IVR. Therefore, the Interrupt Service Routines must write (arbitrary
data) to the AIC_IVR just after reading it. The new context of the AIC, including the value of the
Interrupt Status Register (AIC_ISR), is updated with the current interrupt only when AIC_IVR is
written.
An AIC_IVR read on its own (e.g., by a debugger), modifies neither the AIC context nor the
AIC_ISR. Extra AIC_IVR reads perform the same operations. However, it is recommended to
not stop the processor between the read and the write of AIC_IVR of the interrupt service routine
to make sure the debugger does not modify the AIC context.
326
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To summarize, in normal operating mode, the read of AIC_IVR performs the following operations within the AIC:
1. Calculates active interrupt (higher than current or spurious).
2. Determines and returns the vector of the active interrupt.
3. Memorizes the interrupt.
4. Pushes the current priority level onto the internal stack.
5. Acknowledges the interrupt.
However, while the Protect Mode is activated, only operations 1 to 3 are performed when
AIC_IVR is read. Operations 4 and 5 are only performed by the AIC when AIC_IVR is written.
Software that has been written and debugged using the Protect Mode runs correctly in Normal
Mode without modification. However, in Normal Mode the AIC_IVR write has no effect and can
be removed to optimize the code.
27.7.6
Spurious Interrupt
The Advanced Interrupt Controller features protection against spurious interrupts. A spurious
interrupt is defined as being the assertion of an interrupt source long enough for the AIC to
assert the nIRQ, but no longer present when AIC_IVR is read. This is most prone to occur when:
• An external interrupt source is programmed in level-sensitive mode and an active level occurs
for only a short time.
• An internal interrupt source is programmed in level sensitive and the output signal of the
corresponding embedded peripheral is activated for a short time. (As in the case for the
Watchdog.)
• An interrupt occurs just a few cycles before the software begins to mask it, thus resulting in a
pulse on the interrupt source.
The AIC detects a spurious interrupt at the time the AIC_IVR is read while no enabled interrupt
source is pending. When this happens, the AIC returns the value stored by the programmer in
AIC_SPU (Spurious Vector Register). The programmer must store the address of a spurious
interrupt handler in AIC_SPU as part of the application, to enable an as fast as possible return to
the normal execution flow. This handler writes in AIC_EOICR and performs a return from
interrupt.
27.7.7
General Interrupt Mask
The AIC features a General Interrupt Mask bit to prevent interrupts from reaching the processor.
Both the nIRQ and the nFIQ lines are driven to their inactive state if the bit GMSK in AIC_DCR
(Debug Control Register) is set. However, this mask does not prevent waking up the processor if
it has entered Idle Mode. This function facilitates synchronizing the processor on a next event
and, as soon as the event occurs, performs subsequent operations without having to handle an
interrupt. It is strongly recommended to use this mask with caution.
327
6384E–ATARM–05-Feb-10
27.8
Advanced Interrupt Controller (AIC) User Interface
27.8.1
Base Address
The AIC is mapped at the address 0xFFFF F000. It has a total 4-Kbyte addressing space. This permits the vectoring feature, as the PC-relative load/store instructions of the ARM processor support only a ± 4-Kbyte offset.
Table 27-2.
Register Mapping
Offset
Register
Name
Access
Reset
0x00
0x04
Source Mode Register 0
AIC_SMR0
Read-write
0x0
Source Mode Register 1
AIC_SMR1
Read-write
0x0
---
---
---
---
---
0x7C
Source Mode Register 31
AIC_SMR31
Read-write
0x0
0x80
Source Vector Register 0
AIC_SVR0
Read-write
0x0
0x84
Source Vector Register 1
AIC_SVR1
Read-write
0x0
---
---
---
---
---
0xFC
Source Vector Register 31
AIC_SVR31
Read-write
0x0
0x100
Interrupt Vector Register
AIC_IVR
Read-only
0x0
0x104
FIQ Interrupt Vector Register
AIC_FVR
Read-only
0x0
0x108
Interrupt Status Register
AIC_ISR
Read-only
0x0
AIC_IPR
Read-only
0x0(1)
(2)
0x10C
Interrupt Pending Register
0x110
Interrupt Mask Register(2)
AIC_IMR
Read-only
0x0
0x114
Core Interrupt Status Register
AIC_CISR
Read-only
0x0
0x118 - 0x11C
Reserved
---
---
---
AIC_IECR
Write-only
---
AIC_IDCR
Write-only
---
AIC_ICCR
Write-only
---
AIC_ISCR
Write-only
---
AIC_EOICR
Write-only
---
0x120
Interrupt Enable Command Register
(2)
0x124
Interrupt Disable Command Register
0x128
Interrupt Clear Command Register(2)
(2)
0x12C
Interrupt Set Command Register
0x130
End of Interrupt Command Register
(2)
0x134
Spurious Interrupt Vector Register
AIC_SPU
Read-write
0x0
0x138
Debug Control Register
AIC_DCR
Read-write
0x0
0x13C
Reserved
---
---
---
AIC_FFER
Write-only
---
(2)
0x140
Fast Forcing Enable Register
(2)
0x144
Fast Forcing Disable Register
0x148
Fast Forcing Status Register(2)
0x14C - 0x1E0
Reserved
0x1EC - 0x1FC
Reserved
Notes:
AIC_FFDR
Write-only
---
AIC_FFSR
Read-only
0x0
---
---
---
1. The reset value of this register depends on the level of the external interrupt source. All other sources are cleared at reset,
thus not pending.
2. PID2...PID31 bit fields refer to the identifiers as defined in the Peripheral Identifiers Section of the product datasheet.
3. Values in the Version Register vary with the version of the IP block implementation.
328
AT91SAM9G20
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AT91SAM9G20
27.8.2
AIC Source Mode Register
Register Name:
AIC_SMR0..AIC_SMR31
Access Type:
Read-write
Reset Value:
0x0
31
30
29
28
27
26
25
24
–
–
–
–
–
–
–
–
23
22
21
20
19
18
17
16
–
–
–
–
–
–
–
–
15
14
13
12
11
10
9
8
–
–
–
–
–
–
–
–
7
6
5
4
3
2
1
0
–
–
–
SRCTYPE
PRIOR
• PRIOR: Priority Level
Programs the priority level for all sources except FIQ source (source 0).
The priority level can be between 0 (lowest) and 7 (highest).
The priority level is not used for the FIQ in the related SMR register AIC_SMRx.
• SRCTYPE: Interrupt Source Type
The active level or edge is not programmable for the internal interrupt sources.
SRCTYPE
Internal Interrupt Sources
External Interrupt Sources
0
0
High level Sensitive
Low level Sensitive
0
1
Positive edge triggered
Negative edge triggered
1
0
High level Sensitive
High level Sensitive
1
1
Positive edge triggered
Positive edge triggered
329
6384E–ATARM–05-Feb-10
27.8.3
AIC Source Vector Register
Register Name:
AIC_SVR0..AIC_SVR31
Access Type:
Read-write
Reset Value:
0x0
31
30
29
28
27
26
25
24
19
18
17
16
11
10
9
8
3
2
1
0
VECTOR
23
22
21
20
VECTOR
15
14
13
12
VECTOR
7
6
5
4
VECTOR
• VECTOR: Source Vector
The user may store in these registers the addresses of the corresponding handler for each interrupt source.
330
AT91SAM9G20
6384E–ATARM–05-Feb-10
AT91SAM9G20
27.8.4
AIC Interrupt Vector Register
Register Name:
AIC_IVR
Access Type:
Read-only
Reset Value:
0x0
31
30
29
28
27
26
25
24
19
18
17
16
11
10
9
8
3
2
1
0
IRQV
23
22
21
20
IRQV
15
14
13
12
IRQV
7
6
5
4
IRQV
• IRQV: Interrupt Vector Register
The Interrupt Vector Register contains the vector programmed by the user in the Source Vector Register corresponding to
the current interrupt.
The Source Vector Register is indexed using the current interrupt number when the Interrupt Vector Register is read.
When there is no current interrupt, the Interrupt Vector Register reads the value stored in AIC_SPU.
27.8.5
AIC FIQ Vector Register
Register Name:
AIC_FVR
Access Type:
Read-only
Reset Value:
0x0
31
30
29
28
27
26
25
24
19
18
17
16
11
10
9
8
3
2
1
0
FIQV
23
22
21
20
FIQV
15
14
13
12
FIQV
7
6
5
4
FIQV
• FIQV: FIQ Vector Register
The FIQ Vector Register contains the vector programmed by the user in the Source Vector Register 0. When there is no
fast interrupt, the FIQ Vector Register reads the value stored in AIC_SPU.
331
6384E–ATARM–05-Feb-10
27.8.6
AIC Interrupt Status Register
Register Name:
AIC_ISR
Access Type:
Read-only
Reset Value:
0x0
31
30
29
28
27
26
25
24
–
–
–
–
–
–
–
–
23
22
21
20
19
18
17
16
–
–
–
–
–
–
–
–
15
14
13
12
11
10
9
8
–
–
–
–
–
–
–
–
7
6
5
4
3
2
1
0
–
–
–
IRQID
• IRQID: Current Interrupt Identifier
The Interrupt Status Register returns the current interrupt source number.
27.8.7
AIC Interrupt Pending Register
Register Name:
AIC_IPR
Access Type:
Read-only
Reset Value:
0x0
31
30
29
28
27
26
25
24
PID31
PID30
PID29
PID28
PID27
PID26
PID25
PID24
23
22
21
20
19
18
17
16
PID23
PID22
PID21
PID20
PID19
PID18
PID17
PID16
15
14
13
12
11
10
9
8
PID15
PID14
PID13
PID12
PID11
PID10
PID9
PID8
7
6
5
4
3
2
1
0
PID7
PID6
PID5
PID4
PID3
PID2
SYS
FIQ
• FIQ, SYS, PID2-PID31: Interrupt Pending
0 = Corresponding interrupt is not pending.
1 = Corresponding interrupt is pending.
332
AT91SAM9G20
6384E–ATARM–05-Feb-10
AT91SAM9G20
27.8.8
AIC Interrupt Mask Register
Register Name:
AIC_IMR
Access Type:
Read-only
Reset Value:
0x0
31
30
29
28
27
26
25
24
PID31
PID30
PID29
PID28
PID27
PID26
PID25
PID24
23
22
21
20
19
18
17
16
PID23
PID22
PID21
PID20
PID19
PID18
PID17
PID16
15
14
13
12
11
10
9
8
PID15
PID14
PID13
PID12
PID11
PID10
PID9
PID8
7
6
5
4
3
2
1
0
PID7
PID6
PID5
PID4
PID3
PID2
SYS
FIQ
• FIQ, SYS, PID2-PID31: Interrupt Mask
0 = Corresponding interrupt is disabled.
1 = Corresponding interrupt is enabled.
333
6384E–ATARM–05-Feb-10
27.8.9
AIC Core Interrupt Status Register
Register Name:
AIC_CISR
Access Type:
Read-only
Reset Value:
0x0
31
30
29
28
27
26
25
24
–
–
–
–
–
–
–
–
23
22
21
20
19
18
17
16
–
–
–
–
–
–
–
–
15
14
13
12
11
10
9
8
–
–
–
–
–
–
–
–
7
6
5
4
3
2
1
0
–
–
–
–
–
–
NIRQ
NFIQ
• NFIQ: NFIQ Status
0 = nFIQ line is deactivated.
1 = nFIQ line is active.
• NIRQ: NIRQ Status
0 = nIRQ line is deactivated.
1 = nIRQ line is active.
334
AT91SAM9G20
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AT91SAM9G20
27.8.10 AIC Interrupt Enable Command Register
Register Name:
AIC_IECR
Access Type:
Write-only
31
30
29
28
27
26
25
24
PID31
PID30
PID29
PID28
PID27
PID26
PID25
PID24
23
22
21
20
19
18
17
16
PID23
PID22
PID21
PID20
PID19
PID18
PID17
PID16
15
14
13
12
11
10
9
8
PID15
PID14
PID13
PID12
PID11
PID10
PID9
PID8
7
6
5
4
3
2
1
0
PID7
PID6
PID5
PID4
PID3
PID2
SYS
FIQ
• FIQ, SYS, PID2-PID31: Interrupt Enable
0 = No effect.
1 = Enables corresponding interrupt.
335
6384E–ATARM–05-Feb-10
27.8.11 AIC Interrupt Disable Command Register
Register Name:
AIC_IDCR
Access Type:
Write-only
31
30
29
28
27
26
25
24
PID31
PID30
PID29
PID28
PID27
PID26
PID25
PID24
23
22
21
20
19
18
17
16
PID23
PID22
PID21
PID20
PID19
PID18
PID17
PID16
15
14
13
12
11
10
9
8
PID15
PID14
PID13
PID12
PID11
PID10
PID9
PID8
7
6
5
4
3
2
1
0
PID7
PID6
PID5
PID4
PID3
PID2
SYS
FIQ
• FIQ, SYS, PID2-PID31: Interrupt Disable
0 = No effect.
1 = Disables corresponding interrupt.
27.8.12 AIC Interrupt Clear Command Register
Register Name:
AIC_ICCR
Access Type:
Write-only
31
30
29
28
27
26
25
24
PID31
PID30
PID29
PID28
PID27
PID26
PID25
PID24
23
22
21
20
19
18
17
16
PID23
PID22
PID21
PID20
PID19
PID18
PID17
PID16
15
14
13
12
11
10
9
8
PID15
PID14
PID13
PID12
PID11
PID10
PID9
PID8
7
6
5
4
3
2
1
0
PID7
PID6
PID5
PID4
PID3
PID2
SYS
FIQ
• FIQ, SYS, PID2-PID31: Interrupt Clear
0 = No effect.
1 = Clears corresponding interrupt.
336
AT91SAM9G20
6384E–ATARM–05-Feb-10
AT91SAM9G20
27.8.13 AIC Interrupt Set Command Register
Register Name:
AIC_ISCR
Access Type:
Write-only
31
30
29
28
27
26
25
24
PID31
PID30
PID29
PID28
PID27
PID26
PID25
PID24
23
22
21
20
19
18
17
16
PID23
PID22
PID21
PID20
PID19
PID18
PID17
PID16
15
14
13
12
11
10
9
8
PID15
PID14
PID13
PID12
PID11
PID10
PID9
PID8
7
6
5
4
3
2
1
0
PID7
PID6
PID5
PID4
PID3
PID2
SYS
FIQ
• FIQ, SYS, PID2-PID31: Interrupt Set
0 = No effect.
1 = Sets corresponding interrupt.
27.8.14 AIC End of Interrupt Command Register
Register Name:
AIC_EOICR
Access Type:
Write-only
31
30
29
28
27
26
25
24
–
–
–
–
–
–
–
–
23
22
21
20
19
18
17
16
–
–
–
–
–
–
–
–
15
14
13
12
11
10
9
8
–
–
–
–
–
–
–
–
7
6
5
4
3
2
1
0
–
–
–
–
–
–
–
–
The End of Interrupt Command Register is used by the interrupt routine to indicate that the interrupt treatment is complete.
Any value can be written because it is only necessary to make a write to this register location to signal the end of interrupt
treatment.
337
6384E–ATARM–05-Feb-10
27.8.15 AIC Spurious Interrupt Vector Register
Register Name:
AIC_SPU
Access Type:
Read-write
Reset Value:
0x0
31
30
29
28
27
26
25
24
19
18
17
16
11
10
9
8
3
2
1
0
SIVR
23
22
21
20
SIVR
15
14
13
12
SIVR
7
6
5
4
SIVR
• SIVR: Spurious Interrupt Vector Register
The user may store the address of a spurious interrupt handler in this register. The written value is returned in AIC_IVR in
case of a spurious interrupt and in AIC_FVR in case of a spurious fast interrupt.
27.8.16 AIC Debug Control Register
Register Name:
AIC_DCR
Access Type:
Read-write
Reset Value:
0x0
31
30
29
28
27
26
25
24
–
–
–
–
–
–
–
–
23
22
21
20
19
18
17
16
–
–
–
–
–
–
–
–
15
14
13
12
11
10
9
8
–
–
–
–
–
–
–
–
7
6
5
4
3
2
1
0
–
–
–
–
–
–
GMSK
PROT
• PROT: Protection Mode
0 = The Protection Mode is disabled.
1 = The Protection Mode is enabled.
• GMSK: General Mask
0 = The nIRQ and nFIQ lines are normally controlled by the AIC.
1 = The nIRQ and nFIQ lines are tied to their inactive state.
338
AT91SAM9G20
6384E–ATARM–05-Feb-10
AT91SAM9G20
27.8.17 AIC Fast Forcing Enable Register
Register Name:
AIC_FFER
Access Type:
Write-only
31
30
29
28
27
26
25
24
PID31
PID30
PID29
PID28
PID27
PID26
PID25
PID24
23
22
21
20
19
18
17
16
PID23
PID22
PID21
PID20
PID19
PID18
PID17
PID16
15
14
13
12
11
10
9
8
PID15
PID14
PID13
PID12
PID11
PID10
PID9
PID8
7
6
5
4
3
2
1
0
PID7
PID6
PID5
PID4
PID3
PID2
SYS
–
• SYS, PID2-PID31: Fast Forcing Enable
0 = No effect.
1 = Enables the fast forcing feature on the corresponding interrupt.
339
6384E–ATARM–05-Feb-10
27.8.18 AIC Fast Forcing Disable Register
Register Name:
AIC_FFDR
Access Type:
Write-only
31
30
29
28
27
26
25
24
PID31
PID30
PID29
PID28
PID27
PID26
PID25
PID24
23
22
21
20
19
18
17
16
PID23
PID22
PID21
PID20
PID19
PID18
PID17
PID16
15
14
13
12
11
10
9
8
PID15
PID14
PID13
PID12
PID11
PID10
PID9
PID8
7
6
5
4
3
2
1
0
PID7
PID6
PID5
PID4
PID3
PID2
SYS
–
• SYS, PID2-PID31: Fast Forcing Disable
0 = No effect.
1 = Disables the Fast Forcing feature on the corresponding interrupt.
27.8.19 AIC Fast Forcing Status Register
Register Name:
AIC_FFSR
Access Type:
Read-only
31
30
29
28
27
26
25
24
PID31
PID30
PID29
PID28
PID27
PID26
PID25
PID24
23
22
21
20
19
18
17
16
PID23
PID22
PID21
PID20
PID19
PID18
PID17
PID16
15
14
13
12
11
10
9
8
PID15
PID14
PID13
PID12
PID11
PID10
PID9
PID8
7
6
5
4
3
2
1
0
PID7
PID6
PID5
PID4
PID3
PID2
SYS
–
• SYS, PID2-PID31: Fast Forcing Status
0 = The Fast Forcing feature is disabled on the corresponding interrupt.
1 = The Fast Forcing feature is enabled on the corresponding interrupt.
340
AT91SAM9G20
6384E–ATARM–05-Feb-10
AT91SAM9G20
28. Debug Unit (DBGU)
28.1
Overview
The Debug Unit provides a single entry point from the processor for access to all the debug
capabilities of Atmel’s ARM-based systems.
The Debug Unit features a two-pin UART that can be used for several debug and trace purposes
and offers an ideal medium for in-situ programming solutions and debug monitor communications. The Debug Unit two-pin UART can be used stand-alone for general purpose serial
communication. Moreover, the association with two peripheral data controller channels permits
packet handling for these tasks with processor time reduced to a minimum.
The Debug Unit features a two-pin UART that can be used for several debug and trace purposes
and offers an ideal medium for in-situ programming solutions and debug monitor communications. Moreover, the association with two peripheral data controller channels permits packet
handling for these tasks with processor time reduced to a minimum.
The Debug Unit also makes the Debug Communication Channel (DCC) signals provided by the
In-circuit Emulator of the ARM processor visible to the software. These signals indicate the status of the DCC read and write registers and generate an interrupt to the ARM processor, making
possible the handling of the DCC under interrupt control.
Chip Identifier registers permit recognition of the device and its revision. These registers inform
as to the sizes and types of the on-chip memories, as well as the set of embedded peripherals.
Finally, the Debug Unit features a Force NTRST capability that enables the software to decide
whether to prevent access to the system via the In-circuit Emulator. This permits protection of
the code, stored in ROM.
341
6384E–ATARM–05-Feb-10
28.2
Block Diagram
Figure 28-1. Debug Unit Functional Block Diagram
Peripheral
Bridge
Peripheral DMA Controller
APB
Debug Unit
DTXD
Transmit
Power
Management
Controller
MCK
Parallel
Input/
Output
Baud Rate
Generator
Receive
DRXD
COMMRX
ARM
Processor
COMMTX
DCC
Handler
Chip ID
nTRST
ICE
Access
Handler
Interrupt
Control
dbgu_irq
Power-on
Reset
force_ntrst
Figure 28-2.
Table 28-1.
Debug Unit Pin Description
Pin Name
Description
Type
DRXD
Debug Receive Data
Input
DTXD
Debug Transmit Data
Output
342
AT91SAM9G20
6384E–ATARM–05-Feb-10
AT91SAM9G20
Figure 28-3. Debug Unit Application Example
Boot Program
Debug Monitor
Trace Manager
Debug Unit
RS232 Drivers
Programming Tool
28.3
28.3.1
Debug Console
Trace Console
Product Dependencies
I/O Lines
Depending on product integration, the Debug Unit pins may be multiplexed with PIO lines. In this
case, the programmer must first configure the corresponding PIO Controller to enable I/O lines
operations of the Debug Unit.
28.3.2
Power Management
Depending on product integration, the Debug Unit clock may be controllable through the Power
Management Controller. In this case, the programmer must first configure the PMC to enable the
Debug Unit clock. Usually, the peripheral identifier used for this purpose is 1.
28.3.3
Interrupt Source
Depending on product integration, the Debug Unit interrupt line is connected to one of the interrupt sources of the Advanced Interrupt Controller. Interrupt handling requires programming of
the AIC before configuring the Debug Unit. Usually, the Debug Unit interrupt line connects to the
interrupt source 1 of the AIC, which may be shared with the real-time clock, the system timer
interrupt lines and other system peripheral interrupts, as shown in Figure 28-1. This sharing
requires the programmer to determine the source of the interrupt when the source 1 is triggered.
28.4
UART Operations
The Debug Unit operates as a UART, (asynchronous mode only) and supports only 8-bit character handling (with parity). It has no clock pin.
The Debug Unit's UART is made up of a receiver and a transmitter that operate independently,
and a common baud rate generator. Receiver timeout and transmitter time guard are not implemented. However, all the implemented features are compatible with those of a standard USART.
28.4.1
Baud Rate Generator
The baud rate generator provides the bit period clock named baud rate clock to both the receiver
and the transmitter.
The baud rate clock is the master clock divided by 16 times the value (CD) written in
DBGU_BRGR (Baud Rate Generator Register). If DBGU_BRGR is set to 0, the baud rate clock
is disabled and the Debug Unit's UART remains inactive. The maximum allowable baud rate is
Master Clock divided by 16. The minimum allowable baud rate is Master Clock divided by (16 x
65536).
343
6384E–ATARM–05-Feb-10
MCK
Baud Rate = ---------------------16 × CD
Figure 28-4. Baud Rate Generator
CD
CD
MCK
16-bit Counter
OUT
>1
1
0
Divide
by 16
Baud Rate
Clock
0
Receiver
Sampling Clock
28.4.2
28.4.2.1
Receiver
Receiver Reset, Enable and Disable
After device reset, the Debug Unit receiver is disabled and must be enabled before being used.
The receiver can be enabled by writing the control register DBGU_CR with the bit RXEN at 1. At
this command, the receiver starts looking for a start bit.
The programmer can disable the receiver by writing DBGU_CR with the bit RXDIS at 1. If the
receiver is waiting for a start bit, it is immediately stopped. However, if the receiver has already
detected a start bit and is receiving the data, it waits for the stop bit before actually stopping its
operation.
The programmer can also put the receiver in its reset state by writing DBGU_CR with the bit
RSTRX at 1. In doing so, the receiver immediately stops its current operations and is disabled,
whatever its current state. If RSTRX is applied when data is being processed, this data is lost.
28.4.2.2
Start Detection and Data Sampling
The Debug Unit only supports asynchronous operations, and this affects only its receiver. The
Debug Unit receiver detects the start of a received character by sampling the DRXD signal until
it detects a valid start bit. A low level (space) on DRXD is interpreted as a valid start bit if it is
detected for more than 7 cycles of the sampling clock, which is 16 times the baud rate. Hence, a
space that is longer than 7/16 of the bit period is detected as a valid start bit. A space which is
7/16 of a bit period or shorter is ignored and the receiver continues to wait for a valid start bit.
When a valid start bit has been detected, the receiver samples the DRXD at the theoretical midpoint of each bit. It is assumed that each bit lasts 16 cycles of the sampling clock (1-bit period)
so the bit sampling point is eight cycles (0.5-bit period) after the start of the bit. The first sampling
point is therefore 24 cycles (1.5-bit periods) after the falling edge of the start bit was detected.
Each subsequent bit is sampled 16 cycles (1-bit period) after the previous one.
344
AT91SAM9G20
6384E–ATARM–05-Feb-10
AT91SAM9G20
Figure 28-5. Start Bit Detection
Sampling Clock
DRXD
True Start
Detection
D0
Baud Rate
Clock
Figure 28-6. Character Reception
Example: 8-bit, parity enabled 1 stop
0.5 bit
period
1 bit
period
DRXD
Sampling
28.4.2.3
D0
D1
True Start Detection
D2
D3
D4
D5
D6
Stop Bit
D7
Parity Bit
Receiver Ready
When a complete character is received, it is transferred to the DBGU_RHR and the RXRDY status bit in DBGU_SR (Status Register) is set. The bit RXRDY is automatically cleared when the
receive holding register DBGU_RHR is read.
Figure 28-7. Receiver Ready
DRXD
S
D0
D1
D2
D3
D4
D5
D6
D7
S
P
D0
D1
D2
D3
D4
D5
D6
D7
P
RXRDY
Read DBGU_RHR
28.4.2.4
Receiver Overrun
If DBGU_RHR has not been read by the software (or the Peripheral Data Controller) since the
last transfer, the RXRDY bit is still set and a new character is received, the OVRE status bit in
DBGU_SR is set. OVRE is cleared when the software writes the control register DBGU_CR with
the bit RSTSTA (Reset Status) at 1.
Figure 28-8. Receiver Overrun
DRXD
S
D0
D1
D2
D3
D4
D5
D6
D7
P
stop
S
D0
D1
D2
D3
D4
D5
D6
D7
P
stop
RXRDY
OVRE
RSTSTA
28.4.2.5
Parity Error
Each time a character is received, the receiver calculates the parity of the received data bits, in
accordance with the field PAR in DBGU_MR. It then compares the result with the received parity
345
6384E–ATARM–05-Feb-10
bit. If different, the parity error bit PARE in DBGU_SR is set at the same time the RXRDY is set.
The parity bit is cleared when the control register DBGU_CR is written with the bit RSTSTA
(Reset Status) at 1. If a new character is received before the reset status command is written,
the PARE bit remains at 1.
Figure 28-9. Parity Error
DRXD
S
D0
D1
D2
D3
D4
D5
D6
D7
P
stop
RXRDY
PARE
Wrong Parity Bit
28.4.2.6
RSTSTA
Receiver Framing Error
When a start bit is detected, it generates a character reception when all the data bits have been
sampled. The stop bit is also sampled and when it is detected at 0, the FRAME (Framing Error)
bit in DBGU_SR is set at the same time the RXRDY bit is set. The bit FRAME remains high until
the control register DBGU_CR is written with the bit RSTSTA at 1.
Figure 28-10. Receiver Framing Error
DRXD
S
D0
D1
D2
D3
D4
D5
D6
D7
P
stop
RXRDY
FRAME
Stop Bit
Detected at 0
28.4.3
28.4.3.1
RSTSTA
Transmitter
Transmitter Reset, Enable and Disable
After device reset, the Debug Unit transmitter is disabled and it must be enabled before being
used. The transmitter is enabled by writing the control register DBGU_CR with the bit TXEN at 1.
From this command, the transmitter waits for a character to be written in the Transmit Holding
Register DBGU_THR before actually starting the transmission.
The programmer can disable the transmitter by writing DBGU_CR with the bit TXDIS at 1. If the
transmitter is not operating, it is immediately stopped. However, if a character is being processed into the Shift Register and/or a character has been written in the Transmit Holding
Register, the characters are completed before the transmitter is actually stopped.
The programmer can also put the transmitter in its reset state by writing the DBGU_CR with the
bit RSTTX at 1. This immediately stops the transmitter, whether or not it is processing
characters.
28.4.3.2
346
Transmit Format
The Debug Unit transmitter drives the pin DTXD at the baud rate clock speed. The line is driven
depending on the format defined in the Mode Register and the data stored in the Shift Register.
One start bit at level 0, then the 8 data bits, from the lowest to the highest bit, one optional parity
bit and one stop bit at 1 are consecutively shifted out as shown on the following figure. The field
AT91SAM9G20
6384E–ATARM–05-Feb-10
AT91SAM9G20
PARE in the mode register DBGU_MR defines whether or not a parity bit is shifted out. When a
parity bit is enabled, it can be selected between an odd parity, an even parity, or a fixed space or
mark bit.
Figure 28-11. Character Transmission
Example: Parity enabled
Baud Rate
Clock
DTXD
Start
Bit
28.4.3.3
D0
D1
D2
D3
D4
D5
D6
D7
Parity
Bit
Stop
Bit
Transmitter Control
When the transmitter is enabled, the bit TXRDY (Transmitter Ready) is set in the status register
DBGU_SR. The transmission starts when the programmer writes in the Transmit Holding Register DBGU_THR, and after the written character is transferred from DBGU_THR to the Shift
Register. The bit TXRDY remains high until a second character is written in DBGU_THR. As
soon as the first character is completed, the last character written in DBGU_THR is transferred
into the shift register and TXRDY rises again, showing that the holding register is empty.
When both the Shift Register and the DBGU_THR are empty, i.e., all the characters written in
DBGU_THR have been processed, the bit TXEMPTY rises after the last stop bit has been
completed.
Figure 28-12. Transmitter Control
DBGU_THR
Data 0
Data 1
Shift Register
DTXD
Data 0
S
Data 0
Data 1
P
stop
S
Data 1
P
stop
TXRDY
TXEMPTY
Write Data 0
in DBGU_THR
28.4.4
Write Data 1
in DBGU_THR
Peripheral Data Controller
Both the receiver and the transmitter of the Debug Unit's UART are generally connected to a
Peripheral Data Controller (PDC) channel.
The peripheral data controller channels are programmed via registers that are mapped within
the Debug Unit user interface from the offset 0x100. The status bits are reported in the Debug
Unit status register DBGU_SR and can generate an interrupt.
347
6384E–ATARM–05-Feb-10
The RXRDY bit triggers the PDC channel data transfer of the receiver. This results in a read of
the data in DBGU_RHR. The TXRDY bit triggers the PDC channel data transfer of the transmitter. This results in a write of a data in DBGU_THR.
28.4.5
Test Modes
The Debug Unit supports three tests modes. These modes of operation are programmed by
using the field CHMODE (Channel Mode) in the mode register DBGU_MR.
The Automatic Echo mode allows bit-by-bit retransmission. When a bit is received on the DRXD
line, it is sent to the DTXD line. The transmitter operates normally, but has no effect on the
DTXD line.
The Local Loopback mode allows the transmitted characters to be received. DTXD and DRXD
pins are not used and the output of the transmitter is internally connected to the input of the
receiver. The DRXD pin level has no effect and the DTXD line is held high, as in idle state.
The Remote Loopback mode directly connects the DRXD pin to the DTXD line. The transmitter
and the receiver are disabled and have no effect. This mode allows a bit-by-bit retransmission.
Figure 28-13. Test Modes
Automatic Echo
RXD
Receiver
Transmitter
Disabled
TXD
Local Loopback
Disabled
Receiver
RXD
VDD
Disabled
Transmitter
Remote Loopback
Receiver
Transmitter
28.4.6
348
TXD
VDD
Disabled
Disabled
RXD
TXD
Debug Communication Channel Support
The Debug Unit handles the signals COMMRX and COMMTX that come from the Debug Communication Channel of the ARM Processor and are driven by the In-circuit Emulator.
AT91SAM9G20
6384E–ATARM–05-Feb-10
AT91SAM9G20
The Debug Communication Channel contains two registers that are accessible through the ICE
Breaker on the JTAG side and through the coprocessor 0 on the ARM Processor side.
As a reminder, the following instructions are used to read and write the Debug Communication
Channel:
MRC
p14, 0, Rd, c1, c0, 0
Returns the debug communication data read register into Rd
MCR
p14, 0, Rd, c1, c0, 0
Writes the value in Rd to the debug communication data write register.
The bits COMMRX and COMMTX, which indicate, respectively, that the read register has been
written by the debugger but not yet read by the processor, and that the write register has been
written by the processor and not yet read by the debugger, are wired on the two highest bits of
the status register DBGU_SR. These bits can generate an interrupt. This feature permits handling under interrupt a debug link between a debug monitor running on the target system and a
debugger.
28.4.7
Chip Identifier
The Debug Unit features two chip identifier registers, DBGU_CIDR (Chip ID Register) and
DBGU_EXID (Extension ID). Both registers contain a hard-wired value that is read-only. The first
register contains the following fields:
• EXT - shows the use of the extension identifier register
• NVPTYP and NVPSIZ - identifies the type of embedded non-volatile memory and its size
• ARCH - identifies the set of embedded peripherals
• SRAMSIZ - indicates the size of the embedded SRAM
• EPROC - indicates the embedded ARM processor
• VERSION - gives the revision of the silicon
The second register is device-dependent and reads 0 if the bit EXT is 0.
28.4.8
ICE Access Prevention
The Debug Unit allows blockage of access to the system through the ARM processor's ICE
interface. This feature is implemented via the register Force NTRST (DBGU_FNR), that allows
assertion of the NTRST signal of the ICE Interface. Writing the bit FNTRST (Force NTRST) to 1
in this register prevents any activity on the TAP controller.
On standard devices, the bit FNTRST resets to 0 and thus does not prevent ICE access.
This feature is especially useful on custom ROM devices for customers who do not want their
on-chip code to be visible.
349
6384E–ATARM–05-Feb-10
28.5
Debug Unit (DBGU) User Interface
Table 28-2.
Register Mapping
Offset
Register
Name
Access
Reset
0x0000
Control Register
DBGU_CR
Write-only
–
0x0004
Mode Register
DBGU_MR
Read-write
0x0
0x0008
Interrupt Enable Register
DBGU_IER
Write-only
–
0x000C
Interrupt Disable Register
DBGU_IDR
Write-only
–
0x0010
Interrupt Mask Register
DBGU_IMR
Read-only
0x0
0x0014
Status Register
DBGU_SR
Read-only
–
0x0018
Receive Holding Register
DBGU_RHR
Read-only
0x0
0x001C
Transmit Holding Register
DBGU_THR
Write-only
–
0x0020
Baud Rate Generator Register
DBGU_BRGR
Read-write
0x0
–
–
–
0x0024 - 0x003C
Reserved
0x0040
Chip ID Register
DBGU_CIDR
Read-only
–
0x0044
Chip ID Extension Register
DBGU_EXID
Read-only
–
0x0048
Force NTRST Register
DBGU_FNR
Read-write
0x0
0x004C - 0x00FC
Reserved
–
–
–
0x0100 - 0x0124
PDC Area
–
–
–
350
AT91SAM9G20
6384E–ATARM–05-Feb-10
AT91SAM9G20
28.5.1
Name:
Debug Unit Control Register
DBGU_CR
Access Type: Write-only
31
30
29
28
27
26
25
24
–
–
–
–
–
–
–
–
23
22
21
20
19
18
17
16
–
–
–
–
–
–
–
–
15
14
13
12
11
10
9
8
–
–
–
–
–
–
–
RSTSTA
7
6
5
4
3
2
1
0
TXDIS
TXEN
RXDIS
RXEN
RSTTX
RSTRX
–
–
• RSTRX: Reset Receiver
0 = No effect.
1 = The receiver logic is reset and disabled. If a character is being received, the reception is aborted.
• RSTTX: Reset Transmitter
0 = No effect.
1 = The transmitter logic is reset and disabled. If a character is being transmitted, the transmission is aborted.
• RXEN: Receiver Enable
0 = No effect.
1 = The receiver is enabled if RXDIS is 0.
• RXDIS: Receiver Disable
0 = No effect.
1 = The receiver is disabled. If a character is being processed and RSTRX is not set, the character is completed before the
receiver is stopped.
• TXEN: Transmitter Enable
0 = No effect.
1 = The transmitter is enabled if TXDIS is 0.
• TXDIS: Transmitter Disable
0 = No effect.
1 = The transmitter is disabled. If a character is being processed and a character has been written the DBGU_THR and
RSTTX is not set, both characters are completed before the transmitter is stopped.
• RSTSTA: Reset Status Bits
0 = No effect.
1 = Resets the status bits PARE, FRAME and OVRE in the DBGU_SR.
351
6384E–ATARM–05-Feb-10
28.5.2
Name:
Debug Unit Mode Register
DBGU_MR
Access Type: Read-write
31
30
29
28
27
26
25
24
–
–
–
–
–
–
–
–
23
22
21
20
19
18
17
16
–
–
–
–
–
–
–
–
14
13
12
11
10
9
–
–
15
CHMODE
8
–
PAR
7
6
5
4
3
2
1
0
–
–
–
–
–
–
–
–
• PAR: Parity Type
PAR
Parity Type
0
0
0
Even parity
0
0
1
Odd parity
0
1
0
Space: parity forced to 0
0
1
1
Mark: parity forced to 1
1
x
x
No parity
• CHMODE: Channel Mode
CHMODE
352
Mode Description
0
0
Normal Mode
0
1
Automatic Echo
1
0
Local Loopback
1
1
Remote Loopback
AT91SAM9G20
6384E–ATARM–05-Feb-10
AT91SAM9G20
28.5.3
Name:
Debug Unit Interrupt Enable Register
DBGU_IER
Access Type: Write-only
31
30
29
28
27
26
25
24
COMMRX
COMMTX
–
–
–
–
–
–
23
22
21
20
19
18
17
16
–
–
–
–
–
–
–
–
15
14
13
12
11
10
9
8
–
–
–
RXBUFF
TXBUFE
–
TXEMPTY
–
7
6
5
4
3
2
1
0
PARE
FRAME
OVRE
ENDTX
ENDRX
–
TXRDY
RXRDY
• RXRDY: Enable RXRDY Interrupt
• TXRDY: Enable TXRDY Interrupt
• ENDRX: Enable End of Receive Transfer Interrupt
• ENDTX: Enable End of Transmit Interrupt
• OVRE: Enable Overrun Error Interrupt
• FRAME: Enable Framing Error Interrupt
• PARE: Enable Parity Error Interrupt
• TXEMPTY: Enable TXEMPTY Interrupt
• TXBUFE: Enable Buffer Empty Interrupt
• RXBUFF: Enable Buffer Full Interrupt
• COMMTX: Enable COMMTX (from ARM) Interrupt
• COMMRX: Enable COMMRX (from ARM) Interrupt
0 = No effect.
1 = Enables the corresponding interrupt.
353
6384E–ATARM–05-Feb-10
28.5.4
Name:
Debug Unit Interrupt Disable Register
DBGU_IDR
Access Type: Write-only
31
30
29
28
27
26
25
24
COMMRX
COMMTX
–
–
–
–
–
–
23
22
21
20
19
18
17
16
–
–
–
–
–
–
–
–
15
14
13
12
11
10
9
8
–
–
–
RXBUFF
TXBUFE
–
TXEMPTY
–
7
6
5
4
3
2
1
0
PARE
FRAME
OVRE
ENDTX
ENDRX
–
TXRDY
RXRDY
• RXRDY: Disable RXRDY Interrupt
• TXRDY: Disable TXRDY Interrupt
• ENDRX: Disable End of Receive Transfer Interrupt
• ENDTX: Disable End of Transmit Interrupt
• OVRE: Disable Overrun Error Interrupt
• FRAME: Disable Framing Error Interrupt
• PARE: Disable Parity Error Interrupt
• TXEMPTY: Disable TXEMPTY Interrupt
• TXBUFE: Disable Buffer Empty Interrupt
• RXBUFF: Disable Buffer Full Interrupt
• COMMTX: Disable COMMTX (from ARM) Interrupt
• COMMRX: Disable COMMRX (from ARM) Interrupt
0 = No effect.
1 = Disables the corresponding interrupt.
354
AT91SAM9G20
6384E–ATARM–05-Feb-10
AT91SAM9G20
28.5.5
Name:
Debug Unit Interrupt Mask Register
DBGU_IMR
Access Type: Read-only
31
30
29
28
27
26
25
24
COMMRX
COMMTX
–
–
–
–
–
–
23
22
21
20
19
18
17
16
–
–
–
–
–
–
–
–
15
14
13
12
11
10
9
8
–
–
–
RXBUFF
TXBUFE
–
TXEMPTY
–
7
6
5
4
3
2
1
0
PARE
FRAME
OVRE
ENDTX
ENDRX
–
TXRDY
RXRDY
• RXRDY: Mask RXRDY Interrupt
• TXRDY: Disable TXRDY Interrupt
• ENDRX: Mask End of Receive Transfer Interrupt
• ENDTX: Mask End of Transmit Interrupt
• OVRE: Mask Overrun Error Interrupt
• FRAME: Mask Framing Error Interrupt
• PARE: Mask Parity Error Interrupt
• TXEMPTY: Mask TXEMPTY Interrupt
• TXBUFE: Mask TXBUFE Interrupt
• RXBUFF: Mask RXBUFF Interrupt
• COMMTX: Mask COMMTX Interrupt
• COMMRX: Mask COMMRX Interrupt
0 = The corresponding interrupt is disabled.
1 = The corresponding interrupt is enabled.
355
6384E–ATARM–05-Feb-10
28.5.6
Name:
Debug Unit Status Register
DBGU_SR
Access Type: Read-only
31
30
29
28
27
26
25
24
COMMRX
COMMTX
–
–
–
–
–
–
23
22
21
20
19
18
17
16
–
–
–
–
–
–
–
–
15
14
13
12
11
10
9
8
–
–
–
RXBUFF
TXBUFE
–
TXEMPTY
–
7
6
5
4
3
2
1
0
PARE
FRAME
OVRE
ENDTX
ENDRX
–
TXRDY
RXRDY
• RXRDY: Receiver Ready
0 = No character has been received since the last read of the DBGU_RHR or the receiver is disabled.
1 = At least one complete character has been received, transferred to DBGU_RHR and not yet read.
• TXRDY: Transmitter Ready
0 = A character has been written to DBGU_THR and not yet transferred to the Shift Register, or the transmitter is disabled.
1 = There is no character written to DBGU_THR not yet transferred to the Shift Register.
• ENDRX: End of Receiver Transfer
0 = The End of Transfer signal from the receiver Peripheral Data Controller channel is inactive.
1 = The End of Transfer signal from the receiver Peripheral Data Controller channel is active.
• ENDTX: End of Transmitter Transfer
0 = The End of Transfer signal from the transmitter Peripheral Data Controller channel is inactive.
1 = The End of Transfer signal from the transmitter Peripheral Data Controller channel is active.
• OVRE: Overrun Error
0 = No overrun error has occurred since the last RSTSTA.
1 = At least one overrun error has occurred since the last RSTSTA.
• FRAME: Framing Error
0 = No framing error has occurred since the last RSTSTA.
1 = At least one framing error has occurred since the last RSTSTA.
• PARE: Parity Error
0 = No parity error has occurred since the last RSTSTA.
1 = At least one parity error has occurred since the last RSTSTA.
• TXEMPTY: Transmitter Empty
0 = There are characters in DBGU_THR, or characters being processed by the transmitter, or the transmitter is disabled.
1 = There are no characters in DBGU_THR and there are no characters being processed by the transmitter.
356
AT91SAM9G20
6384E–ATARM–05-Feb-10
AT91SAM9G20
• TXBUFE: Transmission Buffer Empty
0 = The buffer empty signal from the transmitter PDC channel is inactive.
1 = The buffer empty signal from the transmitter PDC channel is active.
• RXBUFF: Receive Buffer Full
0 = The buffer full signal from the receiver PDC channel is inactive.
1 = The buffer full signal from the receiver PDC channel is active.
• COMMTX: Debug Communication Channel Write Status
0 = COMMTX from the ARM processor is inactive.
1 = COMMTX from the ARM processor is active.
• COMMRX: Debug Communication Channel Read Status
0 = COMMRX from the ARM processor is inactive.
1 = COMMRX from the ARM processor is active.
357
6384E–ATARM–05-Feb-10
28.5.7
Name:
Debug Unit Receiver Holding Register
DBGU_RHR
Access Type: Read-only
31
30
29
28
27
26
25
24
–
–
–
–
–
–
–
–
23
22
21
20
19
18
17
16
–
–
–
–
–
–
–
–
15
14
13
12
11
10
9
8
–
–
–
–
–
–
–
–
7
6
5
4
3
2
1
0
RXCHR
• RXCHR: Received Character
Last received character if RXRDY is set.
28.5.8
Name:
Debug Unit Transmit Holding Register
DBGU_THR
Access Type: Write-only
31
30
29
28
27
26
25
24
–
–
–
–
–
–
–
–
23
22
21
20
19
18
17
16
–
–
–
–
–
–
–
–
15
14
13
12
11
10
9
8
–
–
–
–
–
–
–
–
7
6
5
4
3
2
1
0
TXCHR
• TXCHR: Character to be Transmitted
Next character to be transmitted after the current character if TXRDY is not set.
358
AT91SAM9G20
6384E–ATARM–05-Feb-10
AT91SAM9G20
28.5.9
Name:
Debug Unit Baud Rate Generator Register
DBGU_BRGR
Access Type: Read-write
31
30
29
28
27
26
25
24
–
–
–
–
–
–
–
–
23
22
21
20
19
18
17
16
–
–
–
–
–
–
–
–
15
14
13
12
11
10
9
8
3
2
1
0
CD
7
6
5
4
CD
• CD: Clock Divisor
CD
Baud Rate Clock
0
Disabled
1
MCK
2 to 65535
MCK / (CD x 16)
359
6384E–ATARM–05-Feb-10
28.5.10
Name:
Debug Unit Chip ID Register
DBGU_CIDR
Access Type:Read-only
31
30
29
EXT
23
28
27
26
NVPTYP
22
21
20
19
18
ARCH
15
14
13
6
24
17
16
9
8
1
0
SRAMSIZ
12
11
10
NVPSIZ2
7
25
ARCH
NVPSIZ
5
4
3
EPROC
2
VERSION
• VERSION: Version of the Device
Current version of the device.
• EPROC: Embedded Processor
EPROC
Processor
0
0
1
ARM946ES
0
1
0
ARM7TDMI
1
0
0
ARM920T
1
0
1
ARM926EJS
• NVPSIZ: Nonvolatile Program Memory Size
NVPSIZ
360
Size
0
0
0
0
None
0
0
0
1
8K bytes
0
0
1
0
16K bytes
0
0
1
1
32K bytes
0
1
0
0
Reserved
0
1
0
1
64K bytes
0
1
1
0
Reserved
0
1
1
1
128K bytes
1
0
0
0
Reserved
1
0
0
1
256K bytes
1
0
1
0
512K bytes
1
0
1
1
Reserved
1
1
0
0
1024K bytes
AT91SAM9G20
6384E–ATARM–05-Feb-10
AT91SAM9G20
NVPSIZ
Size
1
1
0
1
Reserved
1
1
1
0
2048K bytes
1
1
1
1
Reserved
• NVPSIZ2 Second Nonvolatile Program Memory Size
NVPSIZ2
Size
0
0
0
0
None
0
0
0
1
8K bytes
0
0
1
0
16K bytes
0
0
1
1
32K bytes
0
1
0
0
Reserved
0
1
0
1
64K bytes
0
1
1
0
Reserved
0
1
1
1
128K bytes
1
0
0
0
Reserved
1
0
0
1
256K bytes
1
0
1
0
512K bytes
1
0
1
1
Reserved
1
1
0
0
1024K bytes
1
1
0
1
Reserved
1
1
1
0
2048K bytes
1
1
1
1
Reserved
• SRAMSIZ: Internal SRAM Size
SRAMSIZ
Size
0
0
0
0
Reserved
0
0
0
1
1K bytes
0
0
1
0
2K bytes
0
0
1
1
6K bytes
0
1
0
0
112K bytes
0
1
0
1
4K bytes
0
1
1
0
80K bytes
0
1
1
1
160K bytes
1
0
0
0
8K bytes
1
0
0
1
16K bytes
1
0
1
0
32K bytes
1
0
1
1
64K bytes
361
6384E–ATARM–05-Feb-10
SRAMSIZ
Size
1
1
0
0
128K bytes
1
1
0
1
256K bytes
1
1
1
0
96K bytes
1
1
1
1
512K bytes
• ARCH: Architecture Identifier
ARCH
Hex
Bin
Architecture
0x19
0001 1001
AT91SAM9xx Series
0x29
0010 1001
AT91SAM9XExx Series
0x34
0011 0100
AT91x34 Series
0x37
0011 0111
CAP7 Series
0x39
0011 1001
CAP9 Series
0x3B
0011 1011
CAP11 Series
0x40
0100 0000
AT91x40 Series
0x42
0100 0010
AT91x42 Series
0x55
0101 0101
AT91x55 Series
0x60
0110 0000
AT91SAM7Axx Series
0x61
0110 0001
AT91SAM7AQxx Series
0x63
0110 0011
AT91x63 Series
0x70
0111 0000
AT91SAM7Sxx Series
0x71
0111 0001
AT91SAM7XCxx Series
0x72
0111 0010
AT91SAM7SExx Series
0x73
0111 0011
AT91SAM7Lxx Series
0x75
0111 0101
AT91SAM7Xxx Series
0x92
1001 0010
AT91x92 Series
0xF0
1111 0000
AT75Cxx Series
• NVPTYP: Nonvolatile Program Memory Type
NVPTYP
362
Memory
0
0
0
ROM
0
0
1
ROMless or on-chip Flash
1
0
0
SRAM emulating ROM
0
1
0
Embedded Flash Memory
0
1
1
ROM and Embedded Flash Memory
NVPSIZ is ROM size
NVPSIZ2 is Flash size
AT91SAM9G20
6384E–ATARM–05-Feb-10
AT91SAM9G20
• EXT: Extension Flag
0 = Chip ID has a single register definition without extension
1 = An extended Chip ID exists.
363
6384E–ATARM–05-Feb-10
28.5.11
Name:
Debug Unit Chip ID Extension Register
DBGU_EXID
Access Type: Read-only
31
30
29
28
27
26
25
24
19
18
17
16
11
10
9
8
3
2
1
0
EXID
23
22
21
20
EXID
15
14
13
12
EXID
7
6
5
4
EXID
• EXID: Chip ID Extension
Reads 0 if the bit EXT in DBGU_CIDR is 0.
28.5.12
Name:
Debug Unit Force NTRST Register
DBGU_FNR
Access Type:Read-write
31
30
29
28
27
26
25
24
–
–
–
–
–
–
–
–
23
22
21
20
19
18
17
16
–
–
–
–
–
–
–
–
15
14
13
12
11
10
9
8
–
–
–
–
–
–
–
–
7
6
5
4
3
2
1
0
–
–
–
–
–
–
–
FNTRST
• FNTRST: Force NTRST
0 = NTRST of the ARM processor’s TAP controller is driven by the power_on_reset signal.
1 = NTRST of the ARM processor’s TAP controller is held low.
364
AT91SAM9G20
6384E–ATARM–05-Feb-10
AT91SAM9G20
29. Parallel Input Output Controller (PIO)
29.1
Overview
The Parallel Input/Output Controller (PIO) manages up to 32 fully programmable input/output
lines. Each I/O line may be dedicated as a general-purpose I/O or be assigned to a function of
an embedded peripheral. This assures effective optimization of the pins of a product.
Each I/O line is associated with a bit number in all of the 32-bit registers of the 32-bit wide User
Interface.
Each I/O line of the PIO Controller features:
• An input change interrupt enabling level change detection on any I/O line.
• A glitch filter providing rejection of pulses lower than one-half of clock cycle.
• Multi-drive capability similar to an open drain I/O line.
• Control of the pull-up of the I/O line.
• Input visibility and output control.
The PIO Controller also features a synchronous output providing up to 32 bits of data output in a
single write operation.
365
6384E–ATARM–05-Feb-10
29.2
Block Diagram
Figure 29-1. Block Diagram
PIO Controller
AIC
PIO Interrupt
PIO Clock
PMC
Data, Enable
Up to 32
peripheral IOs
Embedded
Peripheral
PIN 0
Data, Enable
PIN 1
Up to 32 pins
Embedded
Peripheral
Up to 32
peripheral IOs
PIN 31
APB
Figure 29-2. Application Block Diagram
On-Chip Peripheral Drivers
Keyboard Driver
Control & Command
Driver
On-Chip Peripherals
PIO Controller
Keyboard Driver
366
General Purpose I/Os
External Devices
AT91SAM9G20
6384E–ATARM–05-Feb-10
AT91SAM9G20
29.3
Product Dependencies
29.3.1
Pin Multiplexing
Each pin is configurable, according to product definition as either a general-purpose I/O line
only, or as an I/O line multiplexed with one or two peripheral I/Os. As the multiplexing is hardware-defined and thus product-dependent, the hardware designer and programmer must
carefully determine the configuration of the PIO controllers required by their application. When
an I/O line is general-purpose only, i.e. not multiplexed with any peripheral I/O, programming of
the PIO Controller regarding the assignment to a peripheral has no effect and only the PIO Controller can control how the pin is driven by the product.
29.3.2
External Interrupt Lines
The interrupt signals FIQ and IRQ0 to IRQn are most generally multiplexed through the PIO
Controllers. However, it is not necessary to assign the I/O line to the interrupt function as the
PIO Controller has no effect on inputs and the interrupt lines (FIQ or IRQs) are used only as
inputs.
29.3.3
Power Management
The Power Management Controller controls the PIO Controller clock in order to save power.
Writing any of the registers of the user interface does not require the PIO Controller clock to be
enabled. This means that the configuration of the I/O lines does not require the PIO Controller
clock to be enabled.
However, when the clock is disabled, not all of the features of the PIO Controller are available.
Note that the Input Change Interrupt and the read of the pin level require the clock to be
validated.
After a hardware reset, the PIO clock is disabled by default.
The user must configure the Power Management Controller before any access to the input line
information.
29.3.4
Interrupt Generation
For interrupt handling, the PIO Controllers are considered as user peripherals. This means that
the PIO Controller interrupt lines are connected among the interrupt sources 2 to 31. Refer to the
PIO Controller peripheral identifier in the product description to identify the interrupt sources
dedicated to the PIO Controllers.
The PIO Controller interrupt can be generated only if the PIO Controller clock is enabled.
367
6384E–ATARM–05-Feb-10
29.4
Functional Description
The PIO Controller features up to 32 fully-programmable I/O lines. Most of the control logic associated to each I/O is represented in Figure 29-3. In this description each signal shown
represents but one of up to 32 possible indexes.
Figure 29-3. I/O Line Control Logic
PIO_OER[0]
PIO_OSR[0]
PIO_PUER[0]
PIO_ODR[0]
PIO_PUSR[0]
PIO_PUDR[0]
1
Peripheral A
Output Enable
0
0
Peripheral B
Output Enable
0
1
PIO_ASR[0]
PIO_PER[0]
PIO_ABSR[0]
1
PIO_PSR[0]
PIO_BSR[0]
PIO_PDR[0]
Peripheral A
Output
0
Peripheral B
Output
1
PIO_MDER[0]
PIO_MDSR[0]
PIO_MDDR[0]
0
0
PIO_SODR[0]
PIO_ODSR[0]
1
Pad
PIO_CODR[0]
1
Peripheral A
Input
PIO_PDSR[0]
PIO_ISR[0]
0
Edge
Detector
Glitch
Filter
Peripheral B
Input
(Up to 32 possible inputs)
PIO Interrupt
1
PIO_IFER[0]
PIO_IFSR[0]
PIO_IFDR[0]
PIO_IER[0]
PIO_IMR[0]
PIO_IDR[0]
PIO_ISR[31]
PIO_IER[31]
PIO_IMR[31]
PIO_IDR[31]
368
AT91SAM9G20
6384E–ATARM–05-Feb-10
AT91SAM9G20
29.4.1
Pull-up Resistor Control
Each I/O line is designed with an embedded pull-up resistor. The pull-up resistor can be enabled
or disabled by writing respectively PIO_PUER (Pull-up Enable Register) and PIO_PUDR (Pullup Disable Resistor). Writing in these registers results in setting or clearing the corresponding bit
in PIO_PUSR (Pull-up Status Register). Reading a 1 in PIO_PUSR means the pull-up is disabled and reading a 0 means the pull-up is enabled.
Control of the pull-up resistor is possible regardless of the configuration of the I/O line.
After reset, all of the pull-ups are enabled, i.e. PIO_PUSR resets at the value 0x0.
29.4.2
I/O Line or Peripheral Function Selection
When a pin is multiplexed with one or two peripheral functions, the selection is controlled with
the registers PIO_PER (PIO Enable Register) and PIO_PDR (PIO Disable Register). The register PIO_PSR (PIO Status Register) is the result of the set and clear registers and indicates
whether the pin is controlled by the corresponding peripheral or by the PIO Controller. A value of
0 indicates that the pin is controlled by the corresponding on-chip peripheral selected in the
PIO_ABSR (AB Select Status Register). A value of 1 indicates the pin is controlled by the PIO
controller.
If a pin is used as a general purpose I/O line (not multiplexed with an on-chip peripheral),
PIO_PER and PIO_PDR have no effect and PIO_PSR returns 1 for the corresponding bit.
After reset, most generally, the I/O lines are controlled by the PIO controller, i.e. PIO_PSR
resets at 1. However, in some events, it is important that PIO lines are controlled by the peripheral (as in the case of memory chip select lines that must be driven inactive after reset or for
address lines that must be driven low for booting out of an external memory). Thus, the reset
value of PIO_PSR is defined at the product level, depending on the multiplexing of the device.
29.4.3
Peripheral A or B Selection
The PIO Controller provides multiplexing of up to two peripheral functions on a single pin. The
selection is performed by writing PIO_ASR (A Select Register) and PIO_BSR (Select B Register). PIO_ABSR (AB Select Status Register) indicates which peripheral line is currently selected.
For each pin, the corresponding bit at level 0 means peripheral A is selected whereas the corresponding bit at level 1 indicates that peripheral B is selected.
Note that multiplexing of peripheral lines A and B only affects the output line. The peripheral
input lines are always connected to the pin input.
After reset, PIO_ABSR is 0, thus indicating that all the PIO lines are configured on peripheral A.
However, peripheral A generally does not drive the pin as the PIO Controller resets in I/O line
mode.
Writing in PIO_ASR and PIO_BSR manages PIO_ABSR regardless of the configuration of the
pin. However, assignment of a pin to a peripheral function requires a write in the corresponding
peripheral selection register (PIO_ASR or PIO_BSR) in addition to a write in PIO_PDR.
29.4.4
Output Control
When the I/0 line is assigned to a peripheral function, i.e. the corresponding bit in PIO_PSR is at
0, the drive of the I/O line is controlled by the peripheral. Peripheral A or B, depending on the
value in PIO_ABSR, determines whether the pin is driven or not.
When the I/O line is controlled by the PIO controller, the pin can be configured to be driven. This
is done by writing PIO_OER (Output Enable Register) and PIO_ODR (Output Disable Register).
369
6384E–ATARM–05-Feb-10
The results of these write operations are detected in PIO_OSR (Output Status Register). When
a bit in this register is at 0, the corresponding I/O line is used as an input only. When the bit is at
1, the corresponding I/O line is driven by the PIO controller.
The level driven on an I/O line can be determined by writing in PIO_SODR (Set Output Data
Register) and PIO_CODR (Clear Output Data Register). These write operations respectively set
and clear PIO_ODSR (Output Data Status Register), which represents the data driven on the I/O
lines. Writing in PIO_OER and PIO_ODR manages PIO_OSR whether the pin is configured to
be controlled by the PIO controller or assigned to a peripheral function. This enables configuration of the I/O line prior to setting it to be managed by the PIO Controller.
Similarly, writing in PIO_SODR and PIO_CODR effects PIO_ODSR. This is important as it
defines the first level driven on the I/O line.
29.4.5
Synchronous Data Output
Controlling all parallel busses using several PIOs requires two successive write operations in the
PIO_SODR and PIO_CODR registers. This may lead to unexpected transient values. The PIO
controller offers a direct control of PIO outputs by single write access to PIO_ODSR (Output
Data Status Register). Only bits unmasked by PIO_OWSR (Output Write Status Register) are
written. The mask bits in the PIO_OWSR are set by writing to PIO_OWER (Output Write Enable
Register) and cleared by writing to PIO_OWDR (Output Write Disable Register).
After reset, the synchronous data output is disabled on all the I/O lines as PIO_OWSR resets at
0x0.
29.4.6
Multi Drive Control (Open Drain)
Each I/O can be independently programmed in Open Drain by using the Multi Drive feature. This
feature permits several drivers to be connected on the I/O line which is driven low only by each
device. An external pull-up resistor (or enabling of the internal one) is generally required to guarantee a high level on the line.
The Multi Drive feature is controlled by PIO_MDER (Multi-driver Enable Register) and
PIO_MDDR (Multi-driver Disable Register). The Multi Drive can be selected whether the I/O line
is controlled by the PIO controller or assigned to a peripheral function. PIO_MDSR (Multi-driver
Status Register) indicates the pins that are configured to support external drivers.
After reset, the Multi Drive feature is disabled on all pins, i.e. PIO_MDSR resets at value 0x0.
29.4.7
370
Output Line Timings
Figure 29-4 shows how the outputs are driven either by writing PIO_SODR or PIO_CODR, or by
directly writing PIO_ODSR. This last case is valid only if the corresponding bit in PIO_OWSR is
set. Figure 29-4 also shows when the feedback in PIO_PDSR is available.
AT91SAM9G20
6384E–ATARM–05-Feb-10
AT91SAM9G20
Figure 29-4. Output Line Timings
MCK
Write PIO_SODR
Write PIO_ODSR at 1
APB Access
Write PIO_CODR
Write PIO_ODSR at 0
APB Access
PIO_ODSR
2 cycles
2 cycles
PIO_PDSR
29.4.8
Inputs
The level on each I/O line can be read through PIO_PDSR (Pin Data Status Register). This register indicates the level of the I/O lines regardless of their configuration, whether uniquely as an
input or driven by the PIO controller or driven by a peripheral.
Reading the I/O line levels requires the clock of the PIO controller to be enabled, otherwise
PIO_PDSR reads the levels present on the I/O line at the time the clock was disabled.
29.4.9
Input Glitch Filtering
Optional input glitch filters are independently programmable on each I/O line. When the glitch filter is enabled, a glitch with a duration of less than 1/2 Master Clock (MCK) cycle is automatically
rejected, while a pulse with a duration of 1 Master Clock cycle or more is accepted. For pulse
durations between 1/2 Master Clock cycle and 1 Master Clock cycle the pulse may or may not
be taken into account, depending on the precise timing of its occurrence. Thus for a pulse to be
visible it must exceed 1 Master Clock cycle, whereas for a glitch to be reliably filtered out, its
duration must not exceed 1/2 Master Clock cycle. The filter introduces one Master Clock cycle
latency if the pin level change occurs before a rising edge. However, this latency does not
appear if the pin level change occurs before a falling edge. This is illustrated in Figure 29-5.
The glitch filters are controlled by the register set; PIO_IFER (Input Filter Enable Register),
PIO_IFDR (Input Filter Disable Register) and PIO_IFSR (Input Filter Status Register). Writing
PIO_IFER and PIO_IFDR respectively sets and clears bits in PIO_IFSR. This last register
enables the glitch filter on the I/O lines.
When the glitch filter is enabled, it does not modify the behavior of the inputs on the peripherals.
It acts only on the value read in PIO_PDSR and on the input change interrupt detection. The
glitch filters require that the PIO Controller clock is enabled.
371
6384E–ATARM–05-Feb-10
Figure 29-5. Input Glitch Filter Timing
MCK
up to 1.5 cycles
Pin Level
1 cycle
1 cycle
1 cycle
1 cycle
PIO_PDSR
if PIO_IFSR = 0
2 cycles
PIO_PDSR
if PIO_IFSR = 1
29.4.10
up to 2.5 cycles
1 cycle
up to 2 cycles
Input Change Interrupt
The PIO Controller can be programmed to generate an interrupt when it detects an input change
on an I/O line. The Input Change Interrupt is controlled by writing PIO_IER (Interrupt Enable
Register) and PIO_IDR (Interrupt Disable Register), which respectively enable and disable the
input change interrupt by setting and clearing the corresponding bit in PIO_IMR (Interrupt Mask
Register). As Input change detection is possible only by comparing two successive samplings of
the input of the I/O line, the PIO Controller clock must be enabled. The Input Change Interrupt is
available, regardless of the configuration of the I/O line, i.e. configured as an input only, controlled by the PIO Controller or assigned to a peripheral function.
When an input change is detected on an I/O line, the corresponding bit in PIO_ISR (Interrupt
Status Register) is set. If the corresponding bit in PIO_IMR is set, the PIO Controller interrupt
line is asserted. The interrupt signals of the thirty-two channels are ORed-wired together to generate a single interrupt signal to the Advanced Interrupt Controller.
When the software reads PIO_ISR, all the interrupts are automatically cleared. This signifies that
all the interrupts that are pending when PIO_ISR is read must be handled.
Figure 29-6. Input Change Interrupt Timings
MCK
Pin Level
PIO_ISR
APB Access
Read PIO_ISR
29.5
APB Access
I/O Lines Programming Example
The programing example as shown in Table 29-1 below is used to define the following
configuration.
• 4-bit output port on I/O lines 0 to 3, (should be written in a single write operation), open-drain,
with pull-up resistor
372
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AT91SAM9G20
• Four output signals on I/O lines 4 to 7 (to drive LEDs for example), driven high and low, no
pull-up resistor
• Four input signals on I/O lines 8 to 11 (to read push-button states for example), with pull-up
resistors, glitch filters and input change interrupts
• Four input signals on I/O line 12 to 15 to read an external device status (polled, thus no input
change interrupt), no pull-up resistor, no glitch filter
• I/O lines 16 to 19 assigned to peripheral A functions with pull-up resistor
• I/O lines 20 to 23 assigned to peripheral B functions, no pull-up resistor
• I/O line 24 to 27 assigned to peripheral A with Input Change Interrupt and pull-up resistor
Table 29-1.
Programming Example
Register
Value to be Written
PIO_PER
0x0000 FFFF
PIO_PDR
0x0FFF 0000
PIO_OER
0x0000 00FF
PIO_ODR
0x0FFF FF00
PIO_IFER
0x0000 0F00
PIO_IFDR
0x0FFF F0FF
PIO_SODR
0x0000 0000
PIO_CODR
0x0FFF FFFF
PIO_IER
0x0F00 0F00
PIO_IDR
0x00FF F0FF
PIO_MDER
0x0000 000F
PIO_MDDR
0x0FFF FFF0
PIO_PUDR
0x00F0 00F0
PIO_PUER
0x0F0F FF0F
PIO_ASR
0x0F0F 0000
PIO_BSR
0x00F0 0000
PIO_OWER
0x0000 000F
PIO_OWDR
0x0FFF FFF0
373
6384E–ATARM–05-Feb-10
29.6
Parallel Input/Output Controller (PIO) User Interface
Each I/O line controlled by the PIO Controller is associated with a bit in each of the PIO Controller User Interface registers. Each register is 32 bits wide. If a parallel I/O line is not defined,
writing to the corresponding bits has no effect. Undefined bits read zero. If the I/O line is not multiplexed with any peripheral, the I/O line is controlled by the PIO Controller and PIO_PSR returns
1 systematically.
Table 29-2.
Register Mapping
Offset
Register
Name
Access
Reset
0x0000
PIO Enable Register
PIO_PER
Write-only
–
0x0004
PIO Disable Register
PIO_PDR
Write-only
–
PIO_PSR
Read-only
(1)
0x0008
PIO Status Register
0x000C
Reserved
0x0010
Output Enable Register
PIO_OER
Write-only
–
0x0014
Output Disable Register
PIO_ODR
Write-only
–
0x0018
Output Status Register
PIO_OSR
Read-only
0x0000 0000
0x001C
Reserved
0x0020
Glitch Input Filter Enable Register
PIO_IFER
Write-only
–
0x0024
Glitch Input Filter Disable Register
PIO_IFDR
Write-only
–
0x0028
Glitch Input Filter Status Register
PIO_IFSR
Read-only
0x0000 0000
0x002C
Reserved
0x0030
Set Output Data Register
PIO_SODR
Write-only
–
0x0034
Clear Output Data Register
PIO_CODR
Write-only
0x0038
Output Data Status Register
PIO_ODSR
Read-only
or(2)
Read-write
–
0x003C
Pin Data Status Register
PIO_PDSR
Read-only
(3)
0x0040
Interrupt Enable Register
PIO_IER
Write-only
–
0x0044
Interrupt Disable Register
PIO_IDR
Write-only
–
0x0048
Interrupt Mask Register
PIO_IMR
Read-only
0x00000000
0x004C
Interrupt Status Register(4)
PIO_ISR
Read-only
0x00000000
0x0050
Multi-driver Enable Register
PIO_MDER
Write-only
–
0x0054
Multi-driver Disable Register
PIO_MDDR
Write-only
–
0x0058
Multi-driver Status Register
PIO_MDSR
Read-only
0x00000000
0x005C
Reserved
0x0060
Pull-up Disable Register
PIO_PUDR
Write-only
–
0x0064
Pull-up Enable Register
PIO_PUER
Write-only
–
0x0068
Pad Pull-up Status Register
PIO_PUSR
Read-only
0x00000000
0x006C
Reserved
374
AT91SAM9G20
6384E–ATARM–05-Feb-10
AT91SAM9G20
Table 29-2.
Register Mapping (Continued)
Offset
Register
0x0070
0x0074
Name
Peripheral A Select Register
(5)
Peripheral B Select Register
(5)
(5)
Access
Reset
PIO_ASR
Write-only
–
PIO_BSR
Write-only
–
PIO_ABSR
Read-only
0x00000000
0x0078
AB Status Register
0x007C
to
0x009C
Reserved
0x00A0
Output Write Enable
PIO_OWER
Write-only
–
0x00A4
Output Write Disable
PIO_OWDR
Write-only
–
0x00A8
Output Write Status Register
PIO_OWSR
Read-only
0x00000000
0x00AC
Reserved
Notes:
1. Reset value of PIO_PSR depends on the product implementation.
2. PIO_ODSR is Read-only or Read/Write depending on PIO_OWSR I/O lines.
3. Reset value of PIO_PDSR depends on the level of the I/O lines. Reading the I/O line levels requires the clock of the PIO
Controller to be enabled, otherwise PIO_PDSR reads the levels present on the I/O line at the time the clock was disabled.
4. PIO_ISR is reset at 0x0. However, the first read of the register may read a different value as input changes may have
occurred.
5. Only this set of registers clears the status by writing 1 in the first register and sets the status by writing 1 in the second
register.
375
6384E–ATARM–05-Feb-10
29.6.1
Name:
PIO Controller PIO Enable Register
PIO_PER
Access Type:
Write-only
31
30
29
28
27
26
25
24
P31
P30
P29
P28
P27
P26
P25
P24
23
22
21
20
19
18
17
16
P23
P22
P21
P20
P19
P18
P17
P16
15
14
13
12
11
10
9
8
P15
P14
P13
P12
P11
P10
P9
P8
7
6
5
4
3
2
1
0
P7
P6
P5
P4
P3
P2
P1
P0
• P0-P31: PIO Enable
0 = No effect.
1 = Enables the PIO to control the corresponding pin (disables peripheral control of the pin).
29.6.2
Name:
PIO Controller PIO Disable Register
PIO_PDR
Access Type:
Write-only
31
30
29
28
27
26
25
24
P31
P30
P29
P28
P27
P26
P25
P24
23
22
21
20
19
18
17
16
P23
P22
P21
P20
P19
P18
P17
P16
15
14
13
12
11
10
9
8
P15
P14
P13
P12
P11
P10
P9
P8
7
6
5
4
3
2
1
0
P7
P6
P5
P4
P3
P2
P1
P0
• P0-P31: PIO Disable
0 = No effect.
1 = Disables the PIO from controlling the corresponding pin (enables peripheral control of the pin).
376
AT91SAM9G20
6384E–ATARM–05-Feb-10
AT91SAM9G20
29.6.3
Name:
PIO Controller PIO Status Register
PIO_PSR
Access Type:
Read-only
31
30
29
28
27
26
25
24
P31
P30
P29
P28
P27
P26
P25
P24
23
22
21
20
19
18
17
16
P23
P22
P21
P20
P19
P18
P17
P16
15
14
13
12
11
10
9
8
P15
P14
P13
P12
P11
P10
P9
P8
7
6
5
4
3
2
1
0
P7
P6
P5
P4
P3
P2
P1
P0
• P0-P31: PIO Status
0 = PIO is inactive on the corresponding I/O line (peripheral is active).
1 = PIO is active on the corresponding I/O line (peripheral is inactive).
29.6.4
Name:
PIO Controller Output Enable Register
PIO_OER
Access Type:
Write-only
31
30
29
28
27
26
25
24
P31
P30
P29
P28
P27
P26
P25
P24
23
22
21
20
19
18
17
16
P23
P22
P21
P20
P19
P18
P17
P16
15
14
13
12
11
10
9
8
P15
P14
P13
P12
P11
P10
P9
P8
7
6
5
4
3
2
1
0
P7
P6
P5
P4
P3
P2
P1
P0
• P0-P31: Output Enable
0 = No effect.
1 = Enables the output on the I/O line.
377
6384E–ATARM–05-Feb-10
29.6.5
Name:
PIO Controller Output Disable Register
PIO_ODR
Access Type:
Write-only
31
30
29
28
27
26
25
24
P31
P30
P29
P28
P27
P26
P25
P24
23
22
21
20
19
18
17
16
P23
P22
P21
P20
P19
P18
P17
P16
15
14
13
12
11
10
9
8
P15
P14
P13
P12
P11
P10
P9
P8
7
6
5
4
3
2
1
0
P7
P6
P5
P4
P3
P2
P1
P0
• P0-P31: Output Disable
0 = No effect.
1 = Disables the output on the I/O line.
29.6.6
Name:
PIO Controller Output Status Register
PIO_OSR
Access Type:
Read-only
31
30
29
28
27
26
25
24
P31
P30
P29
P28
P27
P26
P25
P24
23
22
21
20
19
18
17
16
P23
P22
P21
P20
P19
P18
P17
P16
15
14
13
12
11
10
9
8
P15
P14
P13
P12
P11
P10
P9
P8
7
6
5
4
3
2
1
0
P7
P6
P5
P4
P3
P2
P1
P0
• P0-P31: Output Status
0 = The I/O line is a pure input.
1 = The I/O line is enabled in output.
378
AT91SAM9G20
6384E–ATARM–05-Feb-10
AT91SAM9G20
29.6.7
Name:
PIO Controller Input Filter Enable Register
PIO_IFER
Access Type:
Write-only
31
30
29
28
27
26
25
24
P31
P30
P29
P28
P27
P26
P25
P24
23
22
21
20
19
18
17
16
P23
P22
P21
P20
P19
P18
P17
P16
15
14
13
12
11
10
9
8
P15
P14
P13
P12
P11
P10
P9
P8
7
6
5
4
3
2
1
0
P7
P6
P5
P4
P3
P2
P1
P0
• P0-P31: Input Filter Enable
0 = No effect.
1 = Enables the input glitch filter on the I/O line.
29.6.8
Name:
PIO Controller Input Filter Disable Register
PIO_IFDR
Access Type:
Write-only
31
30
29
28
27
26
25
24
P31
P30
P29
P28
P27
P26
P25
P24
23
22
21
20
19
18
17
16
P23
P22
P21
P20
P19
P18
P17
P16
15
14
13
12
11
10
9
8
P15
P14
P13
P12
P11
P10
P9
P8
7
6
5
4
3
2
1
0
P7
P6
P5
P4
P3
P2
P1
P0
• P0-P31: Input Filter Disable
0 = No effect.
1 = Disables the input glitch filter on the I/O line.
379
6384E–ATARM–05-Feb-10
29.6.9
Name:
PIO Controller Input Filter Status Register
PIO_IFSR
Access Type:
Read-only
31
30
29
28
27
26
25
24
P31
P30
P29
P28
P27
P26
P25
P24
23
22
21
20
19
18
17
16
P23
P22
P21
P20
P19
P18
P17
P16
15
14
13
12
11
10
9
8
P15
P14
P13
P12
P11
P10
P9
P8
7
6
5
4
3
2
1
0
P7
P6
P5
P4
P3
P2
P1
P0
• P0-P31: Input Filer Status
0 = The input glitch filter is disabled on the I/O line.
1 = The input glitch filter is enabled on the I/O line.
29.6.10
Name:
PIO Controller Set Output Data Register
PIO_SODR
Access Type:
Write-only
31
30
29
28
27
26
25
24
P31
P30
P29
P28
P27
P26
P25
P24
23
22
21
20
19
18
17
16
P23
P22
P21
P20
P19
P18
P17
P16
15
14
13
12
11
10
9
8
P15
P14
P13
P12
P11
P10
P9
P8
7
6
5
4
3
2
1
0
P7
P6
P5
P4
P3
P2
P1
P0
• P0-P31: Set Output Data
0 = No effect.
1 = Sets the data to be driven on the I/O line.
380
AT91SAM9G20
6384E–ATARM–05-Feb-10
AT91SAM9G20
29.6.11
Name:
PIO Controller Clear Output Data Register
PIO_CODR
Access Type:
Write-only
31
30
29
28
27
26
25
24
P31
P30
P29
P28
P27
P26
P25
P24
23
22
21
20
19
18
17
16
P23
P22
P21
P20
P19
P18
P17
P16
15
14
13
12
11
10
9
8
P15
P14
P13
P12
P11
P10
P9
P8
7
6
5
4
3
2
1
0
P7
P6
P5
P4
P3
P2
P1
P0
• P0-P31: Set Output Data
0 = No effect.
1 = Clears the data to be driven on the I/O line.
29.6.12
Name:
PIO Controller Output Data Status Register
PIO_ODSR
Access Type:
Read-only or Read-write
31
30
29
28
27
26
25
24
P31
P30
P29
P28
P27
P26
P25
P24
23
22
21
20
19
18
17
16
P23
P22
P21
P20
P19
P18
P17
P16
15
14
13
12
11
10
9
8
P15
P14
P13
P12
P11
P10
P9
P8
7
6
5
4
3
2
1
0
P7
P6
P5
P4
P3
P2
P1
P0
• P0-P31: Output Data Status
0 = The data to be driven on the I/O line is 0.
1 = The data to be driven on the I/O line is 1.
381
6384E–ATARM–05-Feb-10
29.6.13
Name:
PIO Controller Pin Data Status Register
PIO_PDSR
Access Type:
Read-only
31
30
29
28
27
26
25
24
P31
P30
P29
P28
P27
P26
P25
P24
23
22
21
20
19
18
17
16
P23
P22
P21
P20
P19
P18
P17
P16
15
14
13
12
11
10
9
8
P15
P14
P13
P12
P11
P10
P9
P8
7
6
5
4
3
2
1
0
P7
P6
P5
P4
P3
P2
P1
P0
• P0-P31: Output Data Status
0 = The I/O line is at level 0.
1 = The I/O line is at level 1.
29.6.14
Name:
PIO Controller Interrupt Enable Register
PIO_IER
Access Type:
Write-only
31
30
29
28
27
26
25
24
P31
P30
P29
P28
P27
P26
P25
P24
23
22
21
20
19
18
17
16
P23
P22
P21
P20
P19
P18
P17
P16
15
14
13
12
11
10
9
8
P15
P14
P13
P12
P11
P10
P9
P8
7
6
5
4
3
2
1
0
P7
P6
P5
P4
P3
P2
P1
P0
• P0-P31: Input Change Interrupt Enable
0 = No effect.
1 = Enables the Input Change Interrupt on the I/O line.
382
AT91SAM9G20
6384E–ATARM–05-Feb-10
AT91SAM9G20
29.6.15
Name:
PIO Controller Interrupt Disable Register
PIO_IDR
Access Type:
Write-only
31
30
29
28
27
26
25
24
P31
P30
P29
P28
P27
P26
P25
P24
23
22
21
20
19
18
17
16
P23
P22
P21
P20
P19
P18
P17
P16
15
14
13
12
11
10
9
8
P15
P14
P13
P12
P11
P10
P9
P8
7
6
5
4
3
2
1
0
P7
P6
P5
P4
P3
P2
P1
P0
• P0-P31: Input Change Interrupt Disable
0 = No effect.
1 = Disables the Input Change Interrupt on the I/O line.
29.6.16
Name:
PIO Controller Interrupt Mask Register
PIO_IMR
Access Type:
Read-only
31
30
29
28
27
26
25
24
P31
P30
P29
P28
P27
P26
P25
P24
23
22
21
20
19
18
17
16
P23
P22
P21
P20
P19
P18
P17
P16
15
14
13
12
11
10
9
8
P15
P14
P13
P12
P11
P10
P9
P8
7
6
5
4
3
2
1
0
P7
P6
P5
P4
P3
P2
P1
P0
• P0-P31: Input Change Interrupt Mask
0 = Input Change Interrupt is disabled on the I/O line.
1 = Input Change Interrupt is enabled on the I/O line.
383
6384E–ATARM–05-Feb-10
29.6.17
Name:
PIO Controller Interrupt Status Register
PIO_ISR
Access Type:
Read-only
31
30
29
28
27
26
25
24
P31
P30
P29
P28
P27
P26
P25
P24
23
22
21
20
19
18
17
16
P23
P22
P21
P20
P19
P18
P17
P16
15
14
13
12
11
10
9
8
P15
P14
P13
P12
P11
P10
P9
P8
7
6
5
4
3
2
1
0
P7
P6
P5
P4
P3
P2
P1
P0
• P0-P31: Input Change Interrupt Status
0 = No Input Change has been detected on the I/O line since PIO_ISR was last read or since reset.
1 = At least one Input Change has been detected on the I/O line since PIO_ISR was last read or since reset.
29.6.18
Name:
PIO Multi-driver Enable Register
PIO_MDER
Access Type:
Write-only
31
30
29
28
27
26
25
24
P31
P30
P29
P28
P27
P26
P25
P24
23
22
21
20
19
18
17
16
P23
P22
P21
P20
P19
P18
P17
P16
15
14
13
12
11
10
9
8
P15
P14
P13
P12
P11
P10
P9
P8
7
6
5
4
3
2
1
0
P7
P6
P5
P4
P3
P2
P1
P0
• P0-P31: Multi Drive Enable.
0 = No effect.
1 = Enables Multi Drive on the I/O line.
384
AT91SAM9G20
6384E–ATARM–05-Feb-10
AT91SAM9G20
29.6.19
Name:
PIO Multi-driver Disable Register
PIO_MDDR
Access Type:
Write-only
31
30
29
28
27
26
25
24
P31
P30
P29
P28
P27
P26
P25
P24
23
22
21
20
19
18
17
16
P23
P22
P21
P20
P19
P18
P17
P16
15
14
13
12
11
10
9
8
P15
P14
P13
P12
P11
P10
P9
P8
7
6
5
4
3
2
1
0
P7
P6
P5
P4
P3
P2
P1
P0
• P0-P31: Multi Drive Disable.
0 = No effect.
1 = Disables Multi Drive on the I/O line.
29.6.20
Name:
PIO Multi-driver Status Register
PIO_MDSR
Access Type:
Read-only
31
30
29
28
27
26
25
24
P31
P30
P29
P28
P27
P26
P25
P24
23
22
21
20
19
18
17
16
P23
P22
P21
P20
P19
P18
P17
P16
15
14
13
12
11
10
9
8
P15
P14
P13
P12
P11
P10
P9
P8
7
6
5
4
3
2
1
0
P7
P6
P5
P4
P3
P2
P1
P0
• P0-P31: Multi Drive Status.
0 = The Multi Drive is disabled on the I/O line. The pin is driven at high and low level.
1 = The Multi Drive is enabled on the I/O line. The pin is driven at low level only.
385
6384E–ATARM–05-Feb-10
29.6.21
Name:
PIO Pull Up Disable Register
PIO_PUDR
Access Type:
Write-only
31
30
29
28
27
26
25
24
P31
P30
P29
P28
P27
P26
P25
P24
23
22
21
20
19
18
17
16
P23
P22
P21
P20
P19
P18
P17
P16
15
14
13
12
11
10
9
8
P15
P14
P13
P12
P11
P10
P9
P8
7
6
5
4
3
2
1
0
P7
P6
P5
P4
P3
P2
P1
P0
• P0-P31: Pull Up Disable.
0 = No effect.
1 = Disables the pull up resistor on the I/O line.
29.6.22
Name:
PIO Pull Up Enable Register
PIO_PUER
Access Type:
Write-only
31
30
29
28
27
26
25
24
P31
P30
P29
P28
P27
P26
P25
P24
23
22
21
20
19
18
17
16
P23
P22
P21
P20
P19
P18
P17
P16
15
14
13
12
11
10
9
8
P15
P14
P13
P12
P11
P10
P9
P8
7
6
5
4
3
2
1
0
P7
P6
P5
P4
P3
P2
P1
P0
• P0-P31: Pull Up Enable.
0 = No effect.
1 = Enables the pull up resistor on the I/O line.
386
AT91SAM9G20
6384E–ATARM–05-Feb-10
AT91SAM9G20
29.6.23
Name:
PIO Pull Up Status Register
PIO_PUSR
Access Type:
Read-only
31
30
29
28
27
26
25
24
P31
P30
P29
P28
P27
P26
P25
P24
23
22
21
20
19
18
17
16
P23
P22
P21
P20
P19
P18
P17
P16
15
14
13
12
11
10
9
8
P15
P14
P13
P12
P11
P10
P9
P8
7
6
5
4
3
2
1
0
P7
P6
P5
P4
P3
P2
P1
P0
• P0-P31: Pull Up Status.
0 = Pull Up resistor is enabled on the I/O line.
1 = Pull Up resistor is disabled on the I/O line.
29.6.24
Name:
PIO Peripheral A Select Register
PIO_ASR
Access Type:
Write-only
31
30
29
28
27
26
25
24
P31
P30
P29
P28
P27
P26
P25
P24
23
22
21
20
19
18
17
16
P23
P22
P21
P20
P19
P18
P17
P16
15
14
13
12
11
10
9
8
P15
P14
P13
P12
P11
P10
P9
P8
7
6
5
4
3
2
1
0
P7
P6
P5
P4
P3
P2
P1
P0
• P0-P31: Peripheral A Select.
0 = No effect.
1 = Assigns the I/O line to the Peripheral A function.
387
6384E–ATARM–05-Feb-10
29.6.25
Name:
PIO Peripheral B Select Register
PIO_BSR
Access Type:
Write-only
31
30
29
28
27
26
25
24
P31
P30
P29
P28
P27
P26
P25
P24
23
22
21
20
19
18
17
16
P23
P22
P21
P20
P19
P18
P17
P16
15
14
13
12
11
10
9
8
P15
P14
P13
P12
P11
P10
P9
P8
7
6
5
4
3
2
1
0
P7
P6
P5
P4
P3
P2
P1
P0
• P0-P31: Peripheral B Select.
0 = No effect.
1 = Assigns the I/O line to the peripheral B function.
29.6.26
Name:
PIO Peripheral A B Status Register
PIO_ABSR
Access Type:
Read-only
31
30
29
28
27
26
25
24
P31
P30
P29
P28
P27
P26
P25
P24
23
22
21
20
19
18
17
16
P23
P22
P21
P20
P19
P18
P17
P16
15
14
13
12
11
10
9
8
P15
P14
P13
P12
P11
P10
P9
P8
7
6
5
4
3
2
1
0
P7
P6
P5
P4
P3
P2
P1
P0
• P0-P31: Peripheral A B Status.
0 = The I/O line is assigned to the Peripheral A.
1 = The I/O line is assigned to the Peripheral B.
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29.6.27
Name:
PIO Output Write Enable Register
PIO_OWER
Access Type:
Write-only
31
30
29
28
27
26
25
24
P31
P30
P29
P28
P27
P26
P25
P24
23
22
21
20
19
18
17
16
P23
P22
P21
P20
P19
P18
P17
P16
15
14
13
12
11
10
9
8
P15
P14
P13
P12
P11
P10
P9
P8
7
6
5
4
3
2
1
0
P7
P6
P5
P4
P3
P2
P1
P0
• P0-P31: Output Write Enable.
0 = No effect.
1 = Enables writing PIO_ODSR for the I/O line.
29.6.28
Name:
PIO Output Write Disable Register
PIO_OWDR
Access Type:
Write-only
31
30
29
28
27
26
25
24
P31
P30
P29
P28
P27
P26
P25
P24
23
22
21
20
19
18
17
16
P23
P22
P21
P20
P19
P18
P17
P16
15
14
13
12
11
10
9
8
P15
P14
P13
P12
P11
P10
P9
P8
7
6
5
4
3
2
1
0
P7
P6
P5
P4
P3
P2
P1
P0
• P0-P31: Output Write Disable.
0 = No effect.
1 = Disables writing PIO_ODSR for the I/O line.
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29.6.29
Name:
PIO Output Write Status Register
PIO_OWSR
Access Type:
Read-only
31
30
29
28
27
26
25
24
P31
P30
P29
P28
P27
P26
P25
P24
23
22
21
20
19
18
17
16
P23
P22
P21
P20
P19
P18
P17
P16
15
14
13
12
11
10
9
8
P15
P14
P13
P12
P11
P10
P9
P8
7
6
5
4
3
2
1
0
P7
P6
P5
P4
P3
P2
P1
P0
• P0-P31: Output Write Status.
0 = Writing PIO_ODSR does not affect the I/O line.
1 = Writing PIO_ODSR affects the I/O line.
390
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AT91SAM9G20
30. Serial Peripheral Interface (SPI)
30.1
Overview
The Serial Peripheral Interface (SPI) circuit is a synchronous serial data link that provides communication with external devices in Master or Slave Mode. It also enables communication
between processors if an external processor is connected to the system.
The Serial Peripheral Interface is essentially a shift register that serially transmits data bits to
other SPIs. During a data transfer, one SPI system acts as the “master”' which controls the data
flow, while the other devices act as “slaves'' which have data shifted into and out by the master.
Different CPUs can take turn being masters (Multiple Master Protocol opposite to Single Master
Protocol where one CPU is always the master while all of the others are always slaves) and one
master may simultaneously shift data into multiple slaves. However, only one slave may drive its
output to write data back to the master at any given time.
A slave device is selected when the master asserts its NSS signal. If multiple slave devices
exist, the master generates a separate slave select signal for each slave (NPCS).
The SPI system consists of two data lines and two control lines:
• Master Out Slave In (MOSI): This data line supplies the output data from the master shifted
into the input(s) of the slave(s).
• Master In Slave Out (MISO): This data line supplies the output data from a slave to the input
of the master. There may be no more than one slave transmitting data during any particular
transfer.
• Serial Clock (SPCK): This control line is driven by the master and regulates the flow of the
data bits. The master may transmit data at a variety of baud rates; the SPCK line cycles once
for each bit that is transmitted.
• Slave Select (NSS): This control line allows slaves to be turned on and off by hardware.
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30.2
Block Diagram
Figure 30-1. Block Diagram
PDC
APB
SPCK
MISO
PMC
MOSI
MCK
SPI Interface
PIO
NPCS0/NSS
NPCS1
NPCS2
Interrupt Control
NPCS3
SPI Interrupt
30.3
Application Block Diagram
Figure 30-2. Application Block Diagram: Single Master/Multiple Slave Implementation
SPI Master
SPCK
SPCK
MISO
MISO
MOSI
MOSI
NPCS0
NSS
Slave 0
SPCK
NPCS1
NPCS2
NPCS3
NC
MISO
Slave 1
MOSI
NSS
SPCK
MISO
Slave 2
MOSI
NSS
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AT91SAM9G20
30.4
Signal Description
Table 30-1.
Signal Description
Type
Pin Name
Pin Description
Master
Slave
MISO
Master In Slave Out
Input
Output
MOSI
Master Out Slave In
Output
Input
SPCK
Serial Clock
Output
Input
NPCS1-NPCS3
Peripheral Chip Selects
Output
Unused
NPCS0/NSS
Peripheral Chip Select/Slave Select
Output
Input
30.5
30.5.1
Product Dependencies
I/O Lines
The pins used for interfacing the compliant external devices may be multiplexed with PIO lines.
The programmer must first program the PIO controllers to assign the SPI pins to their peripheral
functions.
30.5.2
Power Management
The SPI may be clocked through the Power Management Controller (PMC), thus the programmer must first configure the PMC to enable the SPI clock.
30.5.3
Interrupt
The SPI interface has an interrupt line connected to the Advanced Interrupt Controller (AIC).
Handling the SPI interrupt requires programming the AIC before configuring the SPI.
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30.6
30.6.1
Functional Description
Modes of Operation
The SPI operates in Master Mode or in Slave Mode.
Operation in Master Mode is programmed by writing at 1 the MSTR bit in the Mode Register.
The pins NPCS0 to NPCS3 are all configured as outputs, the SPCK pin is driven, the MISO line
is wired on the receiver input and the MOSI line driven as an output by the transmitter.
If the MSTR bit is written at 0, the SPI operates in Slave Mode. The MISO line is driven by the
transmitter output, the MOSI line is wired on the receiver input, the SPCK pin is driven by the
transmitter to synchronize the receiver. The NPCS0 pin becomes an input, and is used as a
Slave Select signal (NSS). The pins NPCS1 to NPCS3 are not driven and can be used for other
purposes.
The data transfers are identically programmable for both modes of operations. The baud rate
generator is activated only in Master Mode.
30.6.2
Data Transfer
Four combinations of polarity and phase are available for data transfers. The clock polarity is
programmed with the CPOL bit in the Chip Select Register. The clock phase is programmed with
the NCPHA bit. These two parameters determine the edges of the clock signal on which data is
driven and sampled. Each of the two parameters has two possible states, resulting in four possible combinations that are incompatible with one another. Thus, a master/slave pair must use the
same parameter pair values to communicate. If multiple slaves are used and fixed in different
configurations, the master must reconfigure itself each time it needs to communicate with a different slave.
Table 30-2 shows the four modes and corresponding parameter settings.
Table 30-2.
SPI Bus Protocol Mode
SPI Mode
CPOL
NCPHA
0
0
1
1
0
0
2
1
1
3
1
0
Figure 30-3 and Figure 30-4 show examples of data transfers.
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Figure 30-3. SPI Transfer Format (NCPHA = 1, 8 bits per transfer)
1
SPCK cycle (for reference)
2
3
4
6
5
7
8
SPCK
(CPOL = 0)
SPCK
(CPOL = 1)
MOSI
(from master)
MSB
MISO
(from slave)
MSB
6
5
4
3
2
1
LSB
6
5
4
3
2
1
LSB
*
NSS
(to slave)
* Not defined, but normally MSB of previous character received.
Figure 30-4. SPI Transfer Format (NCPHA = 0, 8 bits per transfer)
1
SPCK cycle (for reference)
2
3
4
5
7
6
8
SPCK
(CPOL = 0)
SPCK
(CPOL = 1)
MOSI
(from master)
MISO
(from slave)
*
MSB
6
5
4
3
2
1
MSB
6
5
4
3
2
1
LSB
LSB
NSS
(to slave)
* Not defined but normally LSB of previous character transmitted.
30.6.3
Master Mode Operations
When configured in Master Mode, the SPI operates on the clock generated by the internal programmable baud rate generator. It fully controls the data transfers to and from the slave(s)
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6384E–ATARM–05-Feb-10
connected to the SPI bus. The SPI drives the chip select line to the slave and the serial clock
signal (SPCK).
The SPI features two holding registers, the Transmit Data Register and the Receive Data Register, and a single Shift Register. The holding registers maintain the data flow at a constant rate.
After enabling the SPI, a data transfer begins when the processor writes to the SPI_TDR (Transmit Data Register). The written data is immediately transferred in the Shift Register and transfer
on the SPI bus starts. While the data in the Shift Register is shifted on the MOSI line, the MISO
line is sampled and shifted in the Shift Register. Transmission cannot occur without reception.
Before writing the TDR, the PCS field must be set in order to select a slave.
If new data is written in SPI_TDR during the transfer, it stays in it until the current transfer is
completed. Then, the received data is transferred from the Shift Register to SPI_RDR, the data
in SPI_TDR is loaded in the Shift Register and a new transfer starts.
The transfer of a data written in SPI_TDR in the Shift Register is indicated by the TDRE bit
(Transmit Data Register Empty) in the Status Register (SPI_SR). When new data is written in
SPI_TDR, this bit is cleared. The TDRE bit is used to trigger the Transmit PDC channel.
The end of transfer is indicated by the TXEMPTY flag in the SPI_SR register. If a transfer delay
(DLYBCT) is greater than 0 for the last transfer, TXEMPTY is set after the completion of said
delay. The master clock (MCK) can be switched off at this time.
The transfer of received data from the Shift Register in SPI_RDR is indicated by the RDRF bit
(Receive Data Register Full) in the Status Register (SPI_SR). When the received data is read,
the RDRF bit is cleared.
If the SPI_RDR (Receive Data Register) has not been read before new data is received, the
Overrun Error bit (OVRES) in SPI_SR is set. As long as this flag is set, data is loaded in
SPI_RDR. The user has to read the status register to clear the OVRES bit.
Figure 30-5 on page 397 shows a block diagram of the SPI when operating in Master Mode. Figure 30-6 on page 398 shows a flow chart describing how transfers are handled.
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AT91SAM9G20
30.6.3.1
Master Mode Block Diagram
Figure 30-5. Master Mode Block Diagram
SPI_CSR0..3
SCBR
Baud Rate Generator
MCK
SPCK
SPI
Clock
SPI_CSR0..3
BITS
NCPHA
CPOL
LSB
MISO
SPI_RDR
RDRF
OVRES
RD
MSB
Shift Register
MOSI
SPI_TDR
TD
TDRE
SPI_CSR0..3
SPI_RDR
CSAAT
PCS
PS
NPCS3
PCSDEC
SPI_MR
PCS
0
NPCS2
Current
Peripheral
NPCS1
SPI_TDR
NPCS0
PCS
1
MSTR
MODF
NPCS0
MODFDIS
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30.6.3.2
Master Mode Flow Diagram
Figure 30-6. Master Mode Flow Diagram
SPI Enable
- NPCS defines the current Chip Select
- CSAAT, DLYBS, DLYBCT refer to the fields of the
Chip Select Register corresponding to the Current Chip Select
- When NPCS is 0xF, CSAAT is 0.
1
TDRE ?
0
1
CSAAT ?
PS ?
0
1
0
Fixed
peripheral
PS ?
1
Fixed
peripheral
0
Variable
peripheral
Variable
peripheral
SPI_TDR(PCS)
= NPCS ?
no
NPCS = SPI_TDR(PCS)
NPCS = SPI_MR(PCS)
yes
SPI_MR(PCS)
= NPCS ?
no
NPCS = 0xF
NPCS = 0xF
Delay DLYBCS
Delay DLYBCS
NPCS = SPI_TDR(PCS)
NPCS = SPI_MR(PCS),
SPI_TDR(PCS)
Delay DLYBS
Serializer = SPI_TDR(TD)
TDRE = 1
Data Transfer
SPI_RDR(RD) = Serializer
RDRF = 1
Delay DLYBCT
0
TDRE ?
1
1
CSAAT ?
0
NPCS = 0xF
Delay DLYBCS
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AT91SAM9G20
30.6.3.3
Clock Generation
The SPI Baud rate clock is generated by dividing the Master Clock (MCK), by a value between 1
and 255.
This allows a maximum operating baud rate at up to Master Clock and a minimum operating
baud rate of MCK divided by 255.
Programming the SCBR field at 0 is forbidden. Triggering a transfer while SCBR is at 0 can lead
to unpredictable results.
At reset, SCBR is 0 and the user has to program it at a valid value before performing the first
transfer.
The divisor can be defined independently for each chip select, as it has to be programmed in the
SCBR field of the Chip Select Registers. This allows the SPI to automatically adapt the baud
rate for each interfaced peripheral without reprogramming.
30.6.3.4
Transfer Delays
Figure 30-7 shows a chip select transfer change and consecutive transfers on the same chip
select. Three delays can be programmed to modify the transfer waveforms:
• The delay between chip selects, programmable only once for all the chip selects by writing
the DLYBCS field in the Mode Register. Allows insertion of a delay between release of one
chip select and before assertion of a new one.
• The delay before SPCK, independently programmable for each chip select by writing the field
DLYBS. Allows the start of SPCK to be delayed after the chip select has been asserted.
• The delay between consecutive transfers, independently programmable for each chip select
by writing the DLYBCT field. Allows insertion of a delay between two transfers occurring on
the same chip select
These delays allow the SPI to be adapted to the interfaced peripherals and their speed and bus
release time.
Figure 30-7. Programmable Delays
Chip Select 1
Chip Select 2
SPCK
DLYBCS
30.6.3.5
DLYBS
DLYBCT
DLYBCT
Peripheral Selection
The serial peripherals are selected through the assertion of the NPCS0 to NPCS3 signals. By
default, all the NPCS signals are high before and after each transfer.
The peripheral selection can be performed in two different ways:
• Fixed Peripheral Select: SPI exchanges data with only one peripheral
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6384E–ATARM–05-Feb-10
• Variable Peripheral Select: Data can be exchanged with more than one peripheral
Fixed Peripheral Select is activated by writing the PS bit to zero in SPI_MR (Mode Register). In
this case, the current peripheral is defined by the PCS field in SPI_MR and the PCS field in the
SPI_TDR has no effect.
Variable Peripheral Select is activated by setting PS bit to one. The PCS field in SPI_TDR is
used to select the current peripheral. This means that the peripheral selection can be defined for
each new data.
The Fixed Peripheral Selection allows buffer transfers with a single peripheral. Using the PDC is
an optimal means, as the size of the data transfer between the memory and the SPI is either 8
bits or 16 bits. However, changing the peripheral selection requires the Mode Register to be
reprogrammed.
The Variable Peripheral Selection allows buffer transfers with multiple peripherals without reprogramming the Mode Register. Data written in SPI_TDR is 32 bits wide and defines the real data
to be transmitted and the peripheral it is destined to. Using the PDC in this mode requires 32-bit
wide buffers, with the data in the LSBs and the PCS and LASTXFER fields in the MSBs, however the SPI still controls the number of bits (8 to16) to be transferred through MISO and MOSI
lines with the chip select configuration registers. This is not the optimal means in term of memory size for the buffers, but it provides a very effective means to exchange data with several
peripherals without any intervention of the processor.
30.6.3.6
Peripheral Chip Select Decoding
The user can program the SPI to operate with up to 15 peripherals by decoding the four Chip
Select lines, NPCS0 to NPCS3 with an external logic. This can be enabled by writing the PCSDEC bit at 1 in the Mode Register (SPI_MR).
When operating without decoding, the SPI makes sure that in any case only one chip select line
is activated, i.e. driven low at a time. If two bits are defined low in a PCS field, only the lowest
numbered chip select is driven low.
When operating with decoding, the SPI directly outputs the value defined by the PCS field of
either the Mode Register or the Transmit Data Register (depending on PS).
As the SPI sets a default value of 0xF on the chip select lines (i.e. all chip select lines at 1) when
not processing any transfer, only 15 peripherals can be decoded.
The SPI has only four Chip Select Registers, not 15. As a result, when decoding is activated,
each chip select defines the characteristics of up to four peripherals. As an example, SPI_CRS0
defines the characteristics of the externally decoded peripherals 0 to 3, corresponding to the
PCS values 0x0 to 0x3. Thus, the user has to make sure to connect compatible peripherals on
the decoded chip select lines 0 to 3, 4 to 7, 8 to 11 and 12 to 14.
30.6.3.7
Peripheral Deselection
When operating normally, as soon as the transfer of the last data written in SPI_TDR is completed, the NPCS lines all rise. This might lead to runtime error if the processor is too long in
responding to an interrupt, and thus might lead to difficulties for interfacing with some serial
peripherals requiring the chip select line to remain active during a full set of transfers.
To facilitate interfacing with such devices, the Chip Select Register can be programmed with the
CSAAT bit (Chip Select Active After Transfer) at 1. This allows the chip select lines to remain in
their current state (low = active) until transfer to another peripheral is required.
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AT91SAM9G20
Figure 30-8. Peripheral Deselection
CSAAT = 0 and CSNAAT = 0
TDRE
NPCS[0..3]
CSAAT = 1 and CSNAAT= 0 / 1
DLYBCT
DLYBCT
A
A
A
A
DLYBCS
A
DLYBCS
PCS = A
PCS = A
Write SPI_TDR
TDRE
NPCS[0..3]
DLYBCT
DLYBCT
A
A
A
A
DLYBCS
A
DLYBCS
PCS=A
PCS = A
Write SPI_TDR
TDRE
NPCS[0..3]
DLYBCT
DLYBCT
A
B
A
B
DLYBCS
PCS = B
DLYBCS
PCS = B
Write SPI_TDR
30.6.3.8
Mode Fault Detection
A mode fault is detected when the SPI is programmed in Master Mode and a low level is driven
by an external master on the NPCS0/NSS signal. NPCS0, MOSI, MISO and SPCK must be configured in open drain through the PIO controller, so that external pull up resistors are needed to
guarantee high level.
When a mode fault is detected, the MODF bit in the SPI_SR is set until the SPI_SR is read and
the SPI is automatically disabled until re-enabled by writing the SPIEN bit in the SPI_CR (Control Register) at 1.
By default, the Mode Fault detection circuitry is enabled. The user can disable Mode Fault
detection by setting the MODFDIS bit in the SPI Mode Register (SPI_MR).
30.6.4
SPI Slave Mode
When operating in Slave Mode, the SPI processes data bits on the clock provided on the SPI
clock pin (SPCK).
The SPI waits for NSS to go active before receiving the serial clock from an external master.
When NSS falls, the clock is validated on the serializer, which processes the number of bits
defined by the BITS field of the Chip Select Register 0 (SPI_CSR0). These bits are processed
following a phase and a polarity defined respectively by the NCPHA and CPOL bits of the
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6384E–ATARM–05-Feb-10
SPI_CSR0. Note that BITS, CPOL and NCPHA of the other Chip Select Registers have no
effect when the SPI is programmed in Slave Mode.
The bits are shifted out on the MISO line and sampled on the MOSI line.
When all the bits are processed, the received data is transferred in the Receive Data Register
and the RDRF bit rises. If the SPI_RDR (Receive Data Register) has not been read before new
data is received, the Overrun Error bit (OVRES) in SPI_SR is set. As long as this flag is set, data
is loaded in SPI_RDR. The user has to read the status register to clear the OVRES bit.
When a transfer starts, the data shifted out is the data present in the Shift Register. If no data
has been written in the Transmit Data Register (SPI_TDR), the last data received is transferred.
If no data has been received since the last reset, all bits are transmitted low, as the Shift Register resets at 0.
When a first data is written in SPI_TDR, it is transferred immediately in the Shift Register and the
TDRE bit rises. If new data is written, it remains in SPI_TDR until a transfer occurs, i.e. NSS falls
and there is a valid clock on the SPCK pin. When the transfer occurs, the last data written in
SPI_TDR is transferred in the Shift Register and the TDRE bit rises. This enables frequent
updates of critical variables with single transfers.
Then, a new data is loaded in the Shift Register from the Transmit Data Register. In case no
character is ready to be transmitted, i.e. no character has been written in SPI_TDR since the last
load from SPI_TDR to the Shift Register, the Shift Register is not modified and the last received
character is retransmitted.
Figure 30-9 shows a block diagram of the SPI when operating in Slave Mode.
Figure 30-9. Slave Mode Functional Block Diagram
SPCK
NSS
SPI
Clock
SPIEN
SPIENS
SPIDIS
SPI_CSR0
BITS
NCPHA
CPOL
MOSI
LSB
SPI_RDR
RDRF
OVRES
RD
MSB
Shift Register
MISO
SPI_TDR
TD
402
TDRE
AT91SAM9G20
6384E–ATARM–05-Feb-10
AT91SAM9G20
30.7
Serial Peripheral Interface (SPI) User Interface
Table 30-3.
Register Mapping
Offset
Register
Name
Access
Reset
0x00
Control Register
SPI_CR
Write-only
---
0x04
Mode Register
SPI_MR
Read-write
0x0
0x08
Receive Data Register
SPI_RDR
Read-only
0x0
0x0C
Transmit Data Register
SPI_TDR
Write-only
---
0x10
Status Register
SPI_SR
Read-only
0x000000F0
0x14
Interrupt Enable Register
SPI_IER
Write-only
---
0x18
Interrupt Disable Register
SPI_IDR
Write-only
---
0x1C
Interrupt Mask Register
SPI_IMR
Read-only
0x0
0x20 - 0x2C
Reserved
0x30
Chip Select Register 0
SPI_CSR0
Read-write
0x0
0x34
Chip Select Register 1
SPI_CSR1
Read-write
0x0
0x38
Chip Select Register 2
SPI_CSR2
Read-write
0x0
0x3C
Chip Select Register 3
SPI_CSR3
Read-write
0x0
–
–
–
0x004C - 0x00F8
0x100 - 0x124
Reserved
Reserved for the PDC
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6384E–ATARM–05-Feb-10
30.7.1
Name:
SPI Control Register
SPI_CR
Access Type:
Write-only
31
30
29
28
27
26
25
24
–
–
–
–
–
–
–
LASTXFER
23
22
21
20
19
18
17
16
–
–
–
–
–
–
–
–
15
14
13
12
11
10
9
8
–
–
–
–
–
–
–
–
7
6
5
4
3
2
1
0
SWRST
–
–
–
–
–
SPIDIS
SPIEN
• SPIEN: SPI Enable
0 = No effect.
1 = Enables the SPI to transfer and receive data.
• SPIDIS: SPI Disable
0 = No effect.
1 = Disables the SPI.
As soon as SPIDIS is set, SPI finishes its transfer.
All pins are set in input mode and no data is received or transmitted.
If a transfer is in progress, the transfer is finished before the SPI is disabled.
If both SPIEN and SPIDIS are equal to one when the control register is written, the SPI is disabled.
• SWRST: SPI Software Reset
0 = No effect.
1 = Reset the SPI. A software-triggered hardware reset of the SPI interface is performed.
The SPI is in slave mode after software reset.
PDC channels are not affected by software reset.
• LASTXFER: Last Transfer
0 = No effect.
1 = The current NPCS will be deasserted after the character written in TD has been transferred. When CSAAT is set, this
allows to close the communication with the current serial peripheral by raising the corresponding NPCS line as soon as TD
transfer has completed.
404
AT91SAM9G20
6384E–ATARM–05-Feb-10
AT91SAM9G20
30.7.2
Name:
SPI Mode Register
SPI_MR
Access Type:
31
Read/Write
30
29
28
27
26
19
18
25
24
17
16
DLYBCS
23
22
21
20
–
–
–
–
15
14
13
12
11
10
9
8
–
–
–
–
–
–
–
–
3
7
6
5
4
LLB
–
–
MODFDIS
PCS
2
1
0
PCSDEC
PS
MSTR
• MSTR: Master/Slave Mode
0 = SPI is in Slave mode.
1 = SPI is in Master mode.
• PS: Peripheral Select
0 = Fixed Peripheral Select.
1 = Variable Peripheral Select.
• PCSDEC: Chip Select Decode
0 = The chip selects are directly connected to a peripheral device.
1 = The four chip select lines are connected to a 4- to 16-bit decoder.
When PCSDEC equals one, up to 15 Chip Select signals can be generated with the four lines using an external 4- to 16-bit
decoder. The Chip Select Registers define the characteristics of the 15 chip selects according to the following rules:
SPI_CSR0 defines peripheral chip select signals 0 to 3.
SPI_CSR1 defines peripheral chip select signals 4 to 7.
SPI_CSR2 defines peripheral chip select signals 8 to 11.
SPI_CSR3 defines peripheral chip select signals 12 to 14.
• MODFDIS: Mode Fault Detection
0 = Mode fault detection is enabled.
1 = Mode fault detection is disabled.
• LLB: Local Loopback Enable
0 = Local loopback path disabled.
1 = Local loopback path enabled.
LLB controls the local loopback on the data serializer for testing in Master Mode only. (MISO is internally connected on
MOSI.)
• PCS: Peripheral Chip Select
This field is only used if Fixed Peripheral Select is active (PS = 0).
405
6384E–ATARM–05-Feb-10
If PCSDEC = 0:
PCS = xxx0
NPCS[3:0] = 1110
PCS = xx01
NPCS[3:0] = 1101
PCS = x011
NPCS[3:0] = 1011
PCS = 0111
NPCS[3:0] = 0111
PCS = 1111
forbidden (no peripheral is selected)
(x = don’t care)
If PCSDEC = 1:
NPCS[3:0] output signals = PCS.
• DLYBCS: Delay Between Chip Selects
This field defines the delay from NPCS inactive to the activation of another NPCS. The DLYBCS time guarantees non-overlapping chip selects and solves bus contentions in case of peripherals having long data float times.
If DLYBCS is less than or equal to six, six MCK periods will be inserted by default.
Otherwise, the following equation determines the delay:
DLYBCS
Delay Between Chip Selects = ------------------------MCK
406
AT91SAM9G20
6384E–ATARM–05-Feb-10
AT91SAM9G20
30.7.3
Name:
SPI Receive Data Register
SPI_RDR
Access Type:
Read-only
31
30
29
28
27
26
25
24
–
–
–
–
–
–
–
–
23
22
21
20
19
18
17
16
–
–
–
–
15
14
13
12
PCS
11
10
9
8
3
2
1
0
RD
7
6
5
4
RD
• RD: Receive Data
Data received by the SPI Interface is stored in this register right-justified. Unused bits read zero.
• PCS: Peripheral Chip Select
In Master Mode only, these bits indicate the value on the NPCS pins at the end of a transfer. Otherwise, these bits read
zero.
407
6384E–ATARM–05-Feb-10
30.7.4
Name:
SPI Transmit Data Register
SPI_TDR
Access Type:
Write-only
31
30
29
28
27
26
25
24
–
–
–
–
–
–
–
LASTXFER
23
22
21
20
19
18
17
16
–
–
–
–
15
14
13
12
PCS
11
10
9
8
3
2
1
0
TD
7
6
5
4
TD
• TD: Transmit Data
Data to be transmitted by the SPI Interface is stored in this register. Information to be transmitted must be written to the
transmit data register in a right-justified format.
• PCS: Peripheral Chip Select
This field is only used if Variable Peripheral Select is active (PS = 1).
If PCSDEC = 0:
PCS = xxx0
NPCS[3:0] = 1110
PCS = xx01
NPCS[3:0] = 1101
PCS = x011
NPCS[3:0] = 1011
PCS = 0111
NPCS[3:0] = 0111
PCS = 1111
forbidden (no peripheral is selected)
(x = don’t care)
If PCSDEC = 1:
NPCS[3:0] output signals = PCS
• LASTXFER: Last Transfer
0 = No effect.
1 = The current NPCS will be deasserted after the character written in TD has been transferred. When CSAAT is set, this
allows to close the communication with the current serial peripheral by raising the corresponding NPCS line as soon as TD
transfer has completed.
This field is only used if Variable Peripheral Select is active (PS = 1).
408
AT91SAM9G20
6384E–ATARM–05-Feb-10
AT91SAM9G20
30.7.5
Name:
SPI Status Register
SPI_SR
Access Type:
Read-only
31
30
29
28
27
26
25
24
–
–
–
–
–
–
–
–
23
22
21
20
19
18
17
16
–
–
–
–
–
–
–
SPIENS
15
14
13
12
11
10
9
8
–
–
–
–
–
-
TXEMPTY
NSSR
7
6
5
4
3
2
1
0
TXBUFE
RXBUFF
ENDTX
ENDRX
OVRES
MODF
TDRE
RDRF
• RDRF: Receive Data Register Full
0 = No data has been received since the last read of SPI_RDR
1 = Data has been received and the received data has been transferred from the serializer to SPI_RDR since the last read
of SPI_RDR.
• TDRE: Transmit Data Register Empty
0 = Data has been written to SPI_TDR and not yet transferred to the serializer.
1 = The last data written in the Transmit Data Register has been transferred to the serializer.
TDRE equals zero when the SPI is disabled or at reset. The SPI enable command sets this bit to one.
• MODF: Mode Fault Error
0 = No Mode Fault has been detected since the last read of SPI_SR.
1 = A Mode Fault occurred since the last read of the SPI_SR.
• OVRES: Overrun Error Status
0 = No overrun has been detected since the last read of SPI_SR.
1 = An overrun has occurred since the last read of SPI_SR.
An overrun occurs when SPI_RDR is loaded at least twice from the serializer since the last read of the SPI_RDR.
• ENDRX: End of RX buffer
0 = The Receive Counter Register has not reached 0 since the last write in SPI_RCR(1) or SPI_RNCR(1).
1 = The Receive Counter Register has reached 0 since the last write in SPI_RCR(1) or SPI_RNCR(1).
• ENDTX: End of TX buffer
0 = The Transmit Counter Register has not reached 0 since the last write in SPI_TCR(1) or SPI_TNCR(1).
1 = The Transmit Counter Register has reached 0 since the last write in SPI_TCR(1) or SPI_TNCR(1).
• RXBUFF: RX Buffer Full
0 = SPI_RCR(1) or SPI_RNCR(1) has a value other than 0.
1 = Both SPI_RCR(1) and SPI_RNCR(1) have a value of 0.
409
6384E–ATARM–05-Feb-10
• TXBUFE: TX Buffer Empty
0 = SPI_TCR(1) or SPI_TNCR(1) has a value other than 0.
1 = Both SPI_TCR(1) and SPI_TNCR(1) have a value of 0.
• NSSR: NSS Rising
0 = No rising edge detected on NSS pin since last read.
1 = A rising edge occurred on NSS pin since last read.
• TXEMPTY: Transmission Registers Empty
0 = As soon as data is written in SPI_TDR.
1 = SPI_TDR and internal shifter are empty. If a transfer delay has been defined, TXEMPTY is set after the completion of
such delay.
• SPIENS: SPI Enable Status
0 = SPI is disabled.
1 = SPI is enabled.
Note:
410
1. SPI_RCR, SPI_RNCR, SPI_TCR, SPI_TNCR are physically located in the PDC.
AT91SAM9G20
6384E–ATARM–05-Feb-10
AT91SAM9G20
30.7.6
Name:
SPI Interrupt Enable Register
SPI_IER
Access Type:
Write-only
31
30
29
28
27
26
25
24
–
–
–
–
–
–
–
–
23
22
21
20
19
18
17
16
–
–
–
–
–
–
–
–
15
14
13
12
11
10
9
8
–
–
–
–
–
-
TXEMPTY
NSSR
7
6
5
4
3
2
1
0
TXBUFE
RXBUFF
ENDTX
ENDRX
OVRES
MODF
TDRE
RDRF
• RDRF: Receive Data Register Full Interrupt Enable
• TDRE: SPI Transmit Data Register Empty Interrupt Enable
• MODF: Mode Fault Error Interrupt Enable
• OVRES: Overrun Error Interrupt Enable
• ENDRX: End of Receive Buffer Interrupt Enable
• ENDTX: End of Transmit Buffer Interrupt Enable
• RXBUFF: Receive Buffer Full Interrupt Enable
• TXBUFE: Transmit Buffer Empty Interrupt Enable
• NSSR: NSS Rising Interrupt Enable
0 = No effect.
1 = Enables the corresponding interrupt.
• TXEMPTY: Transmission Registers Empty Enable
411
6384E–ATARM–05-Feb-10
30.7.7
Name:
SPI Interrupt Disable Register
SPI_IDR
Access Type:
Write-only
31
30
29
28
27
26
25
24
–
–
–
–
–
–
–
–
23
22
21
20
19
18
17
16
–
–
–
–
–
–
–
–
15
14
13
12
11
10
9
8
–
–
–
–
–
-
TXEMPTY
NSSR
7
6
5
4
3
2
1
0
TXBUFE
RXBUFF
ENDTX
ENDRX
OVRES
MODF
TDRE
RDRF
• RDRF: Receive Data Register Full Interrupt Disable
• TDRE: SPI Transmit Data Register Empty Interrupt Disable
• MODF: Mode Fault Error Interrupt Disable
• OVRES: Overrun Error Interrupt Disable
• ENDRX: End of Receive Buffer Interrupt Disable
• ENDTX: End of Transmit Buffer Interrupt Disable
• RXBUFF: Receive Buffer Full Interrupt Disable
• TXBUFE: Transmit Buffer Empty Interrupt Disable
• NSSR: NSS Rising Interrupt Disable
0 = No effect.
1 = Disables the corresponding interrupt.
• TXEMPTY: Transmission Registers Empty Disable
412
AT91SAM9G20
6384E–ATARM–05-Feb-10
AT91SAM9G20
30.7.8
Name:
SPI Interrupt Mask Register
SPI_IMR
Access Type:
Read-only
31
30
29
28
27
26
25
24
–
–
–
–
–
–
–
–
23
22
21
20
19
18
17
16
–
–
–
–
–
–
–
–
15
14
13
12
11
10
–
–
–
–
–
9
8
TXEMPTY
NSSR
7
6
5
4
3
2
1
0
TXBUFE
RXBUFF
ENDTX
ENDRX
OVRES
MODF
TDRE
RDRF
• RDRF: Receive Data Register Full Interrupt Mask
• TDRE: SPI Transmit Data Register Empty Interrupt Mask
• MODF: Mode Fault Error Interrupt Mask
• OVRES: Overrun Error Interrupt Mask
• ENDRX: End of Receive Buffer Interrupt Mask
• ENDTX: End of Transmit Buffer Interrupt Mask
• RXBUFF: Receive Buffer Full Interrupt Mask
• TXBUFE: Transmit Buffer Empty Interrupt Mask
• NSSR: NSS Rising Interrupt Mask
0 = The corresponding interrupt is not enabled.
1 = The corresponding interrupt is enabled.
• TXEMPTY: Transmission Registers Empty Mask
413
6384E–ATARM–05-Feb-10
AT91SAM9G20
30.7.9
Name:
SPI Chip Select Register
SPI_CSR0... SPI_CSR3
Access Type:
31
Read/Write
30
29
28
27
26
25
24
19
18
17
16
11
10
9
8
DLYBCT
23
22
21
20
DLYBS
15
14
13
12
SCBR
7
6
5
4
BITS
3
2
1
0
CSAAT
–
NCPHA
CPOL
• CPOL: Clock Polarity
0 = The inactive state value of SPCK is logic level zero.
1 = The inactive state value of SPCK is logic level one.
CPOL is used to determine the inactive state value of the serial clock (SPCK). It is used with NCPHA to produce the
required clock/data relationship between master and slave devices.
• NCPHA: Clock Phase
0 = Data is changed on the leading edge of SPCK and captured on the following edge of SPCK.
1 = Data is captured on the leading edge of SPCK and changed on the following edge of SPCK.
NCPHA determines which edge of SPCK causes data to change and which edge causes data to be captured. NCPHA is
used with CPOL to produce the required clock/data relationship between master and slave devices.
• CSAAT: Chip Select Active After Transfer
0 = The Peripheral Chip Select Line rises as soon as the last transfer is achieved.
1 = The Peripheral Chip Select does not rise after the last transfer is achieved. It remains active until a new transfer is
requested on a different chip select.
• BITS: Bits Per Transfer
The BITS field determines the number of data bits transferred. Reserved values should not be used.
BITS
0000
0001
0010
0011
0100
0101
0110
0111
1000
1001
1010
1011
Bits Per Transfer
8
9
10
11
12
13
14
15
16
Reserved
Reserved
Reserved
414
6384E–ATARM–05-Feb-10
AT91SAM9G20
BITS
1100
1101
1110
1111
Bits Per Transfer
Reserved
Reserved
Reserved
Reserved
• SCBR: Serial Clock Baud Rate
In Master Mode, the SPI Interface uses a modulus counter to derive the SPCK baud rate from the Master Clock MCK. The
Baud rate is selected by writing a value from 1 to 255 in the SCBR field. The following equations determine the SPCK baud
rate:
MCK
SPCK Baudrate = ----------------SCBR
Programming the SCBR field at 0 is forbidden. Triggering a transfer while SCBR is at 0 can lead to unpredictable results.
At reset, SCBR is 0 and the user has to program it at a valid value before performing the first transfer.
• DLYBS: Delay Before SPCK
This field defines the delay from NPCS valid to the first valid SPCK transition.
When DLYBS equals zero, the NPCS valid to SPCK transition is 1/2 the SPCK clock period.
Otherwise, the following equations determine the delay:
DLYBS
Delay Before SPCK = --------------------MCK
• DLYBCT: Delay Between Consecutive Transfers
This field defines the delay between two consecutive transfers with the same peripheral without removing the chip select.
The delay is always inserted after each transfer and before removing the chip select if needed.
When DLYBCT equals zero, no delay between consecutive transfers is inserted and the clock keeps its duty cycle over the
character transfers.
Otherwise, the following equation determines the delay:
32 × DLYBCT
Delay Between Consecutive Transfers = --------------------------------------MCK
415
6384E–ATARM–05-Feb-10
416
AT91SAM9G20
6384E–ATARM–05-Feb-10
AT91SAM9G20
31. Two-wire Interface (TWI)
31.1
Overview
The Atmel Two-wire Interface (TWI) interconnects components on a unique two-wire bus, made
up of one clock line and one data line with speeds of up to 400 Kbits per second, based on a
byte-oriented transfer format. It can be used with any Atmel Two-wire Interface bus Serial
EEPROM and I²C compatible device such as Real Time Clock (RTC), Dot Matrix/Graphic LCD
Controllers and Temperature Sensor, to name but a few. The TWI is programmable as a master
or a slave with sequential or single-byte access. Multiple master capability is supported. Arbitration of the bus is performed internally and puts the TWI in slave mode automatically if the bus
arbitration is lost.
A configurable baud rate generator permits the output data rate to be adapted to a wide range of
core clock frequencies.
Below, Table 31-1 lists the compatibility level of the Atmel Two-wire Interface in Master Mode and
a full I2C compatible device.
Table 31-1.
Atmel TWI compatibility with i2C Standard
I2C Standard
Atmel TWI
Standard Mode Speed (100 KHz)
Supported
Fast Mode Speed (400 KHz)
Supported
7 or 10 bits Slave Addressing
Supported
(1)
START BYTE
Not Supported
Repeated Start (Sr) Condition
Supported
ACK and NACK Management
Supported
Slope control and input filtering (Fast mode)
Not Supported
Clock stretching
Supported
Note:
31.2
1. START + b000000001 + Ack + Sr
List of Abbreviations
Table 31-2.
Abbreviations
Abbreviation
Description
TWI
Two-wire Interface
A
Acknowledge
NA
Non Acknowledge
P
Stop
S
Start
Sr
Repeated Start
SADR
Slave Address
417
6384E–ATARM–05-Feb-10
Table 31-2.
31.3
Abbreviations
Abbreviation
Description
ADR
Any address except SADR
R
Read
W
Write
Block Diagram
Figure 31-1. Block Diagram
APB Bridge
TWCK
PIO
PMC
MCK
TWD
Two-wire
Interface
TWI
Interrupt
31.4
AIC
Application Block Diagram
Figure 31-2. Application Block Diagram
VDD
Rp
Host with
TWI
Interface
Rp
TWD
TWCK
Atmel TWI
Serial EEPROM
Slave 1
I²C RTC
I²C LCD
Controller
I²C Temp.
Sensor
Slave 2
Slave 3
Slave 4
Rp: Pull up value as given by the I²C Standard
418
AT91SAM9G20
6384E–ATARM–05-Feb-10
AT91SAM9G20
31.4.1
I/O Lines Description
Table 31-3.
I/O Lines Description
Pin Name
Pin Description
TWD
Two-wire Serial Data
Input/Output
TWCK
Two-wire Serial Clock
Input/Output
31.5
31.5.1
Type
Product Dependencies
I/O Lines
Both TWD and TWCK are bidirectional lines, connected to a positive supply voltage via a current
source or pull-up resistor (see Figure 31-2 on page 418). When the bus is free, both lines are
high. The output stages of devices connected to the bus must have an open-drain or open-collector to perform the wired-AND function.
TWD and TWCK pins may be multiplexed with PIO lines. To enable the TWI, the programmer
must perform the following steps:
• Program the PIO controller to:
– Dedicate TWD and TWCK as peripheral lines.
– Define TWD and TWCK as open-drain.
31.5.2
Power Management
• Enable the peripheral clock.
The TWI interface may be clocked through the Power Management Controller (PMC), thus the
programmer must first configure the PMC to enable the TWI clock.
31.5.3
Interrupt
The TWI interface has an interrupt line connected to the Advanced Interrupt Controller (AIC). In
order to handle interrupts, the AIC must be programmed before configuring the TWI.
31.6
31.6.1
Functional Description
Transfer Format
The data put on the TWD line must be 8 bits long. Data is transferred MSB first; each byte must
be followed by an acknowledgement. The number of bytes per transfer is unlimited (see Figure
31-4).
Each transfer begins with a START condition and terminates with a STOP condition (see Figure
31-3).
• A high-to-low transition on the TWD line while TWCK is high defines the START condition.
• A low-to-high transition on the TWD line while TWCK is high defines a STOP condition.
419
6384E–ATARM–05-Feb-10
Figure 31-3.
START and STOP Conditions
TWD
TWCK
Start
Stop
Figure 31-4. Transfer Format
TWD
TWCK
Start
31.6.2
Address
R/W
Ack
Data
Ack
Data
Ack
Stop
Modes of Operation
The TWI has six modes of operations:
• Master transmitter mode
• Master receiver mode
• Multi-master transmitter mode
• Multi-master receiver mode
• Slave transmitter mode
• Slave receiver mode
These modes are described in the following chapters.
420
AT91SAM9G20
6384E–ATARM–05-Feb-10
AT91SAM9G20
31.7
Master Mode
31.7.1
Definition
The Master is the device that starts a transfer, generates a clock and stops it.
31.7.2
Application Block Diagram
Figure 31-5. Master Mode Typical Application Block Diagram
VDD
Rp
Host with
TWI
Interface
Rp
TWD
TWCK
Atmel TWI
Serial EEPROM
Slave 1
I²C RTC
I²C LCD
Controller
I²C Temp.
Sensor
Slave 2
Slave 3
Slave 4
Rp: Pull up value as given by the I²C Standard
31.7.3
Programming Master Mode
The following registers have to be programmed before entering Master mode:
1. DADR (+ IADRSZ + IADR if a 10 bit device is addressed): The device address is used
to access slave devices in read or write mode.
2. CKDIV + CHDIV + CLDIV: Clock Waveform.
3. SVDIS: Disable the slave mode.
4. MSEN: Enable the master mode.
31.7.4
Master Transmitter Mode
After the master initiates a Start condition when writing into the Transmit Holding Register,
TWI_THR, it sends a 7-bit slave address, configured in the Master Mode register (DADR in
TWI_MMR), to notify the slave device. The bit following the slave address indicates the transfer
direction, 0 in this case (MREAD = 0 in TWI_MMR).
The TWI transfers require the slave to acknowledge each received byte. During the acknowledge clock pulse (9th pulse), the master releases the data line (HIGH), enabling the slave to pull
it down in order to generate the acknowledge. The master polls the data line during this clock
pulse and sets the Not Acknowledge bit (NACK) in the status register if the slave does not
acknowledge the byte. As with the other status bits, an interrupt can be generated if enabled in
the interrupt enable register (TWI_IER). If the slave acknowledges the byte, the data written in
the TWI_THR, is then shifted in the internal shifter and transferred. When an acknowledge is
detected, the TXRDY bit is set until a new write in the TWI_THR.
421
6384E–ATARM–05-Feb-10
When no more data is written into the TWI_THR, the master generates a stop condition to end
the transfer. The end of the complete transfer is marked by the TWI_TXCOMP bit set to one.
See Figure 31-6, Figure 31-7, and Figure 31-8.
TXRDY is used as Transmit Ready for the PDC transmit channel.
Figure 31-6. Master Write with On Data Byte
S
TWD
DADR
W
A
DATA
A
P
TXCOMP
TXRDY
STOP sent automaticaly
(ACK received and TXRDY = 1)
Write THR (DATA)
Figure 31-7. Master Write with Multiple Data Byte
TWD
S
DADR
W
A
DATA n
A
DATA n+5
A
DATA n+x
A
P
TXCOMP
TXRDY
Write THR (Data n)
Write THR (Data n+1)
Write THR (Data n+x)
Last data sent
STOP sent automaticaly
(ACK received and TXRDY = 1)
Figure 31-8. Master Write with One Byte Internal Address and Multiple Data Bytes
TWD S
DADR
W
A
IADR(7:0)
A
DATA n
A
DATA n+5
A
DATA n+x
A
P
TXCOMP
TXRDY
Write THR (Data n)
31.7.5
422
Write THR (Data n+1)
Write THR (Data n+x) STOP sent automaticaly
Last data sent (ACK received and TXRDY = 1)
Master Receiver Mode
The read sequence begins by setting the START bit. After the start condition has been sent, the
master sends a 7-bit slave address to notify the slave device. The bit following the slave address
indicates the transfer direction, 1 in this case (MREAD = 1 in TWI_MMR). During the acknowledge clock pulse (9th pulse), the master releases the data line (HIGH), enabling the slave to pull
it down in order to generate the acknowledge. The master polls the data line during this clock
pulse and sets the NACK bit in the status register if the slave does not acknowledge the byte.
AT91SAM9G20
6384E–ATARM–05-Feb-10
AT91SAM9G20
If an acknowledge is received, the master is then ready to receive data from the slave. After data
has been received, the master sends an acknowledge condition to notify the slave that the data
has been received except for the last data, after the stop condition. See Figure 31-9. When the
RXRDY bit is set in the status register, a character has been received in the receive-holding register (TWI_RHR). The RXRDY bit is reset when reading the TWI_RHR.
When a single data byte read is performed, with or without internal address (IADR), the START
and STOP bits must be set at the same time. See Figure 31-9. When a multiple data byte read is
performed, with or without internal address (IADR), the STOP bit must be set after the next-tolast data received. See Figure 31-10. For Internal Address usage see Section 31.7.6.
Figure 31-9. Master Read with One Data Byte
TWD
S
DADR
R
A
DATA
N
P
TXCOMP
Write START &
STOP Bit
RXRDY
Read RHR
Figure 31-10. Master Read with Multiple Data Bytes
TWD
S
DADR
R
A
DATA n
A
DATA (n+1)
A
DATA (n+m)-1
A
DATA (n+m)
N
P
TXCOMP
Write START Bit
RXRDY
Read RHR
DATA n
Read RHR
DATA (n+1)
Read RHR
DATA (n+m)-1
Read RHR
DATA (n+m)
Write STOP Bit
after next-to-last data read
RXRDY is used as Receive Ready for the PDC receive channel.
31.7.6
31.7.6.1
Internal Address
The TWI interface can perform various transfer formats: Transfers with 7-bit slave address
devices and 10-bit slave address devices.
7-bit Slave Addressing
When Addressing 7-bit slave devices, the internal address bytes are used to perform random
address (read or write) accesses to reach one or more data bytes, within a memory page location in a serial memory, for example. When performing read operations with an internal address,
the TWI performs a write operation to set the internal address into the slave device, and then
switch to Master Receiver mode. Note that the second start condition (after sending the IADR) is
423
6384E–ATARM–05-Feb-10
sometimes called “repeated start” (Sr) in I2C fully-compatible devices. See Figure 31-12. See
Figure 31-11 and Figure 31-13 for Master Write operation with internal address.
The three internal address bytes are configurable through the Master Mode register
(TWI_MMR).
If the slave device supports only a 7-bit address, i.e. no internal address, IADRSZ must be set to
0.
In the figures below the following abbreviations are used:
•S
Start
• Sr
Repeated Start
•P
Stop
•W
Write
•R
Read
•A
Acknowledge
•N
Not Acknowledge
• DADR
Device Address
• IADR
Internal Address
Figure 31-11. Master Write with One, Two or Three Bytes Internal Address and One Data Byte
Three bytes internal address
S
TWD
DADR
W
A
IADR(23:16)
A
IADR(15:8)
A
IADR(7:0)
A
W
A
IADR(15:8)
A
IADR(7:0)
A
DATA
A
W
A
IADR(7:0)
A
DATA
A
DATA
A
P
Two bytes internal address
S
TWD
DADR
P
One byte internal address
S
TWD
DADR
P
Figure 31-12. Master Read with One, Two or Three Bytes Internal Address and One Data Byte
Three bytes internal address
S
TWD
DADR
W
A
IADR(23:16)
A
IADR(15:8)
A
IADR(7:0)
A
Sr
DADR
R
A
DATA
N
P
Two bytes internal address
S
TWD
DADR
W
A
IADR(15:8)
A
IADR(7:0)
A
Sr
W
A
IADR(7:0)
A
Sr
R
A
DADR
R
A
DATA
N
P
One byte internal address
TWD
31.7.6.2
424
S
DADR
DADR
DATA
N
P
10-bit Slave Addressing
For a slave address higher than 7 bits, the user must configure the address size (IADRSZ) and
set the other slave address bits in the internal address register (TWI_IADR). The two remaining
AT91SAM9G20
6384E–ATARM–05-Feb-10
AT91SAM9G20
Internal address bytes, IADR[15:8] and IADR[23:16] can be used the same as in 7-bit Slave
Addressing.
Example: Address a 10-bit device (10-bit device address is b1 b2 b3 b4 b5 b6 b7 b8 b9 b10)
1. Program IADRSZ = 1,
2. Program DADR with 1 1 1 1 0 b1 b2 (b1 is the MSB of the 10-bit address, b2, etc.)
3. Program TWI_IADR with b3 b4 b5 b6 b7 b8 b9 b10 (b10 is the LSB of the 10-bit
address)
Figure 31-13 below shows a byte write to an Atmel AT24LC512 EEPROM. This demonstrates
the use of internal addresses to access the device.
Figure 31-13. Internal Address Usage
S
T
A
R
T
Device
Address
W
R
I
T
E
FIRST
WORD ADDRESS
SECOND
WORD ADDRESS
S
T
O
P
DATA
0
M
S
B
LR A
S / C
BW K
M
S
B
A
C
K
LA
SC
BK
A
C
K
425
6384E–ATARM–05-Feb-10
31.7.7
Using the Peripheral DMA Controller (PDC)
The use of the PDC significantly reduces the CPU load.
To assure correct implementation, respect the following programming sequences:
31.7.7.1
Data Transmit with the PDC
1. Initialize the transmit PDC (memory pointers, size, etc.).
2. Configure the master mode (DADR, CKDIV, etc.).
3. Start the transfer by setting the PDC TXTEN bit.
4. Wait for the PDC end TX flag.
5. Disable the PDC by setting the PDC TXDIS bit.
31.7.7.2
Data Receive with the PDC
1. Initialize the receive PDC (memory pointers, size - 1, etc.).
2. Configure the master mode (DADR, CKDIV, etc.).
3. Start the transfer by setting the PDC RXTEN bit.
4. Wait for the PDC end RX flag.
5. Disable the PDC by setting the PDC RXDIS bit.
31.7.8
426
Read-write Flowcharts
The following flowcharts shown in Figure 31-15 on page 428, Figure 31-16 on page 429, Figure
31-17 on page 430, Figure 31-18 on page 431 and Figure 31-19 on page 432 give examples for
read and write operations. A polling or interrupt method can be used to check the status bits.
The interrupt method requires that the interrupt enable register (TWI_IER) be configured first.
AT91SAM9G20
6384E–ATARM–05-Feb-10
AT91SAM9G20
Figure 31-14. TWI Write Operation with Single Data Byte without Internal Address
BEGIN
Set TWI clock
(CLDIV, CHDIV, CKDIV) in TWI_CWGR
(Needed only once)
Set the Control register:
- Master enable
TWI_CR = MSEN + SVDIS
Set the Master Mode register:
- Device slave address (DADR)
- Transfer direction bit
Write ==> bit MREAD = 0
Load Transmit register
TWI_THR = Data to send
Read Status register
No
TXRDY = 1?
Yes
Read Status register
No
TXCOMP = 1?
Yes
Transfer finished
427
6384E–ATARM–05-Feb-10
Figure 31-15. TWI Write Operation with Single Data Byte and Internal Address
BEGIN
Set TWI clock
(CLDIV, CHDIV, CKDIV) in TWI_CWGR
(Needed only once)
Set the Control register:
- Master enable
TWI_CR = MSEN + SVDIS
Set the Master Mode register:
- Device slave address (DADR)
- Internal address size (IADRSZ)
- Transfer direction bit
Write ==> bit MREAD = 0
Set the internal address
TWI_IADR = address
Load transmit register
TWI_THR = Data to send
Read Status register
No
TXRDY = 1?
Yes
Read Status register
TXCOMP = 1?
No
Yes
Transfer finished
428
AT91SAM9G20
6384E–ATARM–05-Feb-10
AT91SAM9G20
Figure 31-16. TWI Write Operation with Multiple Data Bytes with or without Internal Address
BEGIN
Set TWI clock
(CLDIV, CHDIV, CKDIV) in TWI_CWGR
(Needed only once)
Set the Control register:
- Master enable
TWI_CR = MSEN + SVDIS
Set the Master Mode register:
- Device slave address
- Internal address size (if IADR used)
- Transfer direction bit
Write ==> bit MREAD = 0
No
Internal address size = 0?
Set the internal address
TWI_IADR = address
Yes
Load Transmit register
TWI_THR = Data to send
Read Status register
TWI_THR = data to send
No
TXRDY = 1?
Yes
Data to send?
Yes
Read Status register
Yes
No
TXCOMP = 1?
END
429
6384E–ATARM–05-Feb-10
Figure 31-17. TWI Read Operation with Single Data Byte without Internal Address
BEGIN
Set TWI clock
(CLDIV, CHDIV, CKDIV) in TWI_CWGR
(Needed only once)
Set the Control register:
- Master enable
TWI_CR = MSEN + SVDIS
Set the Master Mode register:
- Device slave address
- Transfer direction bit
Read ==> bit MREAD = 1
Start the transfer
TWI_CR = START | STOP
Read status register
RXRDY = 1?
No
Yes
Read Receive Holding Register
Read Status register
No
TXCOMP = 1?
Yes
END
430
AT91SAM9G20
6384E–ATARM–05-Feb-10
AT91SAM9G20
Figure 31-18. TWI Read Operation with Single Data Byte and Internal Address
BEGIN
Set TWI clock
(CLDIV, CHDIV, CKDIV) in TWI_CWGR
(Needed only once)
Set the Control register:
- Master enable
TWI_CR = MSEN + SVDIS
Set the Master Mode register:
- Device slave address
- Internal address size (IADRSZ)
- Transfer direction bit
Read ==> bit MREAD = 1
Set the internal address
TWI_IADR = address
Start the transfer
TWI_CR = START | STOP
Read Status register
No
RXRDY = 1?
Yes
Read Receive Holding register
Read Status register
No
TXCOMP = 1?
Yes
END
431
6384E–ATARM–05-Feb-10
Figure 31-19. TWI Read Operation with Multiple Data Bytes with or without Internal Address
BEGIN
Set TWI clock
(CLDIV, CHDIV, CKDIV) in TWI_CWGR
(Needed only once)
Set the Control register:
- Master enable
TWI_CR = MSEN + SVDIS
Set the Master Mode register:
- Device slave address
- Internal address size (if IADR used)
- Transfer direction bit
Read ==> bit MREAD = 1
Internal address size = 0?
Set the internal address
TWI_IADR = address
Yes
Start the transfer
TWI_CR = START
Read Status register
RXRDY = 1?
No
Yes
Read Receive Holding register (TWI_RHR)
No
Last data to read
but one?
Yes
Stop the transfer
TWI_CR = STOP
Read Status register
No
RXRDY = 1?
Yes
Read Receive Holding register (TWI_RHR)
Read status register
TXCOMP = 1?
No
Yes
END
432
AT91SAM9G20
6384E–ATARM–05-Feb-10
AT91SAM9G20
31.8
Multi-master Mode
31.8.1
Definition
More than one master may handle the bus at the same time without data corruption by using
arbitration.
Arbitration starts as soon as two or more masters place information on the bus at the same time,
and stops (arbitration is lost) for the master that intends to send a logical one while the other
master sends a logical zero.
As soon as arbitration is lost by a master, it stops sending data and listens to the bus in order to
detect a stop. When the stop is detected, the master who has lost arbitration may put its data on
the bus by respecting arbitration.
Arbitration is illustrated in Figure 31-21 on page 434.
31.8.2
Different Multi-master Modes
Two multi-master modes may be distinguished:
1. TWI is considered as a Master only and will never be addressed.
2. TWI may be either a Master or a Slave and may be addressed.
Note:
31.8.2.1
In both Multi-master modes arbitration is supported.
TWI as Master Only
In this mode, TWI is considered as a Master only (MSEN is always at one) and must be driven
like a Master with the ARBLST (ARBitration Lost) flag in addition.
If arbitration is lost (ARBLST = 1), the programmer must reinitiate the data transfer.
If the user starts a transfer (ex.: DADR + START + W + Write in THR) and if the bus is busy, the
TWI automatically waits for a STOP condition on the bus to initiate the transfer (see Figure 3120 on page 434).
Note:
31.8.2.2
The state of the bus (busy or free) is not indicated in the user interface.
TWI as Master or Slave
The automatic reversal from Master to Slave is not supported in case of a lost arbitration.
Then, in the case where TWI may be either a Master or a Slave, the programmer must manage
the pseudo Multi-master mode described in the steps below.
1. Program TWI in Slave mode (SADR + MSDIS + SVEN) and perform Slave Access (if
TWI is addressed).
2. If TWI has to be set in Master mode, wait until TXCOMP flag is at 1.
3. Program Master mode (DADR + SVDIS + MSEN) and start the transfer (ex: START +
Write in THR).
4. As soon as the Master mode is enabled, TWI scans the bus in order to detect if it is
busy or free. When the bus is considered as free, TWI initiates the transfer.
5. As soon as the transfer is initiated and until a STOP condition is sent, the arbitration
becomes relevant and the user must monitor the ARBLST flag.
6. If the arbitration is lost (ARBLST is set to 1), the user must program the TWI in Slave
mode in the case where the Master that won the arbitration wanted to access the TWI.
7. If TWI has to be set in Slave mode, wait until TXCOMP flag is at 1 and then program the
Slave mode.
433
6384E–ATARM–05-Feb-10
Note:
In the case where the arbitration is lost and TWI is addressed, TWI will not acknowledge even if it
is programmed in Slave mode as soon as ARBLST is set to 1. Then, the Master must repeat
SADR.
Figure 31-20. Programmer Sends Data While the Bus is Busy
TWCK
START sent by the TWI
STOP sent by the master
DATA sent by a master
TWD
DATA sent by the TWI
Bus is busy
Bus is free
Transfer is kept
TWI DATA transfer
A transfer is programmed
(DADR + W + START + Write THR)
Bus is considered as free
Transfer is initiated
Figure 31-21. Arbitration Cases
TWCK
TWD
TWCK
Data from a Master
S
1
0 0 1 1
Data from TWI
S
1
0
TWD
S
1
0 0
1
P
Arbitration is lost
TWI stops sending data
1 1
Data from the master
P
Arbitration is lost
S
1
0
S
1
0 0 1
1
S
1
0
1
1
The master stops sending data
0 1
Data from the TWI
ARBLST
Bus is busy
Bus is free
Transfer is kept
TWI DATA transfer
A transfer is programmed
(DADR + W + START + Write THR)
Transfer is stopped
Transfer is programmed again
(DADR + W + START + Write THR)
Bus is considered as free
Transfer is initiated
The flowchart shown in Figure 31-22 on page 435 gives an example of read and write operations
in Multi-master mode.
434
AT91SAM9G20
6384E–ATARM–05-Feb-10
AT91SAM9G20
Figure 31-22. Multi-master Flowchart
START
Programm the SLAVE mode:
SADR + MSDIS + SVEN
Read Status Register
SVACC = 1 ?
Yes
GACC = 1 ?
No
No
SVREAD = 0 ?
No
No
EOSACC = 1 ?
TXRDY= 1 ?
Yes
Yes
Yes
No
Write in TWI_THR
TXCOMP = 1 ?
RXRDY= 0 ?
Yes
No
No
No
Yes
Read TWI_RHR
Need to perform
a master access ?
GENERAL CALL TREATMENT
Yes
Decoding of the
programming sequence
Prog seq
OK ?
No
Change SADR
Program the Master mode
DADR + SVDIS + MSEN + CLK + R / W
Read Status Register
Yes
No
ARBLST = 1 ?
Yes
Yes
MREAD = 1 ?
RXRDY= 0 ?
No
TXRDY= 0 ?
No
Read TWI_RHR
Yes
Yes
No
Data to read?
Data to send ?
No
Yes
Write in TWI_THR
No
Stop transfer
Read Status Register
Yes
TXCOMP = 0 ?
No
435
6384E–ATARM–05-Feb-10
31.9
Slave Mode
31.9.1
Definition
The Slave Mode is defined as a mode where the device receives the clock and the address from
another device called the master.
In this mode, the device never initiates and never completes the transmission (START,
REPEATED_START and STOP conditions are always provided by the master).
31.9.2
Application Block Diagram
Figure 31-23. Slave Mode Typical Application Block Diagram
VDD
R
Master
Host with
TWI
Interface
31.9.3
R
TWD
TWCK
Host with TWI
Interface
Host with TWI
Interface
LCD Controller
Slave 1
Slave 2
Slave 3
Programming Slave Mode
The following fields must be programmed before entering Slave mode:
1. SADR (TWI_SMR): The slave device address is used in order to be accessed by master devices in read or write mode.
2. MSDIS (TWI_CR): Disable the master mode.
3. SVEN (TWI_CR): Enable the slave mode.
As the device receives the clock, values written in TWI_CWGR are not taken into account.
31.9.4
Receiving Data
After a Start or Repeated Start condition is detected and if the address sent by the Master
matches with the Slave address programmed in the SADR (Slave ADdress) field, SVACC (Slave
ACCess) flag is set and SVREAD (Slave READ) indicates the direction of the transfer.
SVACC remains high until a STOP condition or a repeated START is detected. When such a
condition is detected, EOSACC (End Of Slave ACCess) flag is set.
31.9.4.1
Read Sequence
In the case of a Read sequence (SVREAD is high), TWI transfers data written in the TWI_THR
(TWI Transmit Holding Register) until a STOP condition or a REPEATED_START + an address
different from SADR is detected. Note that at the end of the read sequence TXCOMP (Transmission Complete) flag is set and SVACC reset.
As soon as data is written in the TWI_THR, TXRDY (Transmit Holding Register Ready) flag is
reset, and it is set when the shift register is empty and the sent data acknowledged or not. If the
data is not acknowledged, the NACK flag is set.
436
AT91SAM9G20
6384E–ATARM–05-Feb-10
AT91SAM9G20
Note that a STOP or a repeated START always follows a NACK.
See Figure 31-24 on page 438.
31.9.4.2
Write Sequence
In the case of a Write sequence (SVREAD is low), the RXRDY (Receive Holding Register
Ready) flag is set as soon as a character has been received in the TWI_RHR (TWI Receive
Holding Register). RXRDY is reset when reading the TWI_RHR.
TWI continues receiving data until a STOP condition or a REPEATED_START + an address different from SADR is detected. Note that at the end of the write sequence TXCOMP flag is set
and SVACC reset.
See Figure 31-25 on page 438.
31.9.4.3
Clock Synchronization Sequence
In the case where TWI_THR or TWI_RHR is not written/read in time, TWI performs a clock
synchronization.
Clock stretching information is given by the SCLWS (Clock Wait state) bit.
See Figure 31-27 on page 440 and Figure 31-28 on page 441.
31.9.4.4
General Call
In the case where a GENERAL CALL is performed, GACC (General Call ACCess) flag is set.
After GACC is set, it is up to the programmer to interpret the meaning of the GENERAL CALL
and to decode the new address programming sequence.
See Figure 31-26 on page 439.
31.9.4.5
PDC
As it is impossible to know the exact number of data to receive/send, the use of PDC is NOT recommended in SLAVE mode.
31.9.5
31.9.5.1
Data Transfer
Read Operation
The read mode is defined as a data requirement from the master.
After a START or a REPEATED START condition is detected, the decoding of the address
starts. If the slave address (SADR) is decoded, SVACC is set and SVREAD indicates the direction of the transfer.
Until a STOP or REPEATED START condition is detected, TWI continues sending data loaded
in the TWI_THR register.
If a STOP condition or a REPEATED START + an address different from SADR is detected,
SVACC is reset.
Figure 31-24 on page 438 describes the write operation.
437
6384E–ATARM–05-Feb-10
Figure 31-24. Read Access Ordered by a MASTER
SADR matches,
TWI answers with an ACK
SADR does not match,
TWI answers with a NACK
TWD
S
ADR
R
NA
DATA
NA
P/S/Sr
SADR R
A
DATA
A
ACK/NACK from the Master
A
DATA
NA
S/Sr
TXRDY
Read RHR
Write THR
NACK
SVACC
SVREAD
SVREAD has to be taken into account only while SVACC is active
EOSVACC
Notes:
1. When SVACC is low, the state of SVREAD becomes irrelevant.
2. TXRDY is reset when data has been transmitted from TWI_THR to the shift register and set when this data has been
acknowledged or non acknowledged.
31.9.5.2
Write Operation
The write mode is defined as a data transmission from the master.
After a START or a REPEATED START, the decoding of the address starts. If the slave address
is decoded, SVACC is set and SVREAD indicates the direction of the transfer (SVREAD is low in
this case).
Until a STOP or REPEATED START condition is detected, TWI stores the received data in the
TWI_RHR register.
If a STOP condition or a REPEATED START + an address different from SADR is detected,
SVACC is reset.
Figure 31-25 on page 438 describes the Write operation.
Figure 31-25. Write Access Ordered by a Master
SADR does not match,
TWI answers with a NACK
TWD
S
ADR
W
NA
DATA
NA
SADR matches,
TWI answers with an ACK
P/S/Sr
SADR W
A
DATA
A
Read RHR
A
DATA
NA
S/Sr
RXRDY
SVACC
SVREAD
SVREAD has to be taken into account only while SVACC is active
EOSVACC
Notes:
1. When SVACC is low, the state of SVREAD becomes irrelevant.
2. RXRDY is set when data has been transmitted from the shift register to the TWI_RHR and reset when this data is read.
438
AT91SAM9G20
6384E–ATARM–05-Feb-10
AT91SAM9G20
31.9.5.3
General Call
The general call is performed in order to change the address of the slave.
If a GENERAL CALL is detected, GACC is set.
After the detection of General Call, it is up to the programmer to decode the commands which
come afterwards.
In case of a WRITE command, the programmer has to decode the programming sequence and
program a new SADR if the programming sequence matches.
Figure 31-26 on page 439 describes the General Call access.
Figure 31-26. Master Performs a General Call
0000000 + W
TXD
S
GENERAL CALL
RESET command = 00000110X
WRITE command = 00000100X
A
Reset or write DADD
A
DATA1
A
DATA2
A
New SADR
A
P
New SADR
Programming sequence
GCACC
Reset after read
SVACC
Note:
This method allows the user to create an own programming sequence by choosing the programming bytes and the number of them. The programming sequence has to be provided to the
master.
439
6384E–ATARM–05-Feb-10
31.9.5.4
Clock Synchronization
In both read and write modes, it may happen that TWI_THR/TWI_RHR buffer is not filled /emptied before the emission/reception of a new character. In this case, to avoid sending/receiving
undesired data, a clock stretching mechanism is implemented.
31.9.5.5
Clock Synchronization in Read Mode
The clock is tied low if the shift register is empty and if a STOP or REPEATED START condition
was not detected. It is tied low until the shift register is loaded.
Figure 31-27 on page 440 describes the clock synchronization in Read mode.
Figure 31-27. Clock Synchronization in Read Mode
TWI_THR
DATA0
S
SADR
R
DATA1
1
A
DATA0
A
DATA1
DATA2
A
XXXXXXX
DATA2
NA
S
2
TWCK
Write THR
CLOCK is tied low by the TWI
as long as THR is empty
SCLWS
TXRDY
SVACC
SVREAD
As soon as a START is detected
TXCOMP
TWI_THR is transmitted to the shift register
Notes:
Ack or Nack from the master
1
The data is memorized in TWI_THR until a new value is written
2
The clock is stretched after the ACK, the state of TWD is undefined during clock stretching
1. TXRDY is reset when data has been written in the TWI_THR to the shift register and set when this data has been acknowledged or non acknowledged.
2. At the end of the read sequence, TXCOMP is set after a STOP or after a REPEATED_START + an address different from
SADR.
3. SCLWS is automatically set when the clock synchronization mechanism is started.
440
AT91SAM9G20
6384E–ATARM–05-Feb-10
AT91SAM9G20
31.9.5.6
Clock Synchronization in Write Mode
The c lock is tied lo w if the shift register and the TWI_RHR is full. If a STOP or
REPEATED_START condition was not detected, it is tied low until TWI_RHR is read.
Figure 31-28 on page 441 describes the clock synchronization in Read mode.
Figure 31-28. Clock Synchronization in Write Mode
TWCK
CLOCK is tied low by the TWI as long as RHR is full
TWD
S
SADR
W
A
DATA0
TWI_RHR
A
DATA1
A
DATA0 is not read in the RHR
DATA2
DATA1
NA
S
ADR
DATA2
SCLWS
SCL is stretched on the last bit of DATA1
RXRDY
Rd DATA0
Rd DATA1
Rd DATA2
SVACC
SVREAD
TXCOMP
Notes:
As soon as a START is detected
1. At the end of the read sequence, TXCOMP is set after a STOP or after a REPEATED_START + an address different from
SADR.
2. SCLWS is automatically set when the clock synchronization mechanism is started and automatically reset when the mechanism is finished.
441
6384E–ATARM–05-Feb-10
31.9.5.7
Reversal after a Repeated Start
31.9.5.8
Reversal of Read to Write
The master initiates the communication by a read command and finishes it by a write command.
Figure 31-29 on page 442 describes the repeated start + reversal from Read to Write mode.
Figure 31-29. Repeated Start + Reversal from Read to Write Mode
TWI_THR
TWD
DATA0
S
SADR
R
A
DATA0
DATA1
A
DATA1
NA
Sr
SADR
W
A
DATA2
TWI_RHR
A
DATA3
DATA2
A
P
DATA3
SVACC
SVREAD
TXRDY
RXRDY
EOSACC
Cleared after read
As soon as a START is detected
TXCOMP
1. TXCOMP is only set at the end of the transmission because after the repeated start, SADR is detected again.
31.9.5.9
Reversal of Write to Read
The master initiates the communication by a write command and finishes it by a read command.Figure 31-30 on page 442 describes the repeated start + reversal from Write to Read
mode.
Figure 31-30. Repeated Start + Reversal from Write to Read Mode
DATA2
TWI_THR
TWD
S
SADR
W
A
DATA0
TWI_RHR
A
DATA1
DATA0
A
Sr
SADR
R
A
DATA3
DATA2
A
DATA3
NA
P
DATA1
SVACC
SVREAD
TXRDY
RXRDY
EOSACC
TXCOMP
Notes:
Read TWI_RHR
Cleared after read
As soon as a START is detected
1. In this case, if TWI_THR has not been written at the end of the read command, the clock is automatically stretched before
the ACK.
2. TXCOMP is only set at the end of the transmission because after the repeated start, SADR is detected again.
442
AT91SAM9G20
6384E–ATARM–05-Feb-10
AT91SAM9G20
31.9.6
Read Write Flowcharts
The flowchart shown in Figure 31-31 on page 443 gives an example of read and write operations
in Slave mode. A polling or interrupt method can be used to check the status bits. The interrupt
method requires that the interrupt enable register (TWI_IER) be configured first.
Figure 31-31. Read Write Flowchart in Slave Mode
Set the SLAVE mode:
SADR + MSDIS + SVEN
Read Status Register
SVACC = 1 ?
No
No
No
EOSACC = 1 ?
GACC = 1 ?
No
SVREAD = 0 ?
TXRDY= 1 ?
No
No
Write in TWI_THR
TXCOMP = 1 ?
RXRDY= 0 ?
No
END
Read TWI_RHR
GENERAL CALL TREATMENT
Decoding of the
programming sequence
Prog seq
OK ?
No
Change SADR
443
6384E–ATARM–05-Feb-10
31.10 Two-wire Interface (TWI) User Interface
Table 31-4.
Register Mapping
Offset
Register
Name
Access
Reset
0x00
Control Register
TWI_CR
Write-only
N/A
0x04
Master Mode Register
TWI_MMR
Read-write
0x00000000
0x08
Slave Mode Register
TWI_SMR
Read-write
0x00000000
0x0C
Internal Address Register
TWI_IADR
Read-write
0x00000000
0x10
Clock Waveform Generator Register
TWI_CWGR
Read-write
0x00000000
0x20
Status Register
TWI_SR
Read-only
0x0000F009
0x24
Interrupt Enable Register
TWI_IER
Write-only
N/A
0x28
Interrupt Disable Register
TWI_IDR
Write-only
N/A
0x2C
Interrupt Mask Register
TWI_IMR
Read-only
0x00000000
0x30
Receive Holding Register
TWI_RHR
Read-only
0x00000000
0x34
Transmit Holding Register
TWI_THR
Write-only
0x00000000
0x38 - 0xFC
Reserved
–
–
–
0x100 - 0x124
Reserved for the PDC
–
–
–
444
AT91SAM9G20
6384E–ATARM–05-Feb-10
AT91SAM9G20
31.10.1
Name:
TWI Control Register
TWI_CR
Access:
Write-only
Reset Value: 0x00000000
31
–
30
–
29
–
28
–
27
–
26
–
25
–
24
–
23
–
22
–
21
–
20
–
19
–
18
–
17
–
16
–
15
–
14
–
13
–
12
–
11
–
10
–
9
–
8
–
7
SWRST
6
–
5
SVDIS
4
SVEN
3
MSDIS
2
MSEN
1
STOP
0
START
• START: Send a START Condition
0 = No effect.
1 = A frame beginning with a START bit is transmitted according to the features defined in the mode register.
This action is necessary when the TWI peripheral wants to read data from a slave. When configured in Master Mode with a
write operation, a frame is sent as soon as the user writes a character in the Transmit Holding Register (TWI_THR).
• STOP: Send a STOP Condition
0 = No effect.
1 = STOP Condition is sent just after completing the current byte transmission in master read mode.
– In single data byte master read, the START and STOP must both be set.
– In multiple data bytes master read, the STOP must be set after the last data received but one.
– In master read mode, if a NACK bit is received, the STOP is automatically performed.
– In multiple data write operation, when both THR and shift register are empty, a STOP condition is automatically
sent.
• MSEN: TWI Master Mode Enabled
0 = No effect.
1 = If MSDIS = 0, the master mode is enabled.
Note:
Switching from Slave to Master mode is only permitted when TXCOMP = 1.
• MSDIS: TWI Master Mode Disabled
0 = No effect.
1 = The master mode is disabled, all pending data is transmitted. The shifter and holding characters (if it contains data) are
transmitted in case of write operation. In read operation, the character being transferred must be completely received
before disabling.
445
6384E–ATARM–05-Feb-10
• SVEN: TWI Slave Mode Enabled
0 = No effect.
1 = If SVDIS = 0, the slave mode is enabled.
Note:
Switching from Master to Slave mode is only permitted when TXCOMP = 1.
• SVDIS: TWI Slave Mode Disabled
0 = No effect.
1 = The slave mode is disabled. The shifter and holding characters (if it contains data) are transmitted in case of read operation. In write operation, the character being transferred must be completely received before disabling.
• SWRST: Software Reset
0 = No effect.
1 = Equivalent to a system reset.
446
AT91SAM9G20
6384E–ATARM–05-Feb-10
AT91SAM9G20
31.10.2
Name:
TWI Master Mode Register
TWI_MMR
Access:
Read-write
Reset Value: 0x00000000
31
–
30
–
29
–
28
–
27
–
26
–
25
–
24
–
23
–
22
21
20
19
DADR
18
17
16
15
–
14
–
13
–
12
MREAD
11
–
10
–
9
7
–
6
–
5
–
4
–
3
–
2
–
1
–
8
IADRSZ
0
–
• IADRSZ: Internal Device Address Size
IADRSZ[9:8]
0
0
No internal device address
0
1
One-byte internal device address
1
0
Two-byte internal device address
1
1
Three-byte internal device address
• MREAD: Master Read Direction
0 = Master write direction.
1 = Master read direction.
• DADR: Device Address
The device address is used to access slave devices in read or write mode. Those bits are only used in Master mode.
447
6384E–ATARM–05-Feb-10
31.10.3
Name:
Access:
TWI Slave Mode Register
TWI_SMR
Read-write
Reset Value: 0x00000000
31
–
30
–
29
–
28
–
27
–
26
–
25
–
24
–
23
–
22
21
20
19
SADR
18
17
16
15
–
14
–
13
–
12
–
11
–
10
–
9
8
7
–
6
–
5
–
4
–
3
–
2
–
1
–
0
–
• SADR: Slave Address
The slave device address is used in Slave mode in order to be accessed by master devices in read or write mode.
SADR must be programmed before enabling the Slave mode or after a general call. Writes at other times have no effect.
31.10.4
Name:
Access:
TWI Internal Address Register
TWI_IADR
Read-write
Reset Value: 0x00000000
31
–
30
–
29
–
28
–
27
–
26
–
25
–
24
–
23
22
21
20
19
18
17
16
11
10
9
8
3
2
1
0
IADR
15
14
13
12
IADR
7
6
5
4
IADR
• IADR: Internal Address
0, 1, 2 or 3 bytes depending on IADRSZ.
448
AT91SAM9G20
6384E–ATARM–05-Feb-10
AT91SAM9G20
31.10.5
Name:
Access:
TWI Clock Waveform Generator Register
TWI_CWGR
Read-write
Reset Value: 0x00000000
31
–
30
–
29
–
28
–
27
–
26
–
25
–
24
–
23
22
21
20
19
18
17
CKDIV
16
15
14
13
12
11
10
9
8
3
2
1
0
CHDIV
7
6
5
4
CLDIV
TWI_CWGR is only used in Master mode.
• CLDIV: Clock Low Divider
The SCL low period is defined as follows:
T low = ( ( CLDIV × 2
CKDIV
) + 4 ) × T MCK
• CHDIV: Clock High Divider
The SCL high period is defined as follows:
T high = ( ( CHDIV × 2
CKDIV
) + 4 ) × T MCK
• CKDIV: Clock Divider
The CKDIV is used to increase both SCL high and low periods.
449
6384E–ATARM–05-Feb-10
31.10.6
Name:
TWI Status Register
TWI_SR
Access:
Read-only
Reset Value: 0x0000F009
31
–
30
–
29
–
28
–
27
–
26
–
25
–
24
–
23
–
22
–
21
–
20
–
19
–
18
–
17
–
16
–
15
TXBUFE
14
RXBUFF
13
ENDTX
12
ENDRX
11
EOSACC
10
SCLWS
9
ARBLST
8
NACK
7
–
6
OVRE
5
GACC
4
SVACC
3
SVREAD
2
TXRDY
1
RXRDY
0
TXCOMP
• TXCOMP: Transmission Completed (automatically set / reset)
TXCOMP used in Master mode:
0 = During the length of the current frame.
1 = When both holding and shifter registers are empty and STOP condition has been sent.
TXCOMP behavior in Master mode can be seen in Figure 31-7 on page 422 and in Figure 31-10 on page 423.
TXCOMP used in Slave mode:
0 = As soon as a Start is detected.
1 = After a Stop or a Repeated Start + an address different from SADR is detected.
TXCOMP behavior in Slave mode can be seen in Figure 31-27 on page 440, Figure 31-28 on page 441, Figure 31-29 on
page 442 and Figure 31-30 on page 442.
• RXRDY: Receive Holding Register Ready (automatically set / reset)
0 = No character has been received since the last TWI_RHR read operation.
1 = A byte has been received in the TWI_RHR since the last read.
RXRDY behavior in Master mode can be seen in Figure 31-10 on page 423.
RXRDY behavior in Slave mode can be seen in Figure 31-25 on page 438, Figure 31-28 on page 441, Figure 31-29 on
page 442 and Figure 31-30 on page 442.
• TXRDY: Transmit Holding Register Ready (automatically set / reset)
TXRDY used in Master mode:
0 = The transmit holding register has not been transferred into shift register. Set to 0 when writing into TWI_THR register.
1 = As soon as a data byte is transferred from TWI_THR to internal shifter or if a NACK error is detected, TXRDY is set at
the same time as TXCOMP and NACK. TXRDY is also set when MSEN is set (enable TWI).
TXRDY behavior in Master mode can be seen in Figure 31-8 on page 422.
450
AT91SAM9G20
6384E–ATARM–05-Feb-10
AT91SAM9G20
TXRDY used in Slave mode:
0 = As soon as data is written in the TWI_THR, until this data has been transmitted and acknowledged (ACK or NACK).
1 = It indicates that the TWI_THR is empty and that data has been transmitted and acknowledged.
If TXRDY is high and if a NACK has been detected, the transmission will be stopped. Thus when TRDY = NACK = 1, the
programmer must not fill TWI_THR to avoid losing it.
TXRDY behavior in Slave mode can be seen in Figure 31-24 on page 438, Figure 31-27 on page 440, Figure 31-29 on
page 442 and Figure 31-30 on page 442.
• SVREAD: Slave Read (automatically set / reset)
This bit is only used in Slave mode. When SVACC is low (no Slave access has been detected) SVREAD is irrelevant.
0 = Indicates that a write access is performed by a Master.
1 = Indicates that a read access is performed by a Master.
SVREAD behavior can be seen in Figure 31-24 on page 438, Figure 31-25 on page 438, Figure 31-29 on page 442 and
Figure 31-30 on page 442.
• SVACC: Slave Access (automatically set / reset)
This bit is only used in Slave mode.
0 = TWI is not addressed. SVACC is automatically cleared after a NACK or a STOP condition is detected.
1 = Indicates that the address decoding sequence has matched (A Master has sent SADR). SVACC remains high until a
NACK or a STOP condition is detected.
SVACC behavior can be seen in Figure 31-24 on page 438, Figure 31-25 on page 438, Figure 31-29 on page 442 and Figure 31-30 on page 442.
• GACC: General Call Access (clear on read)
This bit is only used in Slave mode.
0 = No General Call has been detected.
1 = A General Call has been detected. After the detection of General Call, the programmer decoded the commands that follow and the programming sequence.
GACC behavior can be seen in Figure 31-26 on page 439.
• OVRE: Overrun Error (clear on read)
This bit is only used in Master mode.
0 = TWI_RHR has not been loaded while RXRDY was set
1 = TWI_RHR has been loaded while RXRDY was set. Reset by read in TWI_SR when TXCOMP is set.
• NACK: Not Acknowledged (clear on read)
NACK used in Master mode:
0 = Each data byte has been correctly received by the far-end side TWI slave component.
1 = A data byte has not been acknowledged by the slave component. Set at the same time as TXCOMP.
451
6384E–ATARM–05-Feb-10
NACK used in Slave Read mode:
0 = Each data byte has been correctly received by the Master.
1 = In read mode, a data byte has not been acknowledged by the Master. When NACK is set the programmer must not fill
TWI_THR even if TXRDY is set, because it means that the Master will stop the data transfer or re initiate it.
Note that in Slave Write mode all data are acknowledged by the TWI.
• ARBLST: Arbitration Lost (clear on read)
This bit is only used in Master mode.
0: Arbitration won.
1: Arbitration lost. Another master of the TWI bus has won the multi-master arbitration. TXCOMP is set at the same time.
• SCLWS: Clock Wait State (automatically set / reset)
This bit is only used in Slave mode.
0 = The clock is not stretched.
1 = The clock is stretched. TWI_THR / TWI_RHR buffer is not filled / emptied before the emission / reception of a new
character.
SCLWS behavior can be seen in Figure 31-27 on page 440 and Figure 31-28 on page 441.
• EOSACC: End Of Slave Access (clear on read)
This bit is only used in Slave mode.
0 = A slave access is being performing.
1 = The Slave Access is finished. End Of Slave Access is automatically set as soon as SVACC is reset.
EOSACC behavior can be seen in Figure 31-29 on page 442 and Figure 31-30 on page 442
• ENDRX: End of RX buffer
This bit is only used in Master mode.
0 = The Receive Counter Register has not reached 0 since the last write in TWI_RCR or TWI_RNCR.
1 = The Receive Counter Register has reached 0 since the last write in TWI_RCR or TWI_RNCR.
• ENDTX: End of TX buffer
This bit is only used in Master mode.
0 = The Transmit Counter Register has not reached 0 since the last write in TWI_TCR or TWI_TNCR.
1 = The Transmit Counter Register has reached 0 since the last write in TWI_TCR or TWI_TNCR.
• RXBUFF: RX Buffer Full
This bit is only used in Master mode.
0 = TWI_RCR or TWI_RNCR have a value other than 0.
1 = Both TWI_RCR and TWI_RNCR have a value of 0.
452
AT91SAM9G20
6384E–ATARM–05-Feb-10
AT91SAM9G20
• TXBUFE: TX Buffer Empty
This bit is only used in Master mode.
0 = TWI_TCR or TWI_TNCR have a value other than 0.
1 = Both TWI_TCR and TWI_TNCR have a value of 0.
453
6384E–ATARM–05-Feb-10
31.10.7
Name:
TWI Interrupt Enable Register
TWI_IER
Access:
Write-only
Reset Value: 0x00000000
31
–
30
–
29
–
28
–
27
–
26
–
25
–
24
–
23
–
22
–
21
–
20
–
19
–
18
–
17
–
16
–
15
TXBUFE
14
RXBUFF
13
ENDTX
12
ENDRX
11
EOSACC
10
SCL_WS
9
ARBLST
8
NACK
7
–
6
OVRE
5
GACC
4
SVACC
3
–
2
TXRDY
1
RXRDY
0
TXCOMP
• TXCOMP: Transmission Completed Interrupt Enable
• RXRDY: Receive Holding Register Ready Interrupt Enable
• TXRDY: Transmit Holding Register Ready Interrupt Enable
• SVACC: Slave Access Interrupt Enable
• GACC: General Call Access Interrupt Enable
• OVRE: Overrun Error Interrupt Enable
• NACK: Not Acknowledge Interrupt Enable
• ARBLST: Arbitration Lost Interrupt Enable
• SCL_WS: Clock Wait State Interrupt Enable
• EOSACC: End Of Slave Access Interrupt Enable
• ENDRX: End of Receive Buffer Interrupt Enable
• ENDTX: End of Transmit Buffer Interrupt Enable
• RXBUFF: Receive Buffer Full Interrupt Enable
• TXBUFE: Transmit Buffer Empty Interrupt Enable
0 = No effect.
1 = Enables the corresponding interrupt.
454
AT91SAM9G20
6384E–ATARM–05-Feb-10
AT91SAM9G20
31.10.8
Name:
TWI Interrupt Disable Register
TWI_IDR
Access:
Write-only
Reset Value: 0x00000000
31
–
30
–
29
–
28
–
27
–
26
–
25
–
24
–
23
–
22
–
21
–
20
–
19
–
18
–
17
–
16
–
15
TXBUFE
14
RXBUFF
13
ENDTX
12
ENDRX
11
EOSACC
10
SCL_WS
9
ARBLST
8
NACK
7
–
6
OVRE
5
GACC
4
SVACC
3
–
2
TXRDY
1
RXRDY
0
TXCOMP
• TXCOMP: Transmission Completed Interrupt Disable
• RXRDY: Receive Holding Register Ready Interrupt Disable
• TXRDY: Transmit Holding Register Ready Interrupt Disable
• SVACC: Slave Access Interrupt Disable
• GACC: General Call Access Interrupt Disable
• OVRE: Overrun Error Interrupt Disable
• NACK: Not Acknowledge Interrupt Disable
• ARBLST: Arbitration Lost Interrupt Disable
• SCL_WS: Clock Wait State Interrupt Disable
• EOSACC: End Of Slave Access Interrupt Disable
• ENDRX: End of Receive Buffer Interrupt Disable
• ENDTX: End of Transmit Buffer Interrupt Disable
• RXBUFF: Receive Buffer Full Interrupt Disable
• TXBUFE: Transmit Buffer Empty Interrupt Disable
0 = No effect.
1 = Disables the corresponding interrupt.
455
6384E–ATARM–05-Feb-10
31.10.9
Name:
TWI Interrupt Mask Register
TWI_IMR
Access:
Read-only
Reset Value: 0x00000000
31
–
30
–
29
–
28
–
27
–
26
–
25
–
24
–
23
–
22
–
21
–
20
–
19
–
18
–
17
–
16
–
15
TXBUFE
14
RXBUFF
13
ENDTX
12
ENDRX
11
EOSACC
10
SCL_WS
9
ARBLST
8
NACK
7
–
6
OVRE
5
GACC
4
SVACC
3
–
2
TXRDY
1
RXRDY
0
TXCOMP
• TXCOMP: Transmission Completed Interrupt Mask
• RXRDY: Receive Holding Register Ready Interrupt Mask
• TXRDY: Transmit Holding Register Ready Interrupt Mask
• SVACC: Slave Access Interrupt Mask
• GACC: General Call Access Interrupt Mask
• OVRE: Overrun Error Interrupt Mask
• NACK: Not Acknowledge Interrupt Mask
• ARBLST: Arbitration Lost Interrupt Mask
• SCL_WS: Clock Wait State Interrupt Mask
• EOSACC: End Of Slave Access Interrupt Mask
• ENDRX: End of Receive Buffer Interrupt Mask
• ENDTX: End of Transmit Buffer Interrupt Mask
• RXBUFF: Receive Buffer Full Interrupt Mask
• TXBUFE: Transmit Buffer Empty Interrupt Mask
0 = The corresponding interrupt is disabled.
1 = The corresponding interrupt is enabled.
456
AT91SAM9G20
6384E–ATARM–05-Feb-10
AT91SAM9G20
31.10.10 TWI Receive Holding Register
Name:
TWI_RHR
Access:
Read-only
Reset Value: 0x00000000
31
–
30
–
29
–
28
–
27
–
26
–
25
–
24
–
23
–
22
–
21
–
20
–
19
–
18
–
17
–
16
–
15
–
14
–
13
–
12
–
11
–
10
–
9
–
8
–
7
6
5
4
3
2
1
0
RXDATA
• RXDATA: Master or Slave Receive Holding Data
457
6384E–ATARM–05-Feb-10
31.10.11 TWI Transmit Holding Register
Name:
TWI_THR
Access:
Read-write
Reset Value: 0x00000000
31
–
30
–
29
–
28
–
27
–
26
–
25
–
24
–
23
–
22
–
21
–
20
–
19
–
18
–
17
–
16
–
15
–
14
–
13
–
12
–
11
–
10
–
9
–
8
–
7
6
5
4
3
2
1
0
TXDATA
• TXDATA: Master or Slave Transmit Holding Data
458
AT91SAM9G20
6384E–ATARM–05-Feb-10
AT91SAM9G20
32. Universal Synchronous Asynchronous Receiver Transmitter (USART)
32.1
Overview
The Universal Synchronous Asynchronous Receiver Transceiver (USART) provides one full
duplex universal synchronous asynchronous serial link. Data frame format is widely programmable (data length, parity, number of stop bits) to support a maximum of standards. The receiver
implements parity error, framing error and overrun error detection. The receiver time-out enables
handling variable-length frames and the transmitter timeguard facilitates communications with
slow remote devices. Multidrop communications are also supported through address bit handling in reception and transmission.
The USART features three test modes: remote loopback, local loopback and automatic echo.
The USART supports specific operating modes providing interfaces on RS485 buses, with
ISO7816 T = 0 or T = 1 smart card slots, infrared transceivers and connection to modem ports.
The hardware handshaking feature enables an out-of-band flow control by automatic management of the pins RTS and CTS.
The USART supports the connection to the Peripheral DMA Controller, which enables data
transfers to the transmitter and from the receiver. The PDC provides chained buffer management without any intervention of the processor.
459
6384E–ATARM–05-Feb-10
32.2
Block Diagram
Figure 32-1. USART Block Diagram
Peripheral DMA
Controller
Channel
Channel
PIO
Controller
USART
RXD
Receiver
RTS
AIC
USART
Interrupt
TXD
Transmitter
CTS
DTR
PMC
Modem
Signals
Control
MCK
DIV
DSR
DCD
MCK/DIV
RI
SLCK
Baud Rate
Generator
SCK
User Interface
APB
460
AT91SAM9G20
6384E–ATARM–05-Feb-10
AT91SAM9G20
32.3
Application Block Diagram
Figure 32-2. Application Block Diagram
IrLAP
PPP
Modem
Driver
Serial
Driver
Field Bus
Driver
EMV
Driver
IrDA
Driver
USART
RS232
Drivers
RS232
Drivers
RS485
Drivers
Serial
Port
Differential
Bus
Smart
Card
Slot
IrDA
Transceivers
Modem
PSTN
461
6384E–ATARM–05-Feb-10
32.4
I/O Lines Description
Table 32-1.
I/O Line Description
Name
Description
Type
SCK
Serial Clock
I/O
TXD
Transmit Serial Data
I/O
RXD
Receive Serial Data
Input
RI
Ring Indicator
Input
Low
DSR
Data Set Ready
Input
Low
DCD
Data Carrier Detect
Input
Low
DTR
Data Terminal Ready
Output
Low
CTS
Clear to Send
Input
Low
RTS
Request to Send
Output
Low
462
Active Level
AT91SAM9G20
6384E–ATARM–05-Feb-10
AT91SAM9G20
32.5
32.5.1
Product Dependencies
I/O Lines
The pins used for interfacing the USART may be multiplexed with the PIO lines. The programmer must first program the PIO controller to assign the desired USART pins to their peripheral
function. If I/O lines of the USART are not used by the application, they can be used for other
purposes by the PIO Controller.
To prevent the TXD line from falling when the USART is disabled, the use of an internal pull up
is mandatory. If the hardware handshaking feature or Modem mode is used, the internal pull up
on TXD must also be enabled.
All the pins of the modems may or may not be implemented on the USART. Only USART0 is
fully equipped with all the modem signals. On USARTs not equipped with the corresponding pin,
the associated control bits and statuses have no effect on the behavior of the USART.
32.5.2
Power Management
The USART is not continuously clocked. The programmer must first enable the USART Clock in
the Power Management Controller (PMC) before using the USART. However, if the application
does not require USART operations, the USART clock can be stopped when not needed and be
restarted later. In this case, the USART will resume its operations where it left off.
Configuring the USART does not require the USART clock to be enabled.
32.5.3
Interrupt
The USART interrupt line is connected on one of the internal sources of the Advanced Interrupt
Controller. Using the USART interrupt requires the AIC to be programmed first. Note that it is not
recommended to use the USART interrupt line in edge sensitive mode.
463
6384E–ATARM–05-Feb-10
32.6
Functional Description
The USART is capable of managing several types of serial synchronous or asynchronous
communications.
It supports the following communication modes:
• 5- to 9-bit full-duplex asynchronous serial communication
– MSB- or LSB-first
– 1, 1.5 or 2 stop bits
– Parity even, odd, marked, space or none
– By 8 or by 16 over-sampling receiver frequency
– Optional hardware handshaking
– Optional modem signals management
– Optional break management
– Optional multidrop serial communication
• High-speed 5- to 9-bit full-duplex synchronous serial communication
– MSB- or LSB-first
– 1 or 2 stop bits
– Parity even, odd, marked, space or none
– By 8 or by 16 over-sampling frequency
– Optional hardware handshaking
– Optional modem signals management
– Optional break management
– Optional multidrop serial communication
• RS485 with driver control signal
• ISO7816, T0 or T1 protocols for interfacing with smart cards
– NACK handling, error counter with repetition and iteration limit
• InfraRed IrDA Modulation and Demodulation
• Test modes
– Remote loopback, local loopback, automatic echo
32.6.1
Baud Rate Generator
The Baud Rate Generator provides the bit period clock named the Baud Rate Clock to both the
receiver and the transmitter.
The Baud Rate Generator clock source can be selected by setting the USCLKS field in the Mode
Register (US_MR) between:
• the Master Clock MCK
• a division of the Master Clock, the divider being product dependent, but generally set to 8
• the external clock, available on the SCK pin
The Baud Rate Generator is based upon a 16-bit divider, which is programmed with the CD field
of the Baud Rate Generator Register (US_BRGR). If CD is programmed at 0, the Baud Rate
Generator does not generate any clock. If CD is programmed at 1, the divider is bypassed and
becomes inactive.
464
AT91SAM9G20
6384E–ATARM–05-Feb-10
AT91SAM9G20
If the external SCK clock is selected, the duration of the low and high levels of the signal provided on the SCK pin must be longer than a Master Clock (MCK) period. The frequency of the
signal provided on SCK must be at least 4.5 times lower than MCK.
Figure 32-3. Baud Rate Generator
USCLKS
MCK
MCK/DIV
SCK
Reserved
CD
CD
SCK
0
1
16-bit Counter
2
FIDI
>1
3
1
0
SYNC
OVER
0
0
Sampling
Divider
0
Baud Rate
Clock
1
1
SYNC
Sampling
Clock
USCLKS = 3
32.6.1.1
Baud Rate in Asynchronous Mode
If the USART is programmed to operate in asynchronous mode, the selected clock is first
divided by CD, which is field programmed in the Baud Rate Generator Register (US_BRGR).
The resulting clock is provided to the receiver as a sampling clock and then divided by 16 or 8,
depending on the programming of the OVER bit in US_MR.
If OVER is set to 1, the receiver sampling is 8 times higher than the baud rate clock. If OVER is
cleared, the sampling is performed at 16 times the baud rate clock.
The following formula performs the calculation of the Baud Rate.
SelectedClockBaudrate = --------------------------------------------( 8 ( 2 – Over )CD )
This gives a maximum baud rate of MCK divided by 8, assuming that MCK is the highest possible clock and that OVER is programmed at 1.
32.6.1.2
Baud Rate Calculation Example
Table 32-2 shows calculations of CD to obtain a baud rate at 38400 bauds for different source
clock frequencies. This table also shows the actual resulting baud rate and the error.
Table 32-2.
Baud Rate Example (OVER = 0)
Source Clock
Expected Baud
Rate
MHz
Bit/s
3 686 400
38 400
6.00
6
38 400.00
0.00%
4 915 200
38 400
8.00
8
38 400.00
0.00%
5 000 000
38 400
8.14
8
39 062.50
1.70%
7 372 800
38 400
12.00
12
38 400.00
0.00%
Calculation Result
CD
Actual Baud Rate
Error
Bit/s
465
6384E–ATARM–05-Feb-10
Table 32-2.
Baud Rate Example (OVER = 0) (Continued)
Source Clock
Expected Baud
Rate
Calculation Result
CD
Actual Baud Rate
Error
8 000 000
38 400
13.02
13
38 461.54
0.16%
12 000 000
38 400
19.53
20
37 500.00
2.40%
12 288 000
38 400
20.00
20
38 400.00
0.00%
14 318 180
38 400
23.30
23
38 908.10
1.31%
14 745 600
38 400
24.00
24
38 400.00
0.00%
18 432 000
38 400
30.00
30
38 400.00
0.00%
24 000 000
38 400
39.06
39
38 461.54
0.16%
24 576 000
38 400
40.00
40
38 400.00
0.00%
25 000 000
38 400
40.69
40
38 109.76
0.76%
32 000 000
38 400
52.08
52
38 461.54
0.16%
32 768 000
38 400
53.33
53
38 641.51
0.63%
33 000 000
38 400
53.71
54
38 194.44
0.54%
40 000 000
38 400
65.10
65
38 461.54
0.16%
50 000 000
38 400
81.38
81
38 580.25
0.47%
The baud rate is calculated with the following formula:
BaudRate = MCK ⁄ CD × 16
The baud rate error is calculated with the following formula. It is not recommended to work with
an error higher than 5%.
ExpectedBaudRate
Error = 1 – ⎛ ---------------------------------------------------------⎞
⎝ ActualBaudRate ⎠
32.6.1.3
Fractional Baud Rate in Asynchronous Mode
The Baud Rate generator previously defined is subject to the following limitation: the output frequency changes by only integer multiples of the reference frequency. An approach to this
problem is to integrate a fractional N clock generator that has a high resolution. The generator
architecture is modified to obtain Baud Rate changes by a fraction of the reference source clock.
This fractional part is programmed with the FP field in the Baud Rate Generator Register
(US_BRGR). If FP is not 0, the fractional part is activated. The resolution is one eighth of the
clock divider. This feature is only available when using USART normal mode. The fractional
Baud Rate is calculated using the following formula:
SelectedClock
Baudrate = -----------------------------------------------------------------⎛ 8 ( 2 – Over ) ⎛ CD + FP
--------⎞ ⎞
⎝
⎝
8 ⎠⎠
The modified architecture is presented below:
466
AT91SAM9G20
6384E–ATARM–05-Feb-10
AT91SAM9G20
Figure 32-4. Fractional Baud Rate Generator
FP
USCLKS
CD
Modulus
Control
FP
MCK
MCK/DIV
SCK
Reserved
CD
SCK
0
1
16-bit Counter
2
3
glitch-free
logic
1
0
FIDI
>1
0
0
SYNC
OVER
Sampling
Divider
0
Baud Rate
Clock
1
1
SYNC
USCLKS = 3
32.6.1.4
Sampling
Clock
Baud Rate in Synchronous Mode
If the USART is programmed to operate in synchronous mode, the selected clock is simply
divided by the field CD in US_BRGR.
BaudRate = SelectedClock
----------------------------------------CD
In synchronous mode, if the external clock is selected (USCLKS = 3), the clock is provided
directly by the signal on the USART SCK pin. No division is active. The value written in
US_BRGR has no effect. The external clock frequency must be at least 4.5 times lower than the
system clock.
When either the external clock SCK or the internal clock divided (MCK/DIV) is selected, the
value programmed in CD must be even if the user has to ensure a 50:50 mark/space ratio on the
SCK pin. If the internal clock MCK is selected, the Baud Rate Generator ensures a 50:50 duty
cycle on the SCK pin, even if the value programmed in CD is odd.
32.6.1.5
Baud Rate in ISO 7816 Mode
The ISO7816 specification defines the bit rate with the following formula:
Di
B = ------ × f
Fi
where:
• B is the bit rate
• Di is the bit-rate adjustment factor
• Fi is the clock frequency division factor
• f is the ISO7816 clock frequency (Hz)
467
6384E–ATARM–05-Feb-10
Di is a binary value encoded on a 4-bit field, named DI, as represented in Table 32-3.
Table 32-3.
Binary and Decimal Values for Di
DI field
0001
0010
0011
0100
0101
0110
1000
1001
1
2
4
8
16
32
12
20
Di (decimal)
Fi is a binary value encoded on a 4-bit field, named FI, as represented in Table 32-4.
Table 32-4.
Binary and Decimal Values for Fi
FI field
0000
0001
0010
0011
0100
0101
0110
1001
1010
1011
1100
1101
Fi (decimal
372
372
558
744
1116
1488
1860
512
768
1024
1536
2048
Table 32-5 shows the resulting Fi/Di Ratio, which is the ratio between the ISO7816 clock and the
baud rate clock.
Table 32-5.
Possible Values for the Fi/Di Ratio
Fi/Di
372
558
774
1116
1488
1806
512
768
1024
1536
2048
1
372
558
744
1116
1488
1860
512
768
1024
1536
2048
2
186
279
372
558
744
930
256
384
512
768
1024
4
93
139.5
186
279
372
465
128
192
256
384
512
8
46.5
69.75
93
139.5
186
232.5
64
96
128
192
256
16
23.25
34.87
46.5
69.75
93
116.2
32
48
64
96
128
32
11.62
17.43
23.25
34.87
46.5
58.13
16
24
32
48
64
12
31
46.5
62
93
124
155
42.66
64
85.33
128
170.6
20
18.6
27.9
37.2
55.8
74.4
93
25.6
38.4
51.2
76.8
102.4
If the USART is configured in ISO7816 Mode, the clock selected by the USCLKS field in the
Mode Register (US_MR) is first divided by the value programmed in the field CD in the Baud
Rate Generator Register (US_BRGR). The resulting clock can be provided to the SCK pin to
feed the smart card clock inputs. This means that the CLKO bit can be set in US_MR.
This clock is then divided by the value programmed in the FI_DI_RATIO field in the FI_DI_Ratio
register (US_FIDI). This is performed by the Sampling Divider, which performs a division by up
to 2047 in ISO7816 Mode. The non-integer values of the Fi/Di Ratio are not supported and the
user must program the FI_DI_RATIO field to a value as close as possible to the expected value.
The FI_DI_RATIO field resets to the value 0x174 (372 in decimal) and is the most common
divider between the ISO7816 clock and the bit rate (Fi = 372, Di = 1).
Figure 32-5 shows the relation between the Elementary Time Unit, corresponding to a bit time,
and the ISO 7816 clock.
468
AT91SAM9G20
6384E–ATARM–05-Feb-10
AT91SAM9G20
Figure 32-5. Elementary Time Unit (ETU)
FI_DI_RATIO
ISO7816 Clock Cycles
ISO7816 Clock
on SCK
ISO7816 I/O Line
on TXD
1 ETU
32.6.2
Receiver and Transmitter Control
After reset, the receiver is disabled. The user must enable the receiver by setting the RXEN bit
in the Control Register (US_CR). However, the receiver registers can be programmed before the
receiver clock is enabled.
After reset, the transmitter is disabled. The user must enable it by setting the TXEN bit in the
Control Register (US_CR). However, the transmitter registers can be programmed before being
enabled.
The Receiver and the Transmitter can be enabled together or independently.
At any time, the software can perform a reset on the receiver or the transmitter of the USART by
setting the corresponding bit, RSTRX and RSTTX respectively, in the Control Register
(US_CR). The software resets clear the status flag and reset internal state machines but the
user interface configuration registers hold the value configured prior to software reset. Regardless of what the receiver or the transmitter is performing, the communication is immediately
stopped.
The user can also independently disable the receiver or the transmitter by setting RXDIS and
TXDIS respectively in US_CR. If the receiver is disabled during a character reception, the
USART waits until the end of reception of the current character, then the reception is stopped. If
the transmitter is disabled while it is operating, the USART waits the end of transmission of both
the current character and character being stored in the Transmit Holding Register (US_THR). If
a timeguard is programmed, it is handled normally.
32.6.3
32.6.3.1
Synchronous and Asynchronous Modes
Transmitter Operations
The transmitter performs the same in both synchronous and asynchronous operating modes
(SYNC = 0 or SYNC = 1). One start bit, up to 9 data bits, one optional parity bit and up to two
stop bits are successively shifted out on the TXD pin at each falling edge of the programmed
serial clock.
The number of data bits is selected by the CHRL field and the MODE 9 bit in the Mode Register
(US_MR). Nine bits are selected by setting the MODE 9 bit regardless of the CHRL field. The
parity bit is set according to the PAR field in US_MR. The even, odd, space, marked or none
parity bit can be configured. The MSBF field in US_MR configures which data bit is sent first. If
written at 1, the most significant bit is sent first. At 0, the less significant bit is sent first. The number of stop bits is selected by the NBSTOP field in US_MR. The 1.5 stop bit is supported in
asynchronous mode only.
469
6384E–ATARM–05-Feb-10
Figure 32-6. Character Transmit
Example: 8-bit, Parity Enabled One Stop
Baud Rate
Clock
TXD
Start
Bit
D0
D1
D2
D3
D4
D5
D6
D7
Parity
Bit
Stop
Bit
The characters are sent by writing in the Transmit Holding Register (US_THR). The transmitter
reports two status bits in the Channel Status Register (US_CSR): TXRDY (Transmitter Ready),
which indicates that US_THR is empty and TXEMPTY, which indicates that all the characters
written in US_THR have been processed. When the current character processing is completed,
the last character written in US_THR is transferred into the Shift Register of the transmitter and
US_THR becomes empty, thus TXRDY rises.
Both TXRDY and TXEMPTY bits are low when the transmitter is disabled. Writing a character in
US_THR while TXRDY is low has no effect and the written character is lost.
Figure 32-7. Transmitter Status
Baud Rate
Clock
TXD
Start
D0
Bit
D1
D2
D3
D4
D5
D6
D7
Parity Stop Start
D0
Bit Bit Bit
D1
D2
D3
D4
D5
D6
D7
Parity Stop
Bit Bit
Write
US_THR
TXRDY
TXEMPTY
32.6.3.2
470
Manchester Encoder
When the Manchester encoder is in use, characters transmitted through the USART are
encoded based on biphase Manchester II format. To enable this mode, set the MAN field in the
US_MR register to 1. Depending on polarity configuration, a logic level (zero or one), is transmitted as a coded signal one-to-zero or zero-to-one. Thus, a transition always occurs at the
midpoint of each bit time. It consumes more bandwidth than the original NRZ signal (2x) but the
receiver has more error control since the expected input must show a change at the center of a
bit cell. An example of Manchester encoded sequence is: the byte 0xB1 or 10110001 encodes
to 10 01 10 10 01 01 01 10, assuming the default polarity of the encoder. Figure 32-8 illustrates
this coding scheme.
AT91SAM9G20
6384E–ATARM–05-Feb-10
AT91SAM9G20
Figure 32-8. NRZ to Manchester Encoding
NRZ
encoded
data
Manchester
encoded
data
1
0
1
1
0
0
0
1
Txd
The Manchester encoded character can also be encapsulated by adding both a configurable
preamble and a start frame delimiter pattern. Depending on the configuration, the preamble is a
training sequence, composed of a pre-defined pattern with a programmable length from 1 to 15
bit times. If the preamble length is set to 0, the preamble waveform is not generated prior to any
character. The preamble pattern is chosen among the following sequences: ALL_ONE,
ALL_ZERO, ONE_ZERO or ZERO_ONE, writing the field TX_PP in the US_MAN register, the
field TX_PL is used to configure the preamble length. Figure 32-9 illustrates and defines the
valid patterns. To improve flexibility, the encoding scheme can be configured using the
TX_MPOL field in the US_MAN register. If the TX_MPOL field is set to zero (default), a logic
zero is encoded with a zero-to-one transition and a logic one is encoded with a one-to-zero transition. If the TX_MPOL field is set to one, a logic one is encoded with a one-to-zero transition
and a logic zero is encoded with a zero-to-one transition.
Figure 32-9. Preamble Patterns, Default Polarity Assumed
Manchester
encoded
data
Txd
SFD
DATA
SFD
DATA
SFD
DATA
SFD
DATA
8 bit width "ALL_ONE" Preamble
Manchester
encoded
data
Txd
8 bit width "ALL_ZERO" Preamble
Manchester
encoded
data
Txd
8 bit width "ZERO_ONE" Preamble
Manchester
encoded
data
Txd
8 bit width "ONE_ZERO" Preamble
A start frame delimiter is to be configured using the ONEBIT field in the US_MR register. It consists of a user-defined pattern that indicates the beginning of a valid data. Figure 32-10
illustrates these patterns. If the start frame delimiter, also known as start bit, is one bit, (ONEBIT
at 1), a logic zero is Manchester encoded and indicates that a new character is being sent serially on the line. If the start frame delimiter is a synchronization pattern also referred to as sync
(ONEBIT at 0), a sequence of 3 bit times is sent serially on the line to indicate the start of a new
471
6384E–ATARM–05-Feb-10
character. The sync waveform is in itself an invalid Manchester waveform as the transition
occurs at the middle of the second bit time. Two distinct sync patterns are used: the command
sync and the data sync. The command sync has a logic one level for one and a half bit times,
then a transition to logic zero for the second one and a half bit times. If the MODSYNC field in
the US_MR register is set to 1, the next character is a command. If it is set to 0, the next character is a data. When direct memory access is used, the MODSYNC field can be immediately
updated with a modified character located in memory. To enable this mode, VAR_SYNC field in
US_MR register must be set to 1. In this case, the MODSYNC field in US_MR is bypassed and
the sync configuration is held in the TXSYNH in the US_THR register. The USART character format is modified and includes sync information.
Figure 32-10. Start Frame Delimiter
Preamble Length
is set to 0
SFD
Manchester
encoded
data
DATA
Txd
One bit start frame delimiter
SFD
Manchester
encoded
data
DATA
Txd
SFD
Manchester
encoded
data
Txd
Command Sync
start frame delimiter
DATA
Data Sync
start frame delimiter
32.6.3.3
472
Drift Compensation
Drift compensation is available only in 16X oversampling mode. An hardware recovery system
allows a larger clock drift. To enable the hardware system, the bit in the USART_MAN register
must be set. If the RXD edge is one 16X clock cycle from the expected edge, this is considered
as normal jitter and no corrective actions is taken. If the RXD event is between 4 and 2 clock
cycles before the expected edge, then the current period is shortened by one clock cycle. If the
RXD event is between 2 and 3 clock cycles after the expected edge, then the current period is
lengthened by one clock cycle. These intervals are considered to be drift and so corrective
actions are automatically taken.
AT91SAM9G20
6384E–ATARM–05-Feb-10
AT91SAM9G20
Figure 32-11. Bit Resynchronization
Oversampling
16x Clock
RXD
Sampling
point
Expected edge
Synchro.
Error
32.6.3.4
Synchro.
Jump
Tolerance
Sync
Jump
Synchro.
Error
Asynchronous Receiver
If the USART is programmed in asynchronous operating mode (SYNC = 0), the receiver oversamples the RXD input line. The oversampling is either 16 or 8 times the Baud Rate clock,
depending on the OVER bit in the Mode Register (US_MR).
The receiver samples the RXD line. If the line is sampled during one half of a bit time at 0, a start
bit is detected and data, parity and stop bits are successively sampled on the bit rate clock.
If the oversampling is 16, (OVER at 0), a start is detected at the eighth sample at 0. Then, data
bits, parity bit and stop bit are sampled on each 16 sampling clock cycle. If the oversampling is 8
(OVER at 1), a start bit is detected at the fourth sample at 0. Then, data bits, parity bit and stop
bit are sampled on each 8 sampling clock cycle.
The number of data bits, first bit sent and parity mode are selected by the same fields and bits
as the transmitter, i.e. respectively CHRL, MODE9, MSBF and PAR. For the synchronization
mechanism only, the number of stop bits has no effect on the receiver as it considers only one
stop bit, regardless of the field NBSTOP, so that resynchronization between the receiver and the
transmitter can occur. Moreover, as soon as the stop bit is sampled, the receiver starts looking
for a new start bit so that resynchronization can also be accomplished when the transmitter is
operating with one stop bit.
Figure 32-12 and Figure 32-13 illustrate start detection and character reception when USART
operates in asynchronous mode.
473
6384E–ATARM–05-Feb-10
Figure 32-12. Asynchronous Start Detection
Baud Rate
Clock
Sampling
Clock (x16)
RXD
Sampling
1
2
3
4
5
6
7
8
1
2
3
4
2
3
4
5
6
7
8
9 10 11 12 13 14 15 16
D0
Sampling
Start
Detection
RXD
Sampling
1
2
3
4
5
6
7
0 1
Start
Rejection
Figure 32-13. Asynchronous Character Reception
Example: 8-bit, Parity Enabled
Baud Rate
Clock
RXD
Start
Detection
16
16
16
16
16
16
16
16
16
16
samples samples samples samples samples samples samples samples samples samples
D0
32.6.3.5
D1
D2
D3
D4
D5
D6
D7
Parity
Bit
Stop
Bit
Manchester Decoder
When the MAN field in US_MR register is set to 1, the Manchester decoder is enabled. The
decoder performs both preamble and start frame delimiter detection. One input line is dedicated
to Manchester encoded input data.
An optional preamble sequence can be defined, its length is user-defined and totally independent of the emitter side. Use RX_PL in US_MAN register to configure the length of the preamble
sequence. If the length is set to 0, no preamble is detected and the function is disabled. In addition, the polarity of the input stream is programmable with RX_MPOL field in US_MAN register.
Depending on the desired application the preamble pattern matching is to be defined via the
RX_PP field in US_MAN. See Figure 32-9 for available preamble patterns.
Unlike preamble, the start frame delimiter is shared between Manchester Encoder and Decoder.
So, if ONEBIT field is set to 1, only a zero encoded Manchester can be detected as a valid start
frame delimiter. If ONEBIT is set to 0, only a sync pattern is detected as a valid start frame
delimiter. Decoder operates by detecting transition on incoming stream. If RXD is sampled during one quarter of a bit time at zero, a start bit is detected. See Figure 32-14.. The sample pulse
rejection mechanism applies.
474
AT91SAM9G20
6384E–ATARM–05-Feb-10
AT91SAM9G20
Figure 32-14. Asynchronous Start Bit Detection
Sampling
Clock
(16 x)
Manchester
encoded
data
Txd
Start
Detection
1
2
3
4
The receiver is activated and starts Preamble and Frame Delimiter detection, sampling the data
at one quarter and then three quarters. If a valid preamble pattern or start frame delimiter is
detected, the receiver continues decoding with the same synchronization. If the stream does not
match a valid pattern or a valid start frame delimiter, the receiver re-synchronizes on the next
valid edge.The minimum time threshold to estimate the bit value is three quarters of a bit time.
If a valid preamble (if used) followed with a valid start frame delimiter is detected, the incoming
stream is decoded into NRZ data and passed to USART for processing. Figure 32-15 illustrates
Manchester pattern mismatch. When incoming data stream is passed to the USART, the
receiver is also able to detect Manchester code violation. A code violation is a lack of transition
in the middle of a bit cell. In this case, MANE flag in US_CSR register is raised. It is cleared by
writing the Control Register (US_CR) with the RSTSTA bit at 1. See Figure 32-16 for an example of Manchester error detection during data phase.
Figure 32-15. Preamble Pattern Mismatch
Preamble Mismatch
Manchester coding error
Manchester
encoded
data
Preamble Mismatch
invalid pattern
SFD
Txd
DATA
Preamble Length is set to 8
Figure 32-16. Manchester Error Flag
Preamble Length
is set to 4
Elementary character bit time
SFD
Manchester
encoded
data
Txd
Entering USART character area
sampling points
Preamble subpacket
and Start Frame Delimiter
were successfully
decoded
Manchester
Coding Error
detected
475
6384E–ATARM–05-Feb-10
When the start frame delimiter is a sync pattern (ONEBIT field at 0), both command and data
delimiter are supported. If a valid sync is detected, the received character is written as RXCHR
field in the US_RHR register and the RXSYNH is updated. RXCHR is set to 1 when the received
character is a command, and it is set to 0 if the received character is a data. This mechanism
alleviates and simplifies the direct memory access as the character contains its own sync field in
the same register.
As the decoder is setup to be used in unipolar mode, the first bit of the frame has to be a zero-toone transition.
32.6.3.6
Radio Interface: Manchester Encoded USART Application
This section describes low data rate RF transmission systems and their integration with a
Manchester encoded USART. These systems are based on transmitter and receiver ICs that
support ASK and FSK modulation schemes.
The goal is to perform full duplex radio transmission of characters using two different frequency
carriers. See the configuration in Figure 32-17.
Figure 32-17. Manchester Encoded Characters RF Transmission
Fup frequency Carrier
ASK/FSK
Upstream Receiver
Upstream
Emitter
LNA
VCO
RF filter
Demod
Serial
Configuration
Interface
control
Fdown frequency Carrier
bi-dir
line
Manchester
decoder
USART
Receiver
Manchester
encoder
USART
Emitter
ASK/FSK
downstream transmitter
Downstream
Receiver
PA
RF filter
Mod
VCO
control
The USART module is configured as a Manchester encoder/decoder. Looking at the downstream communication channel, Manchester encoded characters are serially sent to the RF
emitter. This may also include a user defined preamble and a start frame delimiter. Mostly, preamble is used in the RF receiver to distinguish between a valid data from a transmitter and
signals due to noise. The Manchester stream is then modulated. See Figure 32-18 for an example of ASK modulation scheme. When a logic one is sent to the ASK modulator, the power
amplifier, referred to as PA, is enabled and transmits an RF signal at downstream frequency.
When a logic zero is transmitted, the RF signal is turned off. If the FSK modulator is activated,
two different frequencies are used to transmit data. When a logic 1 is sent, the modulator outputs an RF signal at frequency F0 and switches to F1 if the data sent is a 0. See Figure 32-19.
476
AT91SAM9G20
6384E–ATARM–05-Feb-10
AT91SAM9G20
From the receiver side, another carrier frequency is used. The RF receiver performs a bit check
operation examining demodulated data stream. If a valid pattern is detected, the receiver
switches to receiving mode. The demodulated stream is sent to the Manchester decoder.
Because of bit checking inside RF IC, the data transferred to the microcontroller is reduced by a
user-defined number of bits. The Manchester preamble length is to be defined in accordance
with the RF IC configuration.
Figure 32-18. ASK Modulator Output
1
0
0
1
0
0
1
NRZ stream
Manchester
encoded
data
default polarity
unipolar output
Txd
ASK Modulator
Output
Uptstream Frequency F0
Figure 32-19. FSK Modulator Output
1
NRZ stream
Manchester
encoded
data
default polarity
unipolar output
Txd
FSK Modulator
Output
Uptstream Frequencies
[F0, F0+offset]
32.6.3.7
Synchronous Receiver
In synchronous mode (SYNC = 1), the receiver samples the RXD signal on each rising edge of
the Baud Rate Clock. If a low level is detected, it is considered as a start. All data bits, the parity
bit and the stop bits are sampled and the receiver waits for the next start bit. Synchronous mode
operations provide a high speed transfer capability.
Configuration fields and bits are the same as in asynchronous mode.
Figure 32-20 illustrates a character reception in synchronous mode.
477
6384E–ATARM–05-Feb-10
Figure 32-20. Synchronous Mode Character Reception
Example: 8-bit, Parity Enabled 1 Stop
Baud Rate
Clock
RXD
Sampling
Start
D0
D1
D2
D3
D4
D5
D6
Stop Bit
D7
Parity Bit
32.6.3.8
Receiver Operations
When a character reception is completed, it is transferred to the Receive Holding Register
(US_RHR) and the RXRDY bit in the Status Register (US_CSR) rises. If a character is completed while the RXRDY is set, the OVRE (Overrun Error) bit is set. The last character is
transferred into US_RHR and overwrites the previous one. The OVRE bit is cleared by writing
the Control Register (US_CR) with the RSTSTA (Reset Status) bit at 1.
Figure 32-21. Receiver Status
Baud Rate
Clock
RXD
Start
D0
Bit
D1
D2
D3
D4
D5
D6
D7
Parity Stop Start
D0
Bit Bit Bit
D1
D2
D3
D4
D5
D6
D7
Parity Stop
Bit Bit
RSTSTA = 1
Write
US_CR
Read
US_RHR
RXRDY
OVRE
478
AT91SAM9G20
6384E–ATARM–05-Feb-10
AT91SAM9G20
32.6.3.9
Parity
The USART supports five parity modes selected by programming the PAR field in the Mode
Register (US_MR). The PAR field also enables the Multidrop mode, see “Multidrop Mode” on
page 480. Even and odd parity bit generation and error detection are supported.
If even parity is selected, the parity generator of the transmitter drives the parity bit at 0 if a number of 1s in the character data bit is even, and at 1 if the number of 1s is odd. Accordingly, the
receiver parity checker counts the number of received 1s and reports a parity error if the sampled parity bit does not correspond. If odd parity is selected, the parity generator of the
transmitter drives the parity bit at 1 if a number of 1s in the character data bit is even, and at 0 if
the number of 1s is odd. Accordingly, the receiver parity checker counts the number of received
1s and reports a parity error if the sampled parity bit does not correspond. If the mark parity is
used, the parity generator of the transmitter drives the parity bit at 1 for all characters. The
receiver parity checker reports an error if the parity bit is sampled at 0. If the space parity is
used, the parity generator of the transmitter drives the parity bit at 0 for all characters. The
receiver parity checker reports an error if the parity bit is sampled at 1. If parity is disabled, the
transmitter does not generate any parity bit and the receiver does not report any parity error.
Table 32-6 shows an example of the parity bit for the character 0x41 (character ASCII “A”)
depending on the configuration of the USART. Because there are two bits at 1, 1 bit is added
when a parity is odd, or 0 is added when a parity is even.
Table 32-6.
Parity Bit Examples
Character
Hexa
Binary
Parity Bit
Parity Mode
A
0x41
0100 0001
1
Odd
A
0x41
0100 0001
0
Even
A
0x41
0100 0001
1
Mark
A
0x41
0100 0001
0
Space
A
0x41
0100 0001
None
None
When the receiver detects a parity error, it sets the PARE (Parity Error) bit in the Channel Status
Register (US_CSR). The PARE bit can be cleared by writing the Control Register (US_CR) with
the RSTSTA bit at 1. Figure 32-22 illustrates the parity bit status setting and clearing.
479
6384E–ATARM–05-Feb-10
Figure 32-22. Parity Error
Baud Rate
Clock
RXD
Start
D0
Bit
D1
D2
D3
D4
D5
D6
D7
Bad Stop
Parity Bit
Bit
RSTSTA = 1
Write
US_CR
PARE
RXRDY
32.6.3.10
Multidrop Mode
If the PAR field in the Mode Register (US_MR) is programmed to the value 0x6 or 0x07, the
USART runs in Multidrop Mode. This mode differentiates the data characters and the address
characters. Data is transmitted with the parity bit at 0 and addresses are transmitted with the
parity bit at 1.
If the USART is configured in multidrop mode, the receiver sets the PARE parity error bit when
the parity bit is high and the transmitter is able to send a character with the parity bit high when
the Control Register is written with the SENDA bit at 1.
To handle parity error, the PARE bit is cleared when the Control Register is written with the bit
RSTSTA at 1.
The transmitter sends an address byte (parity bit set) when SENDA is written to US_CR. In this
case, the next byte written to US_THR is transmitted as an address. Any character written in
US_THR without having written the command SENDA is transmitted normally with the parity at
0.
32.6.3.11
Transmitter Timeguard
The timeguard feature enables the USART interface with slow remote devices.
The timeguard function enables the transmitter to insert an idle state on the TXD line between
two characters. This idle state actually acts as a long stop bit.
The duration of the idle state is programmed in the TG field of the Transmitter Timeguard Register (US_TTGR). When this field is programmed at zero no timeguard is generated. Otherwise,
the transmitter holds a high level on TXD after each transmitted byte during the number of bit
periods programmed in TG in addition to the number of stop bits.
As illustrated in Figure 32-23, the behavior of TXRDY and TXEMPTY status bits is modified by
the programming of a timeguard. TXRDY rises only when the start bit of the next character is
sent, and thus remains at 0 during the timeguard transmission if a character has been written in
US_THR. TXEMPTY remains low until the timeguard transmission is completed as the timeguard is part of the current character being transmitted.
480
AT91SAM9G20
6384E–ATARM–05-Feb-10
AT91SAM9G20
Figure 32-23. Timeguard Operations
TG = 4
TG = 4
Baud Rate
Clock
TXD
Start
D0
Bit
D1
D2
D3
D4
D5
D6
D7
Parity Stop
Bit Bit
Start
D0
Bit
D1
D2
D3
D4
D5
D6
D7
Parity Stop
Bit Bit
Write
US_THR
TXRDY
TXEMPTY
Table 32-7 indicates the maximum length of a timeguard period that the transmitter can handle
in relation to the function of the Baud Rate.
Table 32-7.
32.6.3.12
Maximum Timeguard Length Depending on Baud Rate
Baud Rate
Bit time
Timeguard
Bit/sec
µs
ms
1 200
833
212.50
9 600
104
26.56
14400
69.4
17.71
19200
52.1
13.28
28800
34.7
8.85
33400
29.9
7.63
56000
17.9
4.55
57600
17.4
4.43
115200
8.7
2.21
Receiver Time-out
The Receiver Time-out provides support in handling variable-length frames. This feature detects
an idle condition on the RXD line. When a time-out is detected, the bit TIMEOUT in the Channel
Status Register (US_CSR) rises and can generate an interrupt, thus indicating to the driver an
end of frame.
The time-out delay period (during which the receiver waits for a new character) is programmed
in the TO field of the Receiver Time-out Register (US_RTOR). If the TO field is programmed at
0, the Receiver Time-out is disabled and no time-out is detected. The TIMEOUT bit in US_CSR
remains at 0. Otherwise, the receiver loads a 16-bit counter with the value programmed in TO.
This counter is decremented at each bit period and reloaded each time a new character is
received. If the counter reaches 0, the TIMEOUT bit in the Status Register rises. Then, the user
can either:
• Stop the counter clock until a new character is received. This is performed by writing the
Control Register (US_CR) with the STTTO (Start Time-out) bit at 1. In this case, the idle state
481
6384E–ATARM–05-Feb-10
on RXD before a new character is received will not provide a time-out. This prevents having
to handle an interrupt before a character is received and allows waiting for the next idle state
on RXD after a frame is received.
• Obtain an interrupt while no character is received. This is performed by writing US_CR with
the RETTO (Reload and Start Time-out) bit at 1. If RETTO is performed, the counter starts
counting down immediately from the value TO. This enables generation of a periodic interrupt
so that a user time-out can be handled, for example when no key is pressed on a keyboard.
If STTTO is performed, the counter clock is stopped until a first character is received. The idle
state on RXD before the start of the frame does not provide a time-out. This prevents having to
obtain a periodic interrupt and enables a wait of the end of frame when the idle state on RXD is
detected.
If RETTO is performed, the counter starts counting down immediately from the value TO. This
enables generation of a periodic interrupt so that a user time-out can be handled, for example
when no key is pressed on a keyboard.
Figure 32-24 shows the block diagram of the Receiver Time-out feature.
Figure 32-24. Receiver Time-out Block Diagram
TO
Baud Rate
Clock
1
D
Q
Clock
16-bit Time-out
Counter
16-bit
Value
=
STTTO
Character
Received
Load
Clear
TIMEOUT
0
RETTO
Table 32-8 gives the maximum time-out period for some standard baud rates.
Table 32-8.
482
Maximum Time-out Period
Baud Rate
Bit Time
Time-out
bit/sec
µs
ms
600
1 667
109 225
1 200
833
54 613
2 400
417
27 306
4 800
208
13 653
9 600
104
6 827
14400
69
4 551
19200
52
3 413
28800
35
2 276
33400
30
1 962
AT91SAM9G20
6384E–ATARM–05-Feb-10
AT91SAM9G20
Table 32-8.
32.6.3.13
Maximum Time-out Period (Continued)
Baud Rate
Bit Time
Time-out
56000
18
1 170
57600
17
1 138
200000
5
328
Framing Error
The receiver is capable of detecting framing errors. A framing error happens when the stop bit of
a received character is detected at level 0. This can occur if the receiver and the transmitter are
fully desynchronized.
A framing error is reported on the FRAME bit of the Channel Status Register (US_CSR). The
FRAME bit is asserted in the middle of the stop bit as soon as the framing error is detected. It is
cleared by writing the Control Register (US_CR) with the RSTSTA bit at 1.
Figure 32-25. Framing Error Status
Baud Rate
Clock
RXD
Start
D0
Bit
D1
D2
D3
D4
D5
D6
D7
Parity Stop
Bit Bit
RSTSTA = 1
Write
US_CR
FRAME
RXRDY
32.6.3.14
Transmit Break
The user can request the transmitter to generate a break condition on the TXD line. A break condition drives the TXD line low during at least one complete character. It appears the same as a
0x00 character sent with the parity and the stop bits at 0. However, the transmitter holds the
TXD line at least during one character until the user requests the break condition to be removed.
A break is transmitted by writing the Control Register (US_CR) with the STTBRK bit at 1. This
can be performed at any time, either while the transmitter is empty (no character in either the
Shift Register or in US_THR) or when a character is being transmitted. If a break is requested
while a character is being shifted out, the character is first completed before the TXD line is held
low.
Once STTBRK command is requested further STTBRK commands are ignored until the end of
the break is completed.
The break condition is removed by writing US_CR with the STPBRK bit at 1. If the STPBRK is
requested before the end of the minimum break duration (one character, including start, data,
parity and stop bits), the transmitter ensures that the break condition completes.
483
6384E–ATARM–05-Feb-10
The transmitter considers the break as though it is a character, i.e. the STTBRK and STPBRK
commands are taken into account only if the TXRDY bit in US_CSR is at 1 and the start of the
break condition clears the TXRDY and TXEMPTY bits as if a character is processed.
Writing US_CR with the both STTBRK and STPBRK bits at 1 can lead to an unpredictable
result. All STPBRK commands requested without a previous STTBRK command are ignored. A
byte written into the Transmit Holding Register while a break is pending, but not started, is
ignored.
After the break condition, the transmitter returns the TXD line to 1 for a minimum of 12 bit times.
Thus, the transmitter ensures that the remote receiver detects correctly the end of break and the
start of the next character. If the timeguard is programmed with a value higher than 12, the TXD
line is held high for the timeguard period.
After holding the TXD line for this period, the transmitter resumes normal operations.
Figure 32-26 illustrates the effect of both the Start Break (STTBRK) and Stop Break (STPBRK)
commands on the TXD line.
Figure 32-26. Break Transmission
Baud Rate
Clock
TXD
Start
D0
Bit
D1
D2
D3
D4
D5
D6
STTBRK = 1
D7
Parity Stop
Bit Bit
Break Transmission
End of Break
STPBRK = 1
Write
US_CR
TXRDY
TXEMPTY
32.6.3.15
Receive Break
The receiver detects a break condition when all data, parity and stop bits are low. This corresponds to detecting a framing error with data at 0x00, but FRAME remains low.
When the low stop bit is detected, the receiver asserts the RXBRK bit in US_CSR. This bit may
be cleared by writing the Control Register (US_CR) with the bit RSTSTA at 1.
An end of receive break is detected by a high level for at least 2/16 of a bit period in asynchronous operating mode or one sample at high level in synchronous operating mode. The end of
break detection also asserts the RXBRK bit.
32.6.3.16
484
Hardware Handshaking
The USART features a hardware handshaking out-of-band flow control. The RTS and CTS pins
are used to connect with the remote device, as shown in Figure 32-27.
AT91SAM9G20
6384E–ATARM–05-Feb-10
AT91SAM9G20
Figure 32-27. Connection with a Remote Device for Hardware Handshaking
USART
Remote
Device
TXD
RXD
RXD
TXD
CTS
RTS
RTS
CTS
Setting the USART to operate with hardware handshaking is performed by writing the
USART_MODE field in the Mode Register (US_MR) to the value 0x2.
The USART behavior when hardware handshaking is enabled is the same as the behavior in
standard synchronous or asynchronous mode, except that the receiver drives the RTS pin as
described below and the level on the CTS pin modifies the behavior of the transmitter as
described below. Using this mode requires using the PDC channel for reception. The transmitter
can handle hardware handshaking in any case.
Figure 32-28 shows how the receiver operates if hardware handshaking is enabled. The RTS
pin is driven high if the receiver is disabled and if the status RXBUFF (Receive Buffer Full) coming from the PDC channel is high. Normally, the remote device does not start transmitting while
its CTS pin (driven by RTS) is high. As soon as the Receiver is enabled, the RTS falls, indicating
to the remote device that it can start transmitting. Defining a new buffer to the PDC clears the
status bit RXBUFF and, as a result, asserts the pin RTS low.
Figure 32-28. Receiver Behavior when Operating with Hardware Handshaking
RXD
RXEN = 1
RXDIS = 1
Write
US_CR
RTS
RXBUFF
Figure 32-29 shows how the transmitter operates if hardware handshaking is enabled. The CTS
pin disables the transmitter. If a character is being processing, the transmitter is disabled only
after the completion of the current character and transmission of the next character happens as
soon as the pin CTS falls.
Figure 32-29. Transmitter Behavior when Operating with Hardware Handshaking
CTS
TXD
485
6384E–ATARM–05-Feb-10
32.6.4
ISO7816 Mode
The USART features an ISO7816-compatible operating mode. This mode permits interfacing
with smart cards and Security Access Modules (SAM) communicating through an ISO7816 link.
Both T = 0 and T = 1 protocols defined by the ISO7816 specification are supported.
Setting the USART in ISO7816 mode is performed by writing the USART_MODE field in the
Mode Register (US_MR) to the value 0x4 for protocol T = 0 and to the value 0x5 for protocol T =
1.
32.6.4.1
ISO7816 Mode Overview
The ISO7816 is a half duplex communication on only one bidirectional line. The baud rate is
determined by a division of the clock provided to the remote device (see “Baud Rate Generator”
on page 464).
The USART connects to a smart card as shown in Figure 32-30. The TXD line becomes bidirectional and the Baud Rate Generator feeds the ISO7816 clock on the SCK pin. As the TXD pin
becomes bidirectional, its output remains driven by the output of the transmitter but only when
the transmitter is active while its input is directed to the input of the receiver. The USART is considered as the master of the communication as it generates the clock.
Figure 32-30. Connection of a Smart Card to the USART
USART
SCK
TXD
CLK
I/O
Smart
Card
When operating in ISO7816, either in T = 0 or T = 1 modes, the character format is fixed. The
configuration is 8 data bits, even parity and 1 or 2 stop bits, regardless of the values programmed in the CHRL, MODE9, PAR and CHMODE fields. MSBF can be used to transmit LSB
or MSB first. Parity Bit (PAR) can be used to transmit in normal or inverse mode. Refer to
“USART Mode Register” on page 499 and “PAR: Parity Type” on page 500.
The USART cannot operate concurrently in both receiver and transmitter modes as the communication is unidirectional at a time. It has to be configured according to the required mode by
enabling or disabling either the receiver or the transmitter as desired. Enabling both the receiver
and the transmitter at the same time in ISO7816 mode may lead to unpredictable results.
The ISO7816 specification defines an inverse transmission format. Data bits of the character
must be transmitted on the I/O line at their negative value. The USART does not support this format and the user has to perform an exclusive OR on the data before writing it in the Transmit
Holding Register (US_THR) or after reading it in the Receive Holding Register (US_RHR).
32.6.4.2
Protocol T = 0
In T = 0 protocol, a character is made up of one start bit, eight data bits, one parity bit and one
guard time, which lasts two bit times. The transmitter shifts out the bits and does not drive the
I/O line during the guard time.
If no parity error is detected, the I/O line remains at 1 during the guard time and the transmitter
can continue with the transmission of the next character, as shown in Figure 32-31.
486
AT91SAM9G20
6384E–ATARM–05-Feb-10
AT91SAM9G20
If a parity error is detected by the receiver, it drives the I/O line at 0 during the guard time, as
shown in Figure 32-32. This error bit is also named NACK, for Non Acknowledge. In this case,
the character lasts 1 bit time more, as the guard time length is the same and is added to the
error bit time which lasts 1 bit time.
When the USART is the receiver and it detects an error, it does not load the erroneous character
in the Receive Holding Register (US_RHR). It appropriately sets the PARE bit in the Status Register (US_SR) so that the software can handle the error.
Figure 32-31. T = 0 Protocol without Parity Error
Baud Rate
Clock
RXD
Start
Bit
D0
D1
D2
D3
D4
D5
D6
D7
Parity Guard Guard Next
Bit Time 1 Time 2 Start
Bit
Figure 32-32. T = 0 Protocol with Parity Error
32.6.4.3
Receive Error Counter
The USART receiver also records the total number of errors. This can be read in the Number of
Error (US_NER) register. The NB_ERRORS field can record up to 255 errors. Reading US_NER
automatically clears the NB_ERRORS field.
32.6.4.4
Receive NACK Inhibit
The USART can also be configured to inhibit an error. This can be achieved by setting the
INACK bit in the Mode Register (US_MR). If INACK is at 1, no error signal is driven on the I/O
line even if a parity bit is detected, but the INACK bit is set in the Status Register (US_SR). The
INACK bit can be cleared by writing the Control Register (US_CR) with the RSTNACK bit at 1.
Moreover, if INACK is set, the erroneous received character is stored in the Receive Holding
Register, as if no error occurred. However, the RXRDY bit does not raise.
32.6.4.5
Transmit Character Repetition
When the USART is transmitting a character and gets a NACK, it can automatically repeat the
character before moving on to the next one. Repetition is enabled by writing the
MAX_ITERATION field in the Mode Register (US_MR) at a value higher than 0. Each character
can be transmitted up to eight times; the first transmission plus seven repetitions.
If MAX_ITERATION does not equal zero, the USART repeats the character as many times as
the value loaded in MAX_ITERATION.
487
6384E–ATARM–05-Feb-10
When the USART repetition number reaches MAX_ITERATION, the ITERATION bit is set in the
Channel Status Register (US_CSR). If the repetition of the character is acknowledged by the
receiver, the repetitions are stopped and the iteration counter is cleared.
The ITERATION bit in US_CSR can be cleared by writing the Control Register with the RSIT bit
at 1.
32.6.4.6
Disable Successive Receive NACK
The receiver can limit the number of successive NACKs sent back to the remote transmitter.
This is programmed by setting the bit DSNACK in the Mode Register (US_MR). The maximum
number of NACK transmitted is programmed in the MAX_ITERATION field. As soon as
MAX_ITERATION is reached, the character is considered as correct, an acknowledge is sent on
the line and the ITERATION bit in the Channel Status Register is set.
32.6.4.7
Protocol T = 1
When operating in ISO7816 protocol T = 1, the transmission is similar to an asynchronous format with only one stop bit. The parity is generated when transmitting and checked when
receiving. Parity error detection sets the PARE bit in the Channel Status Register (US_CSR).
32.6.5
IrDA Mode
The USART features an IrDA mode supplying half-duplex point-to-point wireless communication. It embeds the modulator and demodulator which allows a glueless connection to the
infrared transceivers, as shown in Figure 32-33. The modulator and demodulator are compliant
with the IrDA specification version 1.1 and support data transfer speeds ranging from 2.4 Kb/s to
115.2 Kb/s.
The USART IrDA mode is enabled by setting the USART_MODE field in the Mode Register
(US_MR) to the value 0x8. The IrDA Filter Register (US_IF) allows configuring the demodulator
filter. The USART transmitter and receiver operate in a normal asynchronous mode and all
parameters are accessible. Note that the modulator and the demodulator are activated.
Figure 32-33. Connection to IrDA Transceivers
USART
IrDA
Transceivers
Receiver
Demodulator
RXD
Transmitter
Modulator
TXD
RX
TX
The receiver and the transmitter must be enabled or disabled according to the direction of the
transmission to be managed.
To receive IrDA signals, the following needs to be done:
• Disable TX and Enable RX
488
AT91SAM9G20
6384E–ATARM–05-Feb-10
AT91SAM9G20
• Configure the TXD pin as PIO and set it as an output at 0 (to avoid LED emission). Disable
the internal pull-up (better for power consumption).
• Receive data
32.6.5.1
IrDA Modulation
For baud rates up to and including 115.2 Kbits/sec, the RZI modulation scheme is used. “0” is
represented by a light pulse of 3/16th of a bit time. Some examples of signal pulse duration are
shown in Table 32-9.
Table 32-9.
IrDA Pulse Duration
Baud Rate
Pulse Duration (3/16)
2.4 Kb/s
78.13 µs
9.6 Kb/s
19.53 µs
19.2 Kb/s
9.77 µs
38.4 Kb/s
4.88 µs
57.6 Kb/s
3.26 µs
115.2 Kb/s
1.63 µs
Figure 32-34 shows an example of character transmission.
Figure 32-34. IrDA Modulation
Start
Bit
Transmitter
Output
0
Stop
Bit
Data Bits
1
0
1
0
0
1
1
0
1
TXD
3
16 Bit Period
Bit Period
32.6.5.2
IrDA Baud Rate
Table 32-10 gives some examples of CD values, baud rate error and pulse duration. Note that
the requirement on the maximum acceptable error of ±1.87% must be met.
Table 32-10. IrDA Baud Rate Error
Peripheral Clock
Baud Rate
CD
Baud Rate Error
Pulse Time
3 686 400
115 200
2
0.00%
1.63
20 000 000
115 200
11
1.38%
1.63
32 768 000
115 200
18
1.25%
1.63
40 000 000
115 200
22
1.38%
1.63
3 686 400
57 600
4
0.00%
3.26
20 000 000
57 600
22
1.38%
3.26
32 768 000
57 600
36
1.25%
3.26
489
6384E–ATARM–05-Feb-10
Table 32-10. IrDA Baud Rate Error (Continued)
Peripheral Clock
32.6.5.3
Baud Rate
CD
Baud Rate Error
Pulse Time
40 000 000
57 600
43
0.93%
3.26
3 686 400
38 400
6
0.00%
4.88
20 000 000
38 400
33
1.38%
4.88
32 768 000
38 400
53
0.63%
4.88
40 000 000
38 400
65
0.16%
4.88
3 686 400
19 200
12
0.00%
9.77
20 000 000
19 200
65
0.16%
9.77
32 768 000
19 200
107
0.31%
9.77
40 000 000
19 200
130
0.16%
9.77
3 686 400
9 600
24
0.00%
19.53
20 000 000
9 600
130
0.16%
19.53
32 768 000
9 600
213
0.16%
19.53
40 000 000
9 600
260
0.16%
19.53
3 686 400
2 400
96
0.00%
78.13
20 000 000
2 400
521
0.03%
78.13
32 768 000
2 400
853
0.04%
78.13
IrDA Demodulator
The demodulator is based on the IrDA Receive filter comprised of an 8-bit down counter which is
loaded with the value programmed in US_IF. When a falling edge is detected on the RXD pin,
the Filter Counter starts counting down at the Master Clock (MCK) speed. If a rising edge is
detected on the RXD pin, the counter stops and is reloaded with US_IF. If no rising edge is
detected when the counter reaches 0, the input of the receiver is driven low during one bit time.
Figure 32-35 illustrates the operations of the IrDA demodulator.
Figure 32-35. IrDA Demodulator Operations
MCK
RXD
Counter
Value
Receiver
Input
6
5
4 3
Pulse
Rejected
2
6
6
5
4
3
2
1
0
Pulse
Accepted
As the IrDA mode uses the same logic as the ISO7816, note that the FI_DI_RATIO field in
US_FIDI must be set to a value higher than 0 in order to assure IrDA communications operate
correctly.
490
AT91SAM9G20
6384E–ATARM–05-Feb-10
AT91SAM9G20
32.6.6
RS485 Mode
The USART features the RS485 mode to enable line driver control. While operating in RS485
mode, the USART behaves as though in asynchronous or synchronous mode and configuration
of all the parameters is possible. The difference is that the RTS pin is driven high when the
transmitter is operating. The behavior of the RTS pin is controlled by the TXEMPTY bit. A typical
connection of the USART to a RS485 bus is shown in Figure 32-36.
Figure 32-36. Typical Connection to a RS485 Bus
USART
RXD
Differential
Bus
TXD
RTS
The USART is set in RS485 mode by programming the USART_MODE field in the Mode Register (US_MR) to the value 0x1.
The RTS pin is at a level inverse to the TXEMPTY bit. Significantly, the RTS pin remains high
when a timeguard is programmed so that the line can remain driven after the last character completion. Figure 32-37 gives an example of the RTS waveform during a character transmission
when the timeguard is enabled.
Figure 32-37. Example of RTS Drive with Timeguard
TG = 4
Baud Rate
Clock
TXD
Start
D0
Bit
D1
D2
D3
D4
D5
D6
D7
Parity Stop
Bit Bit
Write
US_THR
TXRDY
TXEMPTY
RTS
491
6384E–ATARM–05-Feb-10
32.6.7
Modem Mode
The USART features modem mode, which enables control of the signals: DTR (Data Terminal
Ready), DSR (Data Set Ready), RTS (Request to Send), CTS (Clear to Send), DCD (Data Carrier Detect) and RI (Ring Indicator). While operating in modem mode, the USART behaves as a
DTE (Data Terminal Equipment) as it drives DTR and RTS and can detect level change on DSR,
DCD, CTS and RI.
Setting the USART in modem mode is performed by writing the USART_MODE field in the Mode
Register (US_MR) to the value 0x3. While operating in modem mode the USART behaves as
though in asynchronous mode and all the parameter configurations are available.
Table 32-11 gives the correspondence of the USART signals with modem connection standards.
Table 32-11. Circuit References
USART Pin
V24
CCITT
Direction
TXD
2
103
From terminal to modem
RTS
4
105
From terminal to modem
DTR
20
108.2
From terminal to modem
RXD
3
104
From modem to terminal
CTS
5
106
From terminal to modem
DSR
6
107
From terminal to modem
DCD
8
109
From terminal to modem
RI
22
125
From terminal to modem
The control of the DTR output pin is performed by writing the Control Register (US_CR) with the
DTRDIS and DTREN bits respectively at 1. The disable command forces the corresponding pin
to its inactive level, i.e. high. The enable command forces the corresponding pin to its active
level, i.e. low. RTS output pin is automatically controlled in this mode
The level changes are detected on the RI, DSR, DCD and CTS pins. If an input change is
detected, the RIIC, DSRIC, DCDIC and CTSIC bits in the Channel Status Register (US_CSR)
are set respectively and can trigger an interrupt. The status is automatically cleared when
US_CSR is read. Furthermore, the CTS automatically disables the transmitter when it is
detected at its inactive state. If a character is being transmitted when the CTS rises, the character transmission is completed before the transmitter is actually disabled.
•
32.6.8
Test Modes
The USART can be programmed to operate in three different test modes. The internal loopback
capability allows on-board diagnostics. In the loopback mode the USART interface pins are disconnected or not and reconfigured for loopback internally or externally.
492
AT91SAM9G20
6384E–ATARM–05-Feb-10
AT91SAM9G20
32.6.8.1
Normal Mode
Normal mode connects the RXD pin on the receiver input and the transmitter output on the TXD
pin.
Figure 32-38. Normal Mode Configuration
RXD
Receiver
TXD
Transmitter
32.6.8.2
Automatic Echo Mode
Automatic echo mode allows bit-by-bit retransmission. When a bit is received on the RXD pin, it
is sent to the TXD pin, as shown in Figure 32-39. Programming the transmitter has no effect on
the TXD pin. The RXD pin is still connected to the receiver input, thus the receiver remains
active.
Figure 32-39. Automatic Echo Mode Configuration
RXD
Receiver
TXD
Transmitter
32.6.8.3
Local Loopback Mode
Local loopback mode connects the output of the transmitter directly to the input of the receiver,
as shown in Figure 32-40. The TXD and RXD pins are not used. The RXD pin has no effect on
the receiver and the TXD pin is continuously driven high, as in idle state.
Figure 32-40. Local Loopback Mode Configuration
RXD
Receiver
Transmitter
32.6.8.4
1
TXD
Remote Loopback Mode
Remote loopback mode directly connects the RXD pin to the TXD pin, as shown in Figure 32-41.
The transmitter and the receiver are disabled and have no effect. This mode allows bit-by-bit
retransmission.
493
6384E–ATARM–05-Feb-10
Figure 32-41. Remote Loopback Mode Configuration
Receiver
1
RXD
TXD
Transmitter
494
AT91SAM9G20
6384E–ATARM–05-Feb-10
AT91SAM9G20
32.7
Universal Synchronous Asynchronous Receiver Transmitter (USART) User Interface
Table 32-12.
Register Mapping
Offset
Register
Name
Access
Reset
0x0000
Control Register
US_CR
Write-only
–
0x0004
Mode Register
US_MR
Read-write
–
0x0008
Interrupt Enable Register
US_IER
Write-only
–
0x000C
Interrupt Disable Register
US_IDR
Write-only
–
0x0010
Interrupt Mask Register
US_IMR
Read-only
0x0
0x0014
Channel Status Register
US_CSR
Read-only
–
0x0018
Receiver Holding Register
US_RHR
Read-only
0x0
0x001C
Transmitter Holding Register
US_THR
Write-only
–
0x0020
Baud Rate Generator Register
US_BRGR
Read-write
0x0
0x0024
Receiver Time-out Register
US_RTOR
Read-write
0x0
0x0028
Transmitter Timeguard Register
US_TTGR
Read-write
0x0
–
–
–
0x2C - 0x3C
Reserved
0x0040
FI DI Ratio Register
US_FIDI
Read-write
0x174
0x0044
Number of Errors Register
US_NER
Read-only
–
0x0048
Reserved
–
–
–
0x004C
IrDA Filter Register
US_IF
Read-write
0x0
0x0050
Manchester Encoder Decoder Register
US_MAN
Read-write
0x30011004
Reserved
–
–
–
Reserved for PDC Registers
–
–
–
0x5C - 0xFC
0x100 - 0x128
495
6384E–ATARM–05-Feb-10
32.7.1
Name:
USART Control Register
US_CR
Access Type:
Write-only
31
–
30
–
29
–
28
–
27
–
26
–
25
–
24
–
23
–
22
–
21
–
20
–
19
RTSDIS
18
RTSEN
17
DTRDIS
16
DTREN
15
RETTO
14
RSTNACK
13
RSTIT
12
SENDA
11
STTTO
10
STPBRK
9
STTBRK
8
RSTSTA
7
TXDIS
6
TXEN
5
RXDIS
4
RXEN
3
RSTTX
2
RSTRX
1
–
0
–
• RSTRX: Reset Receiver
0: No effect.
1: Resets the receiver.
• RSTTX: Reset Transmitter
0: No effect.
1: Resets the transmitter.
• RXEN: Receiver Enable
0: No effect.
1: Enables the receiver, if RXDIS is 0.
• RXDIS: Receiver Disable
0: No effect.
1: Disables the receiver.
• TXEN: Transmitter Enable
0: No effect.
1: Enables the transmitter if TXDIS is 0.
• TXDIS: Transmitter Disable
0: No effect.
1: Disables the transmitter.
496
AT91SAM9G20
6384E–ATARM–05-Feb-10
AT91SAM9G20
• RSTSTA: Reset Status Bits
0: No effect.
1: Resets the status bits PARE, FRAME, OVRE, MANERR and RXBRK in US_CSR.
• STTBRK: Start Break
0: No effect.
1: Starts transmission of a break after the characters present in US_THR and the Transmit Shift Register have been transmitted. No effect if a break is already being transmitted.
• STPBRK: Stop Break
0: No effect.
1: Stops transmission of the break after a minimum of one character length and transmits a high level during 12-bit periods.
No effect if no break is being transmitted.
• STTTO: Start Time-out
0: No effect.
1: Starts waiting for a character before clocking the time-out counter. Resets the status bit TIMEOUT in US_CSR.
• SENDA: Send Address
0: No effect.
1: In Multidrop Mode only, the next character written to the US_THR is sent with the address bit set.
• RSTIT: Reset Iterations
0: No effect.
1: Resets ITERATION in US_CSR. No effect if the ISO7816 is not enabled.
• RSTNACK: Reset Non Acknowledge
0: No effect
1: Resets NACK in US_CSR.
• RETTO: Rearm Time-out
0: No effect
1: Restart Time-out
• DTREN: Data Terminal Ready Enable
0: No effect.
1: Drives the pin DTR at 0.
• DTRDIS: Data Terminal Ready Disable
0: No effect.
1: Drives the pin DTR to 1.
• RTSEN: Request to Send Enable
0: No effect.
1: Drives the pin RTS to 0.
497
6384E–ATARM–05-Feb-10
• RTSDIS: Request to Send Disable
0: No effect.
1: Drives the pin RTS to 1.
498
AT91SAM9G20
6384E–ATARM–05-Feb-10
AT91SAM9G20
32.7.2
Name:
USART Mode Register
US_MR
Access Type:
Read-write
31
ONEBIT
30
MODSYNC
29
MAN
28
FILTER
27
–
26
25
MAX_ITERATION
24
23
–
22
VAR_SYNC
21
DSNACK
20
INACK
19
OVER
18
CLKO
17
MODE9
16
MSBF
15
14
13
12
11
10
PAR
9
8
SYNC
4
3
2
1
0
CHMODE
7
NBSTOP
6
5
CHRL
USCLKS
USART_MODE
• USART_MODE
USART_MODE
Mode of the USART
0
0
0
0
Normal
0
0
0
1
RS485
0
0
1
0
Hardware Handshaking
0
0
1
1
Modem
0
1
0
0
IS07816 Protocol: T = 0
0
1
1
0
IS07816 Protocol: T = 1
1
0
0
0
IrDA
Others
Reserved
• USCLKS: Clock Selection
USCLKS
Selected Clock
0
0
MCK
0
1
MCK/DIV (DIV = 8)
1
0
Reserved
1
1
SCK
• CHRL: Character Length.
CHRL
Character Length
0
0
5 bits
0
1
6 bits
1
0
7 bits
1
1
8 bits
499
6384E–ATARM–05-Feb-10
• SYNC: Synchronous Mode Select
0: USART operates in Asynchronous Mode.
1: USART operates in Synchronous Mode.
• PAR: Parity Type
PAR
Parity Type
0
0
0
Even parity
0
0
1
Odd parity
0
1
0
Parity forced to 0 (Space)
0
1
1
Parity forced to 1 (Mark)
1
0
x
No parity
1
1
x
Multidrop mode
• NBSTOP: Number of Stop Bits
NBSTOP
Asynchronous (SYNC = 0)
Synchronous (SYNC = 1)
0
0
1 stop bit
1 stop bit
0
1
1.5 stop bits
Reserved
1
0
2 stop bits
2 stop bits
1
1
Reserved
Reserved
• CHMODE: Channel Mode
CHMODE
Mode Description
0
0
Normal Mode
0
1
Automatic Echo. Receiver input is connected to the TXD pin.
1
0
Local Loopback. Transmitter output is connected to the Receiver Input..
1
1
Remote Loopback. RXD pin is internally connected to the TXD pin.
• MSBF: Bit Order
0: Least Significant Bit is sent/received first.
1: Most Significant Bit is sent/received first.
• MODE9: 9-bit Character Length
0: CHRL defines character length.
1: 9-bit character length.
• CLKO: Clock Output Select
0: The USART does not drive the SCK pin.
1: The USART drives the SCK pin if USCLKS does not select the external clock SCK.
• OVER: Oversampling Mode
0: 16x Oversampling.
500
AT91SAM9G20
6384E–ATARM–05-Feb-10
AT91SAM9G20
1: 8x Oversampling.
• INACK: Inhibit Non Acknowledge
0: The NACK is generated.
1: The NACK is not generated.
• DSNACK: Disable Successive NACK
0: NACK is sent on the ISO line as soon as a parity error occurs in the received character (unless INACK is set).
1: Successive parity errors are counted up to the value specified in the MAX_ITERATION field. These parity errors generate a NACK on the ISO line. As soon as this value is reached, no additional NACK is sent on the ISO line. The flag
ITERATION is asserted.
• VAR_SYNC: Variable Synchronization of Command/Data Sync Start Frame Delimiter
0: User defined configuration of command or data sync field depending on SYNC value.
1: The sync field is updated when a character is written into US_THR register.
• MAX_ITERATION
Defines the maximum number of iterations in mode ISO7816, protocol T= 0.
• FILTER: Infrared Receive Line Filter
0: The USART does not filter the receive line.
• 1: The USART filters the receive line using a three-sample filter (1/16-bit clock) (2 over 3 majority).MAN: Manchester
Encoder/Decoder Enable
0: Manchester Encoder/Decoder are disabled.
1: Manchester Encoder/Decoder are enabled.
• MODSYNC: Manchester Synchronization Mode
0:The Manchester Start bit is a 0 to 1 transition
1: The Manchester Start bit is a 1 to 0 transition.
• ONEBIT: Start Frame Delimiter Selector
0: Start Frame delimiter is COMMAND or DATA SYNC.
1: Start Frame delimiter is One Bit.
501
6384E–ATARM–05-Feb-10
32.7.3
Name:
USART Interrupt Enable Register
US_IER
Access Type:
Write-only
31
–
30
–
29
–
28
–
27
–
26
–
25
–
24
MANE
23
–
22
–
21
–
20
MANE
19
CTSIC
18
DCDIC
17
DSRIC
16
RIIC
15
–
14
–
13
NACK
12
RXBUFF
11
TXBUFE
10
ITER
9
TXEMPTY
8
TIMEOUT
7
PARE
6
FRAME
5
OVRE
4
ENDTX
3
ENDRX
2
RXBRK
1
TXRDY
0
RXRDY
• RXRDY: RXRDY Interrupt Enable
• TXRDY: TXRDY Interrupt Enable
• RXBRK: Receiver Break Interrupt Enable
• ENDRX: End of Receive Transfer Interrupt Enable
• ENDTX: End of Transmit Interrupt Enable
• OVRE: Overrun Error Interrupt Enable
• FRAME: Framing Error Interrupt Enable
• PARE: Parity Error Interrupt Enable
• TIMEOUT: Time-out Interrupt Enable
• TXEMPTY: TXEMPTY Interrupt Enable
• ITER: Iteration Interrupt Enable
• TXBUFE: Buffer Empty Interrupt Enable
• RXBUFF: Buffer Full Interrupt Enable
• NACK: Non Acknowledge Interrupt Enable
• RIIC: Ring Indicator Input Change Enable
• DSRIC: Data Set Ready Input Change Enable
• DCDIC: Data Carrier Detect Input Change Interrupt Enable
• CTSIC: Clear to Send Input Change Interrupt Enable
• MANE: Manchester Error Interrupt Enable
502
AT91SAM9G20
6384E–ATARM–05-Feb-10
AT91SAM9G20
32.7.4
Name:
USART Interrupt Disable Register
US_IDR
Access Type:
Write-only
31
–
30
–
29
–
28
–
27
–
26
–
25
–
24
MANE
23
–
22
–
21
–
20
MANE
19
CTSIC
18
DCDIC
17
DSRIC
16
RIIC
15
–
14
–
13
NACK
12
RXBUFF
11
TXBUFE
10
ITER
9
TXEMPTY
8
TIMEOUT
7
PARE
6
FRAME
5
OVRE
4
ENDTX
3
ENDRX
2
RXBRK
1
TXRDY
0
RXRDY
• RXRDY: RXRDY Interrupt Disable
• TXRDY: TXRDY Interrupt Disable
• RXBRK: Receiver Break Interrupt Disable
• ENDRX: End of Receive Transfer Interrupt Disable
• ENDTX: End of Transmit Interrupt Disable
• OVRE: Overrun Error Interrupt Disable
• FRAME: Framing Error Interrupt Disable
• PARE: Parity Error Interrupt Disable
• TIMEOUT: Time-out Interrupt Disable
• TXEMPTY: TXEMPTY Interrupt Disable
• ITER: Iteration Interrupt Enable
• TXBUFE: Buffer Empty Interrupt Disable
• RXBUFF: Buffer Full Interrupt Disable
• NACK: Non Acknowledge Interrupt Disable
• RIIC: Ring Indicator Input Change Disable
• DSRIC: Data Set Ready Input Change Disable
• DCDIC: Data Carrier Detect Input Change Interrupt Disable
• CTSIC: Clear to Send Input Change Interrupt Disable
• MANE: Manchester Error Interrupt Disable
503
6384E–ATARM–05-Feb-10
32.7.5
Name:
USART Interrupt Mask Register
US_IMR
Access Type:
Read-only
31
–
30
–
29
–
28
–
27
–
26
–
25
–
24
MANE
23
–
22
–
21
–
20
MANE
19
CTSIC
18
DCDIC
17
DSRIC
16
RIIC
15
–
14
–
13
NACK
12
RXBUFF
11
TXBUFE
10
ITER
9
TXEMPTY
8
TIMEOUT
7
PARE
6
FRAME
5
OVRE
4
ENDTX
3
ENDRX
2
RXBRK
1
TXRDY
0
RXRDY
• RXRDY: RXRDY Interrupt Mask
• TXRDY: TXRDY Interrupt Mask
• RXBRK: Receiver Break Interrupt Mask
• ENDRX: End of Receive Transfer Interrupt Mask
• ENDTX: End of Transmit Interrupt Mask
• OVRE: Overrun Error Interrupt Mask
• FRAME: Framing Error Interrupt Mask
• PARE: Parity Error Interrupt Mask
• TIMEOUT: Time-out Interrupt Mask
• TXEMPTY: TXEMPTY Interrupt Mask
• ITER: Iteration Interrupt Enable
• TXBUFE: Buffer Empty Interrupt Mask
• RXBUFF: Buffer Full Interrupt Mask
• NACK: Non Acknowledge Interrupt Mask
• RIIC: Ring Indicator Input Change Mask
• DSRIC: Data Set Ready Input Change Mask
• DCDIC: Data Carrier Detect Input Change Interrupt Mask
• CTSIC: Clear to Send Input Change Interrupt Mask
• MANE: Manchester Error Interrupt Mask
504
AT91SAM9G20
6384E–ATARM–05-Feb-10
AT91SAM9G20
32.7.6
Name:
USART Channel Status Register
US_CSR
Access Type:
Read-only
31
–
30
–
29
–
28
–
27
–
26
–
25
–
24
MANERR
23
CTS
22
DCD
21
DSR
20
RI
19
CTSIC
18
DCDIC
17
DSRIC
16
RIIC
15
–
14
–
13
NACK
12
RXBUFF
11
TXBUFE
10
ITER
9
TXEMPTY
8
TIMEOUT
7
PARE
6
FRAME
5
OVRE
4
ENDTX
3
ENDRX
2
RXBRK
1
TXRDY
0
RXRDY
• RXRDY: Receiver Ready
0: No complete character has been received since the last read of US_RHR or the receiver is disabled. If characters were
being received when the receiver was disabled, RXRDY changes to 1 when the receiver is enabled.
1: At least one complete character has been received and US_RHR has not yet been read.
• TXRDY: Transmitter Ready
0: A character is in the US_THR waiting to be transferred to the Transmit Shift Register, or an STTBRK command has been
requested, or the transmitter is disabled. As soon as the transmitter is enabled, TXRDY becomes 1.
1: There is no character in the US_THR.
• RXBRK: Break Received/End of Break
0: No Break received or End of Break detected since the last RSTSTA.
1: Break Received or End of Break detected since the last RSTSTA.
• ENDRX: End of Receiver Transfer
0: The End of Transfer signal from the Receive PDC channel is inactive.
1: The End of Transfer signal from the Receive PDC channel is active.
• ENDTX: End of Transmitter Transfer
0: The End of Transfer signal from the Transmit PDC channel is inactive.
1: The End of Transfer signal from the Transmit PDC channel is active.
• OVRE: Overrun Error
0: No overrun error has occurred since the last RSTSTA.
1: At least one overrun error has occurred since the last RSTSTA.
505
6384E–ATARM–05-Feb-10
• FRAME: Framing Error
0: No stop bit has been detected low since the last RSTSTA.
1: At least one stop bit has been detected low since the last RSTSTA.
• PARE: Parity Error
0: No parity error has been detected since the last RSTSTA.
1: At least one parity error has been detected since the last RSTSTA.
• TIMEOUT: Receiver Time-out
0: There has not been a time-out since the last Start Time-out command (STTTO in US_CR) or the Time-out Register is 0.
1: There has been a time-out since the last Start Time-out command (STTTO in US_CR).
• TXEMPTY: Transmitter Empty
0: There are characters in either US_THR or the Transmit Shift Register, or the transmitter is disabled.
1: There are no characters in US_THR, nor in the Transmit Shift Register.
• ITER: Max number of Repetitions Reached
0: Maximum number of repetitions has not been reached since the last RSTSTA.
1: Maximum number of repetitions has been reached since the last RSTSTA.
• TXBUFE: Transmission Buffer Empty
0: The signal Buffer Empty from the Transmit PDC channel is inactive.
1: The signal Buffer Empty from the Transmit PDC channel is active.
• RXBUFF: Reception Buffer Full
0: The signal Buffer Full from the Receive PDC channel is inactive.
1: The signal Buffer Full from the Receive PDC channel is active.
• NACK: Non Acknowledge
0: No Non Acknowledge has not been detected since the last RSTNACK.
1: At least one Non Acknowledge has been detected since the last RSTNACK.
• RIIC: Ring Indicator Input Change Flag
0: No input change has been detected on the RI pin since the last read of US_CSR.
1: At least one input change has been detected on the RI pin since the last read of US_CSR.
• DSRIC: Data Set Ready Input Change Flag
0: No input change has been detected on the DSR pin since the last read of US_CSR.
1: At least one input change has been detected on the DSR pin since the last read of US_CSR.
• DCDIC: Data Carrier Detect Input Change Flag
0: No input change has been detected on the DCD pin since the last read of US_CSR.
1: At least one input change has been detected on the DCD pin since the last read of US_CSR.
• CTSIC: Clear to Send Input Change Flag
0: No input change has been detected on the CTS pin since the last read of US_CSR.
506
AT91SAM9G20
6384E–ATARM–05-Feb-10
AT91SAM9G20
1: At least one input change has been detected on the CTS pin since the last read of US_CSR.
• RI: Image of RI Input
0: RI is at 0.
1: RI is at 1.
• DSR: Image of DSR Input
0: DSR is at 0
1: DSR is at 1.
• DCD: Image of DCD Input
0: DCD is at 0.
1: DCD is at 1.
• CTS: Image of CTS Input
0: CTS is at 0.
1: CTS is at 1.
• MANERR: Manchester Error
0: No Manchester error has been detected since the last RSTSTA.
1: At least one Manchester error has been detected since the last RSTSTA.
507
6384E–ATARM–05-Feb-10
32.7.7
Name:
USART Receive Holding Register
US_RHR
Access Type:
Read-only
31
–
30
–
29
–
28
–
27
–
26
–
25
–
24
–
23
–
22
–
21
–
20
–
19
–
18
–
17
–
16
–
15
RXSYNH
14
–
13
–
12
–
11
–
10
–
9
–
8
RXCHR
7
6
5
4
3
2
1
0
RXCHR
• RXCHR: Received Character
Last character received if RXRDY is set.
• RXSYNH: Received Sync
0: Last Character received is a Data.
1: Last Character received is a Command.
508
AT91SAM9G20
6384E–ATARM–05-Feb-10
AT91SAM9G20
32.7.8
Name:
USART Transmit Holding Register
US_THR
Access Type:
Write-only
31
–
30
–
29
–
28
–
27
–
26
–
25
–
24
–
23
–
22
–
21
–
20
–
19
–
18
–
17
–
16
–
15
TXSYNH
14
–
13
–
12
–
11
–
10
–
9
–
8
TXCHR
7
6
5
4
3
2
1
0
TXCHR
• TXCHR: Character to be Transmitted
Next character to be transmitted after the current character if TXRDY is not set.
• TXSYNH: Sync Field to be transmitted
0: The next character sent is encoded as a data. Start Frame Delimiter is DATA SYNC.
1: The next character sent is encoded as a command. Start Frame Delimiter is COMMAND SYNC.
509
6384E–ATARM–05-Feb-10
32.7.9
Name:
USART Baud Rate Generator Register
US_BRGR
Access Type:
Read-write
31
–
30
–
29
–
28
–
27
–
26
–
25
–
24
–
23
–
22
–
21
–
20
–
19
–
18
17
FP–
16
15
14
13
12
11
10
9
8
3
2
1
0
CD
7
6
5
4
CD
• CD: Clock Divider
USART_MODE ≠ ISO7816
SYNC = 0
OVER = 0
CD
0
1 to 65535
SYNC = 1
OVER = 1
USART_MODE =
ISO7816
Baud Rate Clock Disabled
Baud Rate =
Selected Clock/16/CD
Baud Rate =
Selected Clock/8/CD
Baud Rate =
Selected Clock /CD
Baud Rate = Selected
Clock/CD/FI_DI_RATIO
• FP: Fractional Part
0: Fractional divider is disabled.
1 - 7: Baudrate resolution, defined by FP x 1/8.
510
AT91SAM9G20
6384E–ATARM–05-Feb-10
AT91SAM9G20
32.7.10
Name:
USART Receiver Time-out Register
US_RTOR
Access Type:
Read-write
31
30
29
28
27
26
25
24
–
–
–
–
–
–
–
–
23
–
22
–
21
–
20
–
19
–
18
–
17
–
16
–
15
14
13
12
11
10
9
8
3
2
1
0
TO
7
6
5
4
TO
• TO: Time-out Value
0: The Receiver Time-out is disabled.
1 - 65535: The Receiver Time-out is enabled and the Time-out delay is TO x Bit Period.
511
6384E–ATARM–05-Feb-10
32.7.11
Name:
USART Transmitter Timeguard Register
US_TTGR
Access Type:
Read-write
31
–
30
–
29
–
28
–
27
–
26
–
25
–
24
–
23
–
22
–
21
–
20
–
19
–
18
–
17
–
16
–
15
–
14
–
13
–
12
–
11
–
10
–
9
–
8
–
7
6
5
4
3
2
1
0
TG
• TG: Timeguard Value
0: The Transmitter Timeguard is disabled.
1 - 255: The Transmitter timeguard is enabled and the timeguard delay is TG x Bit Period.
512
AT91SAM9G20
6384E–ATARM–05-Feb-10
AT91SAM9G20
32.7.12
Name:
USART FI DI RATIO Register
US_FIDI
Access Type:
Read-write
Reset Value:
0x174
31
–
30
–
29
–
28
–
27
–
26
–
25
–
24
–
23
–
22
–
21
–
20
–
19
–
18
–
17
–
16
–
15
–
14
–
13
–
12
–
11
–
10
9
FI_DI_RATIO
8
7
6
5
4
3
2
1
0
FI_DI_RATIO
• FI_DI_RATIO: FI Over DI Ratio Value
0: If ISO7816 mode is selected, the Baud Rate Generator generates no signal.
1 - 2047: If ISO7816 mode is selected, the Baud Rate is the clock provided on SCK divided by FI_DI_RATIO.
32.7.13
Name:
USART Number of Errors Register
US_NER
Access Type:
Read-only
31
–
30
–
29
–
28
–
27
–
26
–
25
–
24
–
23
–
22
–
21
–
20
–
19
–
18
–
17
–
16
–
15
–
14
–
13
–
12
–
11
–
10
–
9
–
8
–
7
6
5
4
3
2
1
0
NB_ERRORS
• NB_ERRORS: Number of Errors
Total number of errors that occurred during an ISO7816 transfer. This register automatically clears when read.
513
6384E–ATARM–05-Feb-10
32.7.14
Name:
USART IrDA FILTER Register
US_IF
Access Type:
Read-write
31
–
30
–
29
–
28
–
27
–
26
–
25
–
24
–
23
–
22
–
21
–
20
–
19
–
18
–
17
–
16
–
15
–
14
–
13
–
12
–
11
–
10
–
9
–
8
–
7
6
5
4
3
2
1
0
IRDA_FILTER
• IRDA_FILTER: IrDA Filter
Sets the filter of the IrDA demodulator.
514
AT91SAM9G20
6384E–ATARM–05-Feb-10
AT91SAM9G20
32.7.15
Name:
USART Manchester Configuration Register
US_MAN
Access Type:
Read-write
31
–
30
DRIFT
29
1
28
RX_MPOL
27
–
26
–
25
24
23
–
22
–
21
–
20
–
19
18
17
16
15
–
14
–
13
–
12
TX_MPOL
11
–
10
–
9
8
7
–
6
–
5
–
4
–
3
2
1
RX_PP
RX_PL
TX_PP
0
TX_PL
• TX_PL: Transmitter Preamble Length
0: The Transmitter Preamble pattern generation is disabled
1 - 15: The Preamble Length is TX_PL x Bit Period
• TX_PP: Transmitter Preamble Pattern
TX_PP
Preamble Pattern default polarity assumed (TX_MPOL field not set)
0
0
ALL_ONE
0
1
ALL_ZERO
1
0
ZERO_ONE
1
1
ONE_ZERO
• TX_MPOL: Transmitter Manchester Polarity
0: Logic Zero is coded as a zero-to-one transition, Logic One is coded as a one-to-zero transition.
1: Logic Zero is coded as a one-to-zero transition, Logic One is coded as a zero-to-one transition.
• RX_PL: Receiver Preamble Length
0: The receiver preamble pattern detection is disabled
1 - 15: The detected preamble length is RX_PL x Bit Period
• RX_PP: Receiver Preamble Pattern detected
RX_PP
Preamble Pattern default polarity assumed (RX_MPOL field not set)
0
0
ALL_ONE
0
1
ALL_ZERO
1
0
ZERO_ONE
1
1
ONE_ZERO
515
6384E–ATARM–05-Feb-10
• RX_MPOL: Receiver Manchester Polarity
0: Logic Zero is coded as a zero-to-one transition, Logic One is coded as a one-to-zero transition.
1: Logic Zero is coded as a one-to-zero transition, Logic One is coded as a zero-to-one transition.
• DRIFT: Drift compensation
0: The USART can not recover from an important clock drift
1: The USART can recover from clock drift. The 16X clock mode must be enabled.
516
AT91SAM9G20
6384E–ATARM–05-Feb-10
AT91SAM9G20
33. Synchronous Serial Controller (SSC)
33.1
Overview
The Atmel Synchronous Serial Controller (SSC) provides a synchronous communication link
with external devices. It supports many serial synchronous communication protocols generally
used in audio and telecom applications such as I2S, Short Frame Sync, Long Frame Sync, etc.
The SSC contains an independent receiver and transmitter and a common clock divider. The
receiver and the transmitter each interface with three signals: the TD/RD signal for data, the
TK/RK signal for the clock and the TF/RF signal for the Frame Sync. The transfers can be programmed to start automatically or on different events detected on the Frame Sync signal.
The SSC’s high-level of programmability and its two dedicated PDC channels of up to 32 bits
permit a continuous high bit rate data transfer without processor intervention.
Featuring connection to two PDC channels, the SSC permits interfacing with low processor
overhead to the following:
• CODEC’s in master or slave mode
• DAC through dedicated serial interface, particularly I2S
• Magnetic card reader
517
6384E–ATARM–05-Feb-10
33.2
Block Diagram
Figure 33-1. Block Diagram
System
Bus
APB Bridge
PDC
Peripheral
Bus
TF
TK
PMC
TD
MCK
PIO
SSC Interface
RF
RK
Interrupt Control
RD
SSC Interrupt
33.3
Application Block Diagram
Figure 33-2. Application Block Diagram
OS or RTOS Driver
Power
Management
Interrupt
Management
Test
Management
SSC
Serial AUDIO
518
Codec
Time Slot
Management
Frame
Management
Line Interface
AT91SAM9G20
6384E–ATARM–05-Feb-10
AT91SAM9G20
33.4
Pin Name List
Table 33-1.
I/O Lines Description
Pin Name
Pin Description
RF
Receiver Frame Synchro
Input/Output
RK
Receiver Clock
Input/Output
RD
Receiver Data
Input
TF
Transmitter Frame Synchro
Input/Output
TK
Transmitter Clock
Input/Output
TD
Transmitter Data
Output
33.5
33.5.1
Type
Product Dependencies
I/O Lines
The pins used for interfacing the compliant external devices may be multiplexed with PIO lines.
Before using the SSC receiver, the PIO controller must be configured to dedicate the SSC
receiver I/O lines to the SSC peripheral mode.
Before using the SSC transmitter, the PIO controller must be configured to dedicate the SSC
transmitter I/O lines to the SSC peripheral mode.
33.5.2
Power Management
The SSC is not continuously clocked. The SSC interface may be clocked through the Power
Management Controller (PMC), therefore the programmer must first configure the PMC to
enable the SSC clock.
33.5.3
Interrupt
The SSC interface has an interrupt line connected to the Advanced Interrupt Controller (AIC).
Handling interrupts requires programming the AIC before configuring the SSC.
All SSC interrupts can be enabled/disabled configuring the SSC Interrupt mask register. Each
pending and unmasked SSC interrupt will assert the SSC interrupt line. The SSC interrupt service routine can get the interrupt origin by reading the SSC interrupt status register.
33.6
Functional Description
This chapter contains the functional description of the following: SSC Functional Block, Clock
Management, Data format, Start, Transmitter, Receiver and Frame Sync.
The receiver and transmitter operate separately. However, they can work synchronously by programming the receiver to use the transmit clock and/or to start a data transfer when transmission
starts. Alternatively, this can be done by programming the transmitter to use the receive clock
and/or to start a data transfer when reception starts. The transmitter and the receiver can be programmed to operate with the clock signals provided on either the TK or RK pins. This allows the
SSC to support many slave-mode data transfers. The maximum clock speed allowed on the TK
and RK pins is the master clock divided by 2.
519
6384E–ATARM–05-Feb-10
Figure 33-3. SSC Functional Block Diagram
Transmitter
MCK
TK Input
Clock
Divider
Transmit Clock
Controller
RX clock
TF
RF
Start
Selector
TX clock
Clock Output
Controller
TK
Frame Sync
Controller
TF
Transmit Shift Register
TX PDC
APB
Transmit Holding
Register
TD
Transmit Sync
Holding Register
Load Shift
User
Interface
Receiver
RK Input
Receive Clock RX Clock
Controller
TX Clock
RF
TF
Start
Selector
Interrupt Control
RK
Frame Sync
Controller
RF
RD
Receive Shift Register
RX PDC
PDC
Clock Output
Controller
Receive Holding
Register
Receive Sync
Holding Register
Load Shift
AIC
33.6.1
Clock Management
The transmitter clock can be generated by:
• an external clock received on the TK I/O pad
• the receiver clock
• the internal clock divider
The receiver clock can be generated by:
• an external clock received on the RK I/O pad
• the transmitter clock
• the internal clock divider
Furthermore, the transmitter block can generate an external clock on the TK I/O pad, and the
receiver block can generate an external clock on the RK I/O pad.
This allows the SSC to support many Master and Slave Mode data transfers.
520
AT91SAM9G20
6384E–ATARM–05-Feb-10
AT91SAM9G20
33.6.1.1
Clock Divider
Figure 33-4. Divided Clock Block Diagram
Clock Divider
SSC_CMR
MCK
12-bit Counter
/2
Divided Clock
The Master Clock divider is determined by the 12-bit field DIV counter and comparator (so its
maximal value is 4095) in the Clock Mode Register SSC_CMR, allowing a Master Clock division
by up to 8190. The Divided Clock is provided to both the Receiver and Transmitter. When this
field is programmed to 0, the Clock Divider is not used and remains inactive.
When DIV is set to a value equal to or greater than 1, the Divided Clock has a frequency of Master Clock divided by 2 times DIV. Each level of the Divided Clock has a duration of the Master
Clock multiplied by DIV. This ensures a 50% duty cycle for the Divided Clock regardless of
whether the DIV value is even or odd.
Figure 33-5.
Divided Clock Generation
Master Clock
Divided Clock
DIV = 1
Divided Clock Frequency = MCK/2
Master Clock
Divided Clock
DIV = 3
Divided Clock Frequency = MCK/6
Table 33-2.
33.6.1.2
Maximum
Minimum
MCK / 2
MCK / 8190
Transmitter Clock Management
The transmitter clock is generated from the receiver clock or the divider clock or an external
clock scanned on the TK I/O pad. The transmitter clock is selected by the CKS field in
SSC_TCMR (Transmit Clock Mode Register). Transmit Clock can be inverted independently by
the CKI bits in SSC_TCMR.
521
6384E–ATARM–05-Feb-10
The transmitter can also drive the TK I/O pad continuously or be limited to the actual data transfer. The clock output is configured by the SSC_TCMR register. The Transmit Clock Inversion
(CKI) bits have no effect on the clock outputs. Programming the TCMR register to select TK pin
(CKS field) and at the same time Continuous Transmit Clock (CKO field) might lead to unpredictable results.
Figure 33-6. Transmitter Clock Management
TK (pin)
Clock
Output
Tri_state
Controller
MUX
Receiver
Clock
Divider
Clock
Data Transfer
CKO
CKS
33.6.1.3
INV
MUX
Tri-state
Controller
CKI
CKG
Transmitter
Clock
Receiver Clock Management
The receiver clock is generated from the transmitter clock or the divider clock or an external
clock scanned on the RK I/O pad. The Receive Clock is selected by the CKS field in
SSC_RCMR (Receive Clock Mode Register). Receive Clocks can be inverted independently by
the CKI bits in SSC_RCMR.
The receiver can also drive the RK I/O pad continuously or be limited to the actual data transfer.
The clock output is configured by the SSC_RCMR register. The Receive Clock Inversion (CKI)
bits have no effect on the clock outputs. Programming the RCMR register to select RK pin (CKS
field) and at the same time Continuous Receive Clock (CKO field) can lead to unpredictable
results.
522
AT91SAM9G20
6384E–ATARM–05-Feb-10
AT91SAM9G20
Figure 33-7. Receiver Clock Management
RK (pin)
Tri-state
Controller
MUX
Clock
Output
Transmitter
Clock
Divider
Clock
Data Transfer
CKO
CKS
33.6.1.4
INV
MUX
Tri-state
Controller
CKI
CKG
Receiver
Clock
Serial Clock Ratio Considerations
The Transmitter and the Receiver can be programmed to operate with the clock signals provided
on either the TK or RK pins. This allows the SSC to support many slave-mode data transfers. In
this case, the maximum clock speed allowed on the RK pin is:
– Master Clock divided by 2 if Receiver Frame Synchro is input
– Master Clock divided by 3 if Receiver Frame Synchro is output
In addition, the maximum clock speed allowed on the TK pin is:
– Master Clock divided by 6 if Transmit Frame Synchro is input
– Master Clock divided by 2 if Transmit Frame Synchro is output
33.6.2
Transmitter Operations
A transmitted frame is triggered by a start event and can be followed by synchronization data
before data transmission.
The start event is configured by setting the Transmit Clock Mode Register (SSC_TCMR). See
“Start” on page 525.
The frame synchronization is configured setting the Transmit Frame Mode Register
(SSC_TFMR). See “Frame Sync” on page 527.
To transmit data, the transmitter uses a shift register clocked by the transmitter clock signal and
the start mode selected in the SSC_TCMR. Data is written by the application to the SSC_THR
register then transferred to the shift register according to the data format selected.
When both the SSC_THR and the transmit shift register are empty, the status flag TXEMPTY is
set in SSC_SR. When the Transmit Holding register is transferred in the Transmit shift register,
the status flag TXRDY is set in SSC_SR and additional data can be loaded in the holding
register.
523
6384E–ATARM–05-Feb-10
Figure 33-8. Transmitter Block Diagram
SSC_CR.TXEN
SSC_SR.TXEN
SSC_CR.TXDIS
SSC_TFMR.DATDEF
1
RF
Transmitter Clock
TF
Transmit Shift Register
SSC_TFMR.FSDEN
SSC_TCMR.STTDLY
SSC_TFMR.DATLEN
33.6.3
TD
0
SSC_TFMR.MSBF
Start
Selector
SSC_TCMR.STTDLY
SSC_TFMR.FSDEN
SSC_TFMR.DATNB
0
SSC_THR
1
SSC_TSHR
SSC_TFMR.FSLEN
Receiver Operations
A received frame is triggered by a start event and can be followed by synchronization data
before data transmission.
The start event is configured setting the Receive Clock Mode Register (SSC_RCMR). See
“Start” on page 525.
The frame synchronization is configured setting the Receive Frame Mode Register
(SSC_RFMR). See “Frame Sync” on page 527.
The receiver uses a shift register clocked by the receiver clock signal and the start mode
selected in the SSC_RCMR. The data is transferred from the shift register depending on the
data format selected.
When the receiver shift register is full, the SSC transfers this data in the holding register, the status flag RXRDY is set in SSC_SR and the data can be read in the receiver holding register. If
another transfer occurs before read of the RHR register, the status flag OVERUN is set in
SSC_SR and the receiver shift register is transferred in the RHR register.
524
AT91SAM9G20
6384E–ATARM–05-Feb-10
AT91SAM9G20
Figure 33-9. Receiver Block Diagram
SSC_CR.RXEN
SSC_SR.RXEN
SSC_CR.RXDIS
RF
Receiver Clock
TF
Start
Selector
SSC_RFMR.MSBF
SSC_RFMR.DATNB
Receive Shift Register
SSC_RSHR
SSC_RHR
SSC_RFMR.FSLEN
SSC_RFMR.DATLEN
RD
SSC_RCMR.STTDLY
33.6.4
Start
The transmitter and receiver can both be programmed to start their operations when an event
occurs, respectively in the Transmit Start Selection (START) field of SSC_TCMR and in the
Receive Start Selection (START) field of SSC_RCMR.
Under the following conditions the start event is independently programmable:
• Continuous. In this case, the transmission starts as soon as a word is written in SSC_THR
and the reception starts as soon as the Receiver is enabled.
• Synchronously with the transmitter/receiver
• On detection of a falling/rising edge on TF/RF
• On detection of a low level/high level on TF/RF
• On detection of a level change or an edge on TF/RF
A start can be programmed in the same manner on either side of the Transmit/Receive Clock
Register (RCMR/TCMR). Thus, the start could be on TF (Transmit) or RF (Receive).
Moreover, the Receiver can start when data is detected in the bit stream with the Compare
Functions.
Detection on TF/RF input/output is done by the field FSOS of the Transmit/Receive Frame Mode
Register (TFMR/RFMR).
525
6384E–ATARM–05-Feb-10
Figure 33-10. Transmit Start Mode
TK
TF
(Input)
Start = Low Level on TF
Start = Falling Edge on TF
Start = High Level on TF
Start = Rising Edge on TF
Start = Level Change on TF
Start = Any Edge on TF
TD
(Output)
TD
(Output)
X
BO
STTDLY
BO
X
B1
STTDLY
BO
X
TD
(Output)
B1
STTDLY
TD
(Output)
BO
X
B1
STTDLY
TD
(Output)
TD
(Output)
B1
BO
X
B1
BO
B1
STTDLY
X
B1
BO
BO
B1
STTDLY
Figure 33-11. Receive Pulse/Edge Start Modes
RK
RF
(Input)
Start = Low Level on RF
Start = Falling Edge on RF
Start = High Level on RF
Start = Rising Edge on RF
Start = Level Change on RF
Start = Any Edge on RF
RD
(Input)
RD
(Input)
X
BO
STTDLY
BO
X
B1
STTDLY
BO
X
RD
(Input)
B1
STTDLY
RD
(Input)
BO
X
B1
STTDLY
RD
(Input)
RD
(Input)
B1
BO
X
B1
BO
B1
STTDLY
X
BO
B1
BO
B1
STTDLY
526
AT91SAM9G20
6384E–ATARM–05-Feb-10
AT91SAM9G20
33.6.5
Frame Sync
The Transmitter and Receiver Frame Sync pins, TF and RF, can be programmed to generate
different kinds of frame synchronization signals. The Frame Sync Output Selection (FSOS) field
in the Receive Frame Mode Register (SSC_RFMR) and in the Transmit Frame Mode Register
(SSC_TFMR) are used to select the required waveform.
• Programmable low or high levels during data transfer are supported.
• Programmable high levels before the start of data transfers or toggling are also supported.
If a pulse waveform is selected, the Frame Sync Length (FSLEN) field in SSC_RFMR and
SSC_TFMR programs the length of the pulse, from 1 bit time up to 256 bit time.
The periodicity of the Receive and Transmit Frame Sync pulse output can be programmed
through the Period Divider Selection (PERIOD) field in SSC_RCMR and SSC_TCMR.
33.6.5.1
Frame Sync Data
Frame Sync Data transmits or receives a specific tag during the Frame Sync signal.
During the Frame Sync signal, the Receiver can sample the RD line and store the data in the
Receive Sync Holding Register and the transmitter can transfer Transmit Sync Holding Register
in the Shifter Register. The data length to be sampled/shifted out during the Frame Sync signal
is programmed by the FSLEN field in SSC_RFMR/SSC_TFMR and has a maximum value of 16.
Concerning the Receive Frame Sync Data operation, if the Frame Sync Length is equal to or
lower than the delay between the start event and the actual data reception, the data sampling
operation is performed in the Receive Sync Holding Register through the Receive Shift Register.
The Transmit Frame Sync Operation is performed by the transmitter only if the bit Frame Sync
Data Enable (FSDEN) in SSC_TFMR is set. If the Frame Sync length is equal to or lower than
the delay between the start event and the actual data transmission, the normal transmission has
priority and the data contained in the Transmit Sync Holding Register is transferred in the Transmit Register, then shifted out.
33.6.5.2
33.6.6
Frame Sync Edge Detection
The Frame Sync Edge detection is programmed by the FSEDGE field in
SSC_RFMR/SSC_TFMR. This sets the corresponding flags RXSYN/TXSYN in the SSC Status
Register (SSC_SR) on frame synchro edge detection (signals RF/TF).
Receive Compare Modes
Figure 33-12. Receive Compare Modes
RK
RD
(Input)
CMP0
CMP1
CMP2
CMP3
Ignored
B0
B1
B2
Start
FSLEN
Up to 16 Bits
(4 in This Example)
STDLY
DATLEN
527
6384E–ATARM–05-Feb-10
33.6.6.1
33.6.7
Compare Functions
Length of the comparison patterns (Compare 0, Compare 1) and thus the number of bits they
are compared to is defined by FSLEN, but with a maximum value of 16 bits. Comparison is
always done by comparing the last bits received with the comparison pattern. Compare 0 can be
one start event of the Receiver. In this case, the receiver compares at each new sample the last
bits received at the Compare 0 pattern contained in the Compare 0 Register (SSC_RC0R).
When this start event is selected, the user can program the Receiver to start a new data transfer
either by writing a new Compare 0, or by receiving continuously until Compare 1 occurs. This
selection is done with the bit (STOP) in SSC_RCMR.
Data Format
The data framing format of both the transmitter and the receiver are programmable through the
Transmitter Frame Mode Register (SSC_TFMR) and the Receiver Frame Mode Register
(SSC_RFMR). In either case, the user can independently select:
• the event that starts the data transfer (START)
• the delay in number of bit periods between the start event and the first data bit (STTDLY)
• the length of the data (DATLEN)
• the number of data to be transferred for each start event (DATNB).
• the length of synchronization transferred for each start event (FSLEN)
• the bit sense: most or lowest significant bit first (MSBF)
Additionally, the transmitter can be used to transfer synchronization and select the level driven
on the TD pin while not in data transfer operation. This is done respectively by the Frame Sync
Data Enable (FSDEN) and by the Data Default Value (DATDEF) bits in SSC_TFMR.
528
AT91SAM9G20
6384E–ATARM–05-Feb-10
AT91SAM9G20
Table 33-3.
Data Frame Registers
Transmitter
Receiver
Field
Length
Comment
SSC_TFMR
SSC_RFMR
DATLEN
Up to 32
Size of word
SSC_TFMR
SSC_RFMR
DATNB
Up to 16
Number of words transmitted in frame
SSC_TFMR
SSC_RFMR
MSBF
SSC_TFMR
SSC_RFMR
FSLEN
Up to 16
Size of Synchro data register
SSC_TFMR
DATDEF
0 or 1
Data default value ended
SSC_TFMR
FSDEN
Most significant bit first
Enable send SSC_TSHR
SSC_TCMR
SSC_RCMR
PERIOD
Up to 512
Frame size
SSC_TCMR
SSC_RCMR
STTDLY
Up to 255
Size of transmit start delay
Figure 33-13. Transmit and Receive Frame Format in Edge/Pulse Start Modes
Start
Start
PERIOD
TF/RF
(1)
FSLEN
TD
(If FSDEN = 1)
TD
(If FSDEN = 0)
RD
Sync Data
Data
Data
From SSC_THR
From SSC_THR
Default
From SSC_TSHR FromDATDEF
Default
Sync Data
Ignored
To SSC_RSHR
STTDLY
From SSC_THR
Data
Data
To SSC_RHR
To SSC_RHR
DATLEN
DATLEN
Sync Data
FromDATDEF
Data
Data
From SSC_THR
From DATDEF
Default
Default
From DATDEF
Ignored
Sync Data
DATNB
Note:
1. Example of input on falling edge of TF/RF.
Figure 33-14. Transmit Frame Format in Continuous Mode
Start
TD
Data
From SSC_THR
Data
Default
From SSC_THR
DATLEN
DATLEN
Start: 1. TXEMPTY set to 1
2. Write into the SSC_THR
529
6384E–ATARM–05-Feb-10
Note:
1. STTDLY is set to 0. In this example, SSC_THR is loaded twice. FSDEN value has no effect on
the transmission. SyncData cannot be output in continuous mode.
Figure 33-15. Receive Frame Format in Continuous Mode
Start = Enable Receiver
Data
Data
To SSC_RHR
To SSC_RHR
DATLEN
DATLEN
RD
Note:
33.6.8
1. STTDLY is set to 0.
Loop Mode
The receiver can be programmed to receive transmissions from the transmitter. This is done by
setting the Loop Mode (LOOP) bit in SSC_RFMR. In this case, RD is connected to TD, RF is
connected to TF and RK is connected to TK.
33.6.9
Interrupt
Most bits in SSC_SR have a corresponding bit in interrupt management registers.
The SSC can be programmed to generate an interrupt when it detects an event. The interrupt is
controlled by writing SSC_IER (Interrupt Enable Register) and SSC_IDR (Interrupt Disable Register) These registers enable and disable, respectively, the corresponding interrupt by setting
and clearing the corresponding bit in SSC_IMR (Interrupt Mask Register), which controls the
generation of interrupts by asserting the SSC interrupt line connected to the AIC.
Figure 33-16. Interrupt Block Diagram
SSC_IMR
SSC_IER
PDC
SSC_IDR
Set
Clear
TXBUFE
ENDTX
Transmitter
TXRDY
TXEMPTY
TXSYNC
Interrupt
Control
RXBUFF
ENDRX
SSC Interrupt
Receiver
RXRDY
OVRUN
RXSYNC
530
AT91SAM9G20
6384E–ATARM–05-Feb-10
AT91SAM9G20
33.7
SSC Application Examples
The SSC can support several serial communication modes used in audio or high speed serial
links. Some standard applications are shown in the following figures. All serial link applications
supported by the SSC are not listed here.
Figure 33-17. Audio Application Block Diagram
Clock SCK
TK
Word Select WS
TF
I2S
RECEIVER
Data SD
SSC
TD
RD
Clock SCK
RF
Word Select WS
RK
MSB
Data SD
LSB
Left Channel
MSB
Right Channel
Figure 33-18. Codec Application Block Diagram
Serial Data Clock (SCLK)
TK
Frame sync (FSYNC)
TF
Serial Data Out
SSC
CODEC
TD
Serial Data In
RD
RF
RK
Serial Data Clock (SCLK)
Frame sync (FSYNC)
First Time Slot
Dstart
Dend
Serial Data Out
Serial Data In
531
6384E–ATARM–05-Feb-10
Figure 33-19. Time Slot Application Block Diagram
SCLK
TK
FSYNC
TF
CODEC
First
Time Slot
Data Out
TD
SSC
RD
Data in
RF
RK
CODEC
Second
Time Slot
Serial Data Clock (SCLK)
Frame sync (FSYNC)
First Time Slot
Dstart
Second Time Slot
Dend
Serial Data Out
Serial Data in
532
AT91SAM9G20
6384E–ATARM–05-Feb-10
AT91SAM9G20
33.8
Syncrhronous Serial Controller (SSC) User Interface
Table 33-4.
Register Mapping
Offset
Register
Name
Access
Reset
0x0
Control Register
SSC_CR
Write
–
0x4
Clock Mode Register
SSC_CMR
Read-write
0x0
0x8
Reserved
–
–
–
0xC
Reserved
–
–
–
0x10
Receive Clock Mode Register
SSC_RCMR
Read-write
0x0
0x14
Receive Frame Mode Register
SSC_RFMR
Read-write
0x0
0x18
Transmit Clock Mode Register
SSC_TCMR
Read-write
0x0
0x1C
Transmit Frame Mode Register
SSC_TFMR
Read-write
0x0
0x20
Receive Holding Register
SSC_RHR
Read
0x0
0x24
Transmit Holding Register
SSC_THR
Write
–
0x28
Reserved
–
–
–
0x2C
Reserved
–
–
–
0x30
Receive Sync. Holding Register
SSC_RSHR
Read
0x0
0x34
Transmit Sync. Holding Register
SSC_TSHR
Read-write
0x0
0x38
Receive Compare 0 Register
SSC_RC0R
Read-write
0x0
0x3C
Receive Compare 1 Register
SSC_RC1R
Read-write
0x0
0x40
Status Register
SSC_SR
Read
0x000000CC
0x44
Interrupt Enable Register
SSC_IER
Write
–
0x48
Interrupt Disable Register
SSC_IDR
Write
–
0x4C
Interrupt Mask Register
SSC_IMR
Read
0x0
0x50-0xFC
Reserved
–
–
–
0x100- 0x124
Reserved for Peripheral Data Controller (PDC)
–
–
–
533
6384E–ATARM–05-Feb-10
33.8.1
Name:
SSC Control Register
SSC_CR
Access Type:
Write-only
31
–
30
–
29
–
28
–
27
–
26
–
25
–
24
–
23
–
22
–
21
–
20
–
19
–
18
–
17
–
16
–
15
SWRST
14
–
13
–
12
–
11
–
10
–
9
TXDIS
8
TXEN
7
–
6
–
5
–
4
–
3
–
2
–
1
RXDIS
0
RXEN
• RXEN: Receive Enable
0 = No effect.
1 = Enables Receive if RXDIS is not set.
• RXDIS: Receive Disable
0 = No effect.
1 = Disables Receive. If a character is currently being received, disables at end of current character reception.
• TXEN: Transmit Enable
0 = No effect.
1 = Enables Transmit if TXDIS is not set.
• TXDIS: Transmit Disable
0 = No effect.
1 = Disables Transmit. If a character is currently being transmitted, disables at end of current character transmission.
• SWRST: Software Reset
0 = No effect.
1 = Performs a software reset. Has priority on any other bit in SSC_CR.
534
AT91SAM9G20
6384E–ATARM–05-Feb-10
AT91SAM9G20
33.8.2
Name:
SSC Clock Mode Register
SSC_CMR
Access Type:
Read-write
31
–
30
–
29
–
28
–
27
–
26
–
25
–
24
–
23
–
22
–
21
–
20
–
19
–
18
–
17
–
16
–
15
–
14
–
13
–
12
–
11
10
9
8
7
6
5
4
1
0
DIV
3
2
DIV
• DIV: Clock Divider
0 = The Clock Divider is not active.
Any Other Value: The Divided Clock equals the Master Clock divided by 2 times DIV. The maximum bit rate is MCK/2. The
minimum bit rate is MCK/2 x 4095 = MCK/8190.
535
6384E–ATARM–05-Feb-10
33.8.3
Name:
SSC Receive Clock Mode Register
SSC_RCMR
Access Type:
31
Read-write
30
29
28
27
26
25
24
19
18
17
16
10
9
8
PERIOD
23
22
21
20
STTDLY
15
–
7
14
–
13
–
12
STOP
11
6
5
CKI
4
3
CKO
CKG
START
2
1
0
CKS
• CKS: Receive Clock Selection
CKS
Selected Receive Clock
0x0
Divided Clock
0x1
TK Clock signal
0x2
RK pin
0x3
Reserved
• CKO: Receive Clock Output Mode Selection
CKO
Receive Clock Output Mode
0x0
None
0x1
Continuous Receive Clock
Output
0x2
Receive Clock only during data transfers
Output
0x3-0x7
RK pin
Input-only
Reserved
• CKI: Receive Clock Inversion
0 = The data inputs (Data and Frame Sync signals) are sampled on Receive Clock falling edge. The Frame Sync signal
output is shifted out on Receive Clock rising edge.
1 = The data inputs (Data and Frame Sync signals) are sampled on Receive Clock rising edge. The Frame Sync signal output is shifted out on Receive Clock falling edge.
CKI affects only the Receive Clock and not the output clock signal.
536
AT91SAM9G20
6384E–ATARM–05-Feb-10
AT91SAM9G20
• CKG: Receive Clock Gating Selection
CKG
Receive Clock Gating
0x0
None, continuous clock
0x1
Receive Clock enabled only if RF Low
0x2
Receive Clock enabled only if RF High
0x3
Reserved
• START: Receive Start Selection
START
Receive Start
0x0
Continuous, as soon as the receiver is enabled, and immediately after the end of transfer of the previous data.
0x1
Transmit start
0x2
Detection of a low level on RF signal
0x3
Detection of a high level on RF signal
0x4
Detection of a falling edge on RF signal
0x5
Detection of a rising edge on RF signal
0x6
Detection of any level change on RF signal
0x7
Detection of any edge on RF signal
0x8
Compare 0
0x9-0xF
Reserved
• STOP: Receive Stop Selection
0 = After completion of a data transfer when starting with a Compare 0, the receiver stops the data transfer and waits for a
new compare 0.
1 = After starting a receive with a Compare 0, the receiver operates in a continuous mode until a Compare 1 is detected.
• STTDLY: Receive Start Delay
If STTDLY is not 0, a delay of STTDLY clock cycles is inserted between the start event and the actual start of reception.
When the Receiver is programmed to start synchronously with the Transmitter, the delay is also applied.
Note: It is very important that STTDLY be set carefully. If STTDLY must be set, it should be done in relation to TAG
(Receive Sync Data) reception.
• PERIOD: Receive Period Divider Selection
This field selects the divider to apply to the selected Receive Clock in order to generate a new Frame Sync Signal. If 0, no
PERIOD signal is generated. If not 0, a PERIOD signal is generated each 2 x (PERIOD+1) Receive Clock.
537
6384E–ATARM–05-Feb-10
33.8.4
Name:
SSC Receive Frame Mode Register
SSC_RFMR
Access Type:
Read-write
31
FSLEN_EXT
30
FSLEN_EXT
29
FSLEN_EXT
FSLEN_EXT
23
–
22
15
–
7
MSBF
28
27
–
26
–
25
–
24
FSEDGE
21
FSOS
20
19
18
17
16
14
–
13
–
12
–
11
9
8
6
–
5
LOOP
4
3
1
0
FSLEN
10
DATNB
2
DATLEN
• DATLEN: Data Length
0 = Forbidden value (1-bit data length not supported).
Any other value: The bit stream contains DATLEN + 1 data bits. Moreover, it defines the transfer size performed by the
PDC2 assigned to the Receiver. If DATLEN is lower or equal to 7, data transfers are in bytes. If DATLEN is between 8 and
15 (included), half-words are transferred, and for any other value, 32-bit words are transferred.
• LOOP: Loop Mode
0 = Normal operating mode.
1 = RD is driven by TD, RF is driven by TF and TK drives RK.
• MSBF: Most Significant Bit First
0 = The lowest significant bit of the data register is sampled first in the bit stream.
1 = The most significant bit of the data register is sampled first in the bit stream.
• DATNB: Data Number per Frame
This field defines the number of data words to be received after each transfer start, which is equal to (DATNB + 1).
• FSLEN: Receive Frame Sync Length
This field defines the number of bits sampled and stored in the Receive Sync Data Register. When this mode is selected by
the START field in the Receive Clock Mode Register, it also determines the length of the sampled data to be compared to
the Compare 0 or Compare 1 register.
This field is used with FSLEN_EXT to determine the pulse length of the Receive Frame Sync signal.
Pulse length is equal to FSLEN + (FSLEN_EXT * 16) + 1 Receive Clock periods.
538
AT91SAM9G20
6384E–ATARM–05-Feb-10
AT91SAM9G20
• FSOS: Receive Frame Sync Output Selection
FSOS
Selected Receive Frame Sync Signal
RF Pin
0x0
None
0x1
Negative Pulse
Output
0x2
Positive Pulse
Output
0x3
Driven Low during data transfer
Output
0x4
Driven High during data transfer
Output
0x5
Toggling at each start of data transfer
Output
0x6-0x7
Input-only
Reserved
Undefined
• FSEDGE: Frame Sync Edge Detection
Determines which edge on Frame Sync will generate the interrupt RXSYN in the SSC Status Register.
FSEDGE
Frame Sync Edge Detection
0x0
Positive Edge Detection
0x1
Negative Edge Detection
• FSLEN_EXT: FSLEN Field Extension
Extends FSLEN field. For details, refer to FSLEN bit description on page 538.
539
6384E–ATARM–05-Feb-10
33.8.5
Name:
SSC Transmit Clock Mode Register
SSC_TCMR
Access Type:
31
Read-write
30
29
28
27
26
25
24
19
18
17
16
10
9
8
PERIOD
23
22
21
20
STTDLY
15
–
7
14
–
13
–
12
–
11
6
5
CKI
4
3
CKO
CKG
START
2
1
0
CKS
• CKS: Transmit Clock Selection
CKS
Selected Transmit Clock
0x0
Divided Clock
0x1
RK Clock signal
0x2
TK Pin
0x3
Reserved
• CKO: Transmit Clock Output Mode Selection
CKO
Transmit Clock Output Mode
0x0
None
0x1
Continuous Transmit Clock
Output
0x2
Transmit Clock only during data transfers
Output
0x3-0x7
TK pin
Input-only
Reserved
• CKI: Transmit Clock Inversion
0 = The data outputs (Data and Frame Sync signals) are shifted out on Transmit Clock falling edge. The Frame sync signal
input is sampled on Transmit clock rising edge.
1 = The data outputs (Data and Frame Sync signals) are shifted out on Transmit Clock rising edge. The Frame sync signal
input is sampled on Transmit clock falling edge.
CKI affects only the Transmit Clock and not the output clock signal.
540
AT91SAM9G20
6384E–ATARM–05-Feb-10
AT91SAM9G20
• CKG: Transmit Clock Gating Selection
CKG
Transmit Clock Gating
0x0
None, continuous clock
0x1
Transmit Clock enabled only if TF Low
0x2
Transmit Clock enabled only if TF High
0x3
Reserved
• START: Transmit Start Selection
START
Transmit Start
0x0
Continuous, as soon as a word is written in the SSC_THR Register (if Transmit is enabled), and
immediately after the end of transfer of the previous data.
0x1
Receive start
0x2
Detection of a low level on TF signal
0x3
Detection of a high level on TF signal
0x4
Detection of a falling edge on TF signal
0x5
Detection of a rising edge on TF signal
0x6
Detection of any level change on TF signal
0x7
Detection of any edge on TF signal
0x8 - 0xF
Reserved
• STTDLY: Transmit Start Delay
If STTDLY is not 0, a delay of STTDLY clock cycles is inserted between the start event and the actual start of transmission
of data. When the Transmitter is programmed to start synchronously with the Receiver, the delay is also applied.
Note: STTDLY must be set carefully. If STTDLY is too short in respect to TAG (Transmit Sync Data) emission, data is emitted instead of the end of TAG.
• PERIOD: Transmit Period Divider Selection
This field selects the divider to apply to the selected Transmit Clock to generate a new Frame Sync Signal. If 0, no period
signal is generated. If not 0, a period signal is generated at each 2 x (PERIOD+1) Transmit Clock.
541
6384E–ATARM–05-Feb-10
33.8.6
Name:
SSC Transmit Frame Mode Register
SSC_TFMR
Access Type:
Read-write
31
FSLEN_EXT
30
FSLEN_EXT
29
FSLEN_EXT
FSLEN_EXT
23
FSDEN
22
15
–
7
MSBF
28
27
–
26
–
25
–
24
FSEDGE
21
FSOS
20
19
18
17
16
14
–
13
–
12
–
11
9
8
6
–
5
DATDEF
4
3
1
0
FSLEN
10
DATNB
2
DATLEN
• DATLEN: Data Length
0 = Forbidden value (1-bit data length not supported).
Any other value: The bit stream contains DATLEN + 1 data bits. Moreover, it defines the transfer size performed by the
PDC2 assigned to the Transmit. If DATLEN is lower or equal to 7, data transfers are bytes, if DATLEN is between 8 and 15
(included), half-words are transferred, and for any other value, 32-bit words are transferred.
• DATDEF: Data Default Value
This bit defines the level driven on the TD pin while out of transmission. Note that if the pin is defined as multi-drive by the
PIO Controller, the pin is enabled only if the SCC TD output is 1.
• MSBF: Most Significant Bit First
0 = The lowest significant bit of the data register is shifted out first in the bit stream.
1 = The most significant bit of the data register is shifted out first in the bit stream.
• DATNB: Data Number per frame
This field defines the number of data words to be transferred after each transfer start, which is equal to (DATNB +1).
• FSLEN: Transmit Frame Sync Length
This field defines the length of the Transmit Frame Sync signal and the number of bits shifted out from the Transmit Sync
Data Register if FSDEN is 1.
This field is used with FSLEN_EXT to determine the pulse length of the Transmit Frame Sync signal.
Pulse length is equal to FSLEN + (FSLEN_EXT * 16) + 1 Transmit Clock periods.
542
AT91SAM9G20
6384E–ATARM–05-Feb-10
AT91SAM9G20
• FSOS: Transmit Frame Sync Output Selection
FSOS
Selected Transmit Frame Sync Signal
TF Pin
0x0
None
0x1
Negative Pulse
Output
0x2
Positive Pulse
Output
0x3
Driven Low during data transfer
Output
0x4
Driven High during data transfer
Output
0x5
Toggling at each start of data transfer
Output
0x6-0x7
Reserved
Input-only
Undefined
• FSDEN: Frame Sync Data Enable
0 = The TD line is driven with the default value during the Transmit Frame Sync signal.
1 = SSC_TSHR value is shifted out during the transmission of the Transmit Frame Sync signal.
• FSEDGE: Frame Sync Edge Detection
Determines which edge on frame sync will generate the interrupt TXSYN (Status Register).
FSEDGE
Frame Sync Edge Detection
0x0
Positive Edge Detection
0x1
Negative Edge Detection
• FSLEN_EXT: FSLEN Field Extension
Extends FSLEN field. For details, refer to FSLEN bit description on page 542.
543
6384E–ATARM–05-Feb-10
33.8.7
Name:
SSC Receive Holding Register
SSC_RHR
Access Type:
31
Read-only
30
29
28
27
26
25
24
19
18
17
16
11
10
9
8
3
2
1
0
RDAT
23
22
21
20
RDAT
15
14
13
12
RDAT
7
6
5
4
RDAT
• RDAT: Receive Data
Right aligned regardless of the number of data bits defined by DATLEN in SSC_RFMR.
33.8.8
Name:
SSC Transmit Holding Register
SSC_THR
Access Type:
31
Write-only
30
29
28
27
26
25
24
19
18
17
16
11
10
9
8
3
2
1
0
TDAT
23
22
21
20
TDAT
15
14
13
12
TDAT
7
6
5
4
TDAT
• TDAT: Transmit Data
Right aligned regardless of the number of data bits defined by DATLEN in SSC_TFMR.
544
AT91SAM9G20
6384E–ATARM–05-Feb-10
AT91SAM9G20
33.8.9
Name:
SSC Receive Synchronization Holding Register
SSC_RSHR
Access Type:
Read-only
31
–
30
–
29
–
28
–
27
–
26
–
25
–
24
–
23
–
22
–
21
–
20
–
19
–
18
–
17
–
16
–
15
14
13
12
11
10
9
8
3
2
1
0
RSDAT
7
6
5
4
RSDAT
• RSDAT: Receive Synchronization Data
33.8.10
Name:
SSC Transmit Synchronization Holding Register
SSC_TSHR
Access Type:
Read-write
31
–
30
–
29
–
28
–
27
–
26
–
25
–
24
–
23
–
22
–
21
–
20
–
19
–
18
–
17
–
16
–
15
14
13
12
11
10
9
8
3
2
1
0
TSDAT
7
6
5
4
TSDAT
• TSDAT: Transmit Synchronization Data
545
6384E–ATARM–05-Feb-10
33.8.11
Name:
SSC Receive Compare 0 Register
SSC_RC0R
Access Type:
Read-write
31
–
30
–
29
–
28
–
27
–
26
–
25
–
24
–
23
–
22
–
21
–
20
–
19
–
18
–
17
–
16
–
15
14
13
12
11
10
9
8
3
2
1
0
CP0
7
6
5
4
CP0
• CP0: Receive Compare Data 0
33.8.12
Name:
SSC Receive Compare 1 Register
SSC_RC1R
Access Type:
Read-write
31
–
30
–
29
–
28
–
27
–
26
–
25
–
24
–
23
–
22
–
21
–
20
–
19
–
18
–
17
–
16
–
15
14
13
12
11
10
9
8
3
2
1
0
CP1
7
6
5
4
CP1
• CP1: Receive Compare Data 1
546
AT91SAM9G20
6384E–ATARM–05-Feb-10
AT91SAM9G20
33.8.13
Name:
SSC Status Register
SSC_SR
Access Type:
Read-only
31
–
30
–
29
–
28
–
27
–
26
–
25
–
24
–
23
–
22
–
21
–
20
–
19
–
18
–
17
RXEN
16
TXEN
15
–
14
–
13
–
12
–
11
RXSYN
10
TXSYN
9
CP1
8
CP0
7
RXBUFF
6
ENDRX
5
OVRUN
4
RXRDY
3
TXBUFE
2
ENDTX
1
TXEMPTY
0
TXRDY
• TXRDY: Transmit Ready
0 = Data has been loaded in SSC_THR and is waiting to be loaded in the Transmit Shift Register (TSR).
1 = SSC_THR is empty.
• TXEMPTY: Transmit Empty
0 = Data remains in SSC_THR or is currently transmitted from TSR.
1 = Last data written in SSC_THR has been loaded in TSR and last data loaded in TSR has been transmitted.
• ENDTX: End of Transmission
0 = The register SSC_TCR has not reached 0 since the last write in SSC_TCR or SSC_TNCR.
1 = The register SSC_TCR has reached 0 since the last write in SSC_TCR or SSC_TNCR.
• TXBUFE: Transmit Buffer Empty
0 = SSC_TCR or SSC_TNCR have a value other than 0.
1 = Both SSC_TCR and SSC_TNCR have a value of 0.
• RXRDY: Receive Ready
0 = SSC_RHR is empty.
1 = Data has been received and loaded in SSC_RHR.
• OVRUN: Receive Overrun
0 = No data has been loaded in SSC_RHR while previous data has not been read since the last read of the Status
Register.
1 = Data has been loaded in SSC_RHR while previous data has not yet been read since the last read of the Status
Register.
• ENDRX: End of Reception
0 = Data is written on the Receive Counter Register or Receive Next Counter Register.
1 = End of PDC transfer when Receive Counter Register has arrived at zero.
547
6384E–ATARM–05-Feb-10
• RXBUFF: Receive Buffer Full
0 = SSC_RCR or SSC_RNCR have a value other than 0.
1 = Both SSC_RCR and SSC_RNCR have a value of 0.
• CP0: Compare 0
0 = A compare 0 has not occurred since the last read of the Status Register.
1 = A compare 0 has occurred since the last read of the Status Register.
• CP1: Compare 1
0 = A compare 1 has not occurred since the last read of the Status Register.
1 = A compare 1 has occurred since the last read of the Status Register.
• TXSYN: Transmit Sync
0 = A Tx Sync has not occurred since the last read of the Status Register.
1 = A Tx Sync has occurred since the last read of the Status Register.
• RXSYN: Receive Sync
0 = An Rx Sync has not occurred since the last read of the Status Register.
1 = An Rx Sync has occurred since the last read of the Status Register.
• TXEN: Transmit Enable
0 = Transmit is disabled.
1 = Transmit is enabled.
• RXEN: Receive Enable
0 = Receive is disabled.
1 = Receive is enabled.
548
AT91SAM9G20
6384E–ATARM–05-Feb-10
AT91SAM9G20
33.8.14
Name:
SSC Interrupt Enable Register
SSC_IER
Access Type:
Write-only
31
–
30
–
29
–
28
–
27
–
26
–
25
–
24
–
23
–
22
–
21
–
20
–
19
–
18
–
17
–
16
–
15
–
14
–
13
–
12
–
11
RXSYN
10
TXSYN
9
CP1
8
CP0
7
RXBUFF
6
ENDRX
5
OVRUN
4
RXRDY
3
TXBUFE
2
ENDTX
1
TXEMPTY
0
TXRDY
• TXRDY: Transmit Ready Interrupt Enable
0 = No effect.
1 = Enables the Transmit Ready Interrupt.
• TXEMPTY: Transmit Empty Interrupt Enable
0 = No effect.
1 = Enables the Transmit Empty Interrupt.
• ENDTX: End of Transmission Interrupt Enable
0 = No effect.
1 = Enables the End of Transmission Interrupt.
• TXBUFE: Transmit Buffer Empty Interrupt Enable
0 = No effect.
1 = Enables the Transmit Buffer Empty Interrupt
• RXRDY: Receive Ready Interrupt Enable
0 = No effect.
1 = Enables the Receive Ready Interrupt.
• OVRUN: Receive Overrun Interrupt Enable
0 = No effect.
1 = Enables the Receive Overrun Interrupt.
• ENDRX: End of Reception Interrupt Enable
0 = No effect.
1 = Enables the End of Reception Interrupt.
549
6384E–ATARM–05-Feb-10
• RXBUFF: Receive Buffer Full Interrupt Enable
0 = No effect.
1 = Enables the Receive Buffer Full Interrupt.
• CP0: Compare 0 Interrupt Enable
0 = No effect.
1 = Enables the Compare 0 Interrupt.
• CP1: Compare 1 Interrupt Enable
0 = No effect.
1 = Enables the Compare 1 Interrupt.
• TXSYN: Tx Sync Interrupt Enable
0 = No effect.
1 = Enables the Tx Sync Interrupt.
• RXSYN: Rx Sync Interrupt Enable
0 = No effect.
1 = Enables the Rx Sync Interrupt.
550
AT91SAM9G20
6384E–ATARM–05-Feb-10
AT91SAM9G20
33.8.15
Name:
SSC Interrupt Disable Register
SSC_IDR
Access Type:
Write-only
31
–
30
–
29
–
28
–
27
–
26
–
25
–
24
–
23
–
22
–
21
–
20
–
19
–
18
–
17
–
16
–
15
–
14
–
13
–
12
–
11
RXSYN
10
TXSYN
9
CP1
8
CP0
7
RXBUFF
6
ENDRX
5
OVRUN
4
RXRDY
3
TXBUFE
2
ENDTX
1
TXEMPTY
0
TXRDY
• TXRDY: Transmit Ready Interrupt Disable
0 = No effect.
1 = Disables the Transmit Ready Interrupt.
• TXEMPTY: Transmit Empty Interrupt Disable
0 = No effect.
1 = Disables the Transmit Empty Interrupt.
• ENDTX: End of Transmission Interrupt Disable
0 = No effect.
1 = Disables the End of Transmission Interrupt.
• TXBUFE: Transmit Buffer Empty Interrupt Disable
0 = No effect.
1 = Disables the Transmit Buffer Empty Interrupt.
• RXRDY: Receive Ready Interrupt Disable
0 = No effect.
1 = Disables the Receive Ready Interrupt.
• OVRUN: Receive Overrun Interrupt Disable
0 = No effect.
1 = Disables the Receive Overrun Interrupt.
• ENDRX: End of Reception Interrupt Disable
0 = No effect.
1 = Disables the End of Reception Interrupt.
551
6384E–ATARM–05-Feb-10
• RXBUFF: Receive Buffer Full Interrupt Disable
0 = No effect.
1 = Disables the Receive Buffer Full Interrupt.
• CP0: Compare 0 Interrupt Disable
0 = No effect.
1 = Disables the Compare 0 Interrupt.
• CP1: Compare 1 Interrupt Disable
0 = No effect.
1 = Disables the Compare 1 Interrupt.
• TXSYN: Tx Sync Interrupt Enable
0 = No effect.
1 = Disables the Tx Sync Interrupt.
• RXSYN: Rx Sync Interrupt Enable
0 = No effect.
1 = Disables the Rx Sync Interrupt.
552
AT91SAM9G20
6384E–ATARM–05-Feb-10
AT91SAM9G20
33.8.16
Name:
SSC Interrupt Mask Register
SSC_IMR
Access Type:
Read-only
31
–
30
–
29
–
28
–
27
–
26
–
25
–
24
–
23
–
22
–
21
–
20
–
19
–
18
–
17
–
16
–
15
–
14
–
13
–
12
–
11
RXSYN
10
TXSYN
9
CP1
8
CP0
7
RXBUF
6
ENDRX
5
OVRUN
4
RXRDY
3
TXBUFE
2
ENDTX
1
TXEMPTY
0
TXRDY
• TXRDY: Transmit Ready Interrupt Mask
0 = The Transmit Ready Interrupt is disabled.
1 = The Transmit Ready Interrupt is enabled.
• TXEMPTY: Transmit Empty Interrupt Mask
0 = The Transmit Empty Interrupt is disabled.
1 = The Transmit Empty Interrupt is enabled.
• ENDTX: End of Transmission Interrupt Mask
0 = The End of Transmission Interrupt is disabled.
1 = The End of Transmission Interrupt is enabled.
• TXBUFE: Transmit Buffer Empty Interrupt Mask
0 = The Transmit Buffer Empty Interrupt is disabled.
1 = The Transmit Buffer Empty Interrupt is enabled.
• RXRDY: Receive Ready Interrupt Mask
0 = The Receive Ready Interrupt is disabled.
1 = The Receive Ready Interrupt is enabled.
• OVRUN: Receive Overrun Interrupt Mask
0 = The Receive Overrun Interrupt is disabled.
1 = The Receive Overrun Interrupt is enabled.
• ENDRX: End of Reception Interrupt Mask
0 = The End of Reception Interrupt is disabled.
1 = The End of Reception Interrupt is enabled.
553
6384E–ATARM–05-Feb-10
• RXBUFF: Receive Buffer Full Interrupt Mask
0 = The Receive Buffer Full Interrupt is disabled.
1 = The Receive Buffer Full Interrupt is enabled.
• CP0: Compare 0 Interrupt Mask
0 = The Compare 0 Interrupt is disabled.
1 = The Compare 0 Interrupt is enabled.
• CP1: Compare 1 Interrupt Mask
0 = The Compare 1 Interrupt is disabled.
1 = The Compare 1 Interrupt is enabled.
• TXSYN: Tx Sync Interrupt Mask
0 = The Tx Sync Interrupt is disabled.
1 = The Tx Sync Interrupt is enabled.
• RXSYN: Rx Sync Interrupt Mask
0 = The Rx Sync Interrupt is disabled.
1 = The Rx Sync Interrupt is enabled.
554
AT91SAM9G20
6384E–ATARM–05-Feb-10
AT91SAM9G20
34. Timer Counter (TC)
34.1
Overview
The Timer Counter (TC) includes three identical 16-bit Timer Counter channels.
Each channel can be independently programmed to perform a wide range of functions including
frequency measurement, event counting, interval measurement, pulse generation, delay timing
and pulse width modulation.
Each channel has three external clock inputs, five internal clock inputs and two multi-purpose
input/output signals which can be configured by the user. Each channel drives an internal interrupt signal which can be programmed to generate processor interrupts.
The Timer Counter block has two global registers which act upon all three TC channels.
The Block Control Register allows the three channels to be started simultaneously with the same
instruction.
The Block Mode Register defines the external clock inputs for each channel, allowing them to be
chained.
Table 34-1 gives the assignment of the device Timer Counter clock inputs common to Timer
Counter 0 to 2
Table 34-1.
Timer Counter Clock Assignment
Name
Definition
TIMER_CLOCK1
MCK/2
TIMER_CLOCK2
MCK/8
TIMER_CLOCK3
MCK/32
TIMER_CLOCK4
MCK/128
TIMER_CLOCK5
SLCK
555
6384E–ATARM–05-Feb-10
34.2
Block Diagram
Figure 34-1. Timer Counter Block Diagram
Parallel I/O
Controller
TIMER_CLOCK1
TCLK0
TIMER_CLOCK2
TIOA1
TIOA2
TIMER_CLOCK3
XC0
XC1
TCLK1
Timer/Counter
Channel 0
TIOA
TIOA0
TIOB0
TIOA0
TIOB
TIMER_CLOCK4
XC2
TCLK2
TIMER_CLOCK5
TIOB0
TC0XC0S
SYNC
TCLK0
TCLK1
TCLK2
INT0
TCLK0
XC0
TCLK1
TIOA0
XC1
Timer/Counter
Channel 1
TIOA
TIOA1
TIOB1
TIOA1
TIOB
TIOA2
TCLK2
XC2
TIOB1
SYNC
TC1XC1S
TCLK0
XC0
TCLK1
XC1
TCLK2
XC2
Timer/Counter
Channel 2
INT1
TIOA
TIOA2
TIOB2
TIOA2
TIOB
TIOA0
TIOA1
TC2XC2S
TIOB2
SYNC
INT2
Timer Counter
Advanced
Interrupt
Controller
Table 34-2.
Signal Name Description
Block/Channel
Signal Name
XC0, XC1, XC2
Channel Signal
External Clock Inputs
TIOA
Capture Mode: Timer Counter Input
Waveform Mode: Timer Counter Output
TIOB
Capture Mode: Timer Counter Input
Waveform Mode: Timer Counter Input/Output
INT
SYNC
556
Description
Interrupt Signal Output
Synchronization Input Signal
AT91SAM9G20
6384E–ATARM–05-Feb-10
AT91SAM9G20
34.3
Pin Name List
Table 34-3.
34.4
34.4.1
TC pin list
Pin Name
Description
Type
TCLK0-TCLK2
External Clock Input
Input
TIOA0-TIOA2
I/O Line A
I/O
TIOB0-TIOB2
I/O Line B
I/O
Product Dependencies
I/O Lines
The pins used for interfacing the compliant external devices may be multiplexed with PIO lines.
The programmer must first program the PIO controllers to assign the TC pins to their peripheral
functions.
34.4.2
Power Management
The TC is clocked through the Power Management Controller (PMC), thus the programmer must
first configure the PMC to enable the Timer Counter clock.
34.4.3
Interrupt
The TC has an interrupt line connected to the Advanced Interrupt Controller (AIC). Handling the
TC interrupt requires programming the AIC before configuring the TC.
557
6384E–ATARM–05-Feb-10
34.5
Functional Description
34.5.1
TC Description
The three channels of the Timer Counter are independent and identical in operation. The registers for channel programming are listed in Table 34-4 on page 571.
34.5.2
16-bit Counter
Each channel is organized around a 16-bit counter. The value of the counter is incremented at
each positive edge of the selected clock. When the counter has reached the value 0xFFFF and
passes to 0x0000, an overflow occurs and the COVFS bit in TC_SR (Status Register) is set.
The current value of the counter is accessible in real time by reading the Counter Value Register, TC_CV. The counter can be reset by a trigger. In this case, the counter value passes to
0x0000 on the next valid edge of the selected clock.
34.5.3
Clock Selection
At block level, input clock signals of each channel can either be connected to the external inputs
TCLK0, TCLK1 or TCLK2, or be connected to the internal I/O signals TIOA0, TIOA1 or TIOA2
for chaining by programming the TC_BMR (Block Mode). See Figure 34-2 on page 559.
Each channel can independently select an internal or external clock source for its counter:
•
Internal clock signals: TIMER_CLOCK1, TIMER_CLOCK2, TIMER_CLOCK3,
TIMER_CLOCK4, TIMER_CLOCK5
•
External clock signals: XC0, XC1 or XC2
This selection is made by the TCCLKS bits in the TC Channel Mode Register.
The selected clock can be inverted with the CLKI bit in TC_CMR. This allows counting on the
opposite edges of the clock.
The burst function allows the clock to be validated when an external signal is high. The BURST
parameter in the Mode Register defines this signal (none, XC0, XC1, XC2). See Figure 34-3 on
page 559
Note:
558
In all cases, if an external clock is used, the duration of each of its levels must be longer than the
master clock period. The external clock frequency must be at least 2.5 times lower than the master clock
AT91SAM9G20
6384E–ATARM–05-Feb-10
AT91SAM9G20
Figure 34-2. Clock Chaining Selection
TC0XC0S
Timer/Counter
Channel 0
TCLK0
TIOA1
XC0
TIOA2
TIOA0
XC1 = TCLK1
XC2 = TCLK2
TIOB0
SYNC
TC1XC1S
Timer/Counter
Channel 1
TCLK1
XC0 = TCLK2
TIOA0
TIOA1
XC1
TIOA2
XC2 = TCLK2
TIOB1
SYNC
Timer/Counter
Channel 2
TC2XC2S
XC0 = TCLK0
TCLK2
TIOA2
XC1 = TCLK1
TIOA0
XC2
TIOB2
TIOA1
SYNC
Figure 34-3. Clock Selection
TCCLKS
TIMER_CLOCK1
TIMER_CLOCK2
CLKI
TIMER_CLOCK3
TIMER_CLOCK4
TIMER_CLOCK5
Selected
Clock
XC0
XC1
XC2
BURST
1
559
6384E–ATARM–05-Feb-10
34.5.4
Clock Control
The clock of each counter can be controlled in two different ways: it can be enabled/disabled
and started/stopped. See Figure 34-4.
•
The clock can be enabled or disabled by the user with the CLKEN and the CLKDIS
commands in the Control Register. In Capture Mode it can be disabled by an RB load event
if LDBDIS is set to 1 in TC_CMR. In Waveform Mode, it can be disabled by an RC Compare
event if CPCDIS is set to 1 in TC_CMR. When disabled, the start or the stop actions have no
effect: only a CLKEN command in the Control Register can re-enable the clock. When the
clock is enabled, the CLKSTA bit is set in the Status Register.
•
The clock can also be started or stopped: a trigger (software, synchro, external or compare)
always starts the clock. The clock can be stopped by an RB load event in Capture Mode
(LDBSTOP = 1 in TC_CMR) or a RC compare event in Waveform Mode (CPCSTOP = 1 in
TC_CMR). The start and the stop commands have effect only if the clock is enabled.
Figure 34-4. Clock Control
Selected
Clock
Trigger
CLKSTA
CLKEN
Q
Q
S
CLKDIS
S
R
R
Counter
Clock
34.5.5
Stop
Event
Disable
Event
TC Operating Modes
Each channel can independently operate in two different modes:
•
Capture Mode provides measurement on signals.
•
Waveform Mode provides wave generation.
The TC Operating Mode is programmed with the WAVE bit in the TC Channel Mode Register.
In Capture Mode, TIOA and TIOB are configured as inputs.
In Waveform Mode, TIOA is always configured to be an output and TIOB is an output if it is not
selected to be the external trigger.
34.5.6
Trigger
A trigger resets the counter and starts the counter clock. Three types of triggers are common to
both modes, and a fourth external trigger is available to each mode.
The following triggers are common to both modes:
560
AT91SAM9G20
6384E–ATARM–05-Feb-10
AT91SAM9G20
•
Software Trigger: Each channel has a software trigger, available by setting SWTRG in
TC_CCR.
•
SYNC: Each channel has a synchronization signal SYNC. When asserted, this signal has
the same effect as a software trigger. The SYNC signals of all channels are asserted
simultaneously by writing TC_BCR (Block Control) with SYNC set.
•
Compare RC Trigger: RC is implemented in each channel and can provide a trigger when
the counter value matches the RC value if CPCTRG is set in TC_CMR.
The channel can also be configured to have an external trigger. In Capture Mode, the external
trigger signal can be selected between TIOA and TIOB. In Waveform Mode, an external event
can be programmed on one of the following signals: TIOB, XC0, XC1 or XC2. This external
event can then be programmed to perform a trigger by setting ENETRG in TC_CMR.
If an external trigger is used, the duration of the pulses must be longer than the master clock
period in order to be detected.
Regardless of the trigger used, it will be taken into account at the following active edge of the
selected clock. This means that the counter value can be read differently from zero just after a
trigger, especially when a low frequency signal is selected as the clock.
34.5.7
Capture Operating Mode
This mode is entered by clearing the WAVE parameter in TC_CMR (Channel Mode Register).
Capture Mode allows the TC channel to perform measurements such as pulse timing, frequency, period, duty cycle and phase on TIOA and TIOB signals which are considered as
inputs.
Figure 34-5 shows the configuration of the TC channel when programmed in Capture Mode.
34.5.8
Capture Registers A and B
Registers A and B (RA and RB) are used as capture registers. This means that they can be
loaded with the counter value when a programmable event occurs on the signal TIOA.
The LDRA parameter in TC_CMR defines the TIOA edge for the loading of register A, and the
LDRB parameter defines the TIOA edge for the loading of Register B.
RA is loaded only if it has not been loaded since the last trigger or if RB has been loaded since
the last loading of RA.
RB is loaded only if RA has been loaded since the last trigger or the last loading of RB.
Loading RA or RB before the read of the last value loaded sets the Overrun Error Flag (LOVRS)
in TC_SR (Status Register). In this case, the old value is overwritten.
34.5.9
Trigger Conditions
In addition to the SYNC signal, the software trigger and the RC compare trigger, an external trigger can be defined.
The ABETRG bit in TC_CMR selects TIOA or TIOB input signal as an external trigger. The
ETRGEDG parameter defines the edge (rising, falling or both) detected to generate an external
trigger. If ETRGEDG = 0 (none), the external trigger is disabled.
561
6384E–ATARM–05-Feb-10
562
MTIOA
MTIOB
1
If RA is not loaded
or RB is Loaded
Edge
Detector
ETRGEDG
SWTRG
Timer/Counter Channel
ABETRG
BURST
CLKI
S
R
OVF
LDRB
Edge
Detector
Edge
Detector
Capture
Register A
LDBSTOP
R
S
CLKEN
LDRA
If RA is Loaded
CPCTRG
16-bit Counter
RESET
Trig
CLK
Q
Q
CLKSTA
LDBDIS
Capture
Register B
CLKDIS
TC1_SR
TIOA
TIOB
SYNC
XC2
XC1
XC0
TIMER_CLOCK5
TIMER_CLOCK4
TIMER_CLOCK3
TIMER_CLOCK2
TIMER_CLOCK1
TCCLKS
Compare RC =
Register C
COVFS
INT
Figure 34-5. Capture Mode
CPCS
LOVRS
LDRBS
ETRGS
LDRAS
TC1_IMR
AT91SAM9G20
6384E–ATARM–05-Feb-10
AT91SAM9G20
34.5.10
Waveform Operating Mode
Waveform operating mode is entered by setting the WAVE parameter in TC_CMR (Channel
Mode Register).
In Waveform Operating Mode the TC channel generates 1 or 2 PWM signals with the same frequency and independently programmable duty cycles, or generates different types of one-shot
or repetitive pulses.
In this mode, TIOA is configured as an output and TIOB is defined as an output if it is not used
as an external event (EEVT parameter in TC_CMR).
Figure 34-6 shows the configuration of the TC channel when programmed in Waveform Operating Mode.
34.5.11
Waveform Selection
Depending on the WAVSEL parameter in TC_CMR (Channel Mode Register), the behavior of
TC_CV varies.
With any selection, RA, RB and RC can all be used as compare registers.
RA Compare is used to control the TIOA output, RB Compare is used to control the TIOB output
(if correctly configured) and RC Compare is used to control TIOA and/or TIOB outputs.
563
6384E–ATARM–05-Feb-10
564
TIOB
SYNC
XC2
XC1
XC0
TIMER_CLOCK5
TIMER_CLOCK4
TIMER_CLOCK3
TIMER_CLOCK2
TIMER_CLOCK1
1
EEVT
BURST
Timer/Counter Channel
Edge
Detector
EEVTEDG
SWTRG
ENETRG
CLKI
Trig
CLK
R
S
OVF
WAVSEL
RESET
16-bit Counter
WAVSEL
Q
Compare RA =
Register A
Q
CLKSTA
Compare RC =
Compare RB =
CPCSTOP
CPCDIS
Register C
CLKDIS
Register B
R
S
CLKEN
CPAS
INT
BSWTRG
BEEVT
BCPB
BCPC
ASWTRG
AEEVT
ACPA
ACPC
Output Controller
Output Controller
TCCLKS
TIOB
MTIOB
TIOA
MTIOA
Figure 34-6. Waveform Mode
CPCS
CPBS
COVFS
TC1_SR
ETRGS
TC1_IMR
AT91SAM9G20
6384E–ATARM–05-Feb-10
AT91SAM9G20
34.5.11.1
WAVSEL = 00
When WAVSEL = 00, the value of TC_CV is incremented from 0 to 0xFFFF. Once 0xFFFF has
been reached, the value of TC_CV is reset. Incrementation of TC_CV starts again and the cycle
continues. See Figure 34-7.
An external event trigger or a software trigger can reset the value of TC_CV. It is important to
note that the trigger may occur at any time. See Figure 34-8.
RC Compare cannot be programmed to generate a trigger in this configuration. At the same
time, RC Compare can stop the counter clock (CPCSTOP = 1 in TC_CMR) and/or disable the
counter clock (CPCDIS = 1 in TC_CMR).
Figure 34-7. WAVSEL= 00 without trigger
Counter Value
Counter cleared by compare match with 0xFFFF
0xFFFF
RC
RB
RA
Waveform Examples
Time
TIOB
TIOA
565
6384E–ATARM–05-Feb-10
Figure 34-8. WAVSEL= 00 with trigger
Counter cleared by compare match with 0xFFFF
Counter Value
0xFFFF
Counter cleared by trigger
RC
RB
RA
Time
Waveform Examples
TIOB
TIOA
34.5.11.2
WAVSEL = 10
When WAVSEL = 10, the value of TC_CV is incremented from 0 to the value of RC, then automatically reset on a RC Compare. Once the value of TC_CV has been reset, it is then
incremented and so on. See Figure 34-9.
It is important to note that TC_CV can be reset at any time by an external event or a software
trigger if both are programmed correctly. See Figure 34-10.
In addition, RC Compare can stop the counter clock (CPCSTOP = 1 in TC_CMR) and/or disable
the counter clock (CPCDIS = 1 in TC_CMR).
Figure 34-9. WAVSEL = 10 Without Trigger
Counter Value
0xFFFF
Counter cleared by compare match with RC
RC
RB
RA
Waveform Examples
Time
TIOB
TIOA
566
AT91SAM9G20
6384E–ATARM–05-Feb-10
AT91SAM9G20
Figure 34-10. WAVSEL = 10 With Trigger
Counter Value
0xFFFF
Counter cleared by compare match with RC
Counter cleared by trigger
RC
RB
RA
Waveform Examples
Time
TIOB
TIOA
34.5.11.3
WAVSEL = 01
When WAVSEL = 01, the value of TC_CV is incremented from 0 to 0xFFFF. Once 0xFFFF is
reached, the value of TC_CV is decremented to 0, then re-incremented to 0xFFFF and so on.
See Figure 34-11.
A trigger such as an external event or a software trigger can modify TC_CV at any time. If a trigger occurs while TC_CV is incrementing, TC_CV then decrements. If a trigger is received while
TC_CV is decrementing, TC_CV then increments. See Figure 34-12.
RC Compare cannot be programmed to generate a trigger in this configuration.
At the same time, RC Compare can stop the counter clock (CPCSTOP = 1) and/or disable the
counter clock (CPCDIS = 1).
567
6384E–ATARM–05-Feb-10
Figure 34-11. WAVSEL = 01 Without Trigger
Counter decremented by compare match with 0xFFFF
Counter Value
0xFFFF
RC
RB
RA
Time
Waveform Examples
TIOB
TIOA
Figure 34-12. WAVSEL = 01 With Trigger
Counter decremented by compare match with 0xFFFF
Counter Value
0xFFFF
Counter decremented
by trigger
RC
RB
Counter incremented
by trigger
RA
Time
Waveform Examples
TIOB
TIOA
34.5.11.4
WAVSEL = 11
When WAVSEL = 11, the value of TC_CV is incremented from 0 to RC. Once RC is reached, the
value of TC_CV is decremented to 0, then re-incremented to RC and so on. See Figure 34-13.
A trigger such as an external event or a software trigger can modify TC_CV at any time. If a trigger occurs while TC_CV is incrementing, TC_CV then decrements. If a trigger is received while
TC_CV is decrementing, TC_CV then increments. See Figure 34-14.
RC Compare can stop the counter clock (CPCSTOP = 1) and/or disable the counter clock (CPCDIS = 1).
568
AT91SAM9G20
6384E–ATARM–05-Feb-10
AT91SAM9G20
Figure 34-13. WAVSEL = 11 Without Trigger
Counter Value
0xFFFF
Counter decremented by compare match with RC
RC
RB
RA
Time
Waveform Examples
TIOB
TIOA
Figure 34-14. WAVSEL = 11 With Trigger
Counter Value
0xFFFF
Counter decremented by compare match with RC
RC
RB
Counter decremented
by trigger
Counter incremented
by trigger
RA
Waveform Examples
Time
TIOB
TIOA
569
6384E–ATARM–05-Feb-10
34.5.12
External Event/Trigger Conditions
An external event can be programmed to be detected on one of the clock sources (XC0, XC1,
XC2) or TIOB. The external event selected can then be used as a trigger.
The EEVT parameter in TC_CMR selects the external trigger. The EEVTEDG parameter defines
the trigger edge for each of the possible external triggers (rising, falling or both). If EEVTEDG is
cleared (none), no external event is defined.
If TIOB is defined as an external event signal (EEVT = 0), TIOB is no longer used as an output
and the compare register B is not used to generate waveforms and subsequently no IRQs. In
this case the TC channel can only generate a waveform on TIOA.
When an external event is defined, it can be used as a trigger by setting bit ENETRG in
TC_CMR.
As in Capture Mode, the SYNC signal and the software trigger are also available as triggers. RC
Compare can also be used as a trigger depending on the parameter WAVSEL.
34.5.13
Output Controller
The output controller defines the output level changes on TIOA and TIOB following an event.
TIOB control is used only if TIOB is defined as output (not as an external event).
The following events control TIOA and TIOB: software trigger, external event and RC compare.
RA compare controls TIOA and RB compare controls TIOB. Each of these events can be programmed to set, clear or toggle the output as defined in the corresponding parameter in
TC_CMR.
570
AT91SAM9G20
6384E–ATARM–05-Feb-10
AT91SAM9G20
34.6
Timer Counter (TC) User Interface
Table 34-4.
Register Mapping
Offset(1)
Register
Name
Access
Reset
0x00 + channel * 0x40 + 0x00
Channel Control Register
TC_CCR
Write-only
–
0x00 + channel * 0x40 + 0x04
Channel Mode Register
TC_CMR
Read-write
0
0x00 + channel * 0x40 + 0x08
Reserved
0x00 + channel * 0x40 + 0x0C
Reserved
0x00 + channel * 0x40 + 0x10
Counter Value
TC_CV
Read-only
0
0x00 + channel * 0x40 + 0x14
Register A
TC_RA
Read-write
(2)
0
Read-write
(2)
0
0x00 + channel * 0x40 + 0x18
Register B
TC_RB
0x00 + channel * 0x40 + 0x1C
Register C
TC_RC
Read-write
0
0x00 + channel * 0x40 + 0x20
Status Register
TC_SR
Read-only
0
0x00 + channel * 0x40 + 0x24
Interrupt Enable Register
TC_IER
Write-only
–
0x00 + channel * 0x40 + 0x28
Interrupt Disable Register
TC_IDR
Write-only
–
0x00 + channel * 0x40 + 0x2C
Interrupt Mask Register
TC_IMR
Read-only
0
0xC0
Block Control Register
TC_BCR
Write-only
–
0xC4
Block Mode Register
TC_BMR
Read-write
0
0xFC
Reserved
–
–
–
Notes:
1. Channel index ranges from 0 to 2.
2. Read-only if WAVE = 0
571
6384E–ATARM–05-Feb-10
34.6.1
TC Block Control Register
Register Name:TC_BCR
Access Type:Write-only
31
30
29
28
27
26
25
24
–
–
–
–
–
–
–
–
23
22
21
20
19
18
17
16
–
–
–
–
–
–
–
–
15
14
13
12
11
10
9
8
–
–
–
–
–
–
–
–
7
6
5
4
3
2
1
0
–
–
–
–
–
–
–
SYNC
• SYNC: Synchro Command
0 = No effect.
1 = Asserts the SYNC signal which generates a software trigger simultaneously for each of the channels.
572
AT91SAM9G20
6384E–ATARM–05-Feb-10
AT91SAM9G20
34.6.2
TC Block Mode Register
Register Name:TC_BMR
Access Type:Read-write
31
30
29
28
27
26
25
24
–
–
–
–
–
–
–
–
23
22
21
20
19
18
17
16
–
–
–
–
–
–
–
–
15
14
13
12
11
10
9
8
–
–
–
–
–
–
–
–
7
6
5
4
3
2
1
–
–
TC2XC2S
TC1XC1S
0
TC0XC0S
• TC0XC0S: External Clock Signal 0 Selection
TC0XC0S
Signal Connected to XC0
0
0
TCLK0
0
1
none
1
0
TIOA1
1
1
TIOA2
• TC1XC1S: External Clock Signal 1 Selection
TC1XC1S
Signal Connected to XC1
0
0
TCLK1
0
1
none
1
0
TIOA0
1
1
TIOA2
• TC2XC2S: External Clock Signal 2 Selection
TC2XC2S
Signal Connected to XC2
0
0
TCLK2
0
1
none
1
0
TIOA0
1
1
TIOA1
573
6384E–ATARM–05-Feb-10
34.6.3
TC Channel Control Register
Register Name:TC_CCRx [x=0..2]
Access Type:Write-only
31
30
29
28
27
26
25
24
–
–
–
–
–
–
–
–
23
22
21
20
19
18
17
16
–
–
–
–
–
–
–
–
15
14
13
12
11
10
9
8
–
–
–
–
–
–
–
–
7
6
5
4
3
2
1
0
–
–
–
–
–
SWTRG
CLKDIS
CLKEN
• CLKEN: Counter Clock Enable Command
0 = No effect.
1 = Enables the clock if CLKDIS is not 1.
• CLKDIS: Counter Clock Disable Command
0 = No effect.
1 = Disables the clock.
• SWTRG: Software Trigger Command
0 = No effect.
1 = A software trigger is performed: the counter is reset and the clock is started.
574
AT91SAM9G20
6384E–ATARM–05-Feb-10
AT91SAM9G20
34.6.4
TC Channel Mode Register: Capture Mode
Register Name:TC_CMRx [x=0..2] (WAVE = 0)
Access Type:Read-write
31
30
29
28
27
26
25
24
–
–
–
–
–
–
–
–
23
22
21
20
19
18
17
–
–
–
–
15
14
13
12
11
10
WAVE
CPCTRG
–
–
–
ABETRG
7
6
5
3
2
LDBDIS
LDBSTOP
16
LDRB
4
BURST
CLKI
LDRA
9
8
ETRGEDG
1
0
TCCLKS
• TCCLKS: Clock Selection
TCCLKS
Clock Selected
0
0
0
TIMER_CLOCK1
0
0
1
TIMER_CLOCK2
0
1
0
TIMER_CLOCK3
0
1
1
TIMER_CLOCK4
1
0
0
TIMER_CLOCK5
1
0
1
XC0
1
1
0
XC1
1
1
1
XC2
• CLKI: Clock Invert
0 = Counter is incremented on rising edge of the clock.
1 = Counter is incremented on falling edge of the clock.
• BURST: Burst Signal Selection
BURST
0
0
The clock is not gated by an external signal.
0
1
XC0 is ANDed with the selected clock.
1
0
XC1 is ANDed with the selected clock.
1
1
XC2 is ANDed with the selected clock.
• LDBSTOP: Counter Clock Stopped with RB Loading
0 = Counter clock is not stopped when RB loading occurs.
1 = Counter clock is stopped when RB loading occurs.
575
6384E–ATARM–05-Feb-10
• LDBDIS: Counter Clock Disable with RB Loading
0 = Counter clock is not disabled when RB loading occurs.
1 = Counter clock is disabled when RB loading occurs.
• ETRGEDG: External Trigger Edge Selection
ETRGEDG
Edge
0
0
none
0
1
rising edge
1
0
falling edge
1
1
each edge
• ABETRG: TIOA or TIOB External Trigger Selection
0 = TIOB is used as an external trigger.
1 = TIOA is used as an external trigger.
• CPCTRG: RC Compare Trigger Enable
0 = RC Compare has no effect on the counter and its clock.
1 = RC Compare resets the counter and starts the counter clock.
• WAVE
0 = Capture Mode is enabled.
1 = Capture Mode is disabled (Waveform Mode is enabled).
• LDRA: RA Loading Selection
LDRA
Edge
0
0
none
0
1
rising edge of TIOA
1
0
falling edge of TIOA
1
1
each edge of TIOA
• LDRB: RB Loading Selection
LDRB
576
Edge
0
0
none
0
1
rising edge of TIOA
1
0
falling edge of TIOA
1
1
each edge of TIOA
AT91SAM9G20
6384E–ATARM–05-Feb-10
AT91SAM9G20
34.6.5
TC Channel Mode Register: Waveform Mode
Register Name:TC_CMRx [x=0..2] (WAVE = 1)
Access Type:Read-write
31
30
29
BSWTRG
23
22
21
ASWTRG
15
28
27
BEEVT
20
19
AEEVT
14
WAVE
13
7
6
CPCDIS
CPCSTOP
24
BCPB
18
11
ENETRG
5
25
17
16
ACPC
12
WAVSEL
26
BCPC
ACPA
10
9
EEVT
4
3
BURST
CLKI
8
EEVTEDG
2
1
0
TCCLKS
• TCCLKS: Clock Selection
TCCLKS
Clock Selected
0
0
0
TIMER_CLOCK1
0
0
1
TIMER_CLOCK2
0
1
0
TIMER_CLOCK3
0
1
1
TIMER_CLOCK4
1
0
0
TIMER_CLOCK5
1
0
1
XC0
1
1
0
XC1
1
1
1
XC2
• CLKI: Clock Invert
0 = Counter is incremented on rising edge of the clock.
1 = Counter is incremented on falling edge of the clock.
• BURST: Burst Signal Selection
BURST
0
0
The clock is not gated by an external signal.
0
1
XC0 is ANDed with the selected clock.
1
0
XC1 is ANDed with the selected clock.
1
1
XC2 is ANDed with the selected clock.
• CPCSTOP: Counter Clock Stopped with RC Compare
0 = Counter clock is not stopped when counter reaches RC.
1 = Counter clock is stopped when counter reaches RC.
577
6384E–ATARM–05-Feb-10
• CPCDIS: Counter Clock Disable with RC Compare
0 = Counter clock is not disabled when counter reaches RC.
1 = Counter clock is disabled when counter reaches RC.
• EEVTEDG: External Event Edge Selection
EEVTEDG
Edge
0
0
none
0
1
rising edge
1
0
falling edge
1
1
each edge
• EEVT: External Event Selection
EEVT
Signal selected as external event
TIOB Direction
0
0
TIOB
input (1)
0
1
XC0
output
1
0
XC1
output
1
1
XC2
output
Note:
1. If TIOB is chosen as the external event signal, it is configured as an input and no longer generates waveforms and subsequently no IRQs.
• ENETRG: External Event Trigger Enable
0 = The external event has no effect on the counter and its clock. In this case, the selected external event only controls the
TIOA output.
1 = The external event resets the counter and starts the counter clock.
• WAVSEL: Waveform Selection
WAVSEL
Effect
0
0
UP mode without automatic trigger on RC Compare
1
0
UP mode with automatic trigger on RC Compare
0
1
UPDOWN mode without automatic trigger on RC Compare
1
1
UPDOWN mode with automatic trigger on RC Compare
• WAVE
0 = Waveform Mode is disabled (Capture Mode is enabled).
1 = Waveform Mode is enabled.
578
AT91SAM9G20
6384E–ATARM–05-Feb-10
AT91SAM9G20
• ACPA: RA Compare Effect on TIOA
ACPA
Effect
0
0
none
0
1
set
1
0
clear
1
1
toggle
• ACPC: RC Compare Effect on TIOA
ACPC
Effect
0
0
none
0
1
set
1
0
clear
1
1
toggle
• AEEVT: External Event Effect on TIOA
AEEVT
Effect
0
0
none
0
1
set
1
0
clear
1
1
toggle
• ASWTRG: Software Trigger Effect on TIOA
ASWTRG
Effect
0
0
none
0
1
set
1
0
clear
1
1
toggle
• BCPB: RB Compare Effect on TIOB
BCPB
Effect
0
0
none
0
1
set
1
0
clear
1
1
toggle
579
6384E–ATARM–05-Feb-10
• BCPC: RC Compare Effect on TIOB
BCPC
Effect
0
0
none
0
1
set
1
0
clear
1
1
toggle
• BEEVT: External Event Effect on TIOB
BEEVT
Effect
0
0
none
0
1
set
1
0
clear
1
1
toggle
• BSWTRG: Software Trigger Effect on TIOB
BSWTRG
580
Effect
0
0
none
0
1
set
1
0
clear
1
1
toggle
AT91SAM9G20
6384E–ATARM–05-Feb-10
AT91SAM9G20
34.6.6
TC Counter Value Register
Register Name:TC_CVx [x=0..2]
Access Type:Read-only
31
30
29
28
27
26
25
24
–
–
–
–
–
–
–
–
23
22
21
20
19
18
17
16
–
–
–
–
–
–
–
–
15
14
13
12
11
10
9
8
3
2
1
0
CV
7
6
5
4
CV
• CV: Counter Value
CV contains the counter value in real time.
581
6384E–ATARM–05-Feb-10
34.6.7
TC Register A
Register Name:TC_RAx [x=0..2]
Access Type:Read-only if WAVE = 0, Read-write if WAVE = 1
31
30
29
28
27
26
25
24
–
–
–
–
–
–
–
–
23
22
21
20
19
18
17
16
–
–
–
–
–
–
–
–
15
14
13
12
11
10
9
8
3
2
1
0
RA
7
6
5
4
RA
• RA: Register A
RA contains the Register A value in real time.
582
AT91SAM9G20
6384E–ATARM–05-Feb-10
AT91SAM9G20
34.6.8
TC Register B
Register Name:TC_RBx [x=0..2]
Access Type:Read-only if WAVE = 0, Read-write if WAVE = 1
31
30
29
28
27
26
25
24
–
–
–
–
–
–
–
–
23
22
21
20
19
18
17
16
–
–
–
–
–
–
–
–
15
14
13
12
11
10
9
8
3
2
1
0
RB
7
6
5
4
RB
• RB: Register B
RB contains the Register B value in real time.
34.6.9
TC Register C
Register Name:TC_RCx [x=0..2]
Access Type:Read-write
31
30
29
28
27
26
25
24
–
–
–
–
–
–
–
–
23
22
21
20
19
18
17
16
–
–
–
–
–
–
–
–
15
14
13
12
11
10
9
8
3
2
1
0
RC
7
6
5
4
RC
• RC: Register C
RC contains the Register C value in real time.
583
6384E–ATARM–05-Feb-10
34.6.10 TC Status Register
Register Name:TC_SRx [x=0..2]
Access Type:Read-only
31
30
29
28
27
26
25
24
–
–
–
–
–
–
–
–
23
22
21
20
19
18
17
16
–
–
–
–
–
MTIOB
MTIOA
CLKSTA
15
14
13
12
11
10
9
8
–
–
–
–
–
–
–
–
7
6
5
4
3
2
1
0
ETRGS
LDRBS
LDRAS
CPCS
CPBS
CPAS
LOVRS
COVFS
• COVFS: Counter Overflow Status
0 = No counter overflow has occurred since the last read of the Status Register.
1 = A counter overflow has occurred since the last read of the Status Register.
• LOVRS: Load Overrun Status
0 = Load overrun has not occurred since the last read of the Status Register or WAVE = 1.
1 = RA or RB have been loaded at least twice without any read of the corresponding register since the last read of the Status Register, if WAVE = 0.
• CPAS: RA Compare Status
0 = RA Compare has not occurred since the last read of the Status Register or WAVE = 0.
1 = RA Compare has occurred since the last read of the Status Register, if WAVE = 1.
• CPBS: RB Compare Status
0 = RB Compare has not occurred since the last read of the Status Register or WAVE = 0.
1 = RB Compare has occurred since the last read of the Status Register, if WAVE = 1.
• CPCS: RC Compare Status
0 = RC Compare has not occurred since the last read of the Status Register.
1 = RC Compare has occurred since the last read of the Status Register.
• LDRAS: RA Loading Status
0 = RA Load has not occurred since the last read of the Status Register or WAVE = 1.
1 = RA Load has occurred since the last read of the Status Register, if WAVE = 0.
• LDRBS: RB Loading Status
0 = RB Load has not occurred since the last read of the Status Register or WAVE = 1.
1 = RB Load has occurred since the last read of the Status Register, if WAVE = 0.
• ETRGS: External Trigger Status
0 = External trigger has not occurred since the last read of the Status Register.
1 = External trigger has occurred since the last read of the Status Register.
584
AT91SAM9G20
6384E–ATARM–05-Feb-10
AT91SAM9G20
• CLKSTA: Clock Enabling Status
0 = Clock is disabled.
1 = Clock is enabled.
• MTIOA: TIOA Mirror
0 = TIOA is low. If WAVE = 0, this means that TIOA pin is low. If WAVE = 1, this means that TIOA is driven low.
1 = TIOA is high. If WAVE = 0, this means that TIOA pin is high. If WAVE = 1, this means that TIOA is driven high.
• MTIOB: TIOB Mirror
0 = TIOB is low. If WAVE = 0, this means that TIOB pin is low. If WAVE = 1, this means that TIOB is driven low.
1 = TIOB is high. If WAVE = 0, this means that TIOB pin is high. If WAVE = 1, this means that TIOB is driven high.
585
6384E–ATARM–05-Feb-10
34.6.11 TC Interrupt Enable Register
Register Name:TC_IERx [x=0..2]
Access Type:Write-only
31
30
29
28
27
26
25
24
–
–
–
–
–
–
–
–
23
22
21
20
19
18
17
16
–
–
–
–
–
–
–
–
15
14
13
12
11
10
9
8
–
–
–
–
–
–
–
–
7
6
5
4
3
2
1
0
ETRGS
LDRBS
LDRAS
CPCS
CPBS
CPAS
LOVRS
COVFS
• COVFS: Counter Overflow
0 = No effect.
1 = Enables the Counter Overflow Interrupt.
• LOVRS: Load Overrun
0 = No effect.
1 = Enables the Load Overrun Interrupt.
• CPAS: RA Compare
0 = No effect.
1 = Enables the RA Compare Interrupt.
• CPBS: RB Compare
0 = No effect.
1 = Enables the RB Compare Interrupt.
• CPCS: RC Compare
0 = No effect.
1 = Enables the RC Compare Interrupt.
• LDRAS: RA Loading
0 = No effect.
1 = Enables the RA Load Interrupt.
• LDRBS: RB Loading
0 = No effect.
1 = Enables the RB Load Interrupt.
• ETRGS: External Trigger
0 = No effect.
1 = Enables the External Trigger Interrupt.
586
AT91SAM9G20
6384E–ATARM–05-Feb-10
AT91SAM9G20
34.6.12 TC Interrupt Disable Register
Register Name:TC_IDRx [x=0..2]
Access Type:Write-only
31
30
29
28
27
26
25
24
–
–
–
–
–
–
–
–
23
22
21
20
19
18
17
16
–
–
–
–
–
–
–
–
15
14
13
12
11
10
9
8
–
–
–
–
–
–
–
–
7
6
5
4
3
2
1
0
ETRGS
LDRBS
LDRAS
CPCS
CPBS
CPAS
LOVRS
COVFS
• COVFS: Counter Overflow
0 = No effect.
1 = Disables the Counter Overflow Interrupt.
• LOVRS: Load Overrun
0 = No effect.
1 = Disables the Load Overrun Interrupt (if WAVE = 0).
• CPAS: RA Compare
0 = No effect.
1 = Disables the RA Compare Interrupt (if WAVE = 1).
• CPBS: RB Compare
0 = No effect.
1 = Disables the RB Compare Interrupt (if WAVE = 1).
• CPCS: RC Compare
0 = No effect.
1 = Disables the RC Compare Interrupt.
• LDRAS: RA Loading
0 = No effect.
1 = Disables the RA Load Interrupt (if WAVE = 0).
• LDRBS: RB Loading
0 = No effect.
1 = Disables the RB Load Interrupt (if WAVE = 0).
• ETRGS: External Trigger
0 = No effect.
1 = Disables the External Trigger Interrupt.
587
6384E–ATARM–05-Feb-10
34.6.13 TC Interrupt Mask Register
Register Name:TC_IMRx [x=0..2]
Access Type:Read-only
31
30
29
28
27
26
25
24
–
–
–
–
–
–
–
–
23
22
21
20
19
18
17
16
–
–
–
–
–
–
–
–
15
14
13
12
11
10
9
8
–
–
–
–
–
–
–
–
7
6
5
4
3
2
1
0
ETRGS
LDRBS
LDRAS
CPCS
CPBS
CPAS
LOVRS
COVFS
• COVFS: Counter Overflow
0 = The Counter Overflow Interrupt is disabled.
1 = The Counter Overflow Interrupt is enabled.
• LOVRS: Load Overrun
0 = The Load Overrun Interrupt is disabled.
1 = The Load Overrun Interrupt is enabled.
• CPAS: RA Compare
0 = The RA Compare Interrupt is disabled.
1 = The RA Compare Interrupt is enabled.
• CPBS: RB Compare
0 = The RB Compare Interrupt is disabled.
1 = The RB Compare Interrupt is enabled.
• CPCS: RC Compare
0 = The RC Compare Interrupt is disabled.
1 = The RC Compare Interrupt is enabled.
• LDRAS: RA Loading
0 = The Load RA Interrupt is disabled.
1 = The Load RA Interrupt is enabled.
• LDRBS: RB Loading
0 = The Load RB Interrupt is disabled.
1 = The Load RB Interrupt is enabled.
• ETRGS: External Trigger
0 = The External Trigger Interrupt is disabled.
1 = The External Trigger Interrupt is enabled.
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35. MultiMedia Card Interface (MCI)
35.1
Overview
The MultiMedia Card Interface (MCI) supports the MultiMedia Card (MMC) Specification V3.11,
the SDIO Specification V1.1 and the SD Memory Card Specification V1.0.
The MCI includes a command register, response registers, data registers, timeout counters and
error detection logic that automatically handle the transmission of commands and, when
required, the reception of the associated responses and data with a limited processor overhead.
The MCI supports stream, block and multi-block data read and write, and is compatible with the
Peripheral DMA Controller (PDC) channels, minimizing processor intervention for large buffer
transfers.
The MCI operates at a rate of up to Master Clock divided by 2 and supports the interfacing of 2
slot(s). Each slot may be used to interface with a MultiMediaCard bus (up to 30 Cards) or with a
SD Memory Card. Only one slot can be selected at a time (slots are multiplexed). A bit field in
the SD Card Register performs this selection.
The SD Memory Card communication is based on a 9-pin interface (clock, command, four data
and three power lines) and the MultiMedia Card on a 7-pin interface (clock, command, one data,
three power lines and one reserved for future use).
The SD Memory Card interface also supports MultiMedia Card operations. The main differences
between SD and MultiMedia Cards are the initialization process and the bus topology.
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35.2
Block Diagram
Figure 35-1. Block Diagram
APB Bridge
PDC
APB
MCCK(1)
MCCDA(1)
MCDA0(1)
PMC
MCK
MCDA1(1)
MCDA2(1)
MCDA3(1)
MCI Interface
PIO
MCCDB(1)
MCDB0(1)
MCDB1(1)
MCDB2(1)
Interrupt Control
MCDB3(1)
MCI Interrupt
Note:
590
When several MCI (x MCI) are embedded in a product, MCCK refers to MCIx_CK, MCCDA to
MCIx_CDA, MCCDB to MCIx_CDB,MCDAy to MCIx_DAy, MCDBy to MCIx_DBy.
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AT91SAM9G20
35.3
Application Block Diagram
Figure 35-2. Application Block Diagram
Application Layer
ex: File System, Audio, Security, etc.
Physical Layer
MCI Interface
1 2 3 4 5 6 78
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9
SDCard
MMC
35.4
Pin Name List
Table 35-1.
I/O Lines Description
Pin Name(2)
Pin Description
Type(1)
Comments
MCCDA/MCCDB
Command/response
I/O/PP/OD
CMD of an MMC or SDCard/SDIO
MCCK
Clock
I/O
CLK of an MMC or SD Card/SDIO
MCDA0 - MCDA3
Data 0..3 of Slot A
I/O/PP
DAT0 of an MMC
DAT[0..3] of an SD Card/SDIO
MCDB0 - MCDB3
Data 0..3 of Slot B
I/O/PP
DAT0 of an MMC
DAT[0..3] of an SD Card/SDIO
Notes:
1. I: Input, O: Output, PP: Push/Pull, OD: Open Drain.
2. When several MCI (x MCI) are embedded in a product, MCCK refers to MCIx_CK, MCCDA to MCIx_CDA, MCCDB to
MCIx_CDB, MCDAy to MCIx_DAy, MCDBy to MCIx_DBy.
35.5
35.5.1
Product Dependencies
I/O Lines
The pins used for interfacing the MultiMedia Cards or SD Cards may be multiplexed with PIO
lines. The programmer must first program the PIO controllers to assign the peripheral functions
to MCI pins.
35.5.2
Power Management
The MCI may be clocked through the Power Management Controller (PMC), so the programmer
must first configure the PMC to enable the MCI clock.
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35.5.3
Interrupt
The MCI interface has an interrupt line connected to the Advanced Interrupt Controller (AIC).
Handling the MCI interrupt requires programming the AIC before configuring the MCI.
35.6
Bus Topology
Figure 35-3. Multimedia Memory Card Bus Topology
1234567
MMC
The MultiMedia Card communication is based on a 7-pin serial bus interface. It has three communication lines and four supply lines.
Table 35-2.
Bus Topology
Pin
Number
Name
Type
Description
MCI Pin Name(2)
(Slot z)
1
RSV
NC
Not connected
-
2
CMD
I/O/PP/OD
Command/response
MCCDz
3
VSS1
S
Supply voltage ground
VSS
4
VDD
S
Supply voltage
VDD
5
CLK
I/O
Clock
MCCK
6
VSS2
S
Supply voltage ground
VSS
7
DAT[0]
I/O/PP
Data 0
MCDz0
Notes:
(1)
1. I: Input, O: Output, PP: Push/Pull, OD: Open Drain.
2. When several MCI (x MCI) are embedded in a product, MCCK refers to MCIx_CK, MCCDA to
MCIx_CDA, MCCDB to MCIx_CDB, MCDAy to MCIx_DAy, MCDBy to MCIx_DBy.
Figure 35-4. MMC Bus Connections (One Slot)
MCI
MCDA0
MCCDA
MCCK
Note:
592
1234567
1234567
1234567
MMC1
MMC2
MMC3
When several MCI (x MCI) are embedded in a product, MCCK refers to MCIx_CK, MCCDA to
MCIx_CDA MCDAy to MCIx_DAy.
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Figure 35-5. SD Memory Card Bus Topology
1 2 3 4 5 6 78
9
SD CARD
The SD Memory Card bus includes the signals listed in Table 35-3.
Table 35-3.
SD Memory Card Bus Signals
Pin Number
Name
Type(1)
Description
MCI Pin Name(2)
(Slot z)
1
CD/DAT[3]
I/O/PP
Card detect/ Data line Bit 3
MCDz3
2
CMD
PP
Command/response
MCCDz
3
VSS1
S
Supply voltage ground
VSS
4
VDD
S
Supply voltage
VDD
5
CLK
I/O
Clock
MCCK
6
VSS2
S
Supply voltage ground
VSS
7
DAT[0]
I/O/PP
Data line Bit 0
MCDz0
8
DAT[1]
I/O/PP
Data line Bit 1 or Interrupt
MCDz1
9
DAT[2]
I/O/PP
Data line Bit 2
MCDz2
Notes:
1. I: input, O: output, PP: Push Pull, OD: Open Drain.
2. When several MCI (x MCI) are embedded in a product, MCCK refers to MCIx_CK, MCCDA to
MCIx_CDA, MCCDB to MCIx_CDB, MCDAy to MCIx_DAy, MCDBy to MCIx_DBy.
MCDA0 - MCDA3
MCCK
SD CARD
9
MCCDA
1 2 3 4 5 6 78
Figure 35-6. SD Card Bus Connections with One Slot
Note:
When several MCI (x MCI) are embedded in a product, MCCK refers to MCIx_CK, MCCDA to
MCIx_CDA MCDAy to MCIx_DAy.
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1 2 3 4 5 6 78
Figure 35-7. SD Card Bus Connections with Two Slots
MCDA0 - MCDA3
MCCK
1 2 3 4 5 6 78
9
MCCDA
SD CARD 1
MCDB0 - MCDB3
9
MCCDB
SD CARD 2
Note:
When several MCI (x MCI) are embedded in a product, MCCK refers to MCIx_CK,MCCDA to
MCIx_CDA, MCDAy to MCIx_DAy, MCCDB to MCIx_CDB, MCDBy to MCIx_DBy.
Figure 35-8. Mixing MultiMedia and SD Memory Cards with Two Slots
MCDA0
MCCDA
MCCK
1234567
MMC1
MMC2
MMC3
SD CARD
9
MCCDB
1234567
1 2 3 4 5 6 78
MCDB0 - MCDB3
1234567
Note:
When several MCI (x MCI) are embedded in a product, MCCK refers to MCIx_CK, MCCDA to
MCIx_CDA, MCDAy to MCIx_DAy, MCCDB to MCIx_CDB, MCDBy to MCIx_DBy.
When the MCI is configured to operate with SD memory cards, the width of the data bus can be
selected in the MCI_SDCR register. Clearing the SDCBUS bit in this register means that the
width is one bit; setting it means that the width is four bits. In the case of multimedia cards, only
the data line 0 is used. The other data lines can be used as independent PIOs.
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35.7
MultiMedia Card Operations
After a power-on reset, the cards are initialized by a special message-based MultiMedia Card
bus protocol. Each message is represented by one of the following tokens:
• Command: A command is a token that starts an operation. A command is sent from the host
either to a single card (addressed command) or to all connected cards (broadcast
command). A command is transferred serially on the CMD line.
• Response: A response is a token which is sent from an addressed card or (synchronously)
from all connected cards to the host as an answer to a previously received command. A
response is transferred serially on the CMD line.
• Data: Data can be transferred from the card to the host or vice versa. Data is transferred via
the data line.
Card addressing is implemented using a session address assigned during the initialization
phase by the bus controller to all currently connected cards. Their unique CID number identifies
individual cards.
The structure of commands, responses and data blocks is described in the MultiMedia-Card
System Specification. See also Table 35-5 on page 596.
MultiMediaCard bus data transfers are composed of these tokens.
There are different types of operations. Addressed operations always contain a command and a
response token. In addition, some operations have a data token; the others transfer their information directly within the command or response structure. In this case, no data token is present
in an operation. The bits on the DAT and the CMD lines are transferred synchronous to the clock
MCI Clock.
Two types of data transfer commands are defined:
• Sequential commands: These commands initiate a continuous data stream. They are
terminated only when a stop command follows on the CMD line. This mode reduces the
command overhead to an absolute minimum.
• Block-oriented commands: These commands send a data block succeeded by CRC bits.
Both read and write operations allow either single or multiple block transmission. A multiple
block transmission is terminated when a stop command follows on the CMD line similarly to the
sequential read or when a multiple block transmission has a pre-defined block count (See “Data
Transfer Operation” on page 597.).
The MCI provides a set of registers to perform the entire range of MultiMedia Card operations.
35.7.1
Command - Response Operation
After reset, the MCI is disabled and becomes valid after setting the MCIEN bit in the MCI_CR
Control Register.
The PWSEN bit saves power by dividing the MCI clock by 2PWSDIV + 1 when the bus is inactive.
The two bits, RDPROOF and WRPROOF in the MCI Mode Register (MCI_MR) allow stopping
the MCI Clock during read or write access if the internal FIFO is full. This will guarantee data
integrity, not bandwidth.
The command and the response of the card are clocked out with the rising edge of the MCI
Clock.
All the timings for MultiMedia Card are defined in the MultiMediaCard System Specification.
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6384E–ATARM–05-Feb-10
The two bus modes (open drain and push/pull) needed to process all the operations are defined
in the MCI command register. The MCI_CMDR allows a command to be carried out.
For example, to perform an ALL_SEND_CID command:
Table 35-4.
Host Command
CMD
S
T
Content
CRC
NID Cycles
E
Z
******
CID
Z
S
T
Content
Z
Z
Z
The command ALL_SEND_CID and the fields and values for the MCI_CMDR Control Register
are described in Table 35-5 and Table 35-6.
Table 35-5.
ALL_SEND_CID Command Description
CMD Index
Type
Argument
Resp
Abbreviation
CMD2
bcr
[31:0] stuff bits
R2
ALL_SEND_CID
Note:
Command
Description
Asks all cards to send
their CID numbers on
the CMD line
bcr means broadcast command with response.
Table 35-6.
Fields and Values for MCI_CMDR Command Register
Field
Value
CMDNB (command number)
2 (CMD2)
RSPTYP (response type)
2 (R2: 136 bits response)
SPCMD (special command)
0 (not a special command)
OPCMD (open drain command)
1
MAXLAT (max latency for command to response)
0 (NID cycles ==> 5 cycles)
TRCMD (transfer command)
0 (No transfer)
TRDIR (transfer direction)
X (available only in transfer command)
TRTYP (transfer type)
X (available only in transfer command)
IOSPCMD (SDIO special command)
0 (not a special command)
The MCI_ARGR contains the argument field of the command.
To send a command, the user must perform the following steps:
• Fill the argument register (MCI_ARGR) with the command argument.
• Set the command register (MCI_CMDR) (see Table 35-6).
The command is sent immediately after writing the command register. The status bit CMDRDY
in the status register (MCI_SR) is asserted when the command is completed. If the command
requires a response, it can be read in the MCI response register (MCI_RSPR). The response
size can be from 48 bits up to 136 bits depending on the command. The MCI embeds an error
detection to prevent any corrupted data during the transfer.
The following flowchart shows how to send a command to the card and read the response if
needed. In this example, the status register bits are polled but setting the appropriate bits in the
interrupt enable register (MCI_IER) allows using an interrupt method.
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Figure 35-9. Command/Response Functional Flow Diagram
Set the command argument
MCI_ARGR = Argument(1)
Set the command
MCI_CMDR = Command
Read MCI_SR
Wait for command
ready status flag
0
CMDRDY
1
Check error bits in the
status register (1)
Yes
Status error flags?
Read response if required
RETURN ERROR(1)
RETURN OK
Note:
35.7.2
1. If the command is SEND_OP_COND, the CRC error flag is always present (refer to R3
response in the MultiMedia Card specification).
Data Transfer Operation
The MultiMedia Card allows several read/write operations (single block, multiple blocks, stream,
etc.). These kind of transfers can be selected setting the Transfer Type (TRTYP) field in the MCI
Command Register (MCI_CMDR).
These operations can be done using the features of the Peripheral DMA Controller (PDC). If the
PDCMODE bit is set in MCI_MR, then all reads and writes use the PDC facilities.
In all cases, the block length (BLKLEN field) must be defined either in the mode register
MCI_MR, or in the Block Register MCI_BLKR. This field determines the size of the data block.
Enabling PDC Force Byte Transfer (PDCFBYTE bit in the MCI_MR) allows the PDC to manage
with internal byte transfers, so that transfer of blocks with a size different from modulo 4 can be
supported. When PDC Force Byte Transfer is disabled, the PDC type of transfers are in words,
otherwise the type of transfers are in bytes.
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Consequent to MMC Specification 3.1, two types of multiple block read (or write) transactions
are defined (the host can use either one at any time):
• Open-ended/Infinite Multiple block read (or write):
The number of blocks for the read (or write) multiple block operation is not defined. The card
will continuously transfer (or program) data blocks until a stop transmission command is
received.
• Multiple block read (or write) with pre-defined block count (since version 3.1 and higher):
The card will transfer (or program) the requested number of data blocks and terminate the
transaction. The stop command is not required at the end of this type of multiple block read
(or write), unless terminated with an error. In order to start a multiple block read (or write)
with pre-defined block count, the host must correctly program the MCI Block Register
(MCI_BLKR). Otherwise the card will start an open-ended multiple block read. The BCNT
field of the Block Register defines the number of blocks to transfer (from 1 to 65535 blocks).
Programming the value 0 in the BCNT field corresponds to an infinite block transfer.
35.7.3
598
Read Operation
The following flowchart shows how to read a single block with or without use of PDC facilities. In
this example (see Figure 35-10), a polling method is used to wait for the end of read. Similarly,
the user can configure the interrupt enable register (MCI_IER) to trigger an interrupt at the end
of read.
AT91SAM9G20
6384E–ATARM–05-Feb-10
AT91SAM9G20
Figure 35-10. Read Functional Flow Diagram
Send SELECT/DESELECT_CARD
command(1) to select the card
(1)
Send SET_BLOCKLEN command
No
Yes
Read with PDC
Reset the PDCMODE bit
MCI_MR &= ~PDCMODE
Set the block length (in bytes)
MCI_MR |= (BlockLenght <<16)(2)
Set the block count (if necessary)
MCI_BLKR |= (BlockCount << 0)
Set the PDCMODE bit
MCI_MR |= PDCMODE
Set the block length (in bytes)
(2)
MCI_MR |= (BlockLength << 16)
Set the block count (if necessary)
MCI_BLKR |= (BlockCount << 0)
Configure the PDC channel
MCI_RPR = Data Buffer Address
MCI_RCR = BlockLength/4
MCI_PTCR = RXTEN
Send READ_SINGLE_BLOCK
command(1)
Number of words to read = BlockLength/4
Send READ_SINGLE_BLOCK
command(1)
Yes
Number of words to read = 0 ?
Read status register MCI_SR
No
Read status register MCI_SR
Poll the bit
ENDRX = 0?
Poll the bit
RXRDY = 0?
Yes
Yes
No
No
RETURN
Read data = MCI_RDR
Number of words to read =
Number of words to read -1
RETURN
Note:
1. It is assumed that this command has been correctly sent (see Figure 35-9).
2. This field is also accessible in the MCI Block Register (MCI_BLKR).
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35.7.4
Write Operation
In write operation, the MCI Mode Register (MCI_MR) is used to define the padding value when
writing non-multiple block size. If the bit PDCPADV is 0, then 0x00 value is used when padding
data, otherwise 0xFF is used.
If set, the bit PDCMODE enables PDC transfer.
The following flowchart shows how to write a single block with or without use of PDC facilities
(see Figure 35-11). Polling or interrupt method can be used to wait for the end of write according
to the contents of the Interrupt Mask Register (MCI_IMR).
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Figure 35-11. Write Functional Flow Diagram
Send SELECT/DESELECT_CARD
command(1) to select the card
Send SET_BLOCKLEN command(1)
Yes
No
Write using PDC
Set the PDCMODE bit
MCI_MR |= PDCMODE
Set the block length (in bytes)
(2)
MCI_MR |= (BlockLength << 16)
Set the block count (if necessary)
MCI_BLKR |= (BlockCount << 0)
Reset the PDCMODE bit
MCI_MR &= ~PDCMODE
Set the block length (in bytes)
MCI_MR |= (BlockLenght <<16)(2)
Set the block count (if necessary)
MCI_BLKR |= (BlockCount << 0)
Configure the PDC channel
MCI_TPR = Data Buffer Address to write
MCI_TCR = BlockLength/4
Send WRITE_SINGLE_BLOCK
command(1)
Number of words to write = BlockLength/4
Send WRITE_SINGLE_BLOCK
command(1)
MCI_PTCR = TXTEN
Yes
Number of words to write = 0 ?
Read status register MCI_SR
No
Read status register MCI_SR
Poll the bit
NOTBUSY= 0?
Poll the bit
TXRDY = 0?
Yes
Yes
No
No
RETURN
MCI_TDR = Data to write
Number of words to write =
Number of words to write -1
RETURN
Notes:
1. It is assumed that this command has been correctly sent (see Figure 35-9).
2. This field is also accessible in the MCI Block Register (MCI_BLKR).
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The following flowchart shows how to manage a multiple write block transfer with the PDC (see
Figure 35-12). Polling or interrupt method can be used to wait for the end of write according to
the contents of the Interrupt Mask Register (MCI_IMR).
Figure 35-12. Multiple Write Functional Flow Diagram
Send SELECT/DESELECT_CARD
command(1) to select the card
Send SET_BLOCKLEN command
(1)
Set the PDCMODE bit
MCI_MR |= PDCMODE
Set the block length (in bytes)
MCI_MR |= (BlockLength << 16)(2)
Set the block count (if necessary)
MCI_BLKR |= (BlockCount << 0)
Configure the PDC channel
MCI_TPR = Data Buffer Address to write
MCI_TCR = BlockLength/4
Send WRITE_MULTIPLE_BLOCK
command(1)
MCI_PTCR = TXTEN
Read status register MCI_SR
Poll the bit
BLKE = 0?
Yes
No
Send STOP_TRANSMISSION
command(1)
Poll the bit
NOTBUSY = 0?
Yes
No
RETURN
Notes:
1. It is assumed that this command has been correctly sent (see Figure 35-9).
2. This field is also accessible in the MCI Block Register (MCI_BLKR).
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35.8
SD/SDIO Card Operations
The MultiMedia Card Interface allows processing of SD Memory (Secure Digital Memory Card)
and SDIO (SD Input Output) Card commands.
SD/SDIO cards are based on the Multi Media Card (MMC) format, but are physically slightly
thicker and feature higher data transfer rates, a lock switch on the side to prevent accidental
overwriting and security features. The physical form factor, pin assignment and data transfer
protocol are forward-compatible with the MultiMedia Card with some additions. SD slots can
actually be used for more than flash memory cards. Devices that support SDIO can use small
devices designed for the SD form factor, such as GPS receivers, Wi-Fi or Bluetooth adapters,
modems, barcode readers, IrDA adapters, FM radio tuners, RFID readers, digital cameras and
more.
SD/SDIO is covered by numerous patents and trademarks, and licensing is only available
through the Secure Digital Card Association.
The SD/SDIO Card communication is based on a 9-pin interface (Clock, Command, 4 x Data
and 3 x Power lines). The communication protocol is defined as a part of this specification. The
main difference between the SD/SDIO Card and the MultiMedia Card is the initialization
process.
The SD/SDIO Card Register (MCI_SDCR) allows selection of the Card Slot and the data bus
width.
The SD/SDIO Card bus allows dynamic configuration of the number of data lines. After power
up, by default, the SD/SDIO Card uses only DAT0 for data transfer. After initialization, the host
can change the bus width (number of active data lines).
35.8.1
SDIO Data Transfer Type
SDIO cards may transfer data in either a multi-byte (1 to 512 bytes) or an optional block format
(1 to 511 blocks), while the SD memory cards are fixed in the block transfer mode. The TRTYP
field in the MCI Command Register (MCI_CMDR) allows to choose between SDIO Byte or SDIO
Block transfer.
The number of bytes/blocks to transfer is set through the BCNT field in the MCI Block Register
(MCI_BLKR). In SDIO Block mode, the field BLKLEN must be set to the data block size while
this field is not used in SDIO Byte mode.
An SDIO Card can have multiple I/O or combined I/O and memory (called Combo Card). Within
a multi-function SDIO or a Combo card, there are multiple devices (I/O and memory) that share
access to the SD bus. In order to allow the sharing of access to the host among multiple devices,
SDIO and combo cards can implement the optional concept of suspend/resume (Refer to the
SDIO Specification for more details). To send a suspend or a resume command, the host must
set the SDIO Special Command field (IOSPCMD) in the MCI Command Register.
35.8.2
SDIO Interrupts
Each function within an SDIO or Combo card may implement interrupts (Refer to the SDIO
Specification for more details). In order to allow the SDIO card to interrupt the host, an interrupt
function is added to a pin on the DAT[1] line to signal the card’s interrupt to the host. An SDIO
interrupt on each slot can be enabled through the MCI Interrupt Enable Register. The SDIO
interrupt is sampled regardless of the currently selected slot.
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35.9
MultiMedia Card Interface (MCI) User Interface
Table 35-7.
Register Mapping
Offset
Access
Reset
Control Register
MCI_CR
Write-only
–
0x04
Mode Register
MCI_MR
Read-write
0x0
0x08
Data Timeout Register
MCI_DTOR
Read-write
0x0
0x0C
SD/SDIO Card Register
MCI_SDCR
Read-write
0x0
0x10
Argument Register
MCI_ARGR
Read-write
0x0
0x14
Command Register
MCI_CMDR
Write-only
–
0x18
Block Register
MCI_BLKR
Read-write
0x0
0x1C
Reserved
–
–
–
(1)
MCI_RSPR
Read-only
0x0
(1)
MCI_RSPR
Read-only
0x0
0x28
(1)
Response Register
MCI_RSPR
Read-only
0x0
0x2C
Response Register(1)
MCI_RSPR
Read-only
0x0
0x30
Receive Data Register
MCI_RDR
Read-only
0x0
0x34
Transmit Data Register
MCI_TDR
Write-only
–
–
–
–
0x24
0x38 - 0x3C
Response Register
Response Register
Reserved
0x40
Status Register
MCI_SR
Read-only
0xC0E5
0x44
Interrupt Enable Register
MCI_IER
Write-only
–
0x48
Interrupt Disable Register
MCI_IDR
Write-only
–
0x4C
Interrupt Mask Register
MCI_IMR
Read-only
0x0
Reserved
–
–
–
Reserved for the PDC
–
–
–
0x50-0xFC
0x100-0x124
604
Name
0x00
0x20
Note:
Register
1. The response register can be read by N accesses at the same MCI_RSPR or at consecutive addresses (0x20 to 0x2C).
N depends on the size of the response.
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AT91SAM9G20
35.9.1
Name:
MCI Control Register
MCI_CR
Access Type: Write-only
31
30
29
28
27
26
25
24
–
–
–
–
–
–
–
–
23
22
21
20
19
18
17
16
–
–
–
–
–
–
–
–
15
14
13
12
11
10
9
8
–
–
–
–
–
–
–
–
7
6
5
4
3
2
1
0
SWRST
–
–
–
PWSDIS
PWSEN
MCIDIS
MCIEN
• MCIEN: Multi-Media Interface Enable
0 = No effect.
1 = Enables the Multi-Media Interface if MCDIS is 0.
• MCIDIS: Multi-Media Interface Disable
0 = No effect.
1 = Disables the Multi-Media Interface.
• PWSEN: Power Save Mode Enable
0 = No effect.
1 = Enables the Power Saving Mode if PWSDIS is 0.
Warning: Before enabling this mode, the user must set a value different from 0 in the PWSDIV field (Mode Register
MCI_MR).
• PWSDIS: Power Save Mode Disable
0 = No effect.
1 = Disables the Power Saving Mode.
• SWRST: Software Reset
0 = No effect.
1 = Resets the MCI. A software triggered hardware reset of the MCI interface is performed.
605
6384E–ATARM–05-Feb-10
35.9.2
Name:
MCI Mode Register
MCI_MR
Access Type: Read-write
31
30
29
28
27
26
25
24
19
18
17
16
10
9
8
BLKLEN
23
22
21
20
BLKLEN
15
14
13
12
11
PDCMODE
PDCPADV
PDCFBYTE
WRPROOF
RDPROOF
7
6
5
4
3
PWSDIV
2
1
0
CLKDIV
• CLKDIV: Clock Divider
Multimedia Card Interface clock (MCCK or MCI_CK) is Master Clock (MCK) divided by (2*(CLKDIV+1)).
• PWSDIV: Power Saving Divider
Multimedia Card Interface clock is divided by 2(PWSDIV) + 1 when entering Power Saving Mode.
Warning: This value must be different from 0 before enabling the Power Save Mode in the MCI_CR (MCI_PWSEN bit).
• RDPROOF Read Proof Enable
Enabling Read Proof allows to stop the MCI Clock during read access if the internal FIFO is full. This will guarantee data
integrity, not bandwidth.
0 = Disables Read Proof.
1 = Enables Read Proof.
• WRPROOF Write Proof Enable
Enabling Write Proof allows to stop the MCI Clock during write access if the internal FIFO is full. This will guarantee data
integrity, not bandwidth.
0 = Disables Write Proof.
1 = Enables Write Proof.
• PDCFBYTE: PDC Force Byte Transfer
Enabling PDC Force Byte Transfer allows the PDC to manage with internal byte transfers, so that transfer of blocks with a
size different from modulo 4 can be supported.
Warning: BLKLEN value depends on PDCFBYTE.
0 = Disables PDC Force Byte Transfer. PDC type of transfer are in words.
1 = Enables PDC Force Byte Transfer. PDC type of transfer are in bytes.
• PDCPADV: PDC Padding Value
0 = 0x00 value is used when padding data in write transfer (not only PDC transfer).
1 = 0xFF value is used when padding data in write transfer (not only PDC transfer).
606
AT91SAM9G20
6384E–ATARM–05-Feb-10
AT91SAM9G20
• PDCMODE: PDC-oriented Mode
0 = Disables PDC transfer
1 = Enables PDC transfer. In this case, UNRE and OVRE flags in the MCI Mode Register (MCI_SR) are deactivated after
the PDC transfer has been completed.
• BLKLEN: Data Block Length
This field determines the size of the data block.
This field is also accessible in the MCI Block Register (MCI_BLKR).
Bits 16 and 17 must be set to 0 if PDCFBYTE is disabled.
Note:
In SDIO Byte mode, BLKLEN field is not used.
607
6384E–ATARM–05-Feb-10
35.9.3
Name:
MCI Data Timeout Register
MCI_DTOR
Access Type: Read-write
31
30
29
28
27
26
25
24
–
–
–
–
–
–
–
–
23
22
21
20
19
18
17
16
–
–
–
–
–
–
–
–
15
14
13
12
11
10
9
8
–
–
–
–
–
–
–
–
7
6
5
4
3
2
1
0
–
DTOMUL
DTOCYC
• DTOCYC: Data Timeout Cycle Number
• DTOMUL: Data Timeout Multiplier
These fields determine the maximum number of Master Clock cycles that the MCI waits between two data block transfers.
It equals (DTOCYC x Multiplier).
Multiplier is defined by DTOMUL as shown in the following table:
DTOMUL
Multiplier
0
0
0
1
0
0
1
16
0
1
0
128
0
1
1
256
1
0
0
1024
1
0
1
4096
1
1
0
65536
1
1
1
1048576
If the data time-out set by DTOCYC and DTOMUL has been exceeded, the Data Time-out Error flag (DTOE) in the MCI
Status Register (MCI_SR) raises.
608
AT91SAM9G20
6384E–ATARM–05-Feb-10
AT91SAM9G20
35.9.4
Name:
MCI SDCard/SDIO Register
MCI_SDCR
Access Type: Read-write
31
30
29
28
27
26
25
24
–
–
–
–
–
–
–
–
23
22
21
20
19
18
17
16
–
–
–
–
–
–
–
–
15
14
13
12
11
10
9
8
–
–
–
–
–
–
–
–
1
7
6
5
4
3
2
SDCBUS
–
–
–
–
–
0
SDCSEL
• SDCSEL: SDCard/SDIO Slot
SDCSEL
SDCard/SDIO Slot
0
0
Slot A is selected.
0
1
Slot B selected
1
0
Reserved
1
1
Reserved
• SDCBUS: SDCard/SDIO Bus Width
0 = 1-bit data bus
1 = 4-bit data bus
609
6384E–ATARM–05-Feb-10
35.9.5
Name:
MCI Argument Register
MCI_ARGR
Access Type: Read-write
31
30
29
28
27
26
25
24
19
18
17
16
11
10
9
8
3
2
1
0
ARG
23
22
21
20
ARG
15
14
13
12
ARG
7
6
5
4
ARG
• ARG: Command Argument
610
AT91SAM9G20
6384E–ATARM–05-Feb-10
AT91SAM9G20
35.9.6
Name:
MCI Command Register
MCI_CMDR
Access Type: Write-only
31
30
29
28
27
26
–
–
–
–
–
–
23
22
21
20
19
–
–
15
14
13
12
11
–
–
–
MAXLAT
OPDCMD
6
5
4
3
7
25
18
TRTYP
24
IOSPCMD
17
TRDIR
RSPTYP
16
TRCMD
10
9
8
SPCMD
2
1
0
CMDNB
This register is write-protected while CMDRDY is 0 in MCI_SR. If an Interrupt command is sent, this register is only writeable by an interrupt response (field SPCMD). This means that the current command execution cannot be interrupted or
modified.
• CMDNB: Command Number
• RSPTYP: Response Type
RSP
Response Type
0
0
No response.
0
1
48-bit response.
1
0
136-bit response.
1
1
Reserved.
• SPCMD: Special Command
SPCMD
Command
0
0
0
Not a special CMD.
0
0
1
Initialization CMD:
74 clock cycles for initialization sequence.
0
1
0
Synchronized CMD:
Wait for the end of the current data block transfer before sending the
pending command.
0
1
1
Reserved.
1
0
0
Interrupt command:
Corresponds to the Interrupt Mode (CMD40).
1
0
1
Interrupt response:
Corresponds to the Interrupt Mode (CMD40).
• OPDCMD: Open Drain Command
0 = Push pull command
1 = Open drain command
611
6384E–ATARM–05-Feb-10
• MAXLAT: Max Latency for Command to Response
0 = 5-cycle max latency
1 = 64-cycle max latency
• TRCMD: Transfer Command
TRCMD
Transfer Type
0
0
No data transfer
0
1
Start data transfer
1
0
Stop data transfer
1
1
Reserved
• TRDIR: Transfer Direction
0 = Write
1 = Read
• TRTYP: Transfer Type
TRTYP
Transfer Type
0
0
0
MMC/SDCard Single Block
0
0
1
MMC/SDCard Multiple Block
0
1
0
MMC Stream
0
1
1
Reserved
1
0
0
SDIO Byte
1
0
1
SDIO Block
1
1
0
Reserved
1
1
1
Reserved
• IOSPCMD: SDIO Special Command
IOSPCMD
612
SDIO Special Command Type
0
0
Not a SDIO Special Command
0
1
SDIO Suspend Command
1
0
SDIO Resume Command
1
1
Reserved
AT91SAM9G20
6384E–ATARM–05-Feb-10
AT91SAM9G20
35.9.7
Name:
MCI Block Register
MCI_BLKR
Access Type: Read-write
31
30
29
28
27
26
25
24
19
18
17
16
11
10
9
8
3
2
1
0
BLKLEN
23
22
21
20
BLKLEN
15
14
13
12
BCNT
7
6
5
4
BCNT
• BCNT: MMC/SDIO Block Count - SDIO Byte Count
This field determines the number of data byte(s) or block(s) to transfer.
The transfer data type and the authorized values for BCNT field are determined by the TRTYP field in the MCI Command
Register (MCI_CMDR):
TRTYP
Type of Transfer
BCNT Authorized Values
0
0
1
MMC/SDCard Multiple Block
From 1 to 65535: Value 0 corresponds to an infinite block transfer.
1
0
0
SDIO Byte
From 1 to 512 bytes: value 0 corresponds to a 512-byte transfer.
Values from 0x200 to 0xFFFF are forbidden.
1
0
1
SDIO Block
From 1 to 511 blocks: value 0 corresponds to an infinite block transfer.
Values from 0x200 to 0xFFFF are forbidden.
-
Reserved.
Other values
Warning: In SDIO Byte and Block modes, writing to the 7 last bits of BCNT field, is forbidden and may lead to unpredictable results.
• BLKLEN: Data Block Length
This field determines the size of the data block.
This field is also accessible in the MCI Mode Register (MCI_MR).
Bits 16 and 17 must be set to 0 if PDCFBYTE is disabled.
Note:
In SDIO Byte mode, BLKLEN field is not used.
613
6384E–ATARM–05-Feb-10
35.9.8
Name:
MCI Response Register
MCI_RSPR
Access Type: Read-only
31
30
29
28
27
26
25
24
19
18
17
16
11
10
9
8
3
2
1
0
RSP
23
22
21
20
RSP
15
14
13
12
RSP
7
6
5
4
RSP
• RSP: Response
Note:
614
1. The response register can be read by N accesses at the same MCI_RSPR or at consecutive addresses (0x20 to 0x2C).
N depends on the size of the response.
AT91SAM9G20
6384E–ATARM–05-Feb-10
AT91SAM9G20
35.9.9
Name:
MCI Receive Data Register
MCI_RDR
Access Type: Read-only
31
30
29
28
27
26
25
24
19
18
17
16
11
10
9
8
3
2
1
0
DATA
23
22
21
20
DATA
15
14
13
12
DATA
7
6
5
4
DATA
• DATA: Data to Read
615
6384E–ATARM–05-Feb-10
35.9.10
Name:
MCI Transmit Data Register
MCI_TDR
Access Type: Write-only
31
30
29
28
27
26
25
24
19
18
17
16
11
10
9
8
3
2
1
0
DATA
23
22
21
20
DATA
15
14
13
12
DATA
7
6
5
4
DATA
• DATA: Data to Write
616
AT91SAM9G20
6384E–ATARM–05-Feb-10
AT91SAM9G20
35.9.11
Name:
MCI Status Register
MCI_SR
Access Type: Read-only
31
30
29
28
27
26
25
24
UNRE
OVRE
–
–
–
–
–
–
23
22
21
20
19
18
17
16
–
DTOE
DCRCE
RTOE
RENDE
RCRCE
RDIRE
RINDE
15
14
13
12
11
10
9
8
TXBUFE
RXBUFF
–
–
-
-
SDIOIRQB
SDIOIRQA
7
6
5
4
3
2
1
0
ENDTX
ENDRX
NOTBUSY
DTIP
BLKE
TXRDY
RXRDY
CMDRDY
• CMDRDY: Command Ready
0 = A command is in progress.
1 = The last command has been sent. Cleared when writing in the MCI_CMDR.
• RXRDY: Receiver Ready
0 = Data has not yet been received since the last read of MCI_RDR.
1 = Data has been received since the last read of MCI_RDR.
• TXRDY: Transmit Ready
0= The last data written in MCI_TDR has not yet been transferred in the Shift Register.
1= The last data written in MCI_TDR has been transferred in the Shift Register.
• BLKE: Data Block Ended
This flag must be used only for Write Operations.
0 = A data block transfer is not yet finished. Cleared when reading the MCI_SR.
1 = A data block transfer has ended, including the CRC16 Status transmission.
In PDC mode (PDCMODE=1), the flag is set when the CRC Status of the last block has been transmitted (TXBUFE already
set).
Otherwise (PDCMODE=0), the flag is set for each transmitted CRC Status.
Refer to the MMC or SD Specification for more details concerning the CRC Status.
• DTIP: Data Transfer in Progress
0 = No data transfer in progress.
1 = The current data transfer is still in progress, including CRC16 calculation. Cleared at the end of the CRC16 calculation.
• NOTBUSY: MCI Not Busy
This flag must be used only for Write Operations.
A block write operation uses a simple busy signalling of the write operation duration on the data (DAT0) line: during a data
transfer block, if the card does not have a free data receive buffer, the card indicates this condition by pulling down the data
line (DAT0) to LOW. The card stops pulling down the data line as soon as at least one receive buffer for the defined data
transfer block length becomes free.
617
6384E–ATARM–05-Feb-10
The NOTBUSY flag allows to deal with these different states.
0 = The MCI is not ready for new data transfer. Cleared at the end of the card response.
1 = The MCI is ready for new data transfer. Set when the busy state on the data line has ended. This corresponds to a free
internal data receive buffer of the card.
Refer to the MMC or SD Specification for more details concerning the busy behavior.
• ENDRX: End of RX Buffer
0 = The Receive Counter Register has not reached 0 since the last write in MCI_RCR or MCI_RNCR.
1 = The Receive Counter Register has reached 0 since the last write in MCI_RCR or MCI_RNCR.
• ENDTX: End of TX Buffer
0 = The Transmit Counter Register has not reached 0 since the last write in MCI_TCR or MCI_TNCR.
1 = The Transmit Counter Register has reached 0 since the last write in MCI_TCR or MCI_TNCR.
Note:
BLKE and NOTBUSY flags can be used to check that the data has been successfully transmitted on the data lines and not only
transferred from the PDC to the MCI Controller.
• RXBUFF: RX Buffer Full
0 = MCI_RCR or MCI_RNCR has a value other than 0.
1 = Both MCI_RCR and MCI_RNCR have a value of 0.
• TXBUFE: TX Buffer Empty
0 = MCI_TCR or MCI_TNCR has a value other than 0.
1 = Both MCI_TCR and MCI_TNCR have a value of 0.
Note:
BLKE and NOTBUSY flags can be used to check that the data has been successfully transmitted on the data lines and not only
transferred from the PDC to the MCI Controller.
• RINDE: Response Index Error
0 = No error.
1 = A mismatch is detected between the command index sent and the response index received. Cleared when writing in
the MCI_CMDR.
• RDIRE: Response Direction Error
0 = No error.
1 = The direction bit from card to host in the response has not been detected.
• RCRCE: Response CRC Error
0 = No error.
1 = A CRC7 error has been detected in the response. Cleared when writing in the MCI_CMDR.
• RENDE: Response End Bit Error
0 = No error.
1 = The end bit of the response has not been detected. Cleared when writing in the MCI_CMDR.
618
AT91SAM9G20
6384E–ATARM–05-Feb-10
AT91SAM9G20
• RTOE: Response Time-out Error
0 = No error.
1 = The response time-out set by MAXLAT in the MCI_CMDR has been exceeded. Cleared when writing in the
MCI_CMDR.
• DCRCE: Data CRC Error
0 = No error.
1 = A CRC16 error has been detected in the last data block. Reset by reading in the MCI_SR register.
• DTOE: Data Time-out Error
0 = No error.
1 = The data time-out set by DTOCYC and DTOMUL in MCI_DTOR has been exceeded. Reset by reading in the MCI_SR
register.
• OVRE: Overrun
0 = No error.
1 = At least one 8-bit received data has been lost (not read). Cleared when sending a new data transfer command.
• UNRE: Underrun
0 = No error.
1 = At least one 8-bit data has been sent without valid information (not written). Cleared when sending a new data transfer
command.
• SDIOIRQA: SDIO Interrupt for Slot A
0 = No interrupt detected on SDIO Slot A.
1 = A SDIO Interrupt on Slot A has reached. Cleared when reading the MCI_SR.
• SDIOIRQB: SDIO Interrupt for Slot B
0 = No interrupt detected on SDIO Slot B.
1 = A SDIO Interrupt on Slot B has reached. Cleared when reading the MCI_SR.
• RXBUFF: RX Buffer Full
0 = MCI_RCR or MCI_RNCR has a value other than 0.
1 = Both MCI_RCR and MCI_RNCR have a value of 0.
• TXBUFE: TX Buffer Empty
0 = MCI_TCR or MCI_TNCR has a value other than 0.
1 = Both MCI_TCR and MCI_TNCR have a value of 0.
619
6384E–ATARM–05-Feb-10
35.9.12
Name:
MCI Interrupt Enable Register
MCI_IER
Access Type: Write-only
31
30
29
28
27
26
25
24
UNRE
OVRE
–
–
–
–
–
–
23
22
21
20
19
18
17
16
–
DTOE
DCRCE
RTOE
RENDE
RCRCE
RDIRE
RINDE
15
14
13
12
11
10
9
8
TXBUFE
RXBUFF
–
–
-
-
SDIOIRQB
SDIOIRQA
7
6
5
4
3
2
1
0
ENDTX
ENDRX
NOTBUSY
DTIP
BLKE
TXRDY
RXRDY
CMDRDY
• CMDRDY: Command Ready Interrupt Enable
• RXRDY: Receiver Ready Interrupt Enable
• TXRDY: Transmit Ready Interrupt Enable
• BLKE: Data Block Ended Interrupt Enable
• DTIP: Data Transfer in Progress Interrupt Enable
• NOTBUSY: Data Not Busy Interrupt Enable
• ENDRX: End of Receive Buffer Interrupt Enable
• ENDTX: End of Transmit Buffer Interrupt Enable
• SDIOIRQA: SDIO Interrupt for Slot A Interrupt Enable
• SDIOIRQB: SDIO Interrupt for Slot B Interrupt Enable
• RXBUFF: Receive Buffer Full Interrupt Enable
• TXBUFE: Transmit Buffer Empty Interrupt Enable
• RINDE: Response Index Error Interrupt Enable
• RDIRE: Response Direction Error Interrupt Enable
• RCRCE: Response CRC Error Interrupt Enable
• RENDE: Response End Bit Error Interrupt Enable
• RTOE: Response Time-out Error Interrupt Enable
• DCRCE: Data CRC Error Interrupt Enable
• DTOE: Data Time-out Error Interrupt Enable
• OVRE: Overrun Interrupt Enable
• UNRE: UnderRun Interrupt Enable
0 = No effect.
1 = Enables the corresponding interrupt.
620
AT91SAM9G20
6384E–ATARM–05-Feb-10
AT91SAM9G20
35.9.13
Name:
MCI Interrupt Disable Register
MCI_IDR
Access Type: Write-only
31
30
29
28
27
26
25
24
UNRE
OVRE
–
–
–
–
–
–
23
22
21
20
19
18
17
16
–
DTOE
DCRCE
RTOE
RENDE
RCRCE
RDIRE
RINDE
15
14
13
12
11
10
9
8
TXBUFE
RXBUFF
–
–
-
-
SDIOIRQB
SDIOIRQA
7
6
5
4
3
2
1
0
ENDTX
ENDRX
NOTBUSY
DTIP
BLKE
TXRDY
RXRDY
CMDRDY
• CMDRDY: Command Ready Interrupt Disable
• RXRDY: Receiver Ready Interrupt Disable
• TXRDY: Transmit Ready Interrupt Disable
• BLKE: Data Block Ended Interrupt Disable
• DTIP: Data Transfer in Progress Interrupt Disable
• NOTBUSY: Data Not Busy Interrupt Disable
• ENDRX: End of Receive Buffer Interrupt Disable
• ENDTX: End of Transmit Buffer Interrupt Disable
• SDIOIRQA: SDIO Interrupt for Slot A Interrupt Disable
• SDIOIRQB: SDIO Interrupt for Slot B Interrupt Disable
• RXBUFF: Receive Buffer Full Interrupt Disable
• TXBUFE: Transmit Buffer Empty Interrupt Disable
• RINDE: Response Index Error Interrupt Disable
• RDIRE: Response Direction Error Interrupt Disable
• RCRCE: Response CRC Error Interrupt Disable
• RENDE: Response End Bit Error Interrupt Disable
• RTOE: Response Time-out Error Interrupt Disable
• DCRCE: Data CRC Error Interrupt Disable
• DTOE: Data Time-out Error Interrupt Disable
• OVRE: Overrun Interrupt Disable
• UNRE: UnderRun Interrupt Disable
0 = No effect.
1 = Disables the corresponding interrupt.
621
6384E–ATARM–05-Feb-10
35.9.14
Name:
MCI Interrupt Mask Register
MCI_IMR
Access Type: Read-only
31
30
29
28
27
26
25
24
UNRE
OVRE
–
–
–
–
–
–
23
22
21
20
19
18
17
16
–
DTOE
DCRCE
RTOE
RENDE
RCRCE
RDIRE
RINDE
15
14
13
12
11
10
9
8
TXBUFE
RXBUFF
–
–
-
-
SDIOIRQB
SDIOIRQA
7
6
5
4
3
2
1
0
ENDTX
ENDRX
NOTBUSY
DTIP
BLKE
TXRDY
RXRDY
CMDRDY
• CMDRDY: Command Ready Interrupt Mask
• RXRDY: Receiver Ready Interrupt Mask
• TXRDY: Transmit Ready Interrupt Mask
• BLKE: Data Block Ended Interrupt Mask
• DTIP: Data Transfer in Progress Interrupt Mask
• NOTBUSY: Data Not Busy Interrupt Mask
• ENDRX: End of Receive Buffer Interrupt Mask
• ENDTX: End of Transmit Buffer Interrupt Mask
• SDIOIRQA: SDIO Interrupt for Slot A Interrupt Mask
• SDIOIRQB: SDIO Interrupt for Slot B Interrupt Mask
• RXBUFF: Receive Buffer Full Interrupt Mask
• TXBUFE: Transmit Buffer Empty Interrupt Mask
• RINDE: Response Index Error Interrupt Mask
• RDIRE: Response Direction Error Interrupt Mask
• RCRCE: Response CRC Error Interrupt Mask
• RENDE: Response End Bit Error Interrupt Mask
• RTOE: Response Time-out Error Interrupt Mask
• DCRCE: Data CRC Error Interrupt Mask
• DTOE: Data Time-out Error Interrupt Mask
• OVRE: Overrun Interrupt Mask
• UNRE: UnderRun Interrupt Mask
0 = The corresponding interrupt is not enabled.
1 = The corresponding interrupt is enabled.
622
AT91SAM9G20
6384E–ATARM–05-Feb-10
AT91SAM9G20
36. Ethernet MAC 10/100 (EMAC)
36.1
Overview
The EMAC module implements a 10/100 Ethernet MAC compatible with the IEEE 802.3 standard using an address checker, statistics and control registers, receive and transmit blocks, and
a DMA interface.
The address checker recognizes four specific 48-bit addresses and contains a 64-bit hash register for matching multicast and unicast addresses. It can recognize the broadcast address of all
ones, copy all frames, and act on an external address match signal.
The statistics register block contains registers for counting various types of event associated
with transmit and receive operations. These registers, along with the status words stored in the
receive buffer list, enable software to generate network management statistics compatible with
IEEE 802.3.
36.2
Block Diagram
Figure 36-1. EMAC Block Diagram
Address Checker
APB
Slave
Register Interface
Statistics Registers
MDIO
Control Registers
DMA Interface
RX FIFO
TX FIFO
Ethernet Receive
MII/RMII
AHB
Master
Ethernet Transmit
623
6384E–ATARM–05-Feb-10
36.3
Functional Description
The MACB has several clock domains:
•
System bus clock (AHB and APB): DMA and register blocks
•
Transmit clock: transmit block
•
Receive clock: receive and address checker blocks
The only system constraint is 160 MHz for the system bus clock, above which MDC would toggle
at above 2.5 MHz.
The system bus clock must run at least as fast as the receive clock and transmit clock (25 MHz
at 100 Mbps, and 2.5 MHZ at 10 Mbps).
Figure 36-1 illustrates the different blocks of the EMAC module.
The control registers drive the MDIO interface, setup up DMA activity, start frame transmission
and select modes of operation such as full- or half-duplex.
The receive block checks for valid preamble, FCS, alignment and length, and presents received
frames to the address checking block and DMA interface.
The transmit block takes data from the DMA interface, adds preamble and, if necessary, pad
and FCS, and transmits data according to the CSMA/CD (carrier sense multiple access with collision detect) protocol. The start of transmission is deferred if CRS (carrier sense) is active.
If COL (collision) becomes active during transmission, a jam sequence is asserted and the
transmission is retried after a random back off. CRS and COL have no effect in full duplex mode.
The DMA block connects to external memory through its AHB bus interface. It contains receive
and transmit FIFOs for buffering frame data. It loads the transmit FIFO and empties the receive
FIFO using AHB bus master operations. Receive data is not sent to memory until the address
checking logic has determined that the frame should be copied. Receive or transmit frames are
stored in one or more buffers. Receive buffers have a fixed length of 128 bytes. Transmit buffers
range in length between 0 and 2047 bytes, and up to 128 buffers are permitted per frame. The
DMA block manages the transmit and receive framebuffer queues. These queues can hold multiple frames.
36.3.1
Clock
Synchronization module in the EMAC requires that the bus clock (hclk) runs at the speed of the
macb_tx/rx_clk at least, which is 25 MHz at 100 Mbps, and 2.5 MHz at 10 Mbps.
36.3.2
Memory Interface
Frame data is transferred to and from the EMAC through the DMA interface. All transfers are 32bit words and may be single accesses or bursts of 2, 3 or 4 words. Burst accesses do not cross
sixteen-byte boundaries. Bursts of 4 words are the default data transfer; single accesses or
bursts of less than four words may be used to transfer data at the beginning or the end of a
buffer.
The DMA controller performs six types of operation on the bus. In order of priority, these are:
1. Receive buffer manager write
2. Receive buffer manager read
3. Transmit data DMA read
4. Receive data DMA write
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5. Transmit buffer manager read
6. Transmit buffer manager write
36.3.2.1
FIFO
The FIFO depths are 128 bytes for receive and 128 bytes for transmit and are a function of the
system clock speed, memory latency and network speed.
Data is typically transferred into and out of the FIFOs in bursts of four words. For receive, a bus
request is asserted when the FIFO contains four words and has space for 28 more. For transmit,
a bus request is generated when there is space for four words, or when there is space for 27
words if the next transfer is to be only one or two words.
Thus the bus latency must be less than the time it takes to load the FIFO and transmit or receive
three words (112 bytes) of data.
At 100 Mbit/s, it takes 8960 ns to transmit or receive 112 bytes of data. In addition, six master
clock cycles should be allowed for data to be loaded from the bus and to propagate through the
FIFOs. For a 133 MHz master clock this takes 45 ns, making the bus latency requirement 8915
ns.
36.3.2.2
Receive Buffers
Received frames, including CRC/FCS optionally, are written to receive buffers stored in memory. Each receive buffer is 128 bytes long. The start location for each receive buffer is stored in
memory in a list of receive buffer descriptors at a location pointed to by the receive buffer queue
pointer register. The receive buffer start location is a word address. For the first buffer of a
frame, the start location can be offset by up to three bytes depending on the value written to bits
14 and 15 of the network configuration register. If the start location of the buffer is offset the
available length of the first buffer of a frame is reduced by the corresponding number of bytes.
Each list entry consists of two words, the first being the address of the receive buffer and the
second being the receive status. If the length of a receive frame exceeds the buffer length, the
status word for the used buffer is written with zeroes except for the “start of frame” bit and the
offset bits, if appropriate. Bit zero of the address field is written to one to show the buffer has
been used. The receive buffer manager then reads the location of the next receive buffer and
fills that with receive frame data. The final buffer descriptor status word contains the complete
frame status. Refer to Table 36-1 for details of the receive buffer descriptor list.
Table 36-1.
Receive Buffer Descriptor Entry
Bit
Function
Word 0
31:2
Address of beginning of buffer
1
Wrap - marks last descriptor in receive buffer descriptor list.
0
Ownership - needs to be zero for the EMAC to write data to the receive buffer. The EMAC sets this to one once it has
successfully written a frame to memory.
Software has to clear this bit before the buffer can be used again.
Word 1
31
Global all ones broadcast address detected
30
Multicast hash match
29
Unicast hash match
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Table 36-1.
Receive Buffer Descriptor Entry (Continued)
Bit
Function
28
External address match
27
Reserved for future use
26
Specific address register 1 match
25
Specific address register 2 match
24
Specific address register 3 match
23
Specific address register 4 match
22
Type ID match
21
VLAN tag detected (i.e., type id of 0x8100)
20
Priority tag detected (i.e., type id of 0x8100 and null VLAN identifier)
19:17
VLAN priority (only valid if bit 21 is set)
16
Concatenation format indicator (CFI) bit (only valid if bit 21 is set)
15
End of frame - when set the buffer contains the end of a frame. If end of frame is not set, then the only other valid status
are bits 12, 13 and 14.
14
Start of frame - when set the buffer contains the start of a frame. If both bits 15 and 14 are set, then the buffer contains a
whole frame.
13:12
Receive buffer offset - indicates the number of bytes by which the data in the first buffer is offset from the word address.
Updated with the current values of the network configuration register. If jumbo frame mode is enabled through bit 3 of the
network configuration register, then bits 13:12 of the receive buffer descriptor entry are used to indicate bits 13:12 of the
frame length.
11:0
Length of frame including FCS (if selected). Bits 13:12 are also used if jumbo frame mode is selected.
To receive frames, the buffer descriptors must be initialized by writing an appropriate address to
bits 31 to 2 in the first word of each list entry. Bit zero must be written with zero. Bit one is the
wrap bit and indicates the last entry in the list.
The start location of the receive buffer descriptor list must be written to the receive buffer queue
pointer register before setting the receive enable bit in the network control register to enable
receive. As soon as the receive block starts writing received frame data to the receive FIFO, the
receive buffer manager reads the first receive buffer location pointed to by the receive buffer
queue pointer register.
If the filter block then indicates that the frame should be copied to memory, the receive data
DMA operation starts writing data into the receive buffer. If an error occurs, the buffer is recovered. If the current buffer pointer has its wrap bit set or is the 1024th descriptor, the next receive
buffer location is read from the beginning of the receive descriptor list. Otherwise, the next
receive buffer location is read from the next word in memory.
There is an 11-bit counter to count out the 2048 word locations of a maximum length, receive
buffer descriptor list. This is added with the value originally written to the receive buffer queue
pointer register to produce a pointer into the list. A read of the receive buffer queue pointer register returns the pointer value, which is the queue entry currently being accessed. The counter is
reset after receive status is written to a descriptor that has its wrap bit set or rolls over to zero
after 1024 descriptors have been accessed. The value written to the receive buffer pointer register may be any word-aligned address, provided that there are at least 2048 word locations
available between the pointer and the top of the memory.
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Section 3.6 of the AMBA 2.0 specification states that bursts should not cross 1K boundaries. As
receive buffer manager writes are bursts of two words, to ensure that this does not occur, it is
best to write the pointer register with the least three significant bits set to zero. As receive buffers
are used, the receive buffer manager sets bit zero of the first word of the descriptor to indicate
used. If a receive error is detected the receive buffer currently being written is recovered. Previous buffers are not recovered. Software should search through the used bits in the buffer
descriptors to find out how many frames have been received. It should be checking the start-offrame and end-of-frame bits, and not rely on the value returned by the receive buffer queue
pointer register which changes continuously as more buffers are used.
For CRC errored frames, excessive length frames or length field mismatched frames, all of
which are counted in the statistics registers, it is possible that a frame fragment might be stored
in a sequence of receive buffers. Software can detect this by looking for start of frame bit set in a
buffer following a buffer with no end of frame bit set.
For a properly working Ethernet system, there should be no excessively long frames or frames
greater than 128 bytes with CRC/FCS errors. Collision fragments are less than 128 bytes long.
Therefore, it is a rare occurrence to find a frame fragment in a receive buffer.
If bit zero is set when the receive buffer manager reads the location of the receive buffer, then
the buffer has already been used and cannot be used again until software has processed the
frame and cleared bit zero. In this case, the DMA block sets the buffer not available bit in the
receive status register and triggers an interrupt.
If bit zero is set when the receive buffer manager reads the location of the receive buffer and a
frame is being received, the frame is discarded and the receive resource error statistics register
is incremented.
A receive overrun condition occurs when bus was not granted in time or because HRESP was
not OK (bus error). In a receive overrun condition, the receive overrun interrupt is asserted and
the buffer currently being written is recovered. The next frame received with an address that is
recognized reuses the buffer.
If bit 17 of the network configuration register is set, the FCS of received frames shall not be copied to memory. The frame length indicated in the receive status field shall be reduced by four
bytes in this case.
36.3.2.3
Transmit Buffer
Frames to be transmitted are stored in one or more transmit buffers. Transmit buffers can be
between 0 and 2047 bytes long, so it is possible to transmit frames longer than the maximum
length specified in IEEE Standard 802.3. Zero length buffers are allowed. The maximum number
of buffers permitted for each transmit frame is 128.
The start location for each transmit buffer is stored in memory in a list of transmit buffer descriptors at a location pointed to by the transmit buffer queue pointer register. Each list entry consists
of two words, the first being the byte address of the transmit buffer and the second containing
the transmit control and status. Frames can be transmitted with or without automatic CRC generation. If CRC is automatically generated, pad is also automatically generated to take frames to
a minimum length of 64 bytes. Table 36-2 on page 628 defines an entry in the transmit buffer
descriptor list. To transmit frames, the buffer descriptors must be initialized by writing an appropriate byte address to bits 31 to 0 in the first word of each list entry. The second transmit buffer
descriptor is initialized with control information that indicates the length of the buffer, whether or
not it is to be transmitted with CRC and whether the buffer is the last buffer in the frame.
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After transmission, the control bits are written back to the second word of the first buffer along
with the “used” bit and other status information. Bit 31 is the “used” bit which must be zero when
the control word is read if transmission is to happen. It is written to one when a frame has been
transmitted. Bits 27, 28 and 29 indicate various transmit error conditions. Bit 30 is the “wrap” bit
which can be set for any buffer within a frame. If no wrap bit is encountered after 1024 descriptors, the queue pointer rolls over to the start in a similar fashion to the receive queue.
The transmit buffer queue pointer register must not be written while transmit is active. If a new
value is written to the transmit buffer queue pointer register, the queue pointer resets itself to
point to the beginning of the new queue. If transmit is disabled by writing to bit 3 of the network
control, the transmit buffer queue pointer register resets to point to the beginning of the transmit
queue. Note that disabling receive does not have the same effect on the receive queue pointer.
Once the transmit queue is initialized, transmit is activated by writing to bit 9, the Transmit Start
bit of the network control register. Transmit is halted when a buffer descriptor with its used bit set
is read, or if a transmit error occurs, or by writing to the transmit halt bit of the network control
register. (Transmission is suspended if a pause frame is received while the pause enable bit is
set in the network configuration register.) Rewriting the start bit while transmission is active is
allowed.
Transmission control is implemented with a Tx_go variable which is readable in the transmit status register at bit location 3. The Tx_go variable is reset when:
– transmit is disabled
– a buffer descriptor with its ownership bit set is read
– a new value is written to the transmit buffer queue pointer register
– bit 10, tx_halt, of the network control register is written
– there is a transmit error such as too many retries or a transmit underrun.
To set tx_go, write to bit 9, tx_start, of the network control register. Transmit halt does not take
effect until any ongoing transmit finishes. If a collision occurs during transmission of a multi-buffer frame, transmission automatically restarts from the first buffer of the frame. If a “used” bit is
read midway through transmission of a multi-buffer frame, this is treated as a transmit error.
Transmission stops, tx_er is asserted and the FCS is bad.
If transmission stops due to a transmit error, the transmit queue pointer resets to point to the
beginning of the transmit queue. Software needs to re-initialize the transmit queue after a transmit error.
If transmission stops due to a “used” bit being read at the start of the frame, the transmission
queue pointer is not reset and transmit starts from the same transmit buffer descriptor when the
transmit start bit is written
Table 36-2.
Transmit Buffer Descriptor Entry
Bit
Function
Word 0
31:0
Byte Address of buffer
Word 1
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Table 36-2.
Transmit Buffer Descriptor Entry (Continued)
Bit
Function
31
Used. Needs to be zero for the EMAC to read data from the transmit buffer. The EMAC sets this to one for the first buffer
of a frame once it has been successfully transmitted.
Software has to clear this bit before the buffer can be used again.
Note:
This bit is only set for the first buffer in a frame unlike receive where all buffers have the Used bit set once used.
30
Wrap. Marks last descriptor in transmit buffer descriptor list.
29
Retry limit exceeded, transmit error detected
28
Transmit underrun, occurs either when hresp is not OK (bus error) or the transmit data could not be fetched in time or
when buffers are exhausted in mid frame.
27
Buffers exhausted in mid frame
26:17
Reserved
16
No CRC. When set, no CRC is appended to the current frame. This bit only needs to be set for the last buffer of a frame.
15
Last buffer. When set, this bit indicates the last buffer in the current frame has been reached.
14:11
Reserved
10:0
Length of buffer
36.3.3
Transmit Block
This block transmits frames in accordance with the Ethernet IEEE 802.3 CSMA/CD protocol.
Frame assembly starts by adding preamble and the start frame delimiter. Data is taken from the
transmit FIFO a word at a time. Data is transmitted least significant nibble first. If necessary,
padding is added to increase the frame length to 60 bytes. CRC is calculated as a 32-bit polynomial. This is inverted and appended to the end of the frame, taking the frame length to a
minimum of 64 bytes. If the No CRC bit is set in the second word of the last buffer descriptor of a
transmit frame, neither pad nor CRC are appended.
In full-duplex mode, frames are transmitted immediately. Back-to-back frames are transmitted at
least 96 bit times apart to guarantee the interframe gap.
In half-duplex mode, the transmitter checks carrier sense. If asserted, it waits for it to de-assert
and then starts transmission after the interframe gap of 96 bit times. If the collision signal is
asserted during transmission, the transmitter transmits a jam sequence of 32 bits taken from the
data register and then retry transmission after the back off time has elapsed.
The back-off time is based on an XOR of the 10 least significant bits of the data coming from the
transmit FIFO and a 10-bit pseudo random number generator. The number of bits used depends
on the number of collisions seen. After the first collision, 1 bit is used, after the second 2, and so
on up to 10. Above 10, all 10 bits are used. An error is indicated and no further attempts are
made if 16 attempts cause collisions.
If transmit DMA underruns, bad CRC is automatically appended using the same mechanism as
jam insertion and the tx_er signal is asserted. For a properly configured system, this should
never happen.
If the back pressure bit is set in the network control register in half duplex mode, the transmit
block transmits 64 bits of data, which can consist of 16 nibbles of 1011 or in bit-rate mode 64 1s,
whenever it sees an incoming frame to force a collision. This provides a way of implementing
flow control in half-duplex mode.
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36.3.4
Pause Frame Support
The start of an 802.3 pause frame is as follows:
Table 36-3.
Start of an 802.3 Pause Frame
Destination Address
Source
Address
Type
(Mac Control Frame)
Pause
Opcode
Pause Time
0x0180C2000001
6 bytes
0x8808
0x0001
2 bytes
The network configuration register contains a receive pause enable bit (13). If a valid pause
frame is received, the pause time register is updated with the frame’s pause time, regardless of
its current contents and regardless of the state of the configuration register bit 13. An interrupt
(12) is triggered when a pause frame is received, assuming it is enabled in the interrupt mask
register. If bit 13 is set in the network configuration register and the value of the pause time register is non-zero, no new frame is transmitted until the pause time register has decremented to
zero.
The loading of a new pause time, and hence the pausing of transmission, only occurs when the
EMAC is configured for full-duplex operation. If the EMAC is configured for half-duplex, there is
no transmission pause, but the pause frame received interrupt is still triggered.
A valid pause frame is defined as having a destination address that matches either the address
stored in specific address register 1 or matches 0x0180C2000001 and has the MAC control
frame type ID of 0x8808 and the pause opcode of 0x0001. Pause frames that have FCS or other
errors are treated as invalid and are discarded. Valid pause frames received increment the
Pause Frame Received statistic register.
The pause time register decrements every 512 bit times (i.e., 128 rx_clks in nibble mode)
once transmission has stopped. For test purposes, the register decrements every rx_clk cycle
once transmission has stopped if bit 12 (retry test) is set in the network configuration register. If
the pause enable bit (13) is not set in the network configuration register, then the decrementing
occurs regardless of whether transmission has stopped or not.
An interrupt (13) is asserted whenever the pause time register decrements to zero (assuming it
is enabled in the interrupt mask register).
36.3.5
Receive Block
The receive block checks for valid preamble, FCS, alignment and length, presents received
frames to the DMA block and stores the frames destination address for use by the address
checking block. If, during frame reception, the frame is found to be too long or rx_er is asserted,
a bad frame indication is sent to the DMA block. The DMA block then ceases sending data to
memory. At the end of frame reception, the receive block indicates to the DMA block whether the
frame is good or bad. The DMA block recovers the current receive buffer if the frame was bad.
The receive block signals the register block to increment the alignment error, the CRC (FCS)
error, the short frame, long frame, jabber error, the receive symbol error statistics and the length
field mismatch statistics.
The enable bit for jumbo frames in the network configuration register allows the EMAC to receive
jumbo frames of up to 10240 bytes in size. This operation does not form part of the IEEE802.3
specification and is disabled by default. When jumbo frames are enabled, frames received with a
frame size greater than 10240 bytes are discarded.
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36.3.6
Address Checking Block
The address checking (or filter) block indicates to the DMA block which receive frames should
be copied to memory. Whether a frame is copied depends on what is enabled in the network
configuration register, the state of the external match pin, the contents of the specific address
and hash registers and the frame’s destination address. In this implementation of the EMAC, the
frame’s source address is not checked. Provided that bit 18 of the Network Configuration register is not set, a frame is not copied to memory if the EMAC is transmitting in half duplex mode at
the time a destination address is received. If bit 18 of the Network Configuration register is set,
frames can be received while transmitting in half-duplex mode.
Ethernet frames are transmitted a byte at a time, least significant bit first. The first six bytes (48
bits) of an Ethernet frame make up the destination address. The first bit of the destination
address, the LSB of the first byte of the frame, is the group/individual bit: this is One for multicast
addresses and Zero for unicast. The All Ones address is the broadcast address, and a special
case of multicast.
The EMAC supports recognition of four specific addresses. Each specific address requires two
registers, specific address register bottom and specific address register top. Specific address
register bottom stores the first four bytes of the destination address and specific address register
top contains the last two bytes. The addresses stored can be specific, group, local or universal.
The destination address of received frames is compared against the data stored in the specific
address registers once they have been activated. The addresses are deactivated at reset or
when their corresponding specific address register bottom is written. They are activated when
specific address register top is written. If a receive frame address matches an active address,
the frame is copied to memory.
The following example illustrates the use of the address match registers for a MAC address of
21:43:65:87:A9:CB.
Preamble 55
SFD D5
DA (Octet0 - LSB) 21
DA(Octet 1) 43
DA(Octet 2) 65
DA(Octet 3) 87
DA(Octet 4) A9
DA (Octet5 - MSB) CB
SA (LSB) 00
SA 00
SA 00
SA 00
SA 00
SA (MSB) 43
SA (LSB) 21
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The sequence above shows the beginning of an Ethernet frame. Byte order of transmission is
from top to bottom as shown. For a successful match to specific address 1, the following
address matching registers must be set up:
• Base address + 0x98 0x87654321 (Bottom)
• Base address + 0x9C 0x0000CBA9 (Top)
And for a successful match to the Type ID register, the following should be set up:
• Base address + 0xB8 0x00004321
36.3.7
Broadcast Address
The broadcast address of 0xFFFFFFFFFFFF is recognized if the ‘no broadcast’ bit in the network configuration register is zero.
36.3.8
Hash Addressing
The hash address register is 64 bits long and takes up two locations in the memory map. The
least significant bits are stored in hash register bottom and the most significant bits in hash register top.
The unicast hash enable and the multicast hash enable bits in the network configuration register
enable the reception of hash matched frames. The destination address is reduced to a 6-bit
index into the 64-bit hash register using the following hash function. The hash function is an
exclusive or of every sixth bit of the destination address.
hash_index[5] = da[5] ^ da[11] ^ da[17] ^ da[23] ^ da[29] ^ da[35] ^ da[41] ^ da[47]
hash_index[4] = da[4] ^ da[10] ^ da[16] ^ da[22] ^ da[28] ^ da[34] ^ da[40] ^ da[46]
hash_index[3] = da[3] ^ da[09] ^ da[15] ^ da[21] ^ da[27] ^ da[33] ^ da[39] ^ da[45]
hash_index[2] = da[2] ^ da[08] ^ da[14] ^ da[20] ^ da[26] ^ da[32] ^ da[38] ^ da[44]
hash_index[1] = da[1] ^ da[07] ^ da[13] ^ da[19] ^ da[25] ^ da[31] ^ da[37] ^ da[43]
hash_index[0] = da[0] ^ da[06] ^ da[12] ^ da[18] ^ da[24] ^ da[30] ^ da[36] ^ da[42]
da[0] represents the least significant bit of the first byte received, that is, the multicast/unicast
indicator, and da[47] represents the most significant bit of the last byte received.
If the hash index points to a bit that is set in the hash register, then the frame is matched according to whether the frame is multicast or unicast.
A multicast match is signalled if the multicast hash enable bit is set. da[0] is 1 and the hash index
points to a bit set in the hash register.
A unicast match is signalled if the unicast hash enable bit is set. da[0] is 0 and the hash index
points to a bit set in the hash register.
To receive all multicast frames, the hash register should be set with all ones and the multicast
hash enable bit should be set in the network configuration register.
36.3.9
632
Copy All Frames (or Promiscuous Mode)
If the copy all frames bit is set in the network configuration register, then all non-errored frames
are copied to memory. For example, frames that are too long, too short, or have FCS errors or
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rx_er asserted during reception are discarded and all others are received. Frames with FCS
errors are copied to memory if bit 19 in the network configuration register is set.
36.3.10
Type ID Checking
The contents of the type_id register are compared against the length/type ID of received frames
(i.e., bytes 13 and 14). Bit 22 in the receive buffer descriptor status is set if there is a match. The
reset state of this register is zero which is unlikely to match the length/type ID of any valid Ethernet frame.
Note:
36.3.11
A type ID match does not affect whether a frame is copied to memory.
VLAN Support
An Ethernet encoded 802.1Q VLAN tag looks like this:
Table 36-4.
802.1Q VLAN Tag
TPID (Tag Protocol Identifier) 16 bits
TCI (Tag Control Information) 16 bits
0x8100
First 3 bits priority, then CFI bit, last 12 bits VID
The VLAN tag is inserted at the 13th byte of the frame, adding an extra four bytes to the frame. If
the VID (VLAN identifier) is null (0x000), this indicates a priority-tagged frame. The MAC can
support frame lengths up to 1536 bytes, 18 bytes more than the original Ethernet maximum
frame length of 1518 bytes. This is achieved by setting bit 8 in the network configuration register.
The following bits in the receive buffer descriptor status word give information about VLAN
tagged frames:
• Bit 21 set if receive frame is VLAN tagged (i.e. type id of 0x8100)
• Bit 20 set if receive frame is priority tagged (i.e. type id of 0x8100 and null VID). (If bit 20 is
set bit 21 is set also.)
• Bit 19, 18 and 17 set to priority if bit 21 is set
• Bit 16 set to CFI if bit 21 is set
36.3.12
PHY Maintenance
The register EMAC_MAN enables the EMAC to communicate with a PHY by means of the MDIO
interface. It is used during auto-negotiation to ensure that the EMAC and the PHY are configured for the same speed and duplex configuration.
The PHY maintenance register is implemented as a shift register. Writing to the register starts a
shift operation which is signalled as complete when bit two is set in the network status register
(about 2000 MCK cycles later when bit ten is set to zero, and bit eleven is set to one in the network configuration register). An interrupt is generated as this bit is set. During this time, the MSB
of the register is output on the MDIO pin and the LSB updated from the MDIO pin with each
MDC cycle. This causes transmission of a PHY management frame on MDIO.
Reading during the shift operation returns the current contents of the shift register. At the end of
management operation, the bits have shifted back to their original locations. For a read operation, the data bits are updated with data read from the PHY. It is important to write the correct
values to the register to ensure a valid PHY management frame is produced.
The MDIO interface can read IEEE 802.3 clause 45 PHYs as well as clause 22 PHYs. To read
clause 45 PHYs, bits[31:28] should be written as 0x0011. For a description of MDC generation,
see the network configuration register in the “Network Control Register” on page 640.
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36.3.13
Media Independent Interface
The Ethernet MAC is capable of interfacing to both RMII and MII Interfaces. The RMII bit in the
EMAC_USRIO register controls the interface that is selected. When this bit is set, the RMII interface is selected, else the MII interface is selected.
The MII and RMII interface are capable of both 10Mb/s and 100Mb/s data rates as described in
the IEEE 802.3u standard. The signals used by the MII and RMII interfaces are described in
Table 36-5.
Table 36-5.
Pin Configuration
Pin Name
ETXCK_EREFCK
MII
RMII
ETXCK: Transmit Clock
EREFCK: Reference Clock
ECRS
ECRS: Carrier Sense
ECOL
ECOL: Collision Detect
ERXDV
ERXDV: Data Valid
ECRSDV: Carrier Sense/Data Valid
ERX0 - ERX3: 4-bit Receive Data
ERX0 - ERX1: 2-bit Receive Data
ERXER
ERXER: Receive Error
ERXER: Receive Error
ERXCK
ERXCK: Receive Clock
ETXEN
ETXEN: Transmit Enable
ETXEN: Transmit Enable
ETX0 - ETX3: 4-bit Transmit Data
ETX0 - ETX1: 2-bit Transmit Data
ERX0 - ERX3
ETX0-ETX3
ETXER
ETXER: Transmit Error
The intent of the RMII is to provide a reduced pin count alternative to the IEEE 802.3u MII. It
uses 2 bits for transmit (ETX0 and ETX1) and two bits for receive (ERX0 and ERX1). There is a
Transmit Enable (ETXEN), a Receive Error (ERXER), a Carrier Sense (ECRS_DV), and a 50
MHz Reference Clock (ETXCK_EREFCK) for 100Mb/s data rate.
36.3.13.1
634
RMII Transmit and Receive Operation
The same signals are used internally for both the RMII and the MII operations. The RMII maps
these signals in a more pin-efficient manner. The transmit and receive bits are converted from a
4-bit parallel format to a 2-bit parallel scheme that is clocked at twice the rate. The carrier sense
and data valid signals are combined into the ECRSDV signal. This signal contains information
on carrier sense, FIFO status, and validity of the data. Transmit error bit (ETXER) and collision
detect (ECOL) are not used in RMII mode.
AT91SAM9G20
6384E–ATARM–05-Feb-10
AT91SAM9G20
36.4
Programming Interface
36.4.1
36.4.1.1
Initialization
Configuration
Initialization of the EMAC configuration (e.g., loop-back mode, frequency ratios) must be done
while the transmit and receive circuits are disabled. See the description of the network control
register and network configuration register earlier in this document.
To change loop-back mode, the following sequence of operations must be followed:
1. Write to network control register to disable transmit and receive circuits.
2. Write to network control register to change loop-back mode.
3. Write to network control register to re-enable transmit or receive circuits.
Note:
36.4.1.2
These writes to network control register cannot be combined in any way.
Receive Buffer List
Receive data is written to areas of data (i.e., buffers) in system memory. These buffers are listed
in another data structure that also resides in main memory. This data structure (receive buffer
queue) is a sequence of descriptor entries as defined in “Receive Buffer Descriptor Entry” on
page 625. It points to this data structure.
Figure 36-2. Receive Buffer List
Receive Buffer 0
Receive Buffer Queue Pointer
(MAC Register)
Receive Buffer 1
Receive Buffer N
Receive Buffer Descriptor List
(In memory)
(In memory)
To create the list of buffers:
1. Allocate a number (n) of buffers of 128 bytes in system memory.
2. Allocate an area 2n words for the receive buffer descriptor entry in system memory and
create n entries in this list. Mark all entries in this list as owned by EMAC, i.e., bit 0 of
word 0 set to 0.
3. If less than 1024 buffers are defined, the last descriptor must be marked with the wrap
bit (bit 1 in word 0 set to 1).
4. Write address of receive buffer descriptor entry to EMAC register receive_buffer
queue pointer.
5. The receive circuits can then be enabled by writing to the address recognition registers
and then to the network control register.
635
6384E–ATARM–05-Feb-10
36.4.1.3
Transmit Buffer List
Transmit data is read from areas of data (the buffers) in system memory These buffers are listed
in another data structure that also resides in main memory. This data structure (Transmit Buffer
Queue) is a sequence of descriptor entries (as defined in Table 36-2 on page 628) that points to
this data structure.
To create this list of buffers:
1. Allocate a number (n) of buffers of between 1 and 2047 bytes of data to be transmitted
in system memory. Up to 128 buffers per frame are allowed.
2. Allocate an area 2n words for the transmit buffer descriptor entry in system memory
and create N entries in this list. Mark all entries in this list as owned by EMAC, i.e. bit 31
of word 1 set to 0.
3. If fewer than 1024 buffers are defined, the last descriptor must be marked with the wrap
bit — bit 30 in word 1 set to 1.
4. Write address of transmit buffer descriptor entry to EMAC register transmit_buffer
queue pointer.
5. The transmit circuits can then be enabled by writing to the network control register.
36.4.1.4
Address Matching
The EMAC register-pair hash address and the four specific address register-pairs must be written with the required values. Each register-pair comprises a bottom register and top register,
with the bottom register being written first. The address matching is disabled for a particular register-pair after the bottom-register has been written and re-enabled when the top register is
written. See “Address Checking Block” on page 631. for details of address matching. Each register-pair may be written at any time, regardless of whether the receive circuits are enabled or
disabled.
36.4.1.5
Interrupts
There are 14 interrupt conditions that are detected within the EMAC. These are ORed to make a
single interrupt. Depending on the overall system design, this may be passed through a further
level of interrupt collection (interrupt controller). On receipt of the interrupt signal, the CPU
enters the interrupt handler (Refer to the AIC programmer datasheet). To ascertain which interrupt has been generated, read the interrupt status register. Note that this register clears itself
when read. At reset, all interrupts are disabled. To enable an interrupt, write to interrupt enable
register with the pertinent interrupt bit set to 1. To disable an interrupt, write to interrupt disable
register with the pertinent interrupt bit set to 1. To check whether an interrupt is enabled or disabled, read interrupt mask register: if the bit is set to 1, the interrupt is disabled.
36.4.1.6
Transmitting Frames
To set up a frame for transmission:
1. Enable transmit in the network control register.
2. Allocate an area of system memory for transmit data. This does not have to be contiguous, varying byte lengths can be used as long as they conclude on byte borders.
3. Set-up the transmit buffer list.
4. Set the network control register to enable transmission and enable interrupts.
5. Write data for transmission into these buffers.
6. Write the address to transmit buffer descriptor queue pointer.
7. Write control and length to word one of the transmit buffer descriptor entry.
636
AT91SAM9G20
6384E–ATARM–05-Feb-10
AT91SAM9G20
8. Write to the transmit start bit in the network control register.
36.4.1.7
Receiving Frames
When a frame is received and the receive circuits are enabled, the EMAC checks the address
and, in the following cases, the frame is written to system memory:
• if it matches one of the four specific address registers.
• if it matches the hash address function.
• if it is a broadcast address (0xFFFFFFFFFFFF) and broadcasts are allowed.
• if the EMAC is configured to copy all frames.
The register receive buffer queue pointer points to the next entry (see Table 36-1 on page 625)
and the EMAC uses this as the address in system memory to write the frame to. Once the frame
has been completely and successfully received and written to system memory, the EMAC then
updates the receive buffer descriptor entry with the reason for the address match and marks the
area as being owned by software. Once this is complete an interrupt receive complete is set.
Software is then responsible for handling the data in the buffer and then releasing the buffer by
writing the ownership bit back to 0.
If the EMAC is unable to write the data at a rate to match the incoming frame, then an interrupt
receive overrun is set. If there is no receive buffer available, i.e., the next buffer is still owned by
software, the interrupt receive buffer not available is set. If the frame is not successfully
received, a statistic register is incremented and the frame is discarded without informing
software.
637
6384E–ATARM–05-Feb-10
36.5
Ethernet MAC 10/100 (EMAC) User Interface
Table 36-6.
Register Mapping
Offset
Register
Name
Access
Reset
0x00
Network Control Register
EMAC_NCR
Read-write
0
0x04
Network Configuration Register
EMAC_NCFG
Read-write
0x800
0x08
Network Status Register
EMAC_NSR
Read-only
-
0x0C
Reserved
0x10
Reserved
0x14
Transmit Status Register
EMAC_TSR
Read-write
0x0000_0000
0x18
Receive Buffer Queue Pointer Register
EMAC_RBQP
Read-write
0x0000_0000
0x1C
Transmit Buffer Queue Pointer Register
EMAC_TBQP
Read-write
0x0000_0000
0x20
Receive Status Register
EMAC_RSR
Read-write
0x0000_0000
0x24
Interrupt Status Register
EMAC_ISR
Read-write
0x0000_0000
0x28
Interrupt Enable Register
EMAC_IER
Write-only
-
0x2C
Interrupt Disable Register
EMAC_IDR
Write-only
-
0x30
Interrupt Mask Register
EMAC_IMR
Read-only
0x0000_3FFF
0x34
Phy Maintenance Register
EMAC_MAN
Read-write
0x0000_0000
0x38
Pause Time Register
EMAC_PTR
Read-write
0x0000_0000
0x3C
Pause Frames Received Register
EMAC_PFR
Read-write
0x0000_0000
0x40
Frames Transmitted Ok Register
EMAC_FTO
Read-write
0x0000_0000
0x44
Single Collision Frames Register
EMAC_SCF
Read-write
0x0000_0000
0x48
Multiple Collision Frames Register
EMAC_MCF
Read-write
0x0000_0000
0x4C
Frames Received Ok Register
EMAC_FRO
Read-write
0x0000_0000
0x50
Frame Check Sequence Errors Register
EMAC_FCSE
Read-write
0x0000_0000
0x54
Alignment Errors Register
EMAC_ALE
Read-write
0x0000_0000
0x58
Deferred Transmission Frames Register
EMAC_DTF
Read-write
0x0000_0000
0x5C
Late Collisions Register
EMAC_LCOL
Read-write
0x0000_0000
0x60
Excessive Collisions Register
EMAC_ECOL
Read-write
0x0000_0000
0x64
Transmit Underrun Errors Register
EMAC_TUND
Read-write
0x0000_0000
0x68
Carrier Sense Errors Register
EMAC_CSE
Read-write
0x0000_0000
0x6C
Receive Resource Errors Register
EMAC_RRE
Read-write
0x0000_0000
0x70
Receive Overrun Errors Register
EMAC_ROV
Read-write
0x0000_0000
0x74
Receive Symbol Errors Register
EMAC_RSE
Read-write
0x0000_0000
0x78
Excessive Length Errors Register
EMAC_ELE
Read-write
0x0000_0000
0x7C
Receive Jabbers Register
EMAC_RJA
Read-write
0x0000_0000
0x80
Undersize Frames Register
EMAC_USF
Read-write
0x0000_0000
0x84
SQE Test Errors Register
EMAC_STE
Read-write
0x0000_0000
0x88
Received Length Field Mismatch Register
EMAC_RLE
Read-write
0x0000_0000
638
AT91SAM9G20
6384E–ATARM–05-Feb-10
AT91SAM9G20
Table 36-6.
Register Mapping (Continued)
Offset
Register
Name
Access
Reset
0x90
Hash Register Bottom [31:0] Register
EMAC_HRB
Read-write
0x0000_0000
0x94
Hash Register Top [63:32] Register
EMAC_HRT
Read-write
0x0000_0000
0x98
Specific Address 1 Bottom Register
EMAC_SA1B
Read-write
0x0000_0000
0x9C
Specific Address 1 Top Register
EMAC_SA1T
Read-write
0x0000_0000
0xA0
Specific Address 2 Bottom Register
EMAC_SA2B
Read-write
0x0000_0000
0xA4
Specific Address 2 Top Register
EMAC_SA2T
Read-write
0x0000_0000
0xA8
Specific Address 3 Bottom Register
EMAC_SA3B
Read-write
0x0000_0000
0xAC
Specific Address 3 Top Register
EMAC_SA3T
Read-write
0x0000_0000
0xB0
Specific Address 4 Bottom Register
EMAC_SA4B
Read-write
0x0000_0000
0xB4
Specific Address 4 Top Register
EMAC_SA4T
Read-write
0x0000_0000
0xB8
Type ID Checking Register
EMAC_TID
Read-write
0x0000_0000
0xC0
User Input/Output Register
EMAC_USRIO
Read-write
0x0000_0000
0xC8 - 0xFC
Reserved
–
–
–
639
6384E–ATARM–05-Feb-10
36.5.1
Network Control Register
Register Name:
EMAC_NCR
Access Type:
Read-write
31
–
30
–
29
–
28
–
27
–
26
–
25
–
24
–
23
–
22
–
21
–
20
–
19
–
18
–
17
–
16
–
15
–
14
–
13
–
12
–
11
–
10
THALT
9
TSTART
8
BP
7
WESTAT
6
INCSTAT
5
CLRSTAT
4
MPE
3
TE
2
RE
1
LLB
0
LB
• LB: LoopBack
Asserts the loopback signal to the PHY.
• LLB: Loopback local
Connects txd to rxd, tx_en to rx_dv, forces full duplex and drives rx_clk and tx_clk with pclk divided by 4.
rx_clk and tx_clk may glitch as the EMAC is switched into and out of internal loop back. It is important that receive
and transmit circuits have already been disabled when making the switch into and out of internal loop back.
• RE: Receive enable
When set, enables the EMAC to receive data. When reset, frame reception stops immediately and the receive FIFO is
cleared. The receive queue pointer register is unaffected.
• TE: Transmit enable
When set, enables the Ethernet transmitter to send data. When reset transmission, stops immediately, the transmit FIFO
and control registers are cleared and the transmit queue pointer register resets to point to the start of the transmit descriptor list.
• MPE: Management port enable
Set to one to enable the management port. When zero, forces MDIO to high impedance state and MDC low.
• CLRSTAT: Clear statistics registers
This bit is write only. Writing a one clears the statistics registers.
• INCSTAT: Increment statistics registers
This bit is write only. Writing a one increments all the statistics registers by one for test purposes.
• WESTAT: Write enable for statistics registers
Setting this bit to one makes the statistics registers writable for functional test purposes.
• BP: Back pressure
If set in half duplex mode, forces collisions on all received frames.
640
AT91SAM9G20
6384E–ATARM–05-Feb-10
AT91SAM9G20
• TSTART: Start transmission
Writing one to this bit starts transmission.
• THALT: Transmit halt
Writing one to this bit halts transmission as soon as any ongoing frame transmission ends.
641
6384E–ATARM–05-Feb-10
36.5.2
Network Configuration Register
Register Name:
EMAC_NCFG
Access Type:
Read-write
31
–
30
–
29
–
28
–
27
–
26
–
25
–
24
–
23
–
22
–
21
–
20
–
19
IRXFCS
18
EFRHD
17
DRFCS
16
RLCE
15
14
13
PAE
12
RTY
11
10
9
–
8
BIG
5
NBC
4
CAF
3
JFRAME
2
–
1
FD
0
SPD
RBOF
7
UNI
6
MTI
CLK
• SPD: Speed
Set to 1 to indicate 100 Mbit/s operation, 0 for 10 Mbit/s. The value of this pin is reflected on the speed pin.
• FD: Full Duplex
If set to 1, the transmit block ignores the state of collision and carrier sense and allows receive while transmitting. Also controls the half_duplex pin.
• CAF: Copy All Frames
When set to 1, all valid frames are received.
• JFRAME: Jumbo Frames
Set to one to enable jumbo frames of up to 10240 bytes to be accepted.
• NBC: No Broadcast
When set to 1, frames addressed to the broadcast address of all ones are not received.
• MTI: Multicast Hash Enable
When set, multicast frames are received when the 6-bit hash function of the destination address points to a bit that is set in
the hash register.
• UNI: Unicast Hash Enable
When set, unicast frames are received when the 6-bit hash function of the destination address points to a bit that is set in
the hash register.
• BIG: Receive 1536 bytes frames
Setting this bit means the EMAC receives frames up to 1536 bytes in length. Normally, the EMAC would reject any frame
above 1518 bytes.
• CLK: MDC clock divider
642
AT91SAM9G20
6384E–ATARM–05-Feb-10
AT91SAM9G20
Set according to system clock speed. This determines by what number system clock is divided to generate MDC. For conformance with 802.3, MDC must not exceed 2.5MHz (MDC is only active during MDIO read and write operations).
CLK
MDC
00
MCK divided by 8 (MCK up to 20 MHz)
01
MCK divided by 16 (MCK up to 40 MHz)
10
MCK divided by 32 (MCK up to 80 MHz)
11
MCK divided by 64 (MCK up to 160 MHz)
• RTY: Retry test
Must be set to zero for normal operation. If set to one, the back off between collisions is always one slot time. Setting this
bit to one helps testing the too many retries condition. Also used in the pause frame tests to reduce the pause counters
decrement time from 512 bit times, to every rx_clk cycle.
• PAE: Pause Enable
When set, transmission pauses when a valid pause frame is received.
• RBOF: Receive Buffer Offset
Indicates the number of bytes by which the received data is offset from the start of the first receive buffer.
RBOF
Offset
00
No offset from start of receive buffer
01
One-byte offset from start of receive buffer
10
Two-byte offset from start of receive buffer
11
Three-byte offset from start of receive buffer
• RLCE: Receive Length field Checking Enable
When set, frames with measured lengths shorter than their length fields are discarded. Frames containing a type ID in
bytes 13 and 14 — length/type ID = 0600 — are not be counted as length errors.
• DRFCS: Discard Receive FCS
When set, the FCS field of received frames are not be copied to memory.
• EFRHD:
Enable Frames to be received in half-duplex mode while transmitting.
• IRXFCS: Ignore RX FCS
When set, frames with FCS/CRC errors are not rejected and no FCS error statistics are counted. For normal operation, this
bit must be set to 0.
643
6384E–ATARM–05-Feb-10
36.5.3
Network Status Register
Register Name:
EMAC_NSR
Access Type:
Read-only
31
–
30
–
29
–
28
–
27
–
26
–
25
–
24
–
23
–
22
–
21
–
20
–
19
–
18
–
17
–
16
–
15
–
14
–
13
–
12
–
11
–
10
–
9
–
8
–
7
–
6
–
5
–
4
–
3
–
2
IDLE
1
MDIO
0
–
• MDIO
Returns status of the mdio_in pin. Use the PHY maintenance register for reading managed frames rather than this bit.
• IDLE
0 = The PHY logic is running.
1 = The PHY management logic is idle (i.e., has completed).
644
AT91SAM9G20
6384E–ATARM–05-Feb-10
AT91SAM9G20
36.5.4
Transmit Status Register
Register Name:
EMAC_TSR
Access Type:
Read-write
31
–
30
–
29
–
28
–
27
–
26
–
25
–
24
–
23
–
22
–
21
–
20
–
19
–
18
–
17
–
16
–
15
–
14
–
13
–
12
–
11
–
10
–
9
–
8
–
7
–
6
UND
5
COMP
4
BEX
3
TGO
2
RLE
1
COL
0
UBR
This register, when read, provides details of the status of a transmit. Once read, individual bits may be cleared by writing 1
to them. It is not possible to set a bit to 1 by writing to the register.
• UBR: Used Bit Read
Set when a transmit buffer descriptor is read with its used bit set. Cleared by writing a one to this bit.
• COL: Collision Occurred
Set by the assertion of collision. Cleared by writing a one to this bit.
• RLE: Retry Limit exceeded
Cleared by writing a one to this bit.
• TGO: Transmit Go
If high transmit is active.
• BEX: Buffers exhausted mid frame
If the buffers run out during transmission of a frame, then transmission stops, FCS shall be bad and tx_er asserted. Cleared
by writing a one to this bit.
• COMP: Transmit Complete
Set when a frame has been transmitted. Cleared by writing a one to this bit.
• UND: Transmit Underrun
Set when transmit DMA was not able to read data from memory, either because the bus was not granted in time, because
a not OK hresp(bus error) was returned or because a used bit was read midway through frame transmission. If this
occurs, the transmitter forces bad CRC. Cleared by writing a one to this bit.
645
6384E–ATARM–05-Feb-10
36.5.5
Receive Buffer Queue Pointer Register
Register Name:
EMAC_RBQP
Access Type:
31
Read-write
30
29
28
27
26
25
24
19
18
17
16
11
10
9
8
3
2
1
–
0
–
ADDR
23
22
21
20
ADDR
15
14
13
12
ADDR
7
6
5
4
ADDR
This register points to the entry in the receive buffer queue (descriptor list) currently being used. It is written with the start
location of the receive buffer descriptor list. The lower order bits increment as buffers are used up and wrap to their original
values after either 1024 buffers or when the wrap bit of the entry is set.
Reading this register returns the location of the descriptor currently being accessed. This value increments as buffers are
used. Software should not use this register for determining where to remove received frames from the queue as it constantly changes as new frames are received. Software should instead work its way through the buffer descriptor queue
checking the used bits.
Receive buffer writes also comprise bursts of two words and, as with transmit buffer reads, it is recommended that bit 2 is
always written with zero to prevent a burst crossing a 1K boundary, in violation of section 3.6 of the AMBA specification.
• ADDR: Receive buffer queue pointer address
Written with the address of the start of the receive queue, reads as a pointer to the current buffer being used.
646
AT91SAM9G20
6384E–ATARM–05-Feb-10
AT91SAM9G20
36.5.6
Transmit Buffer Queue Pointer Register
Register Name:
EMAC_TBQP
Access Type:
31
Read-write
30
29
28
27
26
25
24
19
18
17
16
11
10
9
8
3
2
1
–
0
–
ADDR
23
22
21
20
ADDR
15
14
13
12
ADDR
7
6
5
4
ADDR
This register points to the entry in the transmit buffer queue (descriptor list) currently being used. It is written with the start
location of the transmit buffer descriptor list. The lower order bits increment as buffers are used up and wrap to their original
values after either 1024 buffers or when the wrap bit of the entry is set. This register can only be written when bit 3 in the
transmit status register is low.
As transmit buffer reads consist of bursts of two words, it is recommended that bit 2 is always written with zero to prevent a
burst crossing a 1K boundary, in violation of section 3.6 of the AMBA specification.
• ADDR: Transmit buffer queue pointer address
Written with the address of the start of the transmit queue, reads as a pointer to the first buffer of the frame being transmitted or about to be transmitted.
647
6384E–ATARM–05-Feb-10
36.5.7
Receive Status Register
Register Name:
EMAC_RSR
Access Type:
Read-write
31
–
30
–
29
–
28
–
27
–
26
–
25
–
24
–
23
–
22
–
21
–
20
–
19
–
18
–
17
–
16
–
15
–
14
–
13
–
12
–
11
–
10
–
9
–
8
–
7
–
6
–
5
–
4
–
3
–
2
OVR
1
REC
0
BNA
This register, when read, provides details of the status of a receive. Once read, individual bits may be cleared by writing 1
to them. It is not possible to set a bit to 1 by writing to the register.
• BNA: Buffer Not Available
An attempt was made to get a new buffer and the pointer indicated that it was owned by the processor. The DMA rereads
the pointer each time a new frame starts until a valid pointer is found. This bit is set at each attempt that fails even if it has
not had a successful pointer read since it has been cleared.
Cleared by writing a one to this bit.
• REC: Frame Received
One or more frames have been received and placed in memory. Cleared by writing a one to this bit.
• OVR: Receive Overrun
The DMA block was unable to store the receive frame to memory, either because the bus was not granted in time or
because a not OK hresp(bus error) was returned. The buffer is recovered if this happens.
Cleared by writing a one to this bit.
648
AT91SAM9G20
6384E–ATARM–05-Feb-10
AT91SAM9G20
36.5.8
Interrupt Status Register
Register Name:
EMAC_ISR
Access Type:
Read-write
31
–
30
–
29
–
28
–
27
–
26
–
25
–
24
–
23
–
22
–
21
–
20
–
19
–
18
–
17
–
16
–
15
–
14
–
13
PTZ
12
PFR
11
HRESP
10
ROVR
9
–
8
–
7
TCOMP
6
TXERR
5
RLE
4
TUND
3
TXUBR
2
RXUBR
1
RCOMP
0
MFD
• MFD: Management Frame Done
The PHY maintenance register has completed its operation. Cleared on read.
• RCOMP: Receive Complete
A frame has been stored in memory. Cleared on read.
• RXUBR: Receive Used Bit Read
Set when a receive buffer descriptor is read with its used bit set. Cleared on read.
• TXUBR: Transmit Used Bit Read
Set when a transmit buffer descriptor is read with its used bit set. Cleared on read.
• TUND: Ethernet Transmit Buffer Underrun
The transmit DMA did not fetch frame data in time for it to be transmitted or hresp returned not OK. Also set if a used bit
is read mid-frame or when a new transmit queue pointer is written. Cleared on read.
• RLE: Retry Limit Exceeded
Cleared on read.
• TXERR: Transmit Error
Transmit buffers exhausted in mid-frame - transmit error. Cleared on read.
• TCOMP: Transmit Complete
Set when a frame has been transmitted. Cleared on read.
• ROVR: Receive Overrun
Set when the receive overrun status bit gets set. Cleared on read.
• HRESP: Hresp not OK
Set when the DMA block sees a bus error. Cleared on read.
• PFR: Pause Frame Received
Indicates a valid pause has been received. Cleared on a read.
• PTZ: Pause Time Zero
Set when the pause time register, 0x38 decrements to zero. Cleared on a read.
649
6384E–ATARM–05-Feb-10
36.5.9
Interrupt Enable Register
Register Name:
EMAC_IER
Access Type:
Write-only
31
–
30
–
29
–
28
–
27
–
26
–
25
–
24
–
23
–
22
–
21
–
20
–
19
–
18
–
17
–
16
–
15
–
14
–
13
PTZ
12
PFR
11
HRESP
10
ROVR
9
–
8
–
7
TCOMP
6
TXERR
5
RLE
4
TUND
3
TXUBR
2
RXUBR
1
RCOMP
0
MFD
• MFD: Management Frame sent
Enable management done interrupt.
• RCOMP: Receive Complete
Enable receive complete interrupt.
• RXUBR: Receive Used Bit Read
Enable receive used bit read interrupt.
• TXUBR: Transmit Used Bit Read
Enable transmit used bit read interrupt.
• TUND: Ethernet Transmit Buffer Underrun
Enable transmit underrun interrupt.
• RLE: Retry Limit Exceeded
Enable retry limit exceeded interrupt.
• TXERR
Enable transmit buffers exhausted in mid-frame interrupt.
• TCOMP: Transmit Complete
Enable transmit complete interrupt.
• ROVR: Receive Overrun
Enable receive overrun interrupt.
• HRESP: Hresp not OK
Enable Hresp not OK interrupt.
• PFR: Pause Frame Received
Enable pause frame received interrupt.
• PTZ: Pause Time Zero
Enable pause time zero interrupt.
650
AT91SAM9G20
6384E–ATARM–05-Feb-10
AT91SAM9G20
36.5.10 Interrupt Disable Register
Register Name:
EMAC_IDR
Access Type:
Write-only
31
–
30
–
29
–
28
–
27
–
26
–
25
–
24
–
23
–
22
–
21
–
20
–
19
–
18
–
17
–
16
–
15
–
14
–
13
PTZ
12
PFR
11
HRESP
10
ROVR
9
–
8
–
7
TCOMP
6
TXERR
5
RLE
4
TUND
3
TXUBR
2
RXUBR
1
RCOMP
0
MFD
• MFD: Management Frame sent
Disable management done interrupt.
• RCOMP: Receive Complete
Disable receive complete interrupt.
• RXUBR: Receive Used Bit Read
Disable receive used bit read interrupt.
• TXUBR: Transmit Used Bit Read
Disable transmit used bit read interrupt.
• TUND: Ethernet Transmit Buffer Underrun
Disable transmit underrun interrupt.
• RLE: Retry Limit Exceeded
Disable retry limit exceeded interrupt.
• TXERR
Disable transmit buffers exhausted in mid-frame interrupt.
• TCOMP: Transmit Complete
Disable transmit complete interrupt.
• ROVR: Receive Overrun
Disable receive overrun interrupt.
• HRESP: Hresp not OK
Disable Hresp not OK interrupt.
• PFR: Pause Frame Received
Disable pause frame received interrupt.
• PTZ: Pause Time Zero
Disable pause time zero interrupt.
651
6384E–ATARM–05-Feb-10
36.5.11 Interrupt Mask Register
Register Name:
EMAC_IMR
Access Type:
Read-only
31
–
30
–
29
–
28
–
27
–
26
–
25
–
24
–
23
–
22
–
21
–
20
–
19
–
18
–
17
–
16
–
15
–
14
–
13
PTZ
12
PFR
11
HRESP
10
ROVR
9
–
8
–
7
TCOMP
6
TXERR
5
RLE
4
TUND
3
TXUBR
2
RXUBR
1
RCOMP
0
MFD
• MFD: Management Frame sent
Management done interrupt masked.
• RCOMP: Receive Complete
Receive complete interrupt masked.
• RXUBR: Receive Used Bit Read
Receive used bit read interrupt masked.
• TXUBR: Transmit Used Bit Read
Transmit used bit read interrupt masked.
• TUND: Ethernet Transmit Buffer Underrun
Transmit underrun interrupt masked.
• RLE: Retry Limit Exceeded
Retry limit exceeded interrupt masked.
• TXERR
Transmit buffers exhausted in mid-frame interrupt masked.
• TCOMP: Transmit Complete
Transmit complete interrupt masked.
• ROVR: Receive Overrun
Receive overrun interrupt masked.
• HRESP: Hresp not OK
Hresp not OK interrupt masked.
• PFR: Pause Frame Received
Pause frame received interrupt masked.
• PTZ: Pause Time Zero
Pause time zero interrupt masked.
652
AT91SAM9G20
6384E–ATARM–05-Feb-10
AT91SAM9G20
36.5.12 PHY Maintenance Register
Register Name:
EMAC_MAN
Access Type:
31
Read-write
30
29
SOF
28
27
26
RW
23
PHYA
22
15
14
21
13
25
24
17
16
PHYA
20
REGA
19
18
12
11
10
9
8
3
2
1
0
CODE
DATA
7
6
5
4
DATA
• DATA
For a write operation this is written with the data to be written to the PHY.
After a read operation this contains the data read from the PHY.
• CODE:
Must be written to 10. Reads as written.
• REGA: Register Address
Specifies the register in the PHY to access.
• PHYA: PHY Address
• RW: Read-write
10 is read; 01 is write. Any other value is an invalid PHY management frame
• SOF: Start of frame
Must be written 01 for a valid frame.
653
6384E–ATARM–05-Feb-10
36.5.13 Pause Time Register
Register Name:
EMAC_PTR
Access Type:
Read-write
31
–
30
–
29
–
28
–
27
–
26
–
25
–
24
–
23
–
22
–
21
–
20
–
19
–
18
–
17
–
16
–
15
14
13
12
11
10
9
8
3
2
1
0
PTIME
7
6
5
4
PTIME
• PTIME: Pause Time
Stores the current value of the pause time register which is decremented every 512 bit times.
654
AT91SAM9G20
6384E–ATARM–05-Feb-10
AT91SAM9G20
36.5.14 Hash Register Bottom
Register Name:
EMAC_HRB
Access Type:
31
Read-write
30
29
28
27
26
25
24
19
18
17
16
11
10
9
8
3
2
1
0
27
26
25
24
19
18
17
16
11
10
9
8
3
2
1
0
ADDR
23
22
21
20
ADDR
15
14
13
12
ADDR
7
6
5
4
ADDR
• ADDR:
Bits 31:0 of the hash address register. See “Hash Addressing” on page 632.
36.5.15 Hash Register Top
Register Name:
EMAC_HRT
Access Type:
31
Read-write
30
29
28
ADDR
23
22
21
20
ADDR
15
14
13
12
ADDR
7
6
5
4
ADDR
• ADDR:
Bits 63:32 of the hash address register. See “Hash Addressing” on page 632.
655
6384E–ATARM–05-Feb-10
36.5.16 Specific Address 1 Bottom Register
Register Name:
EMAC_SA1B
Access Type:
31
Read-write
30
29
28
27
26
25
24
19
18
17
16
11
10
9
8
3
2
1
0
ADDR
23
22
21
20
ADDR
15
14
13
12
ADDR
7
6
5
4
ADDR
• ADDR
Least significant bits of the destination address. Bit zero indicates whether the address is multicast or unicast and corresponds to the least significant bit of the first byte received.
36.5.17 Specific Address 1 Top Register
Register Name:
EMAC_SA1T
Access Type:
Read-write
31
–
30
–
29
–
28
–
27
–
26
–
25
–
24
–
23
–
22
–
21
–
20
–
19
–
18
–
17
–
16
–
15
14
13
12
11
10
9
8
3
2
1
0
ADDR
7
6
5
4
ADDR
• ADDR
The most significant bits of the destination address, that is bits 47 to 32.
656
AT91SAM9G20
6384E–ATARM–05-Feb-10
AT91SAM9G20
36.5.18 Specific Address 2 Bottom Register
Register Name:
EMAC_SA2B
Access Type:
31
Read-write
30
29
28
27
26
25
24
19
18
17
16
11
10
9
8
3
2
1
0
ADDR
23
22
21
20
ADDR
15
14
13
12
ADDR
7
6
5
4
ADDR
• ADDR
Least significant bits of the destination address. Bit zero indicates whether the address is multicast or unicast and corresponds to the least significant bit of the first byte received.
36.5.19 Specific Address 2 Top Register
Register Name:
EMAC_SA2T
Access Type:
Read-write
31
–
30
–
29
–
28
–
27
–
26
–
25
–
24
–
23
–
22
–
21
–
20
–
19
–
18
–
17
–
16
–
15
14
13
12
11
10
9
8
3
2
1
0
ADDR
7
6
5
4
ADDR
• ADDR
The most significant bits of the destination address, that is bits 47 to 32.
657
6384E–ATARM–05-Feb-10
36.5.20 Specific Address 3 Bottom Register
Register Name:
EMAC_SA3B
Access Type:
31
Read-write
30
29
28
27
26
25
24
19
18
17
16
11
10
9
8
3
2
1
0
ADDR
23
22
21
20
ADDR
15
14
13
12
ADDR
7
6
5
4
ADDR
• ADDR
Least significant bits of the destination address. Bit zero indicates whether the address is multicast or unicast and corresponds to the least significant bit of the first byte received.
36.5.21 Specific Address 3 Top Register
Register Name:
EMAC_SA3T
Access Type:
Read-write
31
–
30
–
29
–
28
–
27
–
26
–
25
–
24
–
23
–
22
–
21
–
20
–
19
–
18
–
17
–
16
–
15
14
13
12
11
10
9
8
3
2
1
0
ADDR
7
6
5
4
ADDR
• ADDR
The most significant bits of the destination address, that is bits 47 to 32.
658
AT91SAM9G20
6384E–ATARM–05-Feb-10
AT91SAM9G20
36.5.22 Specific Address 4 Bottom Register
Register Name:
EMAC_SA4B
Access Type:
31
Read-write
30
29
28
27
26
25
24
19
18
17
16
11
10
9
8
3
2
1
0
ADDR
23
22
21
20
ADDR
15
14
13
12
ADDR
7
6
5
4
ADDR
• ADDR
Least significant bits of the destination address. Bit zero indicates whether the address is multicast or unicast and corresponds to the least significant bit of the first byte received.
36.5.23 Specific Address 4 Top Register
Register Name:
EMAC_SA4T
Access Type:
Read-write
31
–
30
–
29
–
28
–
27
–
26
–
25
–
24
–
23
–
22
–
21
–
20
–
19
–
18
–
17
–
16
–
15
14
13
12
11
10
9
8
3
2
1
0
ADDR
7
6
5
4
ADDR
• ADDR
The most significant bits of the destination address, that is bits 47 to 32.
659
6384E–ATARM–05-Feb-10
36.5.24 Type ID Checking Register
Register Name:
EMAC_TID
Access Type:
Read-write
31
–
30
–
29
–
28
–
27
–
26
–
25
–
24
–
23
–
22
–
21
–
20
–
19
–
18
–
17
–
16
–
15
14
13
12
11
10
9
8
3
2
1
0
TID
7
6
5
4
TID
• TID: Type ID checking
For use in comparisons with received frames TypeID/Length field.
36.5.25 User Input/Output Register
Register Name:
EMAC_USRIO
Access Type:
Read-write
31
–
30
–
29
–
28
–
27
–
26
–
25
–
24
–
23
–
22
–
21
–
20
–
19
–
18
–
17
–
16
–
15
–
14
–
13
–
12
–
11
–
10
–
9
–
8
–
7
–
6
–
5
–
4
–
3
–
2
–
1
CLKEN
0
RMII
• RMII
When set, this bit enables the RMII operation mode. When reset, it selects the MII mode.
• CLKEN
When set, this bit enables the transceiver input clock.
Setting this bit to 0 reduces power consumption when the treasurer is not used.
660
AT91SAM9G20
6384E–ATARM–05-Feb-10
AT91SAM9G20
36.5.26 EMAC Statistic Registers
These registers reset to zero on a read and stick at all ones when they count to their maximum value. They should be read
frequently enough to prevent loss of data. The receive statistics registers are only incremented when the receive enable bit
is set in the network control register. To write to these registers, bit 7 must be set in the network control register. The statistics register block contains the following registers.
36.5.26.1
Pause Frames Received Register
Register Name:
EMAC_PFR
Access Type:
Read-write
31
–
30
–
29
–
28
–
27
–
26
–
25
–
24
–
23
–
22
–
21
–
20
–
19
–
18
–
17
–
16
–
15
14
13
12
11
10
9
8
3
2
1
0
FROK
7
6
5
4
FROK
• FROK: Pause Frames received OK
A 16-bit register counting the number of good pause frames received. A good frame has a length of 64 to 1518 (1536 if bit
8 set in network configuration register) and has no FCS, alignment or receive symbol errors.
36.5.26.2
Frames Transmitted OK Register
Register Name:
EMAC_FTO
Access Type:
Read-write
31
–
30
–
29
–
28
–
23
22
21
20
27
–
26
–
25
–
24
–
19
18
17
16
11
10
9
8
3
2
1
0
FTOK
15
14
13
12
FTOK
7
6
5
4
FTOK
• FTOK: Frames Transmitted OK
A 24-bit register counting the number of frames successfully transmitted, i.e., no underrun and not too many retries.
661
6384E–ATARM–05-Feb-10
36.5.26.3
Single Collision Frames Register
Register Name:
EMAC_SCF
Access Type:
Read-write
31
–
30
–
29
–
28
–
27
–
26
–
25
–
24
–
23
–
22
–
21
–
20
–
19
–
18
–
17
–
16
–
15
14
13
12
11
10
9
8
3
2
1
0
SCF
7
6
5
4
SCF
• SCF: Single Collision Frames
A 16-bit register counting the number of frames experiencing a single collision before being successfully transmitted, i.e.,
no underrun.
36.5.26.4
Multicollision Frames Register
Register Name:
EMAC_MCF
Access Type:
Read-write
31
–
30
–
29
–
28
–
27
–
26
–
25
–
24
–
23
–
22
–
21
–
20
–
19
–
18
–
17
–
16
–
15
14
13
12
11
10
9
8
3
2
1
0
MCF
7
6
5
4
MCF
• MCF: Multicollision Frames
A 16-bit register counting the number of frames experiencing between two and fifteen collisions prior to being successfully
transmitted, i.e., no underrun and not too many retries.
662
AT91SAM9G20
6384E–ATARM–05-Feb-10
AT91SAM9G20
36.5.26.5
Frames Received OK Register
Register Name:
EMAC_FRO
Access Type:
Read-write
31
–
30
–
29
–
28
–
27
–
26
–
25
–
24
–
23
22
21
20
19
18
17
16
11
10
9
8
3
2
1
0
FROK
15
14
13
12
FROK
7
6
5
4
FROK
• FROK: Frames Received OK
A 24-bit register counting the number of good frames received, i.e., address recognized and successfully copied to memory. A good frame is of length 64 to 1518 bytes (1536 if bit 8 set in network configuration register) and has no FCS,
alignment or receive symbol errors.
36.5.26.6
Frames Check Sequence Errors Register
Register Name:
EMAC_FCSE
Access Type:
Read-write
31
–
30
–
29
–
28
–
27
–
26
–
25
–
24
–
23
–
22
–
21
–
20
–
19
–
18
–
17
–
16
–
15
–
14
–
13
–
12
–
11
–
10
–
9
–
8
–
7
6
5
4
3
2
1
0
FCSE
• FCSE: Frame Check Sequence Errors
An 8-bit register counting frames that are an integral number of bytes, have bad CRC and are between 64 and 1518 bytes
in length (1536 if bit 8 set in network configuration register). This register is also incremented if a symbol error is detected
and the frame is of valid length and has an integral number of bytes.
663
6384E–ATARM–05-Feb-10
36.5.26.7
Alignment Errors Register
Register Name:
EMAC_ALE
Access Type:
Read-write
31
–
30
–
29
–
28
–
27
–
26
–
25
–
24
–
23
–
22
–
21
–
20
–
19
–
18
–
17
–
16
–
15
–
14
–
13
–
12
–
11
–
10
–
9
–
8
–
7
6
5
4
3
2
1
0
ALE
• ALE: Alignment Errors
An 8-bit register counting frames that are not an integral number of bytes long and have bad CRC when their length is truncated to an integral number of bytes and are between 64 and 1518 bytes in length (1536 if bit 8 set in network configuration
register). This register is also incremented if a symbol error is detected and the frame is of valid length and does not have
an integral number of bytes.
36.5.26.8
Deferred Transmission Frames Register
Register Name:
EMAC_DTF
Access Type:
Read-write
31
–
30
–
29
–
28
–
27
–
26
–
25
–
24
–
23
–
22
–
21
–
20
–
19
–
18
–
17
–
16
–
15
14
13
12
11
10
9
8
3
2
1
0
DTF
7
6
5
4
DTF
• DTF: Deferred Transmission Frames
A 16-bit register counting the number of frames experiencing deferral due to carrier sense being active on their first attempt
at transmission. Frames involved in any collision are not counted nor are frames that experienced a transmit underrun.
664
AT91SAM9G20
6384E–ATARM–05-Feb-10
AT91SAM9G20
36.5.26.9
Late Collisions Register
Register Name:
EMAC_LCOL
Access Type:
Read-write
31
–
30
–
29
–
28
–
27
–
26
–
25
–
24
–
23
–
22
–
21
–
20
–
19
–
18
–
17
–
16
–
15
–
14
–
13
–
12
–
11
–
10
–
9
–
8
–
7
6
5
4
3
2
1
0
LCOL
• LCOL: Late Collisions
An 8-bit register counting the number of frames that experience a collision after the slot time (512 bits) has expired. A late
collision is counted twice; i.e., both as a collision and a late collision.
36.5.26.10 Excessive Collisions Register
Register Name:
EMAC_ECOL
Access Type:
Read-write
31
–
30
–
29
–
28
–
27
–
26
–
25
–
24
–
23
–
22
–
21
–
20
–
19
–
18
–
17
–
16
–
15
–
14
–
13
–
12
–
11
–
10
–
9
–
8
–
7
6
5
4
3
2
1
0
EXCOL
• EXCOL: Excessive Collisions
An 8-bit register counting the number of frames that failed to be transmitted because they experienced 16 collisions.
665
6384E–ATARM–05-Feb-10
36.5.26.11 Transmit Underrun Errors Register
Register Name:
EMAC_TUND
Access Type:
Read-write
31
–
30
–
29
–
28
–
27
–
26
–
25
–
24
–
23
–
22
–
21
–
20
–
19
–
18
–
17
–
16
–
15
–
14
–
13
–
12
–
11
–
10
–
9
–
8
–
7
6
5
4
3
2
1
0
TUND
• TUND: Transmit Underruns
An 8-bit register counting the number of frames not transmitted due to a transmit DMA underrun. If this register is incremented, then no other statistics register is incremented.
36.5.26.12 Carrier Sense Errors Register
Register Name:
EMAC_CSE
Access Type:
Read-write
31
–
30
–
29
–
28
–
27
–
26
–
25
–
24
–
23
–
22
–
21
–
20
–
19
–
18
–
17
–
16
–
15
–
14
–
13
–
12
–
11
–
10
–
9
–
8
–
7
6
5
4
3
2
1
0
CSE
• CSE: Carrier Sense Errors
An 8-bit register counting the number of frames transmitted where carrier sense was not seen during transmission or where
carrier sense was deasserted after being asserted in a transmit frame without collision (no underrun). Only incremented in
half-duplex mode. The only effect of a carrier sense error is to increment this register. The behavior of the other statistics
registers is unaffected by the detection of a carrier sense error.
666
AT91SAM9G20
6384E–ATARM–05-Feb-10
AT91SAM9G20
36.5.26.13 Receive Resource Errors Register
Register Name:
EMAC_RRE
Access Type:
Read-write
31
–
30
–
29
–
28
–
27
–
26
–
25
–
24
–
23
–
22
–
21
–
20
–
19
–
18
–
17
–
16
–
15
14
13
12
11
10
9
8
3
2
1
0
RRE
7
6
5
4
RRE
• RRE: Receive Resource Errors
A 16-bit register counting the number of frames that were address matched but could not be copied to memory because no
receive buffer was available.
36.5.26.14 Receive Overrun Errors Register
Register Name:
EMAC_ROV
Access Type:
Read-write
31
–
30
–
29
–
28
–
27
–
26
–
25
–
24
–
23
–
22
–
21
–
20
–
19
–
18
–
17
–
16
–
15
–
14
–
13
–
12
–
11
–
10
–
9
–
8
–
7
6
5
4
3
2
1
0
ROVR
• ROVR: Receive Overrun
An 8-bit register counting the number of frames that are address recognized but were not copied to memory due to a
receive DMA overrun.
667
6384E–ATARM–05-Feb-10
36.5.26.15 Receive Symbol Errors Register
Register Name:
EMAC_RSE
Access Type:
Read-write
31
–
30
–
29
–
28
–
27
–
26
–
25
–
24
–
23
–
22
–
21
–
20
–
19
–
18
–
17
–
16
–
15
–
14
–
13
–
12
–
11
–
10
–
9
–
8
–
7
6
5
4
3
2
1
0
RSE
• RSE: Receive Symbol Errors
An 8-bit register counting the number of frames that had rx_er asserted during reception. Receive symbol errors are also
counted as an FCS or alignment error if the frame is between 64 and 1518 bytes in length (1536 if bit 8 is set in the network
configuration register). If the frame is larger, it is recorded as a jabber error.
36.5.26.16 Excessive Length Errors Register
Register Name:
EMAC_ELE
Access Type:
Read-write
31
–
30
–
29
–
28
–
27
–
26
–
25
–
24
–
23
–
22
–
21
–
20
–
19
–
18
–
17
–
16
–
15
–
14
–
13
–
12
–
11
–
10
–
9
–
8
–
7
6
5
4
3
2
1
0
EXL
• EXL: Excessive Length Errors
An 8-bit register counting the number of frames received exceeding 1518 bytes (1536 if bit 8 set in network configuration
register) in length but do not have either a CRC error, an alignment error nor a receive symbol error.
668
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AT91SAM9G20
36.5.26.17 Receive Jabbers Register
Register Name:
EMAC_RJA
Access Type:
Read-write
31
–
30
–
29
–
28
–
27
–
26
–
25
–
24
–
23
–
22
–
21
–
20
–
19
–
18
–
17
–
16
–
15
–
14
–
13
–
12
–
11
–
10
–
9
–
8
–
7
6
5
4
3
2
1
0
RJB
• RJB: Receive Jabbers
An 8-bit register counting the number of frames received exceeding 1518 bytes (1536 if bit 8 set in network configuration
register) in length and have either a CRC error, an alignment error or a receive symbol error.
36.5.26.18 Undersize Frames Register
Register Name:
EMAC_USF
Access Type:
Read-write
31
–
30
–
29
–
28
–
27
–
26
–
25
–
24
–
23
–
22
–
21
–
20
–
19
–
18
–
17
–
16
–
15
–
14
–
13
–
12
–
11
–
10
–
9
–
8
–
7
6
5
4
3
2
1
0
USF
• USF: Undersize frames
An 8-bit register counting the number of frames received less than 64 bytes in length but do not have either a CRC error, an
alignment error or a receive symbol error.
669
6384E–ATARM–05-Feb-10
36.5.26.19 SQE Test Errors Register
Register Name:
EMAC_STE
Access Type:
Read-write
31
–
30
–
29
–
28
–
27
–
26
–
25
–
24
–
23
–
22
–
21
–
20
–
19
–
18
–
17
–
16
–
15
–
14
–
13
–
12
–
11
–
10
–
9
–
8
–
7
6
5
4
3
2
1
0
SQER
• SQER: SQE test errors
An 8-bit register counting the number of frames where col was not asserted within 96 bit times (an interframe gap) of
tx_en being deasserted in half duplex mode.
36.5.26.20 Received Length Field Mismatch Register
Register Name:
EMAC_RLE
Access Type:
Read-write
31
–
30
–
29
–
28
–
27
–
26
–
25
–
24
–
23
–
22
–
21
–
20
–
19
–
18
–
17
–
16
–
15
–
14
–
13
–
12
–
11
–
10
–
9
–
8
–
7
6
5
4
3
2
1
0
RLFM
• RLFM: Receive Length Field Mismatch
An 8-bit register counting the number of frames received that have a measured length shorter than that extracted from its
length field. Checking is enabled through bit 16 of the network configuration register. Frames containing a type ID in bytes
13 and 14 (i.e., length/type ID ≥ 0x0600) are not counted as length field errors, neither are excessive length frames.
670
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37. USB Device Port (UDP)
37.1
Overview
The USB Device Port (UDP) is compliant with the Universal Serial Bus (USB) V2.0 full-speed
device specification.
Each endpoint can be configured in one of several USB transfer types. It can be associated with
one or two banks of a dual-port RAM used to store the current data payload. If two banks are
used, one DPR bank is read or written by the processor, while the other is read or written by the
USB device peripheral. This feature is mandatory for isochronous endpoints. Thus the device
maintains the maximum bandwidth (1M bytes/s) by working with endpoints with two banks of
DPR.
Table 37-1.
USB Endpoint Description
Mnemonic
Dual-Bank(1)
Max. Endpoint Size
Endpoint Type
0
EP0
No
64
Control/Bulk/Interrupt
1
EP1
Yes
64
Bulk/Iso/Interrupt
2
EP2
Yes
64
Bulk/Iso/Interrupt
3
EP3
No
64
Control/Bulk/Interrupt
4
EP4
Yes
512
Bulk/Iso/Interrupt
EP5
Yes
512
Bulk/Iso/Interrupt
Endpoint Number
5
Note:
1. The Dual-Bank function provides two banks for an endpoint. This feature is used for ping-pong mode.
Suspend and resume are automatically detected by the USB device, which notifies the processor by raising an interrupt. Depending on the product, an external signal can be used to send a
wake up to the USB host controller.
671
6384E–ATARM–05-Feb-10
37.2
Block Diagram
Figure 37-1. Block Diagram
Atmel Bridge
MCK
APB
to
MCU
Bus
UDPCK
USB Device
txoen
U
s
e
r
I
n
t
e
r
f
a
c
e
udp_int
W
r
a
p
p
e
r
FIFO
eopn
Serial
Interface
Engine
12 MHz
SIE
txd
rxdm
Embedded
USB
Transceiver
DP
DM
rxd
rxdp
Suspend/Resume Logic
Master Clock
Domain
external_resume
Dual
Port
RAM
W
r
a
p
p
e
r
Recovered 12 MHz
Domain
Access to the UDP is via the APB bus interface. Read and write to the data FIFO are done by
reading and writing 8-bit values to APB registers.
The UDP peripheral requires two clocks: one peripheral clock used by the Master Clock domain
(MCK) and a 48 MHz clock (UDPCK) used by the 12 MHz domain.
A USB 2.0 full-speed pad is embedded and controlled by the Serial Interface Engine (SIE).
The signal external_resume is optional. It allows the UDP peripheral to wake up once in system
mode. The host is then notified that the device asks for a resume. This optional feature must be
also negotiated with the host during the enumeration.
37.3
Product Dependencies
For further details on the USB Device hardware implementation, see the specific Product Properties document.
The USB physical transceiver is integrated into the product. The bidirectional differential signals
DP and DM are available from the product boundary.
One I/O line may be used by the application to check that VBUS is still available from the host.
Self-powered devices may use this entry to be notified that the host has been powered off. In
this case, the pullup on DP must be disabled in order to prevent feeding current to the host. The
application should disconnect the transceiver, then remove the pullup.
37.3.1
I/O Lines
DP and DM are not controlled by any PIO controllers. The embedded USB physical transceiver
is controlled by the USB device peripheral.
672
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To reserve an I/O line to check VBUS, the programmer must first program the PIO controller to
assign this I/O in input PIO mode.
37.3.2
Power Management
The USB device peripheral requires a 48 MHz clock. This clock must be generated by a PLL
with an accuracy of ± 0.25%.
Thus, the USB device receives two clocks from the Power Management Controller (PMC): the
master clock, MCK, used to drive the peripheral user interface, and the UDPCK, used to interface with the bus USB signals (recovered 12 MHz domain).
WARNING: The UDP peripheral clock in the Power Management Controller (PMC) must be
enabled before any read/write operations to the UDP registers including the UDP_TXCV
register.
37.3.3
Interrupt
The USB device interface has an interrupt line connected to the Advanced Interrupt Controller
(AIC).
Handling the USB device interrupt requires programming the AIC before configuring the UDP.
673
6384E–ATARM–05-Feb-10
37.4
Typical Connection
Figure 37-2. Board Schematic to Interface Device Peripheral
PIO
5V Bus Monitoring
27 K
47 K
REXT
DDM
2
1
3
Type B 4
Connector
DDP
REXT
37.4.1
USB Device Transceiver
The USB device transceiver is embedded in the product. A few discrete components are
required as follows:
• the application detects all device states as defined in chapter 9 of the USB specification;
– VBUS monitoring
• to reduce power consumption the host is disconnected
• for line termination.
37.4.2
VBUS Monitoring
VBUS monitoring is required to detect host connection. VBUS monitoring is done using a standard PIO with internal pullup disabled. When the host is switched off, it should be considered as
a disconnect, the pullup must be disabled in order to prevent powering the host through the pullup resistor.
When the host is disconnected and the transceiver is enabled, then DDP and DDM are floating.
This may lead to over consumption. A solution is to enable the integrated pulldown by disabling
the transceiver (TXVDIS = 1) and then remove the pullup (PUON = 0).
A termination serial resistor must be connected to DP and DM. The resistor value is defined in
the electrical specification of the product (REXT).
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37.5
Functional Description
37.5.1
USB V2.0 Full-speed Introduction
The USB V2.0 full-speed provides communication services between host and attached USB
devices. Each device is offered with a collection of communication flows (pipes) associated with
each endpoint. Software on the host communicates with a USB device through a set of communication flows.
Figure 37-3. Example of USB V2.0 Full-speed Communication Control
USB Host V2.0
Software Client 1
Software Client 2
Data Flow: Control Transfer
EP0
Data Flow: Isochronous In Transfer
USB Device 2.0
EP1 Block 1
Data Flow: Isochronous Out Transfer
EP2
Data Flow: Control Transfer
EP0
Data Flow: Bulk In Transfer
USB Device 2.0
EP4 Block 2
Data Flow: Bulk Out Transfer
EP5
USB Device endpoint configuration requires that
in the first instance Control Transfer must be EP0.
The Control Transfer endpoint EP0 is always used when a USB device is first configured (USB v. 2.0 specifications).
37.5.1.1
Table 37-2.
USB V2.0 Full-speed Transfer Types
A communication flow is carried over one of four transfer types defined by the USB device.
USB Communication Flow
Transfer
Direction
Bandwidth
Supported Endpoint Size
Error Detection
Retrying
Bidirectional
Not guaranteed
8, 16, 32, 64
Yes
Automatic
Isochronous
Unidirectional
Guaranteed
512
Yes
No
Interrupt
Unidirectional
Not guaranteed
≤64
Yes
Yes
Bulk
Unidirectional
Not guaranteed
8, 16, 32, 64
Yes
Yes
Control
37.5.1.2
USB Bus Transactions
Each transfer results in one or more transactions over the USB bus. There are three kinds of
transactions flowing across the bus in packets:
675
6384E–ATARM–05-Feb-10
1. Setup Transaction
2. Data IN Transaction
3. Data OUT Transaction
37.5.1.3
USB Transfer Event Definitions
As indicated below, transfers are sequential events carried out on the USB bus.
Table 37-3.
USB Transfer Events
• Setup transaction > Data IN transactions > Status
OUT transaction
Control Transfers(1) (3)
Interrupt IN Transfer
(device toward host)
• Setup transaction > Data OUT transactions > Status
IN transaction
• Setup transaction > Status IN transaction
• Data IN transaction > Data IN transaction
Interrupt OUT Transfer
(host toward device)
• Data OUT transaction > Data OUT transaction
Isochronous IN Transfer(2)
(device toward host)
• Data IN transaction > Data IN transaction
Isochronous OUT Transfer(2)
(host toward device)
• Data OUT transaction > Data OUT transaction
Bulk IN Transfer
(device toward host)
• Data IN transaction > Data IN transaction
Bulk OUT Transfer
(host toward device)
• Data OUT transaction > Data OUT transaction
Notes:
1. Control transfer must use endpoints with no ping-pong attributes.
2. Isochronous transfers must use endpoints with ping-pong attributes.
3. Control transfers can be aborted using a stall handshake.
A status transaction is a special type of host-to-device transaction used only in a control transfer.
The control transfer must be performed using endpoints with no ping-pong attributes. According
to the control sequence (read or write), the USB device sends or receives a status transaction.
676
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AT91SAM9G20
Figure 37-4. Control Read and Write Sequences
Setup Stage
Control Read
Setup TX
Data Stage
Data OUT TX
No Data
Control
Notes:
Setup TX
Data OUT TX
Data Stage
Setup Stage
Control Write
Status Stage
Data IN TX
Setup Stage
Status Stage
Setup TX
Status IN TX
Data IN TX
Status IN TX
Status Stage
Status OUT TX
1. During the Status IN stage, the host waits for a zero length packet (Data IN transaction with no data) from the device using
DATA1 PID. Refer to Chapter 8 of the Universal Serial Bus Specification, Rev. 2.0, for more information on the protocol layer.
2. During the Status OUT stage, the host emits a zero length packet to the device (Data OUT transaction with no data).
37.5.2
37.5.2.1
Handling Transactions with USB V2.0 Device Peripheral
Setup Transaction
Setup is a special type of host-to-device transaction used during control transfers. Control transfers must be performed using endpoints with no ping-pong attributes. A setup transaction needs
to be handled as soon as possible by the firmware. It is used to transmit requests from the host
to the device. These requests are then handled by the USB device and may require more arguments. The arguments are sent to the device by a Data OUT transaction which follows the setup
transaction. These requests may also return data. The data is carried out to the host by the next
Data IN transaction which follows the setup transaction. A status transaction ends the control
transfer.
When a setup transfer is received by the USB endpoint:
• The USB device automatically acknowledges the setup packet
• RXSETUP is set in the UDP_CSRx register
• An endpoint interrupt is generated while the RXSETUP is not cleared. This interrupt is
carried out to the microcontroller if interrupts are enabled for this endpoint.
Thus, firmware must detect the RXSETUP polling the UDP_CSRx or catching an interrupt, read
the setup packet in the FIFO, then clear the RXSETUP. RXSETUP cannot be cleared before the
setup packet has been read in the FIFO. Otherwise, the USB device would accept the next Data
OUT transfer and overwrite the setup packet in the FIFO.
677
6384E–ATARM–05-Feb-10
Figure 37-5. Setup Transaction Followed by a Data OUT Transaction
Setup Received
USB
Bus Packets
Setup
PID
Data Setup
RXSETUP Flag
Setup Handled by Firmware
ACK
PID
Data OUT
PID
Data OUT
NAK
PID
Data OUT
PID
Data OUT
ACK
PID
Interrupt Pending
Set by USB Device
Cleared by Firmware
Set by USB
Device Peripheral
RX_Data_BKO
(UDP_CSRx)
FIFO (DPR)
Content
Data Out Received
XX
Data Setup
XX
Data OUT
37.5.2.2
Data IN Transaction
Data IN transactions are used in control, isochronous, bulk and interrupt transfers and conduct
the transfer of data from the device to the host. Data IN transactions in isochronous transfer
must be done using endpoints with ping-pong attributes.
37.5.2.3
Using Endpoints Without Ping-pong Attributes
To perform a Data IN transaction using a non ping-pong endpoint:
1. The application checks if it is possible to write in the FIFO by polling TXPKTRDY in the
endpoint’s UDP_CSRx register (TXPKTRDY must be cleared).
2. The application writes the first packet of data to be sent in the endpoint’s FIFO, writing
zero or more byte values in the endpoint’s UDP_FDRx register,
3. The application notifies the USB peripheral it has finished by setting the TXPKTRDY in
the endpoint’s UDP_CSRx register.
4. The application is notified that the endpoint’s FIFO has been released by the USB
device when TXCOMP in the endpoint’s UDP_CSRx register has been set. Then an
interrupt for the corresponding endpoint is pending while TXCOMP is set.
5. The microcontroller writes the second packet of data to be sent in the endpoint’s FIFO,
writing zero or more byte values in the endpoint’s UDP_FDRx register,
6. The microcontroller notifies the USB peripheral it has finished by setting the TXPKTRDY in the endpoint’s UDP_CSRx register.
7. The application clears the TXCOMP in the endpoint’s UDP_CSRx.
After the last packet has been sent, the application must clear TXCOMP once this has been set.
TXCOMP is set by the USB device when it has received an ACK PID signal for the Data IN
packet. An interrupt is pending while TXCOMP is set.
Warning: TX_COMP must be cleared after TX_PKTRDY has been set.
Note:
678
Refer to Chapter 8 of the Universal Serial Bus Specification, Rev 2.0, for more information on the
Data IN protocol layer.
AT91SAM9G20
6384E–ATARM–05-Feb-10
AT91SAM9G20
Figure 37-6. Data IN Transfer for Non Ping-pong Endpoint
Prevous Data IN TX
USB Bus Packets
Data IN
PID
Microcontroller Load Data in FIFO
Data IN 1
ACK
PID
Data IN
PID
NAK
PID
Data is Sent on USB Bus
Data IN
PID
ACK
PID
Data IN 2
TXPKTRDY Flag
(UDP_CSRx)
Set by the firmware
Cleared by Hw
Set by the firmware
Cleared by Hw
Interrupt
Pending
Interrupt Pending
TXCOMP Flag
(UDP_CSRx)
Payload in FIFO
Cleared by Firmware
DPR access by the firmware
FIFO (DPR)
Content
37.5.2.4
Data IN 1
Cleared by
Firmware
DPR access by the hardware
Load In Progress
Data IN 2
Using Endpoints With Ping-pong Attribute
The use of an endpoint with ping-pong attributes is necessary during isochronous transfer. This
also allows handling the maximum bandwidth defined in the USB specification during bulk transfer. To be able to guarantee a constant or the maximum bandwidth, the microcontroller must
prepare the next data payload to be sent while the current one is being sent by the USB device.
Thus two banks of memory are used. While one is available for the microcontroller, the other
one is locked by the USB device.
Figure 37-7. Bank Swapping Data IN Transfer for Ping-pong Endpoints
Microcontroller
1st Data Payload
USB Device
Write
Bank 0
Endpoint 1
USB Bus
Read
Read and Write at the Same Time
2nd Data Payload
Data IN Packet
Bank 1
Endpoint 1
Bank 0
Endpoint 1
1st Data Payload
Bank 0
Endpoint 1
Bank 1
Endpoint 1
2nd Data Payload
Bank 0
Endpoint 1
3rd Data Payload
3rd Data Payload
Data IN Packet
Data IN Packet
When using a ping-pong endpoint, the following procedures are required to perform Data IN
transactions:
679
6384E–ATARM–05-Feb-10
1. The microcontroller checks if it is possible to write in the FIFO by polling TXPKTRDY to
be cleared in the endpoint’s UDP_CSRx register.
2. The microcontroller writes the first data payload to be sent in the FIFO (Bank 0), writing
zero or more byte values in the endpoint’s UDP_FDRx register.
3. The microcontroller notifies the USB peripheral it has finished writing in Bank 0 of the
FIFO by setting the TXPKTRDY in the endpoint’s UDP_CSRx register.
4. Without waiting for TXPKTRDY to be cleared, the microcontroller writes the second
data payload to be sent in the FIFO (Bank 1), writing zero or more byte values in the
endpoint’s UDP_FDRx register.
5. The microcontroller is notified that the first Bank has been released by the USB device
when TXCOMP in the endpoint’s UDP_CSRx register is set. An interrupt is pending
while TXCOMP is being set.
6. Once the microcontroller has received TXCOMP for the first Bank, it notifies the USB
device that it has prepared the second Bank to be sent, raising TXPKTRDY in the endpoint’s UDP_CSRx register.
7. At this step, Bank 0 is available and the microcontroller can prepare a third data payload to be sent.
Figure 37-8. Data IN Transfer for Ping-pong Endpoint
Microcontroller
Load Data IN Bank 0
USB Bus
Packets
Data IN
PID
TXPKTRDY Flag
(UDP_MCSRx)
Microcontroller Load Data IN Bank 1
USB Device Send Bank 0
ACK
PID
Data IN
Microcontroller Load Data IN Bank 0
USB Device Send Bank 1
Data IN
PID
Cleared by USB Device,
Data Payload Fully Transmitted
Set by Firmware,
Data Payload Written in FIFO Bank 0
Set by Firmware,
Data Payload Written in FIFO Bank 1
Interrupt Pending
Set by USB
Device
TXCOMP Flag
(UDP_CSRx)
ACK
PID
Data IN
Set by USB Device
Interrupt Cleared by Firmware
FIFO (DPR) Written by
Microcontroller
Bank 0
FIFO (DPR)
Bank 1
Read by USB Device
Written by
Microcontroller
Written by
Microcontroller
Read by USB Device
Warning: There is software critical path due to the fact that once the second bank is filled, the
driver has to wait for TX_COMP to set TX_PKTRDY. If the delay between receiving TX_COMP
is set and TX_PKTRDY is set too long, some Data IN packets may be NACKed, reducing the
bandwidth.
Warning: TX_COMP must be cleared after TX_PKTRDY has been set.
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37.5.2.5
Data OUT Transaction
Data OUT transactions are used in control, isochronous, bulk and interrupt transfers and conduct the transfer of data from the host to the device. Data OUT transactions in isochronous
transfers must be done using endpoints with ping-pong attributes.
37.5.2.6
Data OUT Transaction Without Ping-pong Attributes
To perform a Data OUT transaction, using a non ping-pong endpoint:
1. The host generates a Data OUT packet.
2. This packet is received by the USB device endpoint. While the FIFO associated to this
endpoint is being used by the microcontroller, a NAK PID is returned to the host. Once
the FIFO is available, data are written to the FIFO by the USB device and an ACK is
automatically carried out to the host.
3. The microcontroller is notified that the USB device has received a data payload polling
RX_DATA_BK0 in the endpoint’s UDP_CSRx register. An interrupt is pending for this
endpoint while RX_DATA_BK0 is set.
4. The number of bytes available in the FIFO is made available by reading RXBYTECNT
in the endpoint’s UDP_CSRx register.
5. The microcontroller carries out data received from the endpoint’s memory to its memory. Data received is available by reading the endpoint’s UDP_FDRx register.
6. The microcontroller notifies the USB device that it has finished the transfer by clearing
RX_DATA_BK0 in the endpoint’s UDP_CSRx register.
7. A new Data OUT packet can be accepted by the USB device.
Figure 37-9. Data OUT Transfer for Non Ping-pong Endpoints
USB Bus
Packets
Host Sends Data Payload
Microcontroller Transfers Data
Host Sends the Next Data Payload
Data OUT
PID
ACK
PID
Data OUT 1
RX_DATA_BK0
(UDP_CSRx)
Data OUT2
PID
Data OUT2
Host Resends the Next Data Payload
NAK
PID
Data OUT
PID
Data OUT2
ACK
PID
Interrupt Pending
Set by USB Device
FIFO (DPR)
Content
Data OUT 1
Written by USB Device
Data OUT 1
Microcontroller Read
Cleared by Firmware,
Data Payload Written in FIFO
Data OUT 2
Written by USB Device
An interrupt is pending while the flag RX_DATA_BK0 is set. Memory transfer between the USB
device, the FIFO and microcontroller memory can not be done after RX_DATA_BK0 has been
cleared. Otherwise, the USB device would accept the next Data OUT transfer and overwrite the
current Data OUT packet in the FIFO.
37.5.2.7
Using Endpoints With Ping-pong Attributes
During isochronous transfer, using an endpoint with ping-pong attributes is obligatory. To be
able to guarantee a constant bandwidth, the microcontroller must read the previous data pay681
6384E–ATARM–05-Feb-10
load sent by the host, while the current data payload is received by the USB device. Thus two
banks of memory are used. While one is available for the microcontroller, the other one is locked
by the USB device.
Figure 37-10. Bank Swapping in Data OUT Transfers for Ping-pong Endpoints
Microcontroller
USB Device
Write
USB Bus
Read
Data IN Packet
Bank 0
Endpoint 1
1st Data Payload
Bank 0
Endpoint 1
Bank 1
Endpoint 1
Data IN Packet
nd
2 Data Payload
Bank 1
Endpoint 1
Bank 0
Endpoint 1
3rd Data Payload
Write and Read at the Same Time
1st Data Payload
2nd Data Payload
Data IN Packet
3rd Data Payload
Bank 0
Endpoint 1
When using a ping-pong endpoint, the following procedures are required to perform Data OUT
transactions:
1. The host generates a Data OUT packet.
2. This packet is received by the USB device endpoint. It is written in the endpoint’s FIFO
Bank 0.
3. The USB device sends an ACK PID packet to the host. The host can immediately send
a second Data OUT packet. It is accepted by the device and copied to FIFO Bank 1.
4. The microcontroller is notified that the USB device has received a data payload, polling
RX_DATA_BK0 in the endpoint’s UDP_CSRx register. An interrupt is pending for this
endpoint while RX_DATA_BK0 is set.
5. The number of bytes available in the FIFO is made available by reading RXBYTECNT
in the endpoint’s UDP_CSRx register.
6. The microcontroller transfers out data received from the endpoint’s memory to the
microcontroller’s memory. Data received is made available by reading the endpoint’s
UDP_FDRx register.
7. The microcontroller notifies the USB peripheral device that it has finished the transfer
by clearing RX_DATA_BK0 in the endpoint’s UDP_CSRx register.
8. A third Data OUT packet can be accepted by the USB peripheral device and copied in
the FIFO Bank 0.
9. If a second Data OUT packet has been received, the microcontroller is notified by the
flag RX_DATA_BK1 set in the endpoint’s UDP_CSRx register. An interrupt is pending
for this endpoint while RX_DATA_BK1 is set.
10. The microcontroller transfers out data received from the endpoint’s memory to the
microcontroller’s memory. Data received is available by reading the endpoint’s
UDP_FDRx register.
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11. The microcontroller notifies the USB device it has finished the transfer by clearing
RX_DATA_BK1 in the endpoint’s UDP_CSRx register.
12. A fourth Data OUT packet can be accepted by the USB device and copied in the FIFO
Bank 0.
Figure 37-11. Data OUT Transfer for Ping-pong Endpoint
Microcontroller Reads Data 1 in Bank 0,
Host Sends Second Data Payload
Host Sends First Data Payload
USB Bus
Packets
Data OUT
PID
RX_DATA_BK0 Flag
(UDP_CSRx)
Data OUT 1
Data OUT
PID
Data OUT 2
Set by USB Device,
Data Payload Written
in FIFO Endpoint Bank 0
ACK
PID
Data OUT 3
A
P
Cleared by Firmware
Set by USB Device,
Data Payload Written
in FIFO Endpoint Bank 1
Interrupt Pending
Data OUT1
Data OUT 1
Data OUT 3
Write by USB Device
Read By Microcontroller
Write In Progress
FIFO (DPR)
Bank 1
Data OUT 2
Write by USB Device
Note:
Data OUT
PID
Cleared by Firmware
Interrupt Pending
RX_DATA_BK1 Flag
(UDP_CSRx)
FIFO (DPR)
Bank 0
ACK
PID
Microcontroller Reads Data2 in Bank 1,
Host Sends Third Data Payload
Data OUT 2
Read By Microcontroller
An interrupt is pending while the RX_DATA_BK0 or RX_DATA_BK1 flag is set.
Warning: When RX_DATA_BK0 and RX_DATA_BK1 are both set, there is no way to determine
which one to clear first. Thus the software must keep an internal counter to be sure to clear alternatively RX_DATA_BK0 then RX_DATA_BK1. This situation may occur when the software
application is busy elsewhere and the two banks are filled by the USB host. Once the application
comes back to the USB driver, the two flags are set.
37.5.2.8
Stall Handshake
A stall handshake can be used in one of two distinct occasions. (For more information on the
stall handshake, refer to Chapter 8 of the Universal Serial Bus Specification, Rev 2.0.)
• A functional stall is used when the halt feature associated with the endpoint is set. (Refer to
Chapter 9 of the Universal Serial Bus Specification, Rev 2.0, for more information on the halt
feature.)
• To abort the current request, a protocol stall is used, but uniquely with control transfer.
The following procedure generates a stall packet:
1. The microcontroller sets the FORCESTALL flag in the UDP_CSRx endpoint’s register.
2. The host receives the stall packet.
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3. The microcontroller is notified that the device has sent the stall by polling the
STALLSENT to be set. An endpoint interrupt is pending while STALLSENT is set. The
microcontroller must clear STALLSENT to clear the interrupt.
When a setup transaction is received after a stall handshake, STALLSENT must be cleared in
order to prevent interrupts due to STALLSENT being set.
Figure 37-12. Stall Handshake (Data IN Transfer)
USB Bus
Packets
Data IN PID
Stall PID
Cleared by Firmware
FORCESTALL
Set by Firmware
Interrupt Pending
Cleared by Firmware
STALLSENT
Set by
USB Device
Figure 37-13. Stall Handshake (Data OUT Transfer)
USB Bus
Packets
Data OUT PID
Data OUT
Stall PID
Set by Firmware
FORCESTALL
Interrupt Pending
STALLSENT
Cleared by Firmware
Set by USB Device
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37.5.2.9
Transmit Data Cancellation
Some endpoints have dual-banks whereas some endpoints have only one bank. The procedure
to cancel transmission data held in these banks is described below.
To see the organization of dual-bank availability refer to Table 37-1 ”USB Endpoint Description”.
37.5.2.10
Endpoints Without Dual-Banks
There are two possibilities: In one case, TXPKTRDY field in UDP_CSR has already been set. In
the other instance, TXPKTRDY is not set.
• TXPKTRDY is not set:
– Reset the endpoint to clear the FIFO (pointers). (See, Section 37.6.9 ”UDP Reset
Endpoint Register”.)
• TXPKTRDY has already been set:
– Clear TXPKTRDY so that no packet is ready to be sent
– Reset the endpoint to clear the FIFO (pointers). (See, Section 37.6.9 ”UDP Reset
Endpoint Register”.)
37.5.2.11
Endpoints With Dual-Banks
There are two possibilities: In one case, TXPKTRDY field in UDP_CSR has already been set. In
the other instance, TXPKTRDY is not set.
• TXPKTRDY is not set:
– Reset the endpoint to clear the FIFO (pointers). (See, Section 37.6.9 ”UDP Reset
Endpoint Register”.)
• TXPKTRDY has already been set:
– Clear TXPKTRDY and read it back until actually read at 0.
– Set TXPKTRDY and read it back until actually read at 1.
– Clear TXPKTRDY so that no packet is ready to be sent.
– Reset the endpoint to clear the FIFO (pointers). (See, Section 37.6.9 ”UDP Reset
Endpoint Register”.)
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37.5.3
Controlling Device States
A USB device has several possible states. Refer to Chapter 9 of the Universal Serial Bus Specification, Rev 2.0.
Figure 37-14. USB Device State Diagram
Attached
Hub Reset
or
Deconfigured
Hub
Configured
Bus Inactive
Powered
Suspended
Bus Activity
Power
Interruption
Reset
Bus Inactive
Suspended
Default
Bus Activity
Reset
Address
Assigned
Bus Inactive
Address
Suspended
Bus Activity
Device
Deconfigured
Device
Configured
Bus Inactive
Configured
Suspended
Bus Activity
Movement from one state to another depends on the USB bus state or on standard requests
sent through control transactions via the default endpoint (endpoint 0).
After a period of bus inactivity, the USB device enters Suspend Mode. Accepting Suspend/Resume requests from the USB host is mandatory. Constraints in Suspend Mode are very
strict for bus-powered applications; devices may not consume more than 500 µA on the USB
bus.
While in Suspend Mode, the host may wake up a device by sending a resume signal (bus activity) or a USB device may send a wake up request to the host, e.g., waking up a PC by moving a
USB mouse.
The wake up feature is not mandatory for all devices and must be negotiated with the host.
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37.5.3.1
Not Powered State
Self powered devices can detect 5V VBUS using a PIO as described in the typical connection
section. When the device is not connected to a host, device power consumption can be reduced
by disabling MCK for the UDP, disabling UDPCK and disabling the transceiver. DDP and DDM
lines are pulled down by 330 KΩ resistors.
37.5.3.2
Entering Attached State
When no device is connected, the USB DP and DM signals are tied to GND by 15 KΩ pull-down
resistors integrated in the hub downstream ports. When a device is attached to a hub downstream port, the device connects a 1.5 KΩ pull-up resistor on DP. The USB bus line goes into
IDLE state, DP is pulled up by the device 1.5 KΩ resistor to 3.3V and DM is pulled down by the
15 KΩ resistor of the host. To enable integrated pullup, the PUON bit in the UDP_TXVC register
must be set.
Warning: To write to the UDP_TXVC register, MCK clock must be enabled on the UDP. This is
done in the Power Management Controller.
After pullup connection, the device enters the powered state. In this state, the UDPCK and MCK
must be enabled in the Power Management Controller. The transceiver can remain disabled.
37.5.3.3
From Powered State to Default State
After its connection to a USB host, the USB device waits for an end-of-bus reset. The
unmaskable flag ENDBUSRES is set in the register UDP_ISR and an interrupt is triggered.
Once the ENDBUSRES interrupt has been triggered, the device enters Default State. In this
state, the UDP software must:
• Enable the default endpoint, setting the EPEDS flag in the UDP_CSR[0] register and,
optionally, enabling the interrupt for endpoint 0 by writing 1 to the UDP_IER register. The
enumeration then begins by a control transfer.
• Configure the interrupt mask register which has been reset by the USB reset detection
• Enable the transceiver clearing the TXVDIS flag in the UDP_TXVC register.
In this state UDPCK and MCK must be enabled.
Warning: Each time an ENDBUSRES interrupt is triggered, the Interrupt Mask Register and
UDP_CSR registers have been reset.
37.5.3.4
From Default State to Address State
After a set address standard device request, the USB host peripheral enters the address state.
Warning: Before the device enters in address state, it must achieve the Status IN transaction of
the control transfer, i.e., the UDP device sets its new address once the TXCOMP flag in the
UDP_CSR[0] register has been received and cleared.
To move to address state, the driver software sets the FADDEN flag in the UDP_GLB_STAT
register, sets its new address, and sets the FEN bit in the UDP_FADDR register.
37.5.3.5
From Address State to Configured State
Once a valid Set Configuration standard request has been received and acknowledged, the
device enables endpoints corresponding to the current configuration. This is done by setting the
EPEDS and EPTYPE fields in the UDP_CSRx registers and, optionally, enabling corresponding
interrupts in the UDP_IER register.
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37.5.3.6
Entering in Suspend State
When a Suspend (no bus activity on the USB bus) is detected, the RXSUSP signal in the
UDP_ISR register is set. This triggers an interrupt if the corresponding bit is set in the UDP_IMR
register.This flag is cleared by writing to the UDP_ICR register. Then the device enters Suspend
Mode.
In this state bus powered devices must drain less than 500uA from the 5V VBUS. As an example, the microcontroller switches to slow clock, disables the PLL and main oscillator, and goes
into Idle Mode. It may also switch off other devices on the board.
The USB device peripheral clocks can be switched off. Resume event is asynchronously
detected. MCK and UDPCK can be switched off in the Power Management controller and the
USB transceiver can be disabled by setting the TXVDIS field in the UDP_TXVC register.
Warning: Read, write operations to the UDP registers are allowed only if MCK is enabled for the
UDP peripheral. Switching off MCK for the UDP peripheral must be one of the last operations
after writing to the UDP_TXVC and acknowledging the RXSUSP.
37.5.3.7
Receiving a Host Resume
In suspend mode, a resume event on the USB bus line is detected asynchronously, transceiver
and clocks are disabled (however the pullup shall not be removed).
Once the resume is detected on the bus, the WAKEUP signal in the UDP_ISR is set. It may generate an interrupt if the corresponding bit in the UDP_IMR register is set. This interrupt may be
used to wake up the core, enable PLL and main oscillators and configure clocks.
Warning: Read, write operations to the UDP registers are allowed only if MCK is enabled for the
UDP peripheral. MCK for the UDP must be enabled before clearing the WAKEUP bit in the
UDP_ICR register and clearing TXVDIS in the UDP_TXVC register.
37.5.3.8
Sending a Device Remote Wakeup
In Suspend state it is possible to wake up the host sending an external resume.
• The device must wait at least 5 ms after being entered in suspend before sending an external
resume.
• The device has 10 ms from the moment it starts to drain current and it forces a K state to
resume the host.
• The device must force a K state from 1 to 15 ms to resume the host
To force a K state to the bus (DM at 3.3V and DP tied to GND), it is possible to use a transistor
to connect a pullup on DM. The K state is obtained by disabling the pullup on DP and enabling
the pullup on DM. This should be under the control of the application.
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Figure 37-15. Board Schematic to Drive a K State
3V3
PIO
0: Force Wake UP (K State)
1: Normal Mode
1.5 K
DM
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37.6
USB Device (UDP) User Interface
WARNING: The UDP peripheral clock in the Power Management Controller (PMC) must be enabled before any read/write
operations to the UDP registers, including the UDP_TXVC register.
Table 37-4.
Register Mapping
Offset
Register
Name
Access
Reset
0x000
Frame Number Register
UDP_FRM_NUM
Read-only
0x0000_0000
0x004
Global State Register
UDP_GLB_STAT
Read-write
0x0000_0000
0x008
Function Address Register
UDP_FADDR
Read-write
0x0000_0100
0x00C
Reserved
–
–
–
0x010
Interrupt Enable Register
UDP_IER
Write-only
0x014
Interrupt Disable Register
UDP_IDR
Write-only
0x018
Interrupt Mask Register
UDP_IMR
Read-only
0x0000_1200
0x01C
Interrupt Status Register
UDP_ISR
Read-only
–(1)
0x020
Interrupt Clear Register
UDP_ICR
Write-only
0x024
Reserved
–
–
–
0x028
Reset Endpoint Register
UDP_RST_EP
Read-write
0x0000_0000
0x02C
Reserved
–
–
–
0x030 + 0x4 * ( ept_num - 1 )
Endpoint Control and Status Register
UDP_CSR
Read-write
0x0000_0000
0x050 + 0x4 * ( ept_num - 1 )
Endpoint FIFO Data Register
UDP_FDR
Read-write
0x0000_0000
0x070
Reserved
–
–
–
Read-write
0x0000_0100
–
–
0x074
Transceiver Control Register
UDP_TXVC
0x078 - 0xFC
Reserved
–
Notes:
(2)
1. Reset values are not defined for UDP_ISR.
2. See Warning above the ”Register Mapping” on this page.
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37.6.1
UDP Frame Number Register
Register Name:UDP_FRM_NUM
Access Type: Read-only
31
---
30
---
29
---
28
---
27
---
26
---
25
---
24
---
23
–
22
–
21
–
20
–
19
–
18
–
17
FRM_OK
16
FRM_ERR
15
–
14
–
13
–
12
–
11
–
10
9
FRM_NUM
8
7
6
5
4
3
2
1
0
FRM_NUM
• FRM_NUM[10:0]: Frame Number as Defined in the Packet Field Formats
This 11-bit value is incremented by the host on a per frame basis. This value is updated at each start of frame.
Value Updated at the SOF_EOP (Start of Frame End of Packet).
• FRM_ERR: Frame Error
This bit is set at SOF_EOP when the SOF packet is received containing an error.
This bit is reset upon receipt of SOF_PID.
• FRM_OK: Frame OK
This bit is set at SOF_EOP when the SOF packet is received without any error.
This bit is reset upon receipt of SOF_PID (Packet Identification).
In the Interrupt Status Register, the SOF interrupt is updated upon receiving SOF_PID. This bit is set without waiting for
EOP.
Note:
In the 8-bit Register Interface, FRM_OK is bit 4 of FRM_NUM_H and FRM_ERR is bit 3 of FRM_NUM_L.
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37.6.2
UDP Global State Register
Register Name:UDP_GLB_STAT
Access Type: Read-write
31
–
30
–
29
–
28
–
27
–
26
–
25
–
24
–
23
–
22
–
21
–
20
–
19
–
18
–
17
–
16
–
15
–
14
–
13
–
12
–
11
–
10
–
9
8
–
–
7
–
6
–
5
–
4
–
3
RSMINPR
2
–
1
CONFG
0
FADDEN
This register is used to get and set the device state as specified in Chapter 9 of the USB Serial Bus Specification, Rev.2.0.
• FADDEN: Function Address Enable
Read:
0 = Device is not in address state.
1 = Device is in address state.
Write:
0 = No effect, only a reset can bring back a device to the default state.
1 = Sets device in address state. This occurs after a successful Set Address request. Beforehand, the UDP_FADDR register must have been initialized with Set Address parameters. Set Address must complete the Status Stage before setting
FADDEN. Refer to chapter 9 of the Universal Serial Bus Specification, Rev. 2.0 for more details.
• CONFG: Configured
Read:
0 = Device is not in configured state.
1 = Device is in configured state.
Write:
0 = Sets device in a non configured state
1 = Sets device in configured state.
The device is set in configured state when it is in address state and receives a successful Set Configuration request. Refer
to Chapter 9 of the Universal Serial Bus Specification, Rev. 2.0 for more details.
• RSMINPR: Resume Interrupt Request
Read:
0 = No effect.
1 = The pin “send_resume” is set to one. A Send Resume request has been detected and the device can send a Remote
Wake Up.
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37.6.3
UDP Function Address Register
Register Name:UDP_FADDR
Access Type: Read-write
31
–
30
–
29
–
28
–
27
–
26
–
25
–
24
–
23
–
22
–
21
–
20
–
19
–
18
–
17
–
16
–
15
–
14
–
13
–
12
–
11
–
10
–
9
8
–
FEN
7
–
6
5
4
3
FADD
2
1
0
• FADD[6:0]: Function Address Value
The Function Address Value must be programmed by firmware once the device receives a set address request from the
host, and has achieved the status stage of the no-data control sequence. Refer to the Universal Serial Bus Specification,
Rev. 2.0 for more information. After power up or reset, the function address value is set to 0.
• FEN: Function Enable
Read:
0 = Function endpoint disabled.
1 = Function endpoint enabled.
Write:
0 = Disables function endpoint.
1 = Default value.
The Function Enable bit (FEN) allows the microcontroller to enable or disable the function endpoints. The microcontroller
sets this bit after receipt of a reset from the host. Once this bit is set, the USB device is able to accept and transfer data
packets from and to the host.
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37.6.4
UDP Interrupt Enable Register
Register Name:UDP_IER
Access Type: Write-only
31
–
30
–
29
–
28
–
27
–
26
–
25
–
24
–
23
–
22
–
21
–
20
–
19
–
18
–
17
–
16
–
15
–
14
–
13
WAKEUP
12
–
11
SOFINT
10
EXTRSM
9
8
RXRSM
RXSUSP
7
6
5
EP5INT
4
EP4INT
3
EP3INT
2
EP2INT
1
EP1INT
0
EP0INT
• EP0INT: Enable Endpoint 0 Interrupt
• EP1INT: Enable Endpoint 1 Interrupt
• EP2INT: Enable Endpoint 2Interrupt
• EP3INT: Enable Endpoint 3 Interrupt
• EP4INT: Enable Endpoint 4 Interrupt
• EP5INT: Enable Endpoint 5 Interrupt
0 = No effect.
1 = Enables corresponding Endpoint Interrupt.
• RXSUSP: Enable UDP Suspend Interrupt
0 = No effect.
1 = Enables UDP Suspend Interrupt.
• RXRSM: Enable UDP Resume Interrupt
0 = No effect.
1 = Enables UDP Resume Interrupt.
• EXTRSM: Enable External Resume Interrupt
0 = No effect.
1 = Enables External Resume Interrupt.
• SOFINT: Enable Start Of Frame Interrupt
0 = No effect.
1 = Enables Start Of Frame Interrupt.
• WAKEUP: Enable UDP bus Wakeup Interrupt
0 = No effect.
1 = Enables USB bus Interrupt.
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37.6.5
UDP Interrupt Disable Register
Register Name:UDP_IDR
Access Type: Write-only
31
–
30
–
29
–
28
–
27
–
26
–
25
–
24
–
23
–
22
–
21
–
20
–
19
–
18
–
17
–
16
–
15
–
14
–
13
WAKEUP
12
–
11
SOFINT
10
EXTRSM
9
8
RXRSM
RXSUSP
7
6
5
EP5INT
4
EP4INT
3
EP3INT
2
EP2INT
1
EP1INT
0
EP0INT
• EP0INT: Disable Endpoint 0 Interrupt
• EP1INT: Disable Endpoint 1 Interrupt
• EP2INT: Disable Endpoint 2 Interrupt
• EP3INT: Disable Endpoint 3 Interrupt
• EP4INT: Disable Endpoint 4 Interrupt
• EP5INT: Disable Endpoint 5 Interrupt
0 = No effect.
1 = Disables corresponding Endpoint Interrupt.
• RXSUSP: Disable UDP Suspend Interrupt
0 = No effect.
1 = Disables UDP Suspend Interrupt.
• RXRSM: Disable UDP Resume Interrupt
0 = No effect.
1 = Disables UDP Resume Interrupt.
• EXTRSM: Disable External Resume Interrupt
0 = No effect.
1 = Disables External Resume Interrupt.
• SOFINT: Disable Start Of Frame Interrupt
0 = No effect.
1 = Disables Start Of Frame Interrupt
• WAKEUP: Disable USB Bus Interrupt
0 = No effect.
1 = Disables USB Bus Wakeup Interrupt.
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37.6.6
UDP Interrupt Mask Register
Register Name:UDP_IMR
Access Type: Read-only
31
–
30
–
29
–
28
–
27
–
26
–
25
–
24
–
23
–
22
–
21
–
20
–
19
–
18
–
17
–
16
–
15
–
14
–
13
WAKEUP
12
BIT12
11
SOFINT
10
EXTRSM
9
8
RXRSM
RXSUSP
7
6
5
EP5INT
4
EP4INT
3
EP3INT
2
EP2INT
1
EP1INT
0
EP0INT
• EP0INT: Mask Endpoint 0 Interrupt
• EP1INT: Mask Endpoint 1 Interrupt
• EP2INT: Mask Endpoint 2 Interrupt
• EP3INT: Mask Endpoint 3 Interrupt
• EP4INT: Mask Endpoint 4 Interrupt
• EP5INT: Mask Endpoint 5 Interrupt
0 = Corresponding Endpoint Interrupt is disabled.
1 = Corresponding Endpoint Interrupt is enabled.
• RXSUSP: Mask UDP Suspend Interrupt
0 = UDP Suspend Interrupt is disabled.
1 = UDP Suspend Interrupt is enabled.
• RXRSM: Mask UDP Resume Interrupt.
0 = UDP Resume Interrupt is disabled.
1 = UDP Resume Interrupt is enabled.
• EXTRSM: Mask External Resume Interrupt
0 = UDP External Resume Interrupt is disabled.
1 = UDP External Resume Interrupt is enabled.
• SOFINT: Mask Start Of Frame Interrupt
0 = Start of Frame Interrupt is disabled.
1 = Start of Frame Interrupt is enabled.
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• BIT12: UDP_IMR Bit 12
Bit 12 of UDP_IMR cannot be masked and is always read at 1.
• WAKEUP: USB Bus WAKEUP Interrupt
0 = USB Bus Wakeup Interrupt is disabled.
1 = USB Bus Wakeup Interrupt is enabled.
Note:
When the USB block is in suspend mode, the application may power down the USB logic. In this case, any USB HOST resume
request that is made must be taken into account and, thus, the reset value of the RXRSM bit of the register UDP_IMR is
enabled.
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37.6.7
UDP Interrupt Status Register
Register Name:UDP_ISR
Access Type: Read-only
31
–
30
–
29
–
28
–
27
–
26
–
25
–
24
–
23
–
22
–
21
–
20
–
19
–
18
–
17
–
16
–
15
–
14
–
13
WAKEUP
12
ENDBUSRES
11
SOFINT
10
EXTRSM
9
8
RXRSM
RXSUSP
7
6
5
EP5INT
4
EP4INT
3
EP3INT
2
EP2INT
1
EP1INT
0
EP0INT
• EP0INT: Endpoint 0 Interrupt Status
• EP1INT: Endpoint 1 Interrupt Status
• EP2INT: Endpoint 2 Interrupt Status
• EP3INT: Endpoint 3 Interrupt Status
• EP4INT: Endpoint 4 Interrupt Status
• EP5INT: Endpoint 5 Interrupt Status
0 = No Endpoint0 Interrupt pending.
1 = Endpoint0 Interrupt has been raised.
Several signals can generate this interrupt. The reason can be found by reading UDP_CSR0:
RXSETUP set to 1
RX_DATA_BK0 set to 1
RX_DATA_BK1 set to 1
TXCOMP set to 1
STALLSENT set to 1
EP0INT is a sticky bit. Interrupt remains valid until EP0INT is cleared by writing in the corresponding UDP_CSR0 bit.
• RXSUSP: UDP Suspend Interrupt Status
0 = No UDP Suspend Interrupt pending.
1 = UDP Suspend Interrupt has been raised.
The USB device sets this bit when it detects no activity for 3ms. The USB device enters Suspend mode.
• RXRSM: UDP Resume Interrupt Status
0 = No UDP Resume Interrupt pending.
1 =UDP Resume Interrupt has been raised.
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The USB device sets this bit when a UDP resume signal is detected at its port.
After reset, the state of this bit is undefined, the application must clear this bit by setting the RXRSM flag in the UDP_ICR
register.
• EXTRSM: UDP External Resume Interrupt Status
0 = No UDP External Resume Interrupt pending.
1 = UDP External Resume Interrupt has been raised.
• SOFINT: Start of Frame Interrupt Status
0 = No Start of Frame Interrupt pending.
1 = Start of Frame Interrupt has been raised.
This interrupt is raised each time a SOF token has been detected. It can be used as a synchronization signal by using
isochronous endpoints.
• ENDBUSRES: End of BUS Reset Interrupt Status
0 = No End of Bus Reset Interrupt pending.
1 = End of Bus Reset Interrupt has been raised.
This interrupt is raised at the end of a UDP reset sequence. The USB device must prepare to receive requests on the endpoint 0. The host starts the enumeration, then performs the configuration.
• WAKEUP: UDP Resume Interrupt Status
0 = No Wakeup Interrupt pending.
1 = A Wakeup Interrupt (USB Host Sent a RESUME or RESET) occurred since the last clear.
After reset the state of this bit is undefined, the application must clear this bit by setting the
WAKEUP flag in the UDP_ICR register.
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37.6.8
UDP Interrupt Clear Register
Register Name:UDP_ICR
Access Type: Write-only
31
–
30
–
29
–
28
–
27
–
26
–
25
–
24
–
23
–
22
–
21
–
20
–
19
–
18
–
17
–
16
–
15
–
14
–
13
WAKEUP
12
ENDBUSRES
11
SOFINT
10
EXTRSM
9
RXRSM
8
RXSUSP
7
–
6
–
5
–
4
–
3
–
2
–
1
–
0
–
• RXSUSP: Clear UDP Suspend Interrupt
0 = No effect.
1 = Clears UDP Suspend Interrupt.
• RXRSM: Clear UDP Resume Interrupt
0 = No effect.
1 = Clears UDP Resume Interrupt.
• EXTRSM: Clear UDP External Resume Interrupt
0 = No effect.
1 = Clears UDP External Resume Interrupt.
• SOFINT: Clear Start Of Frame Interrupt
0 = No effect.
1 = Clears Start Of Frame Interrupt.
• ENDBUSRES: Clear End of Bus Reset Interrupt
0 = No effect.
1 = Clears End of Bus Reset Interrupt.
• WAKEUP: Clear Wakeup Interrupt
0 = No effect.
1 = Clears Wakeup Interrupt.
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37.6.9
UDP Reset Endpoint Register
Register Name:UDP_RST_EP
Access Type: Read-write
31
–
30
–
29
–
28
–
27
–
26
–
25
–
24
–
23
–
22
–
21
–
20
–
19
–
18
–
17
–
16
–
15
–
14
–
13
–
12
–
11
–
10
–
9
8
–
–
7
6
5
EP5
4
EP4
3
EP3
2
EP2
1
EP1
0
EP0
• EP0: Reset Endpoint 0
• EP1: Reset Endpoint 1
• EP2: Reset Endpoint 2
• EP3: Reset Endpoint 3
• EP4: Reset Endpoint 4
• EP5: Reset Endpoint 5
This flag is used to reset the FIFO associated with the endpoint and the bit RXBYTECOUNT in the register UDP_CSRx.It
also resets the data toggle to DATA0. It is useful after removing a HALT condition on a BULK endpoint. Refer to Chapter
5.8.5 in the USB Serial Bus Specification, Rev.2.0.
Warning: This flag must be cleared at the end of the reset. It does not clear UDP_CSRx flags.
0 = No reset.
1 = Forces the corresponding endpoint FIF0 pointers to 0, therefore RXBYTECNT field is read at 0 in UDP_CSRx register.
Resetting the endpoint is a two-step operation:
1. Set the corresponding EPx field.
2. Clear the corresponding EPx field.
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37.6.10 UDP Endpoint Control and Status Register
Register Name:UDP_CSRx [x = 0..5]
Access Type: Read-write
31
–
30
–
29
–
28
–
27
–
26
25
RXBYTECNT
24
23
22
21
20
19
18
17
16
RXBYTECNT
15
EPEDS
14
–
13
–
12
–
11
DTGLE
10
9
EPTYPE
8
7
6
RX_DATA_
BK1
5
FORCE
STALL
4
3
STALLSENT
ISOERROR
2
1
RX_DATA_
BK0
0
DIR
TXPKTRDY
RXSETUP
TXCOMP
WARNING: Due to synchronization between MCK and UDPCK, the software application must wait for the end of the write
operation before executing another write by polling the bits which must be set/cleared.
//! Clear flags of UDP UDP_CSR register and waits for synchronization
#define Udp_ep_clr_flag(pInterface, endpoint, flags) { \
pInterface->UDP_CSR[endpoint] &= ~(flags); \
while ( (pInterface->UDP_CSR[endpoint] & (flags)) == (flags) ); \
}
//! Set flags of UDP UDP_CSR register and waits for synchronization
#define Udp_ep_set_flag(pInterface, endpoint, flags) { \
pInterface->UDP_CSR[endpoint] |= (flags); \
while ( (pInterface->UDP_CSR[endpoint] & (flags)) != (flags) ); \
}
Note:
In a preemptive environment, set or clear the flag and wait for a time of 1 UDPCK clock cycle and 1peripheral clock cycle. However, RX_DATA_BLK0, TXPKTRDY, RX_DATA_BK1 require wait times of 3 UDPCK clock cycles and 3 peripheral clock cycles
before accessing DPR.
• TXCOMP: Generates an IN Packet with Data Previously Written in the DPR
This flag generates an interrupt while it is set to one.
Write (Cleared by the firmware):
0 = Clear the flag, clear the interrupt.
1 = No effect.
Read (Set by the USB peripheral):
0 = Data IN transaction has not been acknowledged by the Host.
1 = Data IN transaction is achieved, acknowledged by the Host.
After having issued a Data IN transaction setting TXPKTRDY, the device firmware waits for TXCOMP to be sure that the
host has acknowledged the transaction.
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• RX_DATA_BK0: Receive Data Bank 0
This flag generates an interrupt while it is set to one.
Write (Cleared by the firmware):
0 = Notify USB peripheral device that data have been read in the FIFO's Bank 0.
1 = To leave the read value unchanged.
Read (Set by the USB peripheral):
0 = No data packet has been received in the FIFO's Bank 0.
1 = A data packet has been received, it has been stored in the FIFO's Bank 0.
When the device firmware has polled this bit or has been interrupted by this signal, it must transfer data from the FIFO to
the microcontroller memory. The number of bytes received is available in RXBYTCENT field. Bank 0 FIFO values are read
through the UDP_FDRx register. Once a transfer is done, the device firmware must release Bank 0 to the USB peripheral
device by clearing RX_DATA_BK0.
After setting or clearing this bit, a wait time of 3 UDPCK clock cycles and 3 peripheral clock cycles is required before
accessing DPR.
• RXSETUP: Received Setup
This flag generates an interrupt while it is set to one.
Read:
0 = No setup packet available.
1 = A setup data packet has been sent by the host and is available in the FIFO.
Write:
0 = Device firmware notifies the USB peripheral device that it has read the setup data in the FIFO.
1 = No effect.
This flag is used to notify the USB device firmware that a valid Setup data packet has been sent by the host and successfully received by the USB device. The USB device firmware may transfer Setup data from the FIFO by reading the
UDP_FDRx register to the microcontroller memory. Once a transfer has been done, RXSETUP must be cleared by the
device firmware.
Ensuing Data OUT transaction is not accepted while RXSETUP is set.
• STALLSENT: Stall Sent (Control, Bulk Interrupt Endpoints)/ISOERROR (Isochronous Endpoints)
This flag generates an interrupt while it is set to one.
STALLSENT: This ends a STALL handshake.
Read:
0 = The host has not acknowledged a STALL.
1 = Host has acknowledged the stall.
Write:
0 = Resets the STALLSENT flag, clears the interrupt.
1 = No effect.
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This is mandatory for the device firmware to clear this flag. Otherwise the interrupt remains.
Refer to chapters 8.4.5 and 9.4.5 of the Universal Serial Bus Specification, Rev. 2.0 for more information on the STALL
handshake.
ISOERROR: A CRC error has been detected in an isochronous transfer.
Read:
0 = No error in the previous isochronous transfer.
1 = CRC error has been detected, data available in the FIFO are corrupted.
Write:
0 = Resets the ISOERROR flag, clears the interrupt.
1 = No effect.
• TXPKTRDY: Transmit Packet Ready
This flag is cleared by the USB device.
This flag is set by the USB device firmware.
Read:
0 = There is no data to send.
1 = The data is waiting to be sent upon reception of token IN.
Write:
0 = Can be used in the procedure to cancel transmission data. (See, Section 37.5.2.9 “Transmit Data Cancellation” on
page 685)
1 = A new data payload has been written in the FIFO by the firmware and is ready to be sent.
This flag is used to generate a Data IN transaction (device to host). Device firmware checks that it can write a data payload
in the FIFO, checking that TXPKTRDY is cleared. Transfer to the FIFO is done by writing in the UDP_FDRx register. Once
the data payload has been transferred to the FIFO, the firmware notifies the USB device setting TXPKTRDY to one. USB
bus transactions can start. TXCOMP is set once the data payload has been received by the host.
After setting or clearing this bit, a wait time of 3 UDPCK clock cycles and 3 peripheral clock cycles is required before
accessing DPR.
• FORCESTALL: Force Stall (used by Control, Bulk and Isochronous Endpoints)
Read:
0 = Normal state.
1 = Stall state.
Write:
0 = Return to normal state.
1 = Send STALL to the host.
Refer to chapters 8.4.5 and 9.4.5 of the Universal Serial Bus Specification, Rev. 2.0 for more information on the STALL
handshake.
Control endpoints: During the data stage and status stage, this bit indicates that the microcontroller cannot complete the
request.
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Bulk and interrupt endpoints: This bit notifies the host that the endpoint is halted.
The host acknowledges the STALL, device firmware is notified by the STALLSENT flag.
• RX_DATA_BK1: Receive Data Bank 1 (only used by endpoints with ping-pong attributes)
This flag generates an interrupt while it is set to one.
Write (Cleared by the firmware):
0 = Notifies USB device that data have been read in the FIFO’s Bank 1.
1 = To leave the read value unchanged.
Read (Set by the USB peripheral):
0 = No data packet has been received in the FIFO's Bank 1.
1 = A data packet has been received, it has been stored in FIFO's Bank 1.
When the device firmware has polled this bit or has been interrupted by this signal, it must transfer data from the FIFO to
microcontroller memory. The number of bytes received is available in RXBYTECNT field. Bank 1 FIFO values are read
through UDP_FDRx register. Once a transfer is done, the device firmware must release Bank 1 to the USB device by clearing RX_DATA_BK1.
After setting or clearing this bit, a wait time of 3 UDPCK clock cycles and 3 peripheral clock cycles is required before
accessing DPR.
• DIR: Transfer Direction (only available for control endpoints)
Read-write
0 = Allows Data OUT transactions in the control data stage.
1 = Enables Data IN transactions in the control data stage.
Refer to Chapter 8.5.3 of the Universal Serial Bus Specification, Rev. 2.0 for more information on the control data stage.
This bit must be set before UDP_CSRx/RXSETUP is cleared at the end of the setup stage. According to the request sent in
the setup data packet, the data stage is either a device to host (DIR = 1) or host to device (DIR = 0) data transfer. It is not
necessary to check this bit to reverse direction for the status stage.
• EPTYPE[2:0]: Endpoint Type
Read-write
000
Control
001
Isochronous OUT
101
Isochronous IN
010
Bulk OUT
110
Bulk IN
011
Interrupt OUT
111
Interrupt IN
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• DTGLE: Data Toggle
Read-only
0 = Identifies DATA0 packet.
1 = Identifies DATA1 packet.
Refer to Chapter 8 of the Universal Serial Bus Specification, Rev. 2.0 for more information on DATA0, DATA1 packet
definitions.
• EPEDS: Endpoint Enable Disable
Read:
0 = Endpoint disabled.
1 = Endpoint enabled.
Write:
0 = Disables endpoint.
1 = Enables endpoint.
Control endpoints are always enabled. Reading or writing this field has no effect on control endpoints.
Note: After reset, all endpoints are configured as control endpoints (zero).
• RXBYTECNT[10:0]: Number of Bytes Available in the FIFO
Read-only
When the host sends a data packet to the device, the USB device stores the data in the FIFO and notifies the microcontroller. The microcontroller can load the data from the FIFO by reading RXBYTECENT bytes in the UDP_FDRx register.
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37.6.11 UDP FIFO Data Register
Register Name:UDP_FDRx [x = 0..5]
Access Type: Read-write
31
–
30
–
29
–
28
–
27
–
26
–
25
–
24
–
23
–
22
–
21
–
20
–
19
–
18
–
17
–
16
–
15
–
14
–
13
–
12
–
11
–
10
–
9
8
–
–
7
6
5
4
3
2
1
0
FIFO_DATA
• FIFO_DATA[7:0]: FIFO Data Value
The microcontroller can push or pop values in the FIFO through this register.
RXBYTECNT in the corresponding UDP_CSRx register is the number of bytes to be read from the FIFO (sent by the host).
The maximum number of bytes to write is fixed by the Max Packet Size in the Standard Endpoint Descriptor. It can not be
more than the physical memory size associated to the endpoint. Refer to the Universal Serial Bus Specification, Rev. 2.0
for more information.
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37.6.12 UDP Transceiver Control Register
Register Name:UDP_TXVC
Access Type: Read-write
31
–
30
–
29
–
28
–
27
–
26
–
25
–
24
–
23
–
22
–
21
–
20
–
19
–
18
–
17
–
16
–
15
–
14
–
13
–
12
–
11
–
10
–
9
8
PUON
TXVDIS
7
–
6
–
5
–
4
–
3
–
2
–
1
0
–
–
WARNING: The UDP peripheral clock in the Power Management Controller (PMC) must be enabled before any read/write
operations to the UDP registers including the UDP_TXVC register.
• TXVDIS: Transceiver Disable
When UDP is disabled, power consumption can be reduced significantly by disabling the embedded transceiver. This can
be done by setting TXVDIS field.
To enable the transceiver, TXVDIS must be cleared.
• PUON: Pullup On
0: The 1.5KΩ integrated pullup on DP is disconnected.
1: The 1.5 KΩ integrated pullup on DP is connected.
NOTE: If the USB pullup is not connected on DP, the user should not write in any UDP register other than the UDP_TXVC
register. This is because if DP and DM are floating at 0, or pulled down, then SE0 is received by the device with the consequence of a USB Reset.
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38. USB Host Port (UHP)
38.1
Overview
The USB Host Port (UHP) interfaces the USB with the host application. It handles Open HCI
protocol (Open Host Controller Interface) as well as USB v2.0 Full-speed and Low-speed
protocols.
The USB Host Port integrates a root hub and transceivers on downstream ports. It provides several high-speed half-duplex serial communication ports at a baud rate of 12 Mbit/s. Up to 127
USB devices (printer, camera, mouse, keyboard, disk, etc.) and the USB hub can be connected
to the USB host in the USB “tiered star” topology.
The USB Host Port controller is fully compliant with the Open HCI specification. The USB Host
Port User Interface (registers description) can be found in the Open HCI Rev 1.0 Specification
available on http://h18000.www1.hp.com/productinfo/development/openhci.html. The standard
OHCI USB stack driver can be easily ported to Atmel’s architecture in the same way all existing
class drivers run without hardware specialization.
This means that all standard class devices are automatically detected and available to the user
application. As an example, integrating an HID (Human Interface Device) class driver provides a
plug & play feature for all USB keyboards and mouses.
38.2
Block Diagram
Figure 38-1. Block Diagram
Access to the USB host operational registers is achieved through the AHB bus slave interface.
The Open HCI host controller initializes master DMA transfers through the ASB bus master interface as follows:
• Fetches endpoint descriptors and transfer descriptors
• Access to endpoint data from system memory
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• Access to the HC communication area
• Write status and retire transfer Descriptor
Memory access errors (abort, misalignment) lead to an “Unrecoverable Error” indicated by the
corresponding flag in the host controller operational registers.
The USB root hub is integrated in the USB host. Several USB downstream ports are available.
The number of downstream ports can be determined by the software driver reading the root
hub’s operational registers. Device connection is automatically detected by the USB host port
logic.
USB physical transceivers are integrated in the product and driven by the root hub’s ports.
Over current protection on ports can be activated by the USB host controller. Atmel’s standard
product does not dedicate pads to external over current protection.
38.3
38.3.1
Product Dependencies
I/O Lines
DPs and DMs are not controlled by any PIO controllers. The embedded USB physical transceivers are controlled by the USB host controller.
38.3.2
Power Management
The USB host controller requires a 48 MHz clock. This clock must be generated by a PLL with a
correct accuracy of ± 0.25%.
Thus the USB device peripheral receives two clocks from the Power Management Controller
(PMC): the master clock MCK used to drive the peripheral user interface (MCK domain) and the
UHPCLK 48 MHz clock used to interface with the bus USB signals (Recovered 12 MHz domain).
38.3.3
Interrupt
The USB host interface has an interrupt line connected to the Advanced Interrupt Controller
(AIC).
Handling USB host interrupts requires programming the AIC before configuring the UHP.
38.4
Functional Description
Please refer to the Open Host Controller Interface Specification for USB Release 1.0.a.
38.4.1
Host Controller Interface
There are two communication channels between the Host Controller and the Host Controller
Driver. The first channel uses a set of operational registers located on the USB Host Controller.
The Host Controller is the target for all communications on this channel. The operational registers contain control, status and list pointer registers. They are mapped in the memory mapped
area. Within the operational register set there is a pointer to a location in the processor address
space named the Host Controller Communication Area (HCCA). The HCCA is the second communication channel. The host controller is the master for all communication on this channel. The
HCCA contains the head pointers to the interrupt Endpoint Descriptor lists, the head pointer to
the done queue and status information associated with start-of-frame processing.
The basic building blocks for communication across the interface are Endpoint Descriptors (ED,
4 double words) and Transfer Descriptors (TD, 4 or 8 double words). The host controller assigns
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an Endpoint Descriptor to each endpoint in the system. A queue of Transfer Descriptors is linked
to the Endpoint Descriptor for the specific endpoint.
Figure 38-2. USB Host Communication Channels
38.4.2
Host Controller Driver
Figure 38-3. USB Host Drivers
USB Handling is done through several layers as follows:
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• Host controller hardware and serial engine: Transmits and receives USB data on the bus.
• Host controller driver: Drives the Host controller hardware and handles the USB protocol.
• USB Bus driver and hub driver: Handles USB commands and enumeration. Offers a
hardware independent interface.
• Mini driver: Handles device specific commands.
• Class driver: Handles standard devices. This acts as a generic driver for a class of devices,
for example the HID driver.
38.5
Typical Connection
Figure 38-4. Board Schematic to Interface UHP Device Controller
A termination serial resistor must be connected to HDP and HDM. The resistor value is defined
in the electrical specification of the product (REXT).
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39. Image Sensor Interface (ISI)
39.1
Overview
The Image Sensor Interface (ISI) connects a CMOS-type image sensor to the processor and
provides image capture in various formats. It does data conversion, if necessary, before the storage in memory through DMA.
The ISI supports color CMOS image sensor and grayscale image sensors with a reduced set of
functionalities.
In grayscale mode, the data stream is stored in memory without any processing and so is not
compatible with the LCD controller.
Internal FIFOs on the preview and codec paths are used to store the incoming data. The RGB
output on the preview path is compatible with the LCD controller. This module outputs the data
in RGB format (LCD compatible) and has scaling capabilities to make it compliant to the LCD
display resolution (See Table 39-3 on page 716).
Several input formats such as preprocessed RGB or YCbCr are supported through the data bus
interface.
It supports two modes of synchronization:
1. The hardware with ISI_VSYNC and ISI_HSYNC signals
2. The International Telecommunication Union Recommendation ITU-R BT.656-4 Start-ofActive-Video (SAV) and End-of-Active-Video (EAV) synchronization sequence.
Using EAV/SAV for synchronization reduces the pin count (ISI_VSYNC, ISI_HSYNC not used).
The polarity of the synchronization pulse is programmable to comply with the sensor signals.
Table 39-1.
I/O Description
Signal
Dir
Description
ISI_VSYNC
IN
Vertical Synchronization
ISI_HSYNC
IN
Horizontal Synchronization
ISI_DATA[11..0]
IN
Sensor Pixel Data
ISI_MCK
OUT
ISI_PCK
IN
Master Clock Provided to the Image Sensor
Pixel Clock Provided by the Image Sensor
Figure 39-1. ISI Connection Example
Image Sensor
Image Sensor Interface
data[11..0]
ISI_DATA[11..0]
CLK
ISI_MCK
PCLK
ISI_PCK
VSYNC
ISI_VSYNC
HSYNC
ISI_HSYNC
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39.2
Block Diagram
Timing Signals
Interface
CCIR-656
Embedded Timing
Decoder(SAV/EAV)
CMOS
sensor
Pixel input
up to 12 bit
YCbCr 4:2:2
8:8:8
RGB 5:6:5
CMOS
sensor
pixel clock
input
39.3
Config
Registers
Camera
Interrupt
Controller
Camera
Interrupt Request Line
From
Rx buffers
Pixel
Clock Domain
APB
Interface
APB
Clock Domain
AHB
Clock Domain
Frame Rate
Clipping + Color
Conversion
YCC to RGB
Pixel Sampling
Module
Clipping + Color
Conversion
RGB to YCC
2-D Image
Scaler
Pixel
Formatter
Packed
Formatter
Rx Direct
Display
FIFO
Rx Direct
Capture
FIFO
Core
Video
Arbiter
Camera
AHB
Master
Interface
Scatter
Mode
Support
AHB bus
Hsync/Len
Vsync/Fen
APB bus
Figure 39-2. Image Sensor Interface Block Diagram
codec_on
Functional Description
The Image Sensor Interface (ISI) supports direct connection to the ITU-R BT. 601/656 8-bit
mode compliant sensors and up to 12-bit grayscale sensors. It receives the image data stream
from the image sensor on the 12-bit data bus.
This module receives up to 12 bits for data, the horizontal and vertical synchronizations and the
pixel clock. The reduced pin count alternative for synchronization is supported for sensors that
embed SAV (start of active video) and EAV (end of active video) delimiters in the data stream.
The Image Sensor Interface interrupt line is generally connected to the Advanced Interrupt Controller and can trigger an interrupt at the beginning of each frame and at the end of a DMA frame
transfer. If the SAV/EAV synchronization is used, an interrupt can be triggered on each delimiter
event.
For 8-bit color sensors, the data stream received can be in several possible formats: YCbCr
4:2:2, RGB 8:8:8, RGB 5:6:5 and may be processed before the storage in memory. The data
stream may be sent on both preview path and codec path if the bit CODEC_ON in the ISI_CR1
is one. To optimize the bandwidth, the codec path should be enabled only when a capture is
required.
In grayscale mode, the input data stream is stored in memory without any processing. The 12-bit
data, which represent the grayscale level for the pixel, is stored in memory one or two pixels per
word, depending on the GS_MODE bit in the ISI_CR2 register. The codec datapath is not available when grayscale image is selected.
A frame rate counter allows users to capture all frames or 1 out of every 2 to 8 frames.
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39.3.1
Data Timing
The two data timings using horizontal and vertical synchronization and EAV/SAV sequence synchronization are shown in Figure 39-3 and Figure 39-4.
In the VSYNC/HSYNC synchronization, the valid data is captured with the active edge of the
pixel clock (ISI_PCK), after SFD lines of vertical blanking and SLD pixel clock periods delay programmed in the control register.
The ITU-RBT.656-4 defines the functional timing for an 8-bit wide interface.
There are two timing reference signals, one at the beginning of each video data block SAV
(0xFF000080) and one at the end of each video data block EAV(0xFF00009D). Only data sent
between EAV and SAV is captured. Horizontal blanking and vertical blanking are ignored. Use of
the SAV and EAV synchronization eliminates the ISI_VSYNC and ISI_HSYNC signals from the
interface, thereby reducing the pin count. In order to retrieve both frame and line synchronization
properly, at least one line of vertical blanking is mandatory.
Figure 39-3. HSYNC and VSYNC Synchronization
Frame
ISI_VSYNC
1 line
ISI_HSYNC
ISI_PCK
DATA[7..0]
Y
Cb
Y
Cr
Y
Cb
Y
Cr
Y
Cb
Y
Y
Cr
Cr
Figure 39-4. SAV and EAV Sequence Synchronization
ISII_PCK
DATA[7..0]
FF
00 00
SAV
80
Y
Cb
Y
Cr
Y
Cb Y
Cr
Active Video
Y
Y
Cb FF
00 00
EAV
9D
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39.3.2
Data Ordering
The RGB color space format is required for viewing images on a display screen preview, and the
YCbCr color space format is required for encoding.
All the sensors do not output the YCbCr or RGB components in the same order. The ISI allows
the user to program the same component order as the sensor, reducing software treatments to
restore the right format.
Table 39-2.
Table 39-3.
Mode
Data Ordering in YCbCr Mode
Mode
Byte 0
Byte 1
Byte 2
Byte 3
Default
Cb(i)
Y(i)
Cr(i)
Y(i+1)
Mode1
Cr(i)
Y(i)
Cb(i)
Y(i+1)
Mode2
Y(i)
Cb(i)
Y(i+1)
Cr(i)
Mode3
Y(i)
Cr(i)
Y(i+1)
Cb(i)
RGB Format in Default Mode, RGB_CFG = 00, No Swap
Byte
D7
D6
D5
D4
D3
D2
D1
D0
Byte 0
R7(i)
R6(i)
R5(i)
R4(i)
R3(i)
R2(i)
R1(i)
R0(i)
Byte 1
G7(i)
G6(i)
G5(i)
G4(i)
G3(i)
G2(i)
G1(i)
G0(i)
Byte 2
B7(i)
B6(i)
B5(i)
B4(i)
B3(i)
B2(i)
B1(i)
B0(i)
Byte 3
R7(i+1)
R6(i+1)
R5(i+1)
R4(i+1)
R3(i+1)
R2(i+1)
R1(i+1)
R0(i+1)
Byte 0
R4(i)
R3(i)
R2(i)
R1(i)
R0(i)
G5(i)
G4(i)
G3(i)
Byte 1
G2(i)
G1(i)
G0(i)
B4(i)
B3(i)
B2(i)
B1(i)
B0(i)
Byte 2
R4(i+1)
R3(i+1)
R2(i+1)
R1(i+1)
R0(i+1)
G5(i+1)
G4(i+1)
G3(i+1)
Byte 3
G2(i+1)
G1(i+1)
G0(i+1)
B4(i+1)
B3(i+1)
B2(i+1)
B1(i+1)
B0(i+1)
RGB 8:8:8
RGB 5:6:5
Table 39-4.
Mode
RGB Format, RGB_CFG = 10 (Mode 2), No Swap
Byte
D7
D6
D5
D4
D3
D2
D1
D0
Byte 0
G2(i)
G1(i)
G0(i)
R4(i)
R3(i)
R2(i)
R1(i)
R0(i)
Byte 1
B4(i)
B3(i)
B2(i)
B1(i)
B0(i)
G5(i)
G4(i)
G3(i)
Byte 2
G2(i+1)
G1(i+1)
G0(i+1)
R4(i+1)
R3(i+1)
R2(i+1)
R1(i+1)
R0(i+1)
Byte 3
B4(i+1)
B3(i+1)
B2(i+1)
B1(i+1)
B0(i+1)
G5(i+1)
G4(i+1)
G3(i+1)
RGB 5:6:5
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Table 39-5.
Mode
RGB Format in Default Mode, RGB_CFG = 00, Swap Activated
Byte
D7
D6
D5
D4
D3
D2
D1
D0
Byte 0
R0(i)
R1(i)
R2(i)
R3(i)
R4(i)
R5(i)
R6(i)
R7(i)
Byte 1
G0(i)
G1(i)
G2(i)
G3(i)
G4(i)
G5(i)
G6(i)
G7(i)
Byte 2
B0(i)
B1(i)
B2(i)
B3(i)
B4(i)
B5(i)
B6(i)
B7(i)
Byte 3
R0(i+1)
R1(i+1)
R2(i+1)
R3(i+1)
R4(i+1)
R5(i+1)
R6(i+1)
R7(i+1)
Byte 0
G3(i)
G4(i)
G5(i)
R0(i)
R1(i)
R2(i)
R3(i)
R4(i)
Byte 1
B0(i)
B1(i)
B2(i)
B3(i)
B4(i)
G0(i)
G1(i)
G2(i)
Byte 2
G3(i+1)
G4(i+1)
G5(i+1)
R0(i+1)
R1(i+1)
R2(i+1)
R3(i+1)
R4(i+1)
Byte 3
B0(i+1)
B1(i+1)
B2(i+1)
B3(i+1)
B4(i+1)
G0(i+1)
G1(i+1)
G2(i+1)
RGB 8:8:8
RGB 5:6:5
The RGB 5:6:5 input format is processed to be displayed as RGB 5:5:5 format, compliant with
the 16-bit mode of the LCD controller.
39.3.3
Clocks
The sensor master clock (ISI_MCK) can be generated either by the Advanced Power Management Controller (APMC) through a Programmable Clock output or by an external oscillator
connected to the sensor.
None of the sensors embeds a power management controller, so providing the clock by the
APMC is a simple and efficient way to control power consumption of the system.
Care must be taken when programming the system clock. The ISI has two clock domains, the
system bus clock and the pixel clock provided by sensor. The two clock domains are not synchronized, but the system clock must be faster than pixel clock.
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39.3.4
Preview Path
39.3.4.1
Scaling, Decimation (Subsampling)
This module resizes captured 8-bit color sensor images to fit the LCD display format. The resize
module performs only downscaling. The same ratio is applied for both horizontal and vertical
resize, then a fractional decimation algorithm is applied.
The decimation factor is a multiple of 1/16 and values 0 to 15 are forbidden.
Table 39-6.
Decimation Factor
Dec value
0->15
16
17
18
19
...
124
125
126
127
Dec Factor
X
1
1.063
1.125
1.188
...
7.750
7.813
7.875
7.938
Table 39-7.
Decimation and Scaler Offset Values
INPUT
OUTPUT
352*288
640*480
800*600
1280*1024
1600*1200
2048*1536
VGA
640*480
F
NA
16
20
32
40
51
QVGA
320*240
F
16
32
40
64
80
102
CIF
352*288
F
16
26
33
56
66
85
QCIF
176*144
F
16
53
66
113
133
170
Example:
Input 1280*1024 Output=640*480
Hratio = 1280/640 =2
Vratio = 1024/480 =2.1333
The decimation factor is 2 so 32/16.
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Figure 39-5. Resize Examples
1280
32/16 decimation
640
1024
480
1280
56/16 decimation
352
1024
39.3.4.2
288
Color Space Conversion
This module converts YCrCb or YUV pixels to RGB color space. Clipping is performed to ensure
that the samples value do not exceed the allowable range. The conversion matrix is defined
below and is fully programmable:
C0 0 C1
Y – Y off
R
=
×
C
–
C
–
C
C
G
0
2
3
b – C boff
B
C0 C4 0
C r – C roff
Example of programmable value to convert YCrCb to RGB:
⎧ R = 1.164 ⋅ ( Y – 16 ) + 1.596 ⋅ ( C r – 128 )
⎪
⎨ G = 1.164 ⋅ ( Y – 16 ) – 0.813 ⋅ ( C r – 128 ) – 0.392 ⋅ ( C b – 128 )
⎪
⎩ B = 1.164 ⋅ ( Y – 16 ) + 2.107 ⋅ ( C b – 128 )
An example of programmable value to convert from YUV to RGB:
⎧ R = Y + 1.596 ⋅ V
⎪
⎨ G = Y – 0.394 ⋅ U – 0.436 ⋅ V
⎪ B = Y + 2.032 ⋅ U
⎩
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39.3.4.3
Memory Interface
Preview datapath contains a data formatter that converts 8:8:8 pixel to RGB 5:5:5 format compliant with 16-bit format of the LCD controller. In general, when converting from a color channel
with more bits to one with fewer bits, formatter module discards the lower-order bits. Example:
Converting from RGB 8:8:8 to RGB 5:6:5, it discards the three LSBs from the red and blue channels, and two LSBs from the green channel. When grayscale mode is enabled, two memory
format are supported. One mode supports 2 pixels per word, and the other mode supports 1
pixel per word.
Table 39-8.
39.3.4.4
Grayscale Memory Mapping Configuration for 12-bit Data
GS_MODE
DATA[31:24]
DATA[23:16]
DATA[15:8]
DATA[7:0]
0
P_0[11:4]
P_0[3:0], 0000
P_1[11:4]
P_1[3:0], 0000
1
P_0[11:4]
P_0[3:0], 0000
0
0
FIFO and DMA Features
Both preview and Codec datapaths contain FIFOs, asynchronous buffers that are used to safely
transfer formatted pixels from Pixel clock domain to AHB clock domain. A video arbiter is used to
manage FIFO thresholds and triggers a relevant DMA request through the AHB master interface. Thus, depending on FIFO state, a specified length burst is asserted. Regarding AHB
master interface, it supports Scatter DMA mode through linked list operation. This mode of operation improves flexibility of image buffer location and allows the user to allocate two or more
frame buffers. The destination frame buffers are defined by a series of Frame Buffer Descriptors
(FBD). Each FBD controls the transfer of one entire frame and then optionally loads a further
FBD to switch the DMA operation at another frame buffer address. The FBD is defined by a
series of two words. The first one defines the current frame buffer address, and the second
defines the next FBD memory location. This DMA transfer mode is only available for preview
datapath and is configured in the ISI_PPFBD register that indicates the memory location of the
first FBD.
The primary FBD is programmed into the camera interface controller. The data to be transferred
described by an FBD requires several burst access. In the example below, the use of 2 pingpong frame buffers is described.
Example
The first FBD, stored at address 0x30000, defines the location of the first frame buffer.
Destination Address: frame buffer ID0 0x02A000
Next FBD address: 0x30010
Second FBD, stored at address 0x30010, defines the location of the second frame buffer.
Destination Address: frame buffer ID1 0x3A000
Transfer width: 32 bit
Next FBD address: 0x30000, wrapping to first FBD.
Using this technique, several frame buffers can be configured through the linked list. Figure 39-6
illustrates a typical three frame buffer application. Frame n is mapped to frame buffer 0, frame
n+1 is mapped to frame buffer 1, frame n+2 is mapped to Frame buffer 2, further frames wrap. A
codec request occurs, and the full-size 4:2:2 encoded frame is stored in a dedicated memory
space.
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Figure 39-6. Three Frame Buffers Application and Memory Mapping
Codec Done
Codec Request
frame n-1
frame n
frame n+1
frame n+2
frame n+3
frame n+4
Memory Space
Frame Buffer 3
Frame Buffer 0
LCD
Frame Buffer 1
ISI config Space
4:2:2 Image
Full ROI
39.3.5
39.3.5.1
Codec Path
Color Space Conversion
Depending on user selection, this module can be bypassed so that input YCrCb stream is
directly connected to the format converter module. If the RGB input stream is selected, this module converts RGB to YCrCb color space with the formulas given below:
Y
Cr =
Cb
C0 C1 C2
Y off
R
C 3 – C 4 – C 5 × G + Cr off
B
–C6 –C7 C8
Cb off
An example of coefficients is given below:
⎧ Y = 0.257 ⋅ R + 0.504 ⋅ G + 0.098 ⋅ B + 16
⎪ C = 0.439 ⋅ R – 0.368 ⋅ G – 0.071 ⋅ B + 128
⎨ r
⎪ C = – 0.148 ⋅ R – 0.291 ⋅ G + 0.439 ⋅ B + 128
⎩ b
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39.3.5.2
Memory Interface
Dedicated FIFO are used to support packed memory mapping. YCrCb pixel components are
sent in a single 32-bit word in a contiguous space (packed). Data is stored in the order of natural
scan lines. Planar mode is not supported.
39.3.5.3
DMA Features
Unlike preview datapath, codec datapath DMA mode does not support linked list operation. Only
the CODEC_DMA_ADDR register is used to configure the frame buffer base address.
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39.4
Image Sensor Interface (ISI) User Interface
Table 39-9.
ISI Memory Mapping
Offset
Register
Register
Access
Reset
0x00
ISI Control 1 Register
ISI_CR1
Read-write
0x00000002
0x04
ISI Control 2 Register
ISI_CR2
Read-write
0x00000000
0x08
ISI Status Register
ISI_SR
Read
0x00000000
0x0C
ISI Interrupt Enable Register
ISI_IER
Read-write
0x00000000
0x10
ISI Interrupt Disable Register
ISI_IDR
Read-write
0x00000000
0x14
ISI Interrupt Mask Register
ISI_IMR
Read-write
0x00000000
0x18
Reserved
-
-
-
0x1C
Reserved
-
-
-
0x20
ISI Preview Size Register
ISI_PSIZE
Read-write
0x00000000
0x24
ISI Preview Decimation Factor Register
ISI_PDECF
Read-write
0x00000010
0x28
ISI Preview Primary FBD Register
ISI_PPFBD
Read-write
0x00000000
0x2C
ISI Codec DMA Base Address Register
ISI_CDBA
Read-write
0x00000000
0x30
ISI CSC YCrCb To RGB Set 0 Register
ISI_Y2R_SET0
Read-write
0x6832cc95
0x34
ISI CSC YCrCb To RGB Set 1 Register
ISI_Y2R_SET1
Read-write
0x00007102
0x38
ISI CSC RGB To YCrCb Set 0 Register
ISI_R2Y_SET0
Read-write
0x01324145
0x3C
ISI CSC RGB To YCrCb Set 1 Register
ISI_R2Y_SET1
Read-write
0x01245e38
0x40
ISI CSC RGB To YCrCb Set 2 Register
ISI_R2Y_SET2
Read-write
0x01384a4b
0x44-0xF8
Reserved
–
–
–
0xFC
Reserved
–
–
–
Note:
Several parts of the ISI controller use the pixel clock provided by the image sensor (ISI_PCK). Thus the user must first program
the image sensor to provide this clock (ISI_PCK) before programming the Image Sensor Controller.
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39.4.1
ISI Control 1 Register
Register Name: ISI_CR1
Access Type: Read-write
Reset Value: 0x00000002
31
30
29
28
27
26
25
24
19
18
17
16
SFD
23
22
21
20
SLD
15
CODEC_ON
14
7
CRC_SYNC
6
EMB_SYNC
13
12
FULL
11
-
10
9
FRATE
8
5
-
4
PIXCLK_POL
3
VSYNC_POL
2
HSYNC_POL
1
ISI_DIS
0
ISI_RST
THMASK
• ISI_RST: Image Sensor Interface Reset
Write-only. Refer to bit SOFTRST in Section 39.4.3 “ISI Status Register” on page 728 for soft reset status.
0: No action
1: Resets the image sensor interface.
• ISI_DIS: Image Sensor Disable:
0: Enable the image sensor interface.
1: Finish capturing the current frame and then shut down the module.
• HSYNC_POL: Horizontal Synchronization Polarity
0: HSYNC active high
1: HSYNC active low
• VSYNC_POL: Vertical sYnchronization Polarity
0: VSYNC active high
1: VSYNC active low
• PIXCLK_POL: Pixel Clock Polarity
0: Data is sampled on rising edge of pixel clock
1: Data is sampled on falling edge of pixel clock
• EMB_SYNC: Embedded Synchronization
0: Synchronization by HSYNC, VSYNC
1: Synchronization by embedded synchronization sequence SAV/EAV
• CRC_SYNC: Embedded Synchronization
0: No CRC correction is performed on embedded synchronization
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1: CRC correction is performed. if the correction is not possible, the current frame is discarded and the CRC_ERR is set in
the status register.
• FRATE: Frame Rate [0..7]
0: All the frames are captured, else one frame every FRATE+1 is captured.
• FULL: Full Mode is Allowed
1: Both codec and preview datapaths are working simultaneously
• THMASK: Threshold Mask
0: 4, 8 and 16 AHB bursts are allowed
1: 8 and 16 AHB bursts are allowed
2: Only 16 AHB bursts are allowed
• CODEC_ON: Enable the Codec Path Enable Bit
Write-only.
0: The codec path is disabled
1: The codec path is enabled and the next frame is captured. Refer to bit CDC_PND in “ISI Status Register” on page 728.
• SLD: Start of Line Delay
SLD pixel clock periods to wait before the beginning of a line.
• SFD: Start of Frame Delay
SFD lines are skipped at the beginning of the frame.
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39.4.2
ISI Control 2 Register
Register Name: ISI_CR2
Access Type: Read-write
Reset Value: 0x0
31
30
29
RGB_CFG
23
28
YCC_SWAP
22
21
20
27
-
26
25
IM_HSIZE
24
19
18
17
16
IM_HSIZE
15
COL_SPACE
14
RGB_SWAP
13
GRAYSCALE
12
RGB_MODE
11
GS_MODE
10
9
IM_VSIZE
8
7
6
5
4
3
2
1
0
IM_VSIZE
• IM_VSIZE: Vertical Size of the Image Sensor [0..2047]
Vertical size = IM_VSIZE + 1
• GS_MODE
0: 2 pixels per word
1: 1 pixel per word
• RGB_MODE: RGB Input Mode
0: RGB 8:8:8 24 bits
1: RGB 5:6:5 16 bits
• GRAYSCALE
0: Grayscale mode is disabled
1: Input image is assumed to be grayscale coded
• RGB_SWAP
0: D7 -> R7
1: D0 -> R7
The RGB_SWAP has no effect when the grayscale mode is enabled.
• COL_SPACE: Color Space for The Image Data
0: YCbCr
1: RGB
• IM_HSIZE: Horizontal Size of the Image Sensor [0..2047]
Horizontal size = IM_HSIZE + 1
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• YCC_SWAP: Defines the YCC Image Data
YCC_SWAP
Byte 0
Byte 1
Byte 2
Byte 3
00: Default
Cb(i)
Y(i)
Cr(i)
Y(i+1)
01: Mode1
Cr(i)
Y(i)
Cb(i)
Y(i+1)
10: Mode2
Y(i)
Cb(i)
Y(i+1)
Cr(i)
11: Mode3
Y(i)
Cr(i)
Y(i+1)
Cb(i)
• RGB_CFG: Defines RGB Pattern when RGB_MODE is set to 1
RGB_CFG
Byte 0
Byte 1
Byte 2
Byte 3
00: Default
R/G(MSB)
G(LSB)/B
R/G(MSB)
G(LSB)/B
01: Mode1
B/G(MSB)
G(LSB)/R
B/G(MSB)
G(LSB)/R
10: Mode2
G(LSB)/R
B/G(MSB)
G(LSB)/R
B/G(MSB)
11: Mode3
G(LSB)/B
R/G(MSB)
G(LSB)/B
R/G(MSB)
If RGB_MODE is set to RGB 8:8:8, then RGB_CFG = 0 implies RGB color sequence, else it implies BGR color sequence.
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39.4.3
ISI Status Register
Register Name: ISI_SR
Access Type: Read
Reset Value: 0x0
31
–
30
–
29
–
28
–
27
–
26
–
25
–
24
–
23
–
22
–
21
–
20
–
19
–
18
–
17
–
16
–
15
–
14
–
13
–
12
–
11
–
10
–
9
FR_OVR
8
FO_C_EMP
7
FO_P_EMP
6
FO_P_OVF
5
FO_C_OVF
4
CRC_ERR
3
CDC_PND
2
SOFTRST
1
DIS
0
SOF
• SOF: Start of Frame
0: No start of frame has been detected.
1: A start of frame has been detected.
• DIS: Image Sensor Interface Disable
0: The image sensor interface is enabled.
1: The image sensor interface is disabled and stops capturing data. The DMA controller and the core can still read the
FIFOs.
• SOFTRST: Software Reset
0: Software reset not asserted or not completed.
1: Software reset has completed successfully.
• CDC_PND: Codec Request Pending
0: No request asserted.
1: A codec request is pending. If a codec request is asserted during a frame, the CDC_PND bit rises until the start of a new
frame. The capture is completed when the flag FO_C_EMP = 1.
• CRC_ERR: CRC Synchronization Error
0: No CRC error in the embedded synchronization frame (SAV/EAV)
1: The CRC_SYNC is enabled in the control register and an error has been detected and not corrected. The frame is discarded and the ISI waits for a new one.
• FO_C_OVF: FIFO Codec Overflow
0: No overflow
1: An overrun condition has occurred in input FIFO on the codec path. The overrun happens when the FIFO is full and an
attempt is made to write a new sample to the FIFO.
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• FO_P_OVF: FIFO Preview Overflow
0: No overflow
1: An overrun condition has occurred in input FIFO on the preview path. The overrun happens when the FIFO is full and an
attempt is made to write a new sample to the FIFO.
• FO_P_EMP
0:The DMA has not finished transferring all the contents of the preview FIFO.
1:The DMA has finished transferring all the contents of the preview FIFO.
• FO_C_EMP
0: The DMA has not finished transferring all the contents of the codec FIFO.
1: The DMA has finished transferring all the contents of the codec FIFO.
• FR_OVR: Frame Rate Overrun
0: No frame overrun.
1: Frame overrun, the current frame is being skipped because a vsync signal has been detected while flushing FIFOs.
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39.4.4
Interrupt Enable Register
Register Name: ISI_IER
Access Type: Read-write
Reset Value: 0x0
31
–
30
–
29
–
28
–
27
–
26
–
25
–
24
–
23
–
22
–
21
–
20
–
19
–
18
–
17
–
16
–
15
–
14
–
13
–
12
–
11
–
10
–
9
FR_OVR
8
FO_C_EMP
7
FO_P_EMP
6
FO_P_OVF
5
FO_C_OVF
4
CRC_ERR
3
–
2
SOFTRST
1
DIS
0
SOF
• SOF: Start of Frame
1: Enables the Start of Frame interrupt.
• DIS: Image Sensor Interface Disable
1: Enables the DIS interrupt.
• SOFTRST: Soft Reset
1: Enables the Soft Reset Completion interrupt.
• CRC_ERR: CRC Synchronization Error
1: Enables the CRC_SYNC interrupt.
• FO_C_OVF: FIFO Codec Overflow
1: Enables the codec FIFO overflow interrupt.
• FO_P_OVF: FIFO Preview Overflow
1: Enables the preview FIFO overflow interrupt.
• FO_P_EMP
1: Enables the preview FIFO empty interrupt.
• FO_C_EMP
1: Enables the codec FIFO empty interrupt.
• FR_OVR: Frame Overrun
1: Enables the Frame overrun interrupt.
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39.4.5
ISI Interrupt Disable Register
Register Name: ISI_IDR
Access Type: Read-write
Reset Value: 0x0
31
–
30
–
29
–
28
–
27
–
26
–
25
–
24
–
23
–
22
–
21
–
20
–
19
–
18
–
17
–
16
–
15
–
14
–
13
–
12
–
11
–
10
–
9
FR_OVR
8
FO_C_EMP
7
FO_P_EMP
6
FO_P_OVF
5
FO_C_OVF
4
CRC_ERR
3
–
2
SOFTRST
1
DIS
0
SOF
• SOF: Start of Frame
1: Disables the Start of Frame interrupt.
• DIS: Image Sensor Interface Disable
1: Disables the DIS interrupt.
• SOFTRST
1: Disables the soft reset completion interrupt.
• CRC_ERR: CRC Synchronization Error
1: Disables the CRC_SYNC interrupt.
• FO_C_OVF: FIFO Codec Overflow
1: Disables the codec FIFO overflow interrupt.
• FO_P_OVF: FIFO Preview Overflow
1: Disables the preview FIFO overflow interrupt.
• FO_P_EMP
1: Disables the preview FIFO empty interrupt.
• FO_C_EMP
1: Disables the codec FIFO empty interrupt.
• FR_OVR
1: Disables frame overrun interrupt.
731
6384E–ATARM–05-Feb-10
39.4.6
ISI Interrupt Mask Register
Register Name: ISI_IMR
Access Type: Read-write
Reset Value: 0x0
31
–
30
–
29
–
28
–
27
–
26
–
25
–
24
–
23
–
22
–
21
–
20
–
19
–
18
–
17
–
16
–
15
–
14
–
13
–
12
–
11
–
10
–
9
FR_OVR
8
FO_C_EMP
7
FO_P_EMP
6
FO_P_OVF
5
FO_C_OVF
4
CRC_ERR
3
–
2
SOFTRST
1
DIS
0
SOF
• SOF: Start of Frame
0: The Start of Frame interrupt is disabled.
1: The Start of Frame interrupt is enabled.
• DIS: Image Sensor Interface Disable
0: The DIS interrupt is disabled.
1: The DIS interrupt is enabled.
• SOFTRST
0: The soft reset completion interrupt is enabled.
1: The soft reset completion interrupt is disabled.
• CRC_ERR: CRC Synchronization Error
0: The CRC_SYNC interrupt is disabled.
1: The CRC_SYNC interrupt is enabled.
• FO_C_OVF: FIFO Codec Overflow
0: The codec FIFO overflow interrupt is disabled.
1: The codec FIFO overflow interrupt is enabled.
• FO_P_OVF: FIFO Preview Overflow
0: The preview FIFO overflow interrupt is disabled.
1: The preview FIFO overflow interrupt is enabled.
• FO_P_EMP
0: The preview FIFO empty interrupt is disabled.
1: The preview FIFO empty interrupt is enabled.
732
AT91SAM9G20
6384E–ATARM–05-Feb-10
AT91SAM9G20
• FO_C_EMP
0: The codec FIFO empty interrupt is disabled.
1: The codec FIFO empty interrupt is enabled.
• FR_OVR: Frame Rate Overrun
0: The frame overrun interrupt is disabled.
1: The frame overrun interrupt is enabled.
733
6384E–ATARM–05-Feb-10
39.4.7
ISI Preview Register
Register Name: ISI_PSIZE
Access Type: Read-write
Reset Value: 0x0
31
–
30
–
29
–
28
–
23
22
21
20
27
–
26
–
25
19
18
17
24
PREV_HSIZE
16
PREV_HSIZE
15
–
14
–
13
–
12
–
11
–
10
–
9
7
6
5
4
3
2
1
8
PREV_VSIZE
0
PREV_VSIZE
• PREV_VSIZE: Vertical Size for the Preview Path
Vertical Preview size = PREV_VSIZE + 1 (480 max only in RGB mode).
• PREV_HSIZE: Horizontal Size for the Preview Path
Horizontal Preview size = PREV_HSIZE + 1 (640 max only in RGB mode).
734
AT91SAM9G20
6384E–ATARM–05-Feb-10
AT91SAM9G20
39.4.8
ISI Preview Decimation Factor Register
Register Name: ISI_PDECF
Access Type: Read-write
Reset Value: 0x00000010
31
–
30
–
29
–
28
–
27
–
26
–
25
–
24
–
23
–
22
–
21
–
20
–
19
–
18
–
17
–
16
–
15
–
14
–
13
–
12
–
11
–
10
–
9
–
8
–
7
6
5
4
3
2
1
0
DEC_FACTOR
• DEC_FACTOR: Decimation Factor
DEC_FACTOR is 8-bit width, range is from 16 to 255. Values from 0 to 16 do not perform any decimation.
735
6384E–ATARM–05-Feb-10
39.4.9
ISI Preview Primary FBD Register
Register Name: ISI_PPFBD
Access Type: Read-write
Reset Value: 0x0
31
30
29
28
27
PREV_FBD_ADDR
26
25
24
23
22
21
20
19
PREV_FBD_ADDR
18
17
16
15
14
13
12
11
PREV_FBD_ADDR
10
9
8
7
6
5
4
3
PREV_FBD_ADDR
2
1
0
• PREV_FBD_ADDR: Base Address for Preview Frame Buffer Descriptor
Written with the address of the start of the preview frame buffer queue, reads as a pointer to the current buffer being used.
The frame buffer is forced to word alignment.
736
AT91SAM9G20
6384E–ATARM–05-Feb-10
AT91SAM9G20
39.4.10 ISI Codec DMA Base Address Register
Register Name: ISI_CDBA
Access Type: Read-write
Reset Value: 0x0
31
30
29
28
27
CODEC_DMA_ADDR
26
25
24
23
22
21
20
19
CODEC_DMA_ADDR
18
17
16
15
14
13
12
11
CODEC_DMA_ADDR
10
9
8
7
6
5
4
3
CODEC_DMA_ADDR
2
1
0
• CODEC_DMA_ADDR: Base Address for Codec DMA
This register contains codec datapath start address of buffer location.
737
6384E–ATARM–05-Feb-10
39.4.11 ISI Color Space Conversion YCrCb to RGB Set 0 Register
Register Name: ISI_Y2R_SET0
Access Type: Read-write
Reset Value: 0x6832cc95
31
30
29
28
27
26
25
24
19
18
17
16
11
10
9
8
3
2
1
0
C3
23
22
21
20
C2
15
14
13
12
C1
7
6
5
4
C0
• C0: Color Space Conversion Matrix Coefficient C0
C0 element, default step is 1/128, ranges from 0 to 1.9921875.
• C1: Color Space Conversion Matrix Coefficient C1
C1 element, default step is 1/128, ranges from 0 to 1.9921875.
• C2: Color Space Conversion Matrix Coefficient C2
C2 element, default step is 1/128, ranges from 0 to 1.9921875.
• C3: Color Space Conversion Matrix Coefficient C3
C3 element default step is 1/128, ranges from 0 to 1.9921875.
738
AT91SAM9G20
6384E–ATARM–05-Feb-10
AT91SAM9G20
39.4.12 ISI Color Space Conversion YCrCb to RGB Set 1 Register
Register Name: ISI_Y2R_SET1
Access Type: Read-write
Reset Value: 0x00007102
31
–
30
–
29
–
28
–
27
–
26
–
25
–
24
–
23
–
22
–
21
–
20
–
19
–
18
–
17
–
16
–
15
–
14
Cboff
13
Croff
12
Yoff
11
–
10
–
9
–
8
C4
C4
• C4: Color Space Conversion Matrix Coefficient C4
C4 element default step is 1/128, ranges from 0 to 3.9921875.
• Yoff: Color Space Conversion Luminance Default Offset
0: No offset.
1: Offset = 128.
• Croff: Color Space Conversion Red Chrominance Default Offset
0: No offset.
1: Offset = 16.
• Cboff: Color Space Conversion Blue Chrominance Default Offset
0: No offset.
1: Offset = 16.
739
6384E–ATARM–05-Feb-10
39.4.13 ISI Color Space Conversion RGB to YCrCb Set 0 Register
Register Name: ISI_R2Y_SET0
Access Type: Read-write
Reset Value: 0x01324145
31
–
30
–
29
–
28
–
23
22
21
20
27
–
26
–
25
–
24
Roff
19
18
17
16
11
10
9
8
3
2
1
0
C2
15
14
13
12
C1
7
6
5
4
C0
• C0: Color Space Conversion Matrix Coefficient C0
C0 element default step is 1/256, from 0 to 0.49609375.
• C1: Color Space Conversion Matrix Coefficient C1
C1 element default step is 1/128, from 0 to 0.9921875.
• C2: Color Space Conversion Matrix Coefficient C2
C2 element default step is 1/512, from 0 to 0.2480468875.
• Roff: Color Space Conversion Red Component Offset
0: No offset.
1: Offset = 16.
740
AT91SAM9G20
6384E–ATARM–05-Feb-10
AT91SAM9G20
39.4.14 ISI Color Space Conversion RGB to YCrCb Set 1 Register
Register Name: ISI_R2Y_SET1
Access Type: Read-write
Reset Value: 0x01245e38
31
–
30
–
29
–
28
–
23
22
21
20
27
–
26
–
25
–
24
Goff
19
18
17
16
11
10
9
8
3
2
1
0
C5
15
14
13
12
C4
7
6
5
4
C3
• C3: Color Space Conversion Matrix Coefficient C3
C0 element default step is 1/128, ranges from 0 to 0.9921875.
• C4: Color Space Conversion Matrix Coefficient C4
C1 element default step is 1/256, ranges from 0 to 0.49609375.
• C5: Color Space Conversion Matrix Coefficient C5
C1 element default step is 1/512, ranges from 0 to 0.2480468875.
• Goff: Color Space Conversion Green Component Offset
0: No offset.
1: Offset = 128.
741
6384E–ATARM–05-Feb-10
39.4.15 ISI Color Space Conversion RGB to YCrCb Set 2 Register
Register Name: ISI_R2Y_SET2
Access Type: Read-write
Reset Value: 0x01384a4b
31
–
30
–
29
–
28
–
23
22
21
20
27
–
26
–
25
–
24
Boff
19
18
17
16
11
10
9
8
3
2
1
0
C8
15
14
13
12
C7
7
6
5
4
C6
• C6: Color Space Conversion Matrix Coefficient C6
C6 element default step is 1/512, ranges from 0 to 0.2480468875.
• C7: Color Space Conversion Matrix coefficient C7
C7 element default step is 1/256, ranges from 0 to 0.49609375.
• C8: Color Space Conversion Matrix Coefficient C8
C8 element default step is 1/128, ranges from 0 to 0.9921875.
• Boff: Color Space Conversion Blue Component Offset
0: No offset.
1: Offset = 128.
742
AT91SAM9G20
6384E–ATARM–05-Feb-10
AT91SAM9G20
40. Analog-to-digital Converter (ADC)
40.1
Overview
The ADC is based on a Successive Approximation Register (SAR) 10-bit Analog-to-Digital Converter (ADC). It also integrates a 4-to-1 analog multiplexer, making possible the analog-to-digital
conversions of 4 analog lines. The conversions extend from 0V to ADVREF.
The ADC supports an 8-bit or 10-bit resolution mode, and conversion results are reported in a
common register for all channels, as well as in a channel-dedicated register. Software trigger,
external trigger on rising edge of the ADTRG pin or internal triggers from Timer Counter output(s) are configurable.
The ADC also integrates a Sleep Mode and a conversion sequencer and connects with a PDC
channel. These features reduce both power consumption and processor intervention.
Finally, the user can configure ADC timings, such as Startup Time and Sample & Hold Time.
40.2
Block Diagram
Figure 40-1. Analog-to-Digital Converter Block Diagram
Timer
Counter
Channels
ADC
Trigger
Selection
ADTRG
Control
Logic
ADC Interrupt
AIC
VDDANA
ADVREF
ASB
AD-
Dedicated
Analog
Inputs
PDC
ADUser
Interface
AD-
AD-
Analog Inputs
Multiplexed
with I/O lines
PIO
AD-
Peripheral Bridge
Successive
Approximation
Register
Analog-to-Digital
Converter
APB
AD-
GND
743
6384E–ATARM–05-Feb-10
40.3
Signal Description
Table 40-1.
ADC Pin Description
Pin Name
Description
VDDANA
Analog power supply
ADVREF
Reference voltage
AD0 - AD3
Analog input channels
ADTRG
External trigger
40.4
Product Dependencies
40.4.1
Power Management
The ADC is automatically clocked after the first conversion in Normal Mode. In Sleep Mode, the
ADC clock is automatically stopped after each conversion. As the logic is small and the ADC cell
can be put into Sleep Mode, the Power Management Controller has no effect on the ADC
behavior.
40.4.2
Interrupt Sources
The ADC interrupt line is connected on one of the internal sources of the Advanced Interrupt
Controller. Using the ADC interrupt requires the AIC to be programmed first.
40.4.3
Analog Inputs
The analog input pins can be multiplexed with PIO lines. In this case, the assignment of the ADC
input is automatically done as soon as the corresponding channel is enabled by writing the register ADC_CHER. By default, after reset, the PIO line is configured as input with its pull-up
enabled and the ADC input is connected to the GND.
40.4.4
I/O Lines
The pin ADTRG may be shared with other peripheral functions through the PIO Controller. In
this case, the PIO Controller should be set accordingly to assign the pin ADTRG to the ADC
function.
40.4.5
Timer Triggers
Timer Counters may or may not be used as hardware triggers depending on user requirements.
Thus, some or all of the timer counters may be non-connected.
40.4.6
744
Conversion Performances
For performance and electrical characteristics of the ADC, see the DC Characteristics section.
AT91SAM9G20
6384E–ATARM–05-Feb-10
AT91SAM9G20
40.5
40.5.1
Functional Description
Analog-to-digital Conversion
The ADC uses the ADC Clock to perform conversions. Converting a single analog value to a 10bit digital data requires Sample and Hold Clock cycles as defined in the field SHTIM of the “ADC
Mode Register” on page 752 and 10 ADC Clock cycles. The ADC Clock frequency is selected in
the PRESCAL field of the Mode Register (ADC_MR).
The ADC clock range is between MCK/2, if PRESCAL is 0, and MCK/128, if PRESCAL is set to
63 (0x3F). PRESCAL must be programmed in order to provide an ADC clock frequency according to the parameters given in the Product definition section.
40.5.2
Conversion Reference
The conversion is performed on a full range between 0V and the reference voltage pin ADVREF.
Analog inputs between these voltages convert to values based on a linear conversion.
40.5.3
Conversion Resolution
The ADC supports 8-bit or 10-bit resolutions. The 8-bit selection is performed by setting the bit
LOWRES in the ADC Mode Register (ADC_MR). By default, after a reset, the resolution is the
highest and the DATA field in the data registers is fully used. By setting the bit LOWRES, the
ADC switches in the lowest resolution and the conversion results can be read in the eight lowest
significant bits of the data registers. The two highest bits of the DATA field in the corresponding
ADC_CDR register and of the LDATA field in the ADC_LCDR register read 0.
Moreover, when a PDC channel is connected to the ADC, 10-bit resolution sets the transfer
request sizes to 16-bit. Setting the bit LOWRES automatically switches to 8-bit data transfers. In
this case, the destination buffers are optimized.
745
6384E–ATARM–05-Feb-10
40.5.4
Conversion Results
When a conversion is completed, the resulting 10-bit digital value is stored in the Channel Data
Register (ADC_CDR) of the current channel and in the ADC Last Converted Data Register
(ADC_LCDR).
The channel EOC bit in the Status Register (ADC_SR) is set and the DRDY is set. In the case of
a connected PDC channel, DRDY rising triggers a data transfer request. In any case, either
EOC and DRDY can trigger an interrupt.
Reading one of the ADC_CDR registers clears the corresponding EOC bit. Reading ADC_LCDR
clears the DRDY bit and the EOC bit corresponding to the last converted channel.
Figure 40-2. EOCx and DRDY Flag Behavior
Write the ADC_CR
with START = 1
Read the ADC_CDRx
Write the ADC_CR
with START = 1
Read the ADC_LCDR
CHx
(ADC_CHSR)
EOCx
(ADC_SR)
Conversion Time
Conversion Time
DRDY
(ADC_SR)
746
AT91SAM9G20
6384E–ATARM–05-Feb-10
AT91SAM9G20
If the ADC_CDR is not read before further incoming data is converted, the corresponding Overrun Error (OVRE) flag is set in the Status Register (ADC_SR).
In the same way, new data converted when DRDY is high sets the bit GOVRE (General Overrun
Error) in ADC_SR.
The OVRE and GOVRE flags are automatically cleared when ADC_SR is read.
Figure 40-3. GOVRE and OVREx Flag Behavior
Read ADC_SR
ADTRG
CH0
(ADC_CHSR)
CH1
(ADC_CHSR)
ADC_LCDR
Undefined Data
ADC_CDR0
Undefined Data
ADC_CDR1
EOC0
(ADC_SR)
EOC1
(ADC_SR)
Data B
Data A
Data C
Data A
Data C
Undefined Data
Data B
Conversion
Conversion
Conversion
Read ADC_CDR0
Read ADC_CDR1
GOVRE
(ADC_SR)
DRDY
(ADC_SR)
OVRE0
(ADC_SR)
Warning: If the corresponding channel is disabled during a conversion or if it is disabled and
then reenabled during a conversion, its associated data and its corresponding EOC and OVRE
flags in ADC_SR are unpredictable.
747
6384E–ATARM–05-Feb-10
40.5.5
Conversion Triggers
Conversions of the active analog channels are started with a software or a hardware trigger. The
software trigger is provided by writing the Control Register (ADC_CR) with the bit START at 1.
The hardware trigger can be one of the TIOA outputs of the Timer Counter channels, or the
external trigger input of the ADC (ADTRG). The hardware trigger is selected with the field TRGSEL in the Mode Register (ADC_MR). The selected hardware trigger is enabled with the bit
TRGEN in the Mode Register (ADC_MR).
If a hardware trigger is selected, the start of a conversion is detected at each rising edge of the
selected signal. If one of the TIOA outputs is selected, the corresponding Timer Counter channel
must be programmed in Waveform Mode.
Only one start command is necessary to initiate a conversion sequence on all the channels. The
ADC hardware logic automatically performs the conversions on the active channels, then waits
for a new request. The Channel Enable (ADC_CHER) and Channel Disable (ADC_CHDR) Registers enable the analog channels to be enabled or disabled independently.
If the ADC is used with a PDC, only the transfers of converted data from enabled channels are
performed and the resulting data buffers should be interpreted accordingly.
Warning: Enabling hardware triggers does not disable the software trigger functionality. Thus, if
a hardware trigger is selected, the start of a conversion can be initiated either by the hardware or
the software trigger.
40.5.6
Sleep Mode and Conversion Sequencer
The ADC Sleep Mode maximizes power saving by automatically deactivating the ADC when it is
not being used for conversions. Sleep Mode is selected by setting the bit SLEEP in the Mode
Register ADC_MR.
The SLEEP mode is automatically managed by a conversion sequencer, which can automatically process the conversions of all channels at lowest power consumption.
When a start conversion request occurs, the ADC is automatically activated. As the analog cell
requires a start-up time, the logic waits during this time and starts the conversion on the enabled
channels. When all conversions are complete, the ADC is deactivated until the next trigger. Triggers occurring during the sequence are not taken into account.
The conversion sequencer allows automatic processing with minimum processor intervention
and optimized power consumption. Conversion sequences can be performed periodically using
a Timer/Counter output. The periodic acquisition of several samples can be processed automatically without any intervention of the processor thanks to the PDC.
Note:
748
The reference voltage pins always remain connected in normal mode as in sleep mode.
AT91SAM9G20
6384E–ATARM–05-Feb-10
AT91SAM9G20
40.5.7
ADC Timings
Each ADC has its own minimal Startup Time that is programmed through the field STARTUP in
the Mode Register ADC_MR.
In the same way, a minimal Sample and Hold Time is necessary for the ADC to guarantee the
best converted final value between two channels selection. This time has to be programmed
through the bitfield SHTIM in the Mode Register ADC_MR.
Warning: No input buffer amplifier to isolate the source is included in the ADC. This must be
taken into consideration to program a precise value in the SHTIM field. See the section, ADC
Characteristics in the product datasheet.
749
6384E–ATARM–05-Feb-10
40.6
Analog-to-Digital Converter (ADC) User Interface
Table 40-2.
Offset
Register
Name
Access
Reset
0x00
Control Register
ADC_CR
Write-only
–
0x04
Mode Register
ADC_MR
Read-write
0x00000000
0x08
Reserved
–
–
–
0x0C
Reserved
–
–
–
0x10
Channel Enable Register
ADC_CHER
Write-only
–
0x14
Channel Disable Register
ADC_CHDR
Write-only
–
0x18
Channel Status Register
ADC_CHSR
Read-only
0x00000000
0x1C
Status Register
ADC_SR
Read-only
0x000C0000
0x20
Last Converted Data Register
ADC_LCDR
Read-only
0x00000000
0x24
Interrupt Enable Register
ADC_IER
Write-only
–
0x28
Interrupt Disable Register
ADC_IDR
Write-only
–
0x2C
Interrupt Mask Register
ADC_IMR
Read-only
0x00000000
0x30
Channel Data Register 0
ADC_CDR0
Read-only
0x00000000
0x34
Channel Data Register 1
ADC_CDR1
Read-only
0x00000000
...
...
...
ADC_CDR3
Read-only
0x00000000
–
–
–
...
0x3C
0x44 - 0xFC
750
Register Mapping
...
Channel Data Register 3
Reserved
AT91SAM9G20
6384E–ATARM–05-Feb-10
AT91SAM9G20
40.6.1
Name:
ADC Control Register
ADC_CR
Access:
Write-only
31
30
29
28
27
26
25
24
–
–
–
–
–
–
–
–
23
22
21
20
19
18
17
16
–
–
–
–
–
–
–
–
15
14
13
12
11
10
9
8
–
–
–
–
–
–
–
–
7
6
5
4
3
2
1
0
–
–
–
–
–
–
START
SWRST
• SWRST: Software Reset
0 = No effect.
1 = Resets the ADC simulating a hardware reset.
• START: Start Conversion
0 = No effect.
1 = Begins analog-to-digital conversion.
751
6384E–ATARM–05-Feb-10
40.6.2
Name:
ADC Mode Register
ADC_MR
Access:
Read-write
31
30
29
28
–
–
–
–
23
22
21
20
–
–
–
15
14
13
–
–
27
26
25
24
17
16
10
9
8
2
1
SHTIM
19
18
STARTUP
12
11
PRESCAL
7
6
5
4
–
–
SLEEP
LOWRES
3
TRGSEL
0
TRGEN
• TRGEN: Trigger Enable
TRGEN
Selected TRGEN
0
Hardware triggers are disabled. Starting a conversion is only possible by software.
1
Hardware trigger selected by TRGSEL field is enabled.
• TRGSEL: Trigger Selection
TRGSEL
Selected TRGSEL
0
0
0
TIOA Ouput of the Timer Counter Channel 0
0
0
1
TIOA Ouput of the Timer Counter Channel 1
0
1
0
TIOA Ouput of the Timer Counter Channel 2
0
1
1
Reserved
1
0
0
Reserved
1
0
1
Reserved
1
1
0
External trigger
1
1
1
Reserved
• LOWRES: Resolution
LOWRES
Selected Resolution
0
10-bit resolution
1
8-bit resolution
• SLEEP: Sleep Mode
SLEEP
752
Selected Mode
0
Normal Mode
1
Sleep Mode
AT91SAM9G20
6384E–ATARM–05-Feb-10
AT91SAM9G20
• PRESCAL: Prescaler Rate Selection
ADCClock = MCK / ( (PRESCAL+1) * 2 )
• STARTUP: Start Up Time
Startup Time = (STARTUP+1) * 8 / ADCClock
• SHTIM: Sample & Hold Time
Sample & Hold Time = (SHTIM+1) / ADCClock
753
6384E–ATARM–05-Feb-10
40.6.3
Name:
ADC Channel Enable Register
ADC_CHER
Access:
Write-only
31
30
29
28
27
26
25
24
–
–
–
–
–
–
–
–
23
22
21
20
19
18
17
16
–
–
–
–
–
–
–
–
15
14
13
12
11
10
9
8
–
–
–
–
–
–
–
–
7
6
5
4
3
2
1
0
–
–
–
–
CH3
CH2
CH1
CH0
• CHx: Channel x Enable
0 = No effect.
1 = Enables the corresponding channel.
754
AT91SAM9G20
6384E–ATARM–05-Feb-10
AT91SAM9G20
40.6.4
Name:
ADC Channel Disable Register
ADC_CHDR
Access:
Write-only
31
30
29
28
27
26
25
24
–
–
–
–
–
–
–
–
23
22
21
20
19
18
17
16
–
–
–
–
–
–
–
–
15
14
13
12
11
10
9
8
–
–
–
–
–
–
–
–
7
6
5
4
3
2
1
0
–
–
–
–
CH3
CH2
CH1
CH0
• CHx: Channel x Disable
0 = No effect.
1 = Disables the corresponding channel.
Warning: If the corresponding channel is disabled during a conversion or if it is disabled then reenabled during a conversion, its associated data and its corresponding EOC and OVRE flags in ADC_SR are unpredictable.
755
6384E–ATARM–05-Feb-10
40.6.5
Name:
ADC Channel Status Register
ADC_CHSR
Access:
Read-only
31
30
29
28
27
26
25
24
–
–
–
–
–
–
–
–
23
22
21
20
19
18
17
16
–
–
–
–
–
–
–
–
15
14
13
12
11
10
9
8
–
–
–
–
–
–
–
–
7
6
5
4
3
2
1
0
–
–
–
–
CH3
CH2
CH1
CH0
• CHx: Channel x Status
0 = Corresponding channel is disabled.
1 = Corresponding channel is enabled.
756
AT91SAM9G20
6384E–ATARM–05-Feb-10
AT91SAM9G20
40.6.6
Name:
ADC Status Register
ADC_SR
Access:
Read-only
31
30
29
28
27
26
25
24
–
–
–
–
–
–
–
–
23
22
21
20
19
18
17
16
–
–
–
–
RXBUFF
ENDRX
GOVRE
DRDY
15
14
13
12
11
10
9
8
–
–
–
–
OVRE3
OVRE2
OVRE1
OVRE0
7
6
5
4
3
2
1
0
–
–
–
–
EOC3
EOC2
EOC1
EOC0
• EOCx: End of Conversion x
0 = Corresponding analog channel is disabled, or the conversion is not finished.
1 = Corresponding analog channel is enabled and conversion is complete.
• OVREx: Overrun Error x
0 = No overrun error on the corresponding channel since the last read of ADC_SR.
1 = There has been an overrun error on the corresponding channel since the last read of ADC_SR.
• DRDY: Data Ready
0 = No data has been converted since the last read of ADC_LCDR.
1 = At least one data has been converted and is available in ADC_LCDR.
• GOVRE: General Overrun Error
0 = No General Overrun Error occurred since the last read of ADC_SR.
1 = At least one General Overrun Error has occurred since the last read of ADC_SR.
• ENDRX: End of RX Buffer
0 = The Receive Counter Register has not reached 0 since the last write in ADC_RCR or ADC_RNCR.
1 = The Receive Counter Register has reached 0 since the last write in ADC_RCR or ADC_RNCR.
• RXBUFF: RX Buffer Full
0 = ADC_RCR or ADC_RNCR have a value other than 0.
1 = Both ADC_RCR and ADC_RNCR have a value of 0.
757
6384E–ATARM–05-Feb-10
40.6.7
Name:
ADC Last Converted Data Register
ADC_LCDR
Access:
Read-only
31
30
29
28
27
26
25
24
–
–
–
–
–
–
–
–
23
22
21
20
19
18
17
16
–
–
–
–
–
–
–
–
15
14
13
12
11
10
9
–
–
–
–
–
–
7
6
5
4
3
2
8
LDATA
1
0
LDATA
• LDATA: Last Data Converted
The analog-to-digital conversion data is placed into this register at the end of a conversion and remains until a new conversion is completed.
758
AT91SAM9G20
6384E–ATARM–05-Feb-10
AT91SAM9G20
40.6.8
Name:
ADC Interrupt Enable Register
ADC_IER
Access:
Write-only
31
30
29
28
27
26
25
24
–
–
–
–
–
–
–
–
23
22
21
20
19
18
17
16
–
–
–
–
RXBUFF
ENDRX
GOVRE
DRDY
15
14
13
12
11
10
9
8
–
–
–
–
OVRE3
OVRE2
OVRE1
OVRE0
7
6
5
4
3
2
1
0
–
–
–
–
EOC3
EOC2
EOC1
EOC0
• EOCx: End of Conversion Interrupt Enable x
• OVREx: Overrun Error Interrupt Enable x
• DRDY: Data Ready Interrupt Enable
• GOVRE: General Overrun Error Interrupt Enable
• ENDRX: End of Receive Buffer Interrupt Enable
• RXBUFF: Receive Buffer Full Interrupt Enable
0 = No effect.
1 = Enables the corresponding interrupt.
759
6384E–ATARM–05-Feb-10
40.6.9
Name:
ADC Interrupt Disable Register
ADC_IDR
Access:
Write-only
31
30
29
28
27
26
25
24
–
–
–
–
–
–
–
–
23
22
21
20
19
18
17
16
–
–
–
–
RXBUFF
ENDRX
GOVRE
DRDY
15
14
13
12
11
10
9
8
–
–
–
–
OVRE3
OVRE2
OVRE1
OVRE0
7
6
5
4
3
2
1
0
–
–
–
–
EOC3
EOC2
EOC1
EOC0
• EOCx: End of Conversion Interrupt Disable x
• OVREx: Overrun Error Interrupt Disable x
• DRDY: Data Ready Interrupt Disable
• GOVRE: General Overrun Error Interrupt Disable
• ENDRX: End of Receive Buffer Interrupt Disable
• RXBUFF: Receive Buffer Full Interrupt Disable
0 = No effect.
1 = Disables the corresponding interrupt.
760
AT91SAM9G20
6384E–ATARM–05-Feb-10
AT91SAM9G20
40.6.10
Name:
Access:
ADC Interrupt Mask Register
ADC_IMR
Read-only
31
30
29
28
27
26
25
24
–
–
–
–
–
–
–
–
23
22
21
20
19
18
17
16
–
–
–
–
RXBUFF
ENDRX
GOVRE
DRDY
15
14
13
12
11
10
9
8
–
–
–
–
OVRE3
OVRE2
OVRE1
OVRE0
7
6
5
4
3
2
1
0
–
–
–
–
EOC3
EOC2
EOC1
EOC0
• EOCx: End of Conversion Interrupt Mask x
• OVREx: Overrun Error Interrupt Mask x
• DRDY: Data Ready Interrupt Mask
• GOVRE: General Overrun Error Interrupt Mask
• ENDRX: End of Receive Buffer Interrupt Mask
• RXBUFF: Receive Buffer Full Interrupt Mask
0 = The corresponding interrupt is disabled.
1 = The corresponding interrupt is enabled.
761
6384E–ATARM–05-Feb-10
40.6.11
Name:
Access:
ADC Channel Data Register
ADC_CDRx
Read-only
31
30
29
28
27
26
25
24
–
–
–
–
–
–
–
–
23
22
21
20
19
18
17
16
–
–
–
–
–
–
–
–
15
14
13
12
11
10
9
–
–
–
–
–
–
7
6
5
4
3
2
8
DATA
1
0
DATA
• DATA: Converted Data
The analog-to-digital conversion data is placed into this register at the end of a conversion and remains until a new conversion is completed. The Convert Data Register (CDR) is only loaded if the corresponding analog channel is enabled.
762
AT91SAM9G20
6384E–ATARM–05-Feb-10
AT91SAM9G20
41. AT91SAM9G20 Electrical Characteristics
41.1
Absolute Maximum Ratings
Table 41-1.
Absolute Maximum Ratings*
Operating Temperature (Industrial)............. -40° C to + 85° C
Junction Temperature ............................................... +125°C
Storage Temperature ................................. -40°C to + 150°C
Voltage on Input Pins
with Respect to Ground .... -0.3V to VDDIO+0.3V (+4V max)
*NOTICE:
Stresses beyond those listed under “Absolute Maximum
Ratings” may cause permanent damage to the device.
This is a stress rating only and functional operation of
the device at these or other conditions beyond those
indicated in the operational sections of this specification
is not implied. Exposure to absolute maximum rating
conditions for extended periods may affect device reliability.
Maximum Operating Voltage
(VDDCORE, VDDPLL and VDDBU).............................. 1.2V
Maximum Operating Voltage
(VDDIOM and VDDIOP) ................................................ 4.0V
Total DC Output Current on all I/O lines ................... 350 mA
763
6384E–ATARM–05-Feb-10
41.2
DC Characteristics
The following characteristics are applicable to the operating temperature range: TA = -40°C to 85°C, unless otherwise
specified.
Table 41-2.
Symbol
DC Characteristics
Min
Typ
Max
Units
VVDDCORE DC Supply Core
0.9
1.0
1.1
V
VVDDBU
DC Supply Backup
0.9
1.0
1.1
V
VVDDPLL
DC Supply PLL
0.9
1.0
1.1
V
VVDDOSC
DC Supply Oscillator
1.65
3.6
V
VVDDIOM
DC Supply Memory I/Os
1.95/3.6
V
VVDDIOP
DC Supply Peripheral I/Os
1.65
3.6
V
VVDDANA
DC Supply Analog
3.0
3.3
3.6
V
VVDDUSB
DC Supply USB
3.0
3.3
3.6
V
VIL
Input Low-level Voltage
VIH
Input High-level Voltage
VOL
VOH
RPULLUP
IO
Parameter
Output Low-level Voltage
Output High-level Voltage
Pull-up Resistance
Output Current
Conditions
selectable by software
1.65/3.0
VVDDIO from 3.0V to 3.6V
-0.3
0.8
V
VVDDIO from 1.65V to 1.95V
-0.3
0.3 x VVDDIO
V
2
VVDDIO + 0.3
V
0.7 x VVDDIO
VVDDIO + 0.3
V
IO Max, VVDDIO from 3.0V to 3.6V
0.4
V
CMOS (IO <0.3 mA) VVDDIO from 1.65V
to 1.95V
0.1
V
TTL (IO Max) VVDDIO from 1.65V
to 1.95V
0.4
V
VVDDIO from 3.0V to 3.6V
VVDDIO from 1.65V to 1.95V
IO Max, VVDDIO from 3.0V to 3.6V
VVDDIO - 0.4
V
CMOS (IO <0.3 mA) VVDDIO from 1.65V
to 1.95V
VVDDIO - 0.1
V
TTL (IO Max) VVDDIO from 1.65V
to 1.95V
VVDDIO - 0.4
V
PA0-PA31, PB0-PB31, PC0-PC3,
NTRST and NRST
40
PC4 - PC31 VVDDIOM in 1.8V range
240
1000
PC4 - PC31 VVDDIOM in 3.3V range
140
450
Static Current
IIN
3.3V I/O Input leakage current
764
AT91SAM9G20
75
190
PA0-PA31 PB0-PB31 PC0-PC3
8
PC4 - PC31 in 3.3V range
2
PC4 - PC31 in 1.8V range
4
On VVDDCORE = 1.0V,
T = 25°C
MCK = 0 Hz, excluding POR A
ISC
1.8/3.3
All inputs driven TMS, TDI,
TCK, NRST = 1
TA = 85°C
On VVDDBU = 1.0V,
Logic cells consumption,
excluding POR
TA = 25°C
All inputs driven WKUP = 0
TA = 85°C
VIN = 3.3V or 0
kOhm
mA
25
mA
100
9
µA
25
±1
µA
6384E–ATARM–05-Feb-10
AT91SAM9G20
41.3
Power Consumption
• Typical power consumption of PLLs, Slow Clock and Main Oscillator.
• Power consumption of power supply in four different modes: Active, Idle, Ultra Low-power
and Backup.
• Power consumption by peripheral: calculated as the difference in current measurement after
having enabled then disabled the corresponding clock.
41.3.1
Power Consumption versus Modes
The values in Table 41-3 and Table 41-4 on page 766 are estimated values of the power consumption with operating conditions as follows:
• VDDIOM = VDDIOP = 3.3V
• VDDPLL = 1.0V
• VDDCORE = VDDBU = 1.0V
• TA = 25° C
• There is no consumption on the I/Os of the device
Figure 41-1. Measures Schematics
VDDBU
AMP1
VDDCORE
AMP2
These figures represent the power consumption estimated on the power supplies.
Table 41-3.
Power Consumption for Different Modes
Mode
Conditions
Consumption
Unit
Active
ARM Core clock is 400 MHz.
MCK is 133 MHz.
All peripheral clocks de-activated.
onto AMP2
50
mA
Idle
Idle state, waiting an interrupt.
All peripheral clocks de-activated.
onto AMP2
20
mA
Ultra low
power
ARM Core clock is 500 Hz.
All peripheral clocks de-activated.
onto AMP2
8
mA
Backup
Device only VDDBU powered
onto AMP1
9
µA
765
6384E–ATARM–05-Feb-10
Table 41-4.
Power Consumption by Peripheral in Active Mode
Peripheral
Consumption
PIO Controller
2.5
USART
7.0
UHP
5.4
UDP
4.9
ADC
4.1
TWI
4.6
SPI
4.0
MCI
6.4
SSC
7.0
Timer Counter Channels
1.8
ISI
4.6
EMAC
34.6
Unit
µA/MHz
766
AT91SAM9G20
6384E–ATARM–05-Feb-10
AT91SAM9G20
41.4
Clock Characteristics
41.4.1
Processor Clock Characteristics
Table 41-5.
Processor Clock Waveform Parameters
Symbol
Parameter
Conditions
1/(tCPPCK)
Processor Clock Frequency
VVDDCORE = 0.9V
T = 85°C
41.4.2
Min
Units
400
MHz
Max
Units
133
MHz
Master Clock Characteristics
Table 41-6.
Master Clock Waveform Parameters
Symbol
Parameter
Conditions
1/(tCPMCK)
Master Clock Frequency
VVDDCORE = 0.9V
T = 85°C
Note:
Max
Min
1. The system clock is the maximum clock at which the system is able to run. It is given by the smallest value of the
processor clock, internal bus clock, EBI clock.
41.4.3
XIN Clock Characteristics
Table 41-7.
XIN Clock Electrical Characteristics
Symbol
Parameter
1/(tCPXIN)
XIN Clock Frequency
tCPXIN
XIN Clock Period
tCHXIN
XIN Clock High Half-period
0.4 x tCPXIN
0.6 x tCPXIN
ns
tCLXIN
XIN Clock Low Half-period
0.4 x tCPXIN
0.6 x tCPXIN
ns
CIN
XIN Input Capacitance
(1)
25
pF
XIN Pull-down Resistor
(1)
1000
kΩ
XIN Voltage
(1)
VDDOSC
V
RIN
VIN
Notes:
Conditions
Min
Max
Units
50
MHz
20
VDDOSC
ns
1. These characteristics apply only when the Main Oscillator is in bypass mode (i.e. when MOSCEN = 0 and OSCBYPASS = 1)
in the CKGR_MOR register. See “PMC Clock Generator Main Oscillator Register” in the PMC section.
767
6384E–ATARM–05-Feb-10
41.4.4
I/O Slew Rates
The IOSR and VDDIOMSEL bits in the EBI_CSA register allow the user to program the rising
and falling times of SDRAM signals. Rising/Falling time is given between 30% and 70%.
Table 41-8.
Rising time
(ns)
Falling time
(ns)
1.8V range, FAST slew rate,
CLOAD = 10 pF
0.8
1.0
1
1.8V range, SLOW slew rate,
CLOAD = 10 pF
1.6
1.5
1
0
3.3V range, FAST slew rate,
CLOAD = 10 pF
0.8
0.8
1
1
3.3V range, SLOW slew rate,
CLOAD = 10 pF
1.5
1.6
Rising time
(ns)
Falling time
(ns)
VDDIOMSEL
IOSR
0
0
0
Table 41-9.
768
SDRAM Clock
Conditions
SDRAM Data, Address and Control
VDDIOMSEL
IOSR
Conditions
0
0
1.8V range, FAST slew rate,
CLOAD = 30 pF
1.5
1.5
0
1
1.8V range, SLOW slew rate,
CLOAD = 30 pF
1.7
1.8
1
0
3.3V range, FAST slew rate,
CLOAD = 50 pF
2.8
3.1
1
1
3.3V range, SLOW slew rate,
CLOAD = 50 pF
6.0
5.7
AT91SAM9G20
6384E–ATARM–05-Feb-10
AT91SAM9G20
41.5
Crystal Oscillator Characteristics
The following characteristics are applicable to the operating temperature range: TA = -40°C to 85°C and worst case of
power supply, unless otherwise specified.
41.5.1
32 kHz Oscillator Characteristics
Table 41-10. 32 kHz Oscillator Characteristics
Symbol
Parameter
Conditions
1/(tCP32KHz)
Crystal Oscillator Frequency
CCRYSTAL32
Load Capacitance
CLEXT32(2)
External Load Capacitance
Min
Notes:
Max
32 768
Crystal @ 32.768 kHz
Unit
kHz
6
12.5
pF
CCRYSTAL32 = 6 pF
6
pF
CCRYSTAL32 = 12.5 pF
19
pF
Duty Cycle
40
60
%
VDDBU = 1.0V,
RS = 50 kΩ(1)
CCRYSTAL32 = 6 pF
300
ms
CCRYSTAL32 = 12.5 pF
900
ms
VDDBU = 1.0V
RS = 100 kΩ(1)
CCRYSTAL32 = 6 pF
600
ms
CCRYSTAL32 = 12.5 pF
1200
ms
Startup Time
tST
Typ
1. RS is the equivalent series resistance.
2. CLEXT32 is determined by taking into account internal, parasitic and package load capacitance.
AT91SAM92G20
XIN32
XOUT32
GNDBU
CCRYSTAL32
CLEXT32
41.5.2
CLEXT32
32 kHz Crystal Characteristics
Table 41-11. 32 kHz Crystal Characteristics
Symbol
Parameter
Conditions
ESR
Equivalent Series Resistor Rs
Crystal @ 32.768 kHz
CM
Motional Capacitance
CS
Shunt Capacitance
Min
Typ
Max
Unit
50
100
kΩ
Crystal @ 32.768 kHz
3
fF
Crystal @ 32.768 kHz
2
pF
769
6384E–ATARM–05-Feb-10
41.5.3
RC Oscillator Characteristics
Table 41-12. RC Oscillator Characteristics
Symbol
Parameter
1/(tCPRCz)
tST
41.5.4
Conditions
Min
Typ
Max
Unit
Crystal Oscillator Frequency
20
32
44
kHz
Duty Cycle
45
55
%
75
µs
Startup Time
Slow Clock Selection
Table 41-13 defines the states for OSCSEL signal.
Table 41-13. Slow Clock Selection
OSCSEL
Slow Clock
Startup Time (Max)
0
Internal RC
150 µs
1
External 32768Hz
1200 ms
The startup counter delay for the slow clock oscillator depends on the OSCSEL signal. The
32,768 Hz startup delay is 1200 ms whereas it is 150 µs for the internal RC oscillator (refer to
Table 41-13). The pin OSCSEL must be tied either to GND or VDDBU for correct operation of
the device.
770
AT91SAM9G20
6384E–ATARM–05-Feb-10
AT91SAM9G20
41.5.5
Main Oscillator Characteristics
Table 41-14. Main Oscillator Characteristics
Symbol
Parameter
1/(tCPMAIN)
Crystal Oscillator Frequency
CCRYSTAL
Crystal Load Capacitance
CLEXT(7)
External Load Capacitance
Conditions
Min
Typ
Max
Unit
3
16
20
MHz
17.5
pF
12.5
CCRYSTAL = 12.5 pF(6)
16
pF
(6)
26
pF
CCRYSTAL = 17.5 pF
Duty Cycle
40
50
60
tST
Startup Time
VDDOSC = 3 to 3.6V
CS = 3 pF(1) 1/(tCPMAIN) = 3 MHz
CS = 7 pF(1) 1/(tCPMAIN) = 8 MHz
CS = 7 pF(1) 1/(tCPMAIN) = 16 MHz
CS = 7 pF(1) 1/(tCPMAIN) = 20 MHz
IDDST
Standby Current Consumption
Standby mode
1
@ 3 MHz
15
@ 8 MHz
30
@ 16 MHz
50
@ 20 MHz
50
PON
IDD ON
Notes:
14.5
4
1.4
1
Drive Level
Current Dissipation
%
ms
µA
µW
@ 3 MHz
(2)
280
380
@ 8 MHz
(3)
380
510
@ 16 MHz(4)
500
630
@ 20 MHz(5)
580
750
µA
1. CS is the shunt capacitance.
2. RS = 100 to 200 Ω; CS = 2.0 to 2.5 pF; CM = 2 to 1.5 pF (typ, worst case) using 1 kΩ serial resistor on XOUT.
3. RS = 50 to 100 Ω; CS = 2.0 to 2.5 pF; CM = 4 to 3 pF (typ, worst case).
4. RS = 25 to 50 Ω; CS = 2.5 to 3.0 pF; CM = 7 to 5 pF (typ, worst case).
5. RS = 20 to 50 Ω; CS = 3.2 to 4.0 pF; CM = 10 to 8 pF (typ, worst case).
6. Additional user load capacitance should be subtracted from CLEXT.
7. CLEXT is determined by taking into account internal, parasitic and package load capacitance.
AT91SAM92G20
XIN
XOUT
GNDPLL
1K
CCRYSTAL
CLEXT
CLEXT
771
6384E–ATARM–05-Feb-10
41.5.6
Crystal Characteristics
Table 41-15. Crystal Characteristics
Symbol
ESR
Parameter
Conditions
Min
Typ
Max
Fundamental @ 3 MHz
200
Fundamental @ 8 MHz
100
Fundamental @ 16 MHz
80
Fundamental @ 20 MHz
50
Unit
Ω
Equivalent Series Resistor Rs
CM
Motional Capacitance
8
pF
CS
Shunt Capacitance
7
pF
Max
Unit
41.5.7
PLL Characteristics
Table 41-16. PLLA Characteristics
Symbol
Parameter
Conditions
Min
FOUT
Output Frequency
Refer to following table
400
800
MHz
FIN
Input Frequency
2
32
MHz
8
mA
IPLL
Current Consumption
1
µA
T
Startup Time
50
µs
active mode
Typ
3.6
standby mode
Following configuration of ICPLLA and OUTA must be done for each PLLA frequency range.
Table 41-17. PLLA Frequency Regarding ICPLLA and OUTA
PLL Frequency Range (MHz)
ICPLLA
OUTA
745 - 800
0
0
0
695 - 750
0
0
1
645 - 700
0
1
0
595 - 650
0
1
1
545 - 600
1
0
0
495 - 550
1
0
1
445 - 500
1
1
0
400 - 450
1
1
1
Table 41-18. PLLB Characteristics
Symbol
Parameter
Conditions
FOUT
Output Frequency
Field OUT of CKGR_PLL is 00
FIN
Input Frequency
IPLL
Current Consumption
T
Startup Time
Active mode @100 MHz
772
Standby mode
Min
Typ
Max
Unit
30
100
MHz
2
32
MHz
1.2
mA
1
µA
100
µs
AT91SAM9G20
6384E–ATARM–05-Feb-10
AT91SAM9G20
41.6
ADC
Table 41-19. ADC Characteristics 9-bit Mode
Code
Parameter
Condition & Notes
R
Resolution
INL
Integral Non-linearity
DNL
Differential Non-linearity
No missing code
OS
Offset Error
Not including VREFN error
GE
Gain Error
fCLK
Clock Frequency
Min
Typ
Max
9
-1
-1.5
No missing code
Unit
Bits
±2
LSB
+2
LSB
±3
LSB
3.5
LSB
5
MHz
Converion Rate:
Conversion Time
Clock Frequency = 5 MHz
(1)
Track-and-Hold Acquistion Time
see Note
Throughput Rate
@ fCLK = 5 MHz with TTH = 1 µs
2
µs
500
ns
330
KSPS
Max
Unit
Table 41-20. ADC Characteristics 10-bit Mode
Code
Parameter
Condition & Notes
R
Resolution
INL
Integral Non-linearity
DNL
Differential Non-linearity
No missing code
OS
Offset Error
Not including VREFN error
GE
Gain Error
fCLK
Clock Frequency
Min
Typ
10
-1
-1.5
No missing code
Bits
±2
LSB
±1
LSB
±3
LSB
3.5
LSB
1
MHz
Converion Rate:
Conversion Time
Note:
Clock Frequency = 5 MHz
(1)
Track-and-Hold Acquistion Time
see Note
Throughput Rate
@ fCLK = 5 MHz with TTH = 1 µs
10
µs
500
ns
95
KSPS
1. In worst case, the Track-and-Hold Acquisition Time is given by:
TTH (µs) = 1.2 + ( 0.09 × Z IN ) ( kOhm )
In case of very high input impedance, this value must be respected in order to guarantee the correct converted value. An
internal input current buffer supplies the current required for the low input impedance (1 mA max).
773
6384E–ATARM–05-Feb-10
To achieve optimal performance of the ADC, the analog power supply VDDANA and the ADVREF input voltage must be
decoupled with a 4.7 µF capacitor in parallel with a 100 nF capacitor.
Table 41-21. External Voltage Reference Input
Parameter
ADVREF Input Voltage Range
Conditions
Min
Typ
Max
Units
VDDANA
V
220
µA
300
620
µA
Typ
Max
Units
ADVREF
V
1
µA
2.4
ADVREF Average Current
Current Consumption on VDDANA
Table 41-22. Analog Inputs
Parameter
Input Voltage Range
Min
0
Input Leakage Current
Input Capacitance
774
8
pF
AT91SAM9G20
6384E–ATARM–05-Feb-10
AT91SAM9G20
41.7
USB Transceiver Characteristics
41.7.1
Electrical Characteristics
Table 41-23. Electrical Parameters
Symbol
Parameter
Conditions
Min
Typ
Max
Unit
0.8
V
Input Levels
VIL
Low Level
VIH
High Level
VDI
Differential Input Sensitivity
VCM
Differential Input Common
Mode Range
CIN
Transceiver capacitance
Capacitance to ground on each line
I
Hi-Z State Data Line Leakage
0V < VIN < 3.3V
REXT
Recommended External USB
Series Resistor
In series with each USB pin with ±5%
VOL
Low Level Output
Measured with RL of 1.425 kΩ tied to
3.6V
0.0
0.3
V
VOH
High Level Output
Measured with RL of 14.25 kΩ tied to
GND
2.8
3.6
V
VCRS
Output Signal Crossover
Voltage
Measure conditions described in
Figure 41-23
1.3
2.0
V
|(D+) - (D-)|
2.0
V
0.2
V
0.8
- 10
2.5
V
9.18
pF
+ 10
µA
Ω
27
Output Levels
Pull-up and Pull-down Resistor
RPUI
Bus Pull-up Resistor on
Upstream Port (idle bus)
0.900
1.575
kOhm
RPUA
Bus Pull-up Resistor on
Upstream Port (upstream port
receiving)
1.425
3.090
kOhm
RPD
Bus Pull-down resistor
14.25
24.8
kOhm
775
6384E–ATARM–05-Feb-10
41.8
Core Power Supply POR Characteristics
Table 41-24. Power-On-Reset Characteristics
Symbol
Parameter
Conditions
Min
Typ
Max
Units
Vth+
Threshold Voltage Rising
Minimum Slope of +1.0V/100ms
0.5
0.7
0.89
V
Vth-
Threshold Voltage Falling
0.4
0.6
0.85
V
TRES
Reset Time
30
70
130
µs
41.8.1
Power Sequence Requirements
The AT91SAM9G20 board design must comply with the power-up and power-down sequence
guidelines below to guarantee reliable operation of the device. Any deviation from these
sequences may lead to the following situations:
• Excessive current consumption during the power-up phase which, in the worst case, can
result in irreversible damage to the device.
• Prevent the device from booting.
41.8.2
Power-up Sequence
The power sequence described below is applicable to all the AT91SAM9G20 revisions. However, the power sequence can be simplified for the revision B device. In this revision, the over
consumption during the power-up phase has been limited to less than 200 mA. This current can
not damage the device and if it is acceptable for the final application, the power sequence
becomes VDDIO followed by VDDCORE. VDDIO must be established first (>0.7V) to ensure a
correct sampling of the BMS signal and also to guarantee the correct voltage level when accessing an external memory.
Figure 41-2. VDDCORE and VDDIO Constraints at Startup
VDD (V)
VDDIO
VDDIOtyp
VDDIO > Voh
Voh (2.6V)
VDDCORE
VDDCOREtyp
0.7V
Vth+ (0.5V)
t
<--------------------- T1---------------------><T2><T3><-------------T4----------->
Core Supply POR output
SLCK
776
AT91SAM9G20
6384E–ATARM–05-Feb-10
AT91SAM9G20
Shown below is an example of the implementation on the AT91SAM9G20-EK Rev.C.
10 SQUARE CM COPPER AREA FOR HEAT SINKING
WITH NO SOLDER MASK
R168
MN1
LT1963AEQ-3.3
J1
5V
C2
10μF
10V
2
R3
100K
1
2
+
3
C1
330μF
CR1
5V
NOT POPULATED
3V3 CURRENT MEASURE
6
GND
VIN
VOUT
SD
GND
FB
1
3
5
3V3
IRLML6402
J2
4
Q3
3
2
C3
10μF
C4
10μF
1
REGULATED
5V ONLY
R163
10K
5V
R161
82K
R164
1K
8
MN15B
7
5 +
6 Q2
6
Si1563EDH
5
4
5V
LM293
4
R162
15K
C147
100NF
J3
FORCE
POWER
ON
1
C14
15PF
2
3
R9
10K
R10
10K
R169
NOT POPULATED
C5
1μF
C6
1μF
SHDN
8
5V
C1M
5
5V
6
3
4
C1P C2M
VIN
1V0
C11
R7
22μF 30K
C2P
VOUT
7
C12
10PF
5V
R167
10K
R165
15K
1
2
-
3
+
R166
10K
TPS60500
C15
4.7μF
MN15A
1
EN
MN3
GND
FB
10
PG
2
R11
120K
9
LM293
D1
MMSD4148
VDDCORE and VDDBU are controlled by Power-on-Reset (POR) to gurantee that these power
sources reach their target values prior to the release of POR. (See Figure 41-2.)
• VDDIOM and VDDIOP must NOT be powered until VDDCORE has reached a level superior
or equal to Vth+ (0.5V).
• VDDIOM and VDDIOP must be ≥ 0.7V within (T2 + T3) after VDDCORE reaches
Vth+ (0.5V).
• VDDIOM and VDDIOP must reach Voh (2.6V) within (T2 +T3 +T4) after VDDCORE has
reached Vth+ (0.5V).
• T2 = Tres = 30 µs
• T3 = 3 x Tslck
• T4 = 14 x Tslck
777
6384E–ATARM–05-Feb-10
Tsclk min (22 µs) is obtained for the maximum frequency of the internal RC oscillator (44 kHz).
This gives:
• T2 = Tres = 30 µs
• T3 = 66 µs
• T4 = 308 µs
41.8.3
778
Power-down Sequence
Switch off the VDDIOM and VDDIOP power supplies prior to, or at the same time, as
VDDCORE. No power-up or power-down restrictions apply to VDDBU, VDDPL, VDDANA and
VDDUSB.
AT91SAM9G20
6384E–ATARM–05-Feb-10
AT91SAM9G20
41.9
EBI Timings
SMC Timings are given in MAX (T = 85°C, VDDCORE = 0.9V) corner.
Timings are given assuming a capacitance load on data, control and address pads:
Table 41-25. Capacitance Load
Corner
IO Supply
MAX
3.3V
50 pF
1.8V
30 pF
In the following tables tCPMCK is MCK period.
41.9.1
Read Timings
Table 41-26. SMC Read Signals - NRD Controlled (READ_MODE= 1)
Symbol
Parameter
Min
VDDIOM Supply
1.8V
Units
3.3V
NO HOLD SETTINGS (nrd hold = 0)
SMC1
Data Setup before NRD High
SMC2
Data Hold after NRD High
13.0
11.4
ns
0
0
ns
9.6
8.0
ns
0
0
ns
HOLD SETTINGS (nrd hold ≠ 0)
SMC3
Data Setup before NRD High
SMC4
Data Hold after NRD High
HOLD or NO HOLD SETTINGS (nrd hold ≠ 0, nrd hold =0)
NBS0/A0, NBS1, NBS2/A1, NBS3,
A2 - A25 Valid before NRD High
(nrd setup + nrd
pulse)* tCPMCK 0.4
(nrd setup + nrd
pulse)* tCPMCK 0.4
ns
SMC6
NCS low before NRD High
(nrd setup + nrd
pulse - ncs rd
setup) * tCPMCK +
0.5
(nrd setup + nrd
pulse - ncs rd
setup) * tCPMCK +
0.4
ns
SMC7
NRD Pulse Width
nrd pulse *
tCPMCK + 0.2
nrd pulse *
tCPMCK + 0.1
ns
SMC5
Table 41-27. SMC Read Signals - NCS Controlled (READ_MODE= 0)
Symbol
Parameter
Min
VDDIOM supply
1.8V
Units
3.3V
NO HOLD SETTINGS (ncs rd hold = 0)
SMC8
Data Setup before NCS High
SMC9
Data Hold after NCS High
12.6
11.0
ns
0
0
ns
779
6384E–ATARM–05-Feb-10
Table 41-27. SMC Read Signals - NCS Controlled (READ_MODE= 0) (Continued)
HOLD SETTINGS (ncs rd hold ≠ 0)
SMC10
Data Setup before NCS High
SMC11
Data Hold after NCS High
9.2
7.6
ns
0
0
ns
HOLD or NO HOLD SETTINGS (ncs rd hold ≠ 0, ncs rd hold = 0)
NBS0/A0, NBS1, NBS2/A1, NBS3,
A2 - A25 valid before NCS High
(ncs rd setup +
ncs rd pulse)*
tCPMCK -0.8
(ncs rd setup +
ncs rd pulse)*
tCPMCK -0.6
ns
SMC13
NRD low before NCS High
(ncs rd setup +
ncs rd pulse nrd setup)*
tCPMCK -0.2
(ncs rd setup +
ncs rd pulse nrd setup)*
tCPMCK -0.3
ns
SMC14
NCS Pulse Width
ncs rd pulse
length * tCPMCK +
0.1
ncs rd pulse
length * tCPMCK 0.1
ns
SMC12
41.9.2
Write Timings
Table 41-28. SMC Write Signals - NWE controlled (WRITE_MODE = 1)
Min
Symbol
Parameter
1.8V Supply
3.3V Supply
Units
HOLD or NO HOLD SETTINGS (nwe hold ≠ 0, nwe hold = 0)
SMC15
Data Out Valid before NWE High
nwe pulse *
tCPMCK -0.8
nwe pulse *
tCPMCK -0.8
ns
SMC16
NWE Pulse Width
nwe pulse *
tCPMCK -0.4
nwe pulse *
tCPMCK -0.4
ns
SMC17
NBS0/A0 NBS1, NBS2/A1, NBS3, A2
- A25 valid before NWE low
nwe setup *
tCPMCK -0.5
nwe setup *
tCPMCK -0.5
ns
(nwe setup - ncs
rd setup + nwe
pulse) * tCPMCK 0.2
(nwe setup - ncs
rd setup + nwe
pulse) * tCPMCK 0.2
ns
NCS low before NWE high
SMC18
HOLD SETTINGS (nwe hold ≠ 0)
SMC19
NWE High to Data OUT, NBS0/A0
NBS1, NBS2/A1, NBS3, A2 - A25
change
nwe hold * tCPMCK
-0.4
nwe hold *
tCPMCK -0.4
ns
SMC20
NWE High to NCS Inactive (1)
(nwe hold - ncs
wr hold)* tCPMCK 0.3
(nwe hold - ncs
wr hold)* tCPMCK
-0.3
ns
3.1
ns
NO HOLD SETTINGS (nwe hold = 0)
NWE High to Data OUT, NBS0/A0
NBS1, NBS2/A1, NBS3, A2 - A25,
NCS change(1)
SMC21
Note:
780
3.4
1. hold length = total cycle duration - setup duration - pulse duration. “hold length” is for “ncs wr
hold length” or “NWE hold length”.
AT91SAM9G20
6384E–ATARM–05-Feb-10
AT91SAM9G20
Table 41-29. SMC Write NCS Controlled (WRITE_MODE = 0)
Min
Symbol
Parameter
1.8V Supply
3.3V Supply
Units
SMC22
Data Out Valid before NCS High
ncs wr pulse *
tCPMCK -0.8
ncs wr pulse *
tCPMCK -0.7
ns
SMC23
NCS Pulse Width
ncs wr pulse *
tCPMCK + 0.1
ncs wr pulse *
tCPMCK -0.1
ns
SMC24
NBS0/A0 NBS1, NBS2/A1, NBS3, A2
- A25 valid before NCS low
ncs wr setup *
tCPMCK -0.6
ncs wr setup *
tCPMCK -0.6
ns
(ncs wr setup nwe setup + ncs
pulse)* tCPMCK 0.4
(ncs wr setup nwe setup + ncs
pulse)* tCPMCK 0.3
ns
SMC25
NWE low before NCS high
SMC26
NCS High to Data Out, NBS0/A0,
NBS1, NBS2/A1, NBS3, A2 - A25,
change
ncs wr hold *
tCPMCK -0.2
ncs wr hold *
tCPMCK -0.2
ns
SMC27
NCS High to NWE Inactive
(ncs wr hold nwe hold)*
tCPMCK -0.2
(ncs wr hold nwe hold)*
tCPMCK -0.2
ns
Figure 41-3. SMC Timings - NCS Controlled Read and Write
SMC12
SMC12
SMC26
SMC24
A0/A1/NBS[3:0]/A2-A25
SMC13
SMC13
NRD
NCS
SMC14
SMC14
SMC8
SMC9
SMC10
SMC23
SMC11
SMC22
SMC26
D0 - D15
SMC25
SMC27
NWE
NCS Controlled READ
with NO HOLD
NCS Controlled READ
with HOLD
NCS Controlled WRITE
781
6384E–ATARM–05-Feb-10
Figure 41-4. SMC Timings - NRD Controlled Read and NWE Controlled Write
SMC21
SMC17
SMC5
SMC5
SMC17
SMC19
A0/A1/NBS[3:0]/A2-A25
SMC6
SMC21 SMC6
SMC18
SMC18
SMC20
NCS
NRD
SMC7
SMC7
SMC1
SMC2
SMC15
SMC21
SMC3
SMC15
SMC4
SMC19
D0 - D31
NWE
SMC16
NRD Controlled READ
with NO HOLD
SMC16
NWE Controlled WRITE
with NO HOLD
NRD Controlled READ
with HOLD
NWE Controlled WRITE
with HOLD
41.10 SDRAMC Timings
Timings are given assuming a capacitance load on data, control and address pads :
Table 41-30. Capacitance Load on data, control and address pads
Corner
IO Supply
MAX
3.3V
50pF
1.8V
30 pF
Table 41-31. Capacitance Load on SDCK pad
Corner
IO Supply
MAX
3.3V
10pF
1.8V
10pF
The SDRAM Controller satisfies the timings of standard PC100, PC133 (3.3V supply) and
Mobile SDRAM (1.8 supply) that are given in Table 41-32, Table 41-33 and Table 41-34.
Table 41-32. SDRAM PC100 Characteristics
Parameter
Min
Max
3.3V Supply
3.3V Supply
Units
100
MHz
SDRAM Controller Clock Frequency
(1)(2)
Control/Address/Data In Setup
(1)(2)
Control/Address/Data In Hold
2
ns
1
ns
Data Out Access time after SDCK rising
Data Out change time after SDCK rising
782
6
3
ns
ns
AT91SAM9G20
6384E–ATARM–05-Feb-10
AT91SAM9G20
Table 41-33. SDRAM PC133 Characteristics
Parameter
Min
Max
3.3V Supply
3.3V Supply
Units
133
MHz
SDRAM Controller Clock Frequency
Control/Address/Data In Setup(1)(2)
(1)(2)
Control/Address/Data In Hold
1.5
ns
0.8
ns
Data Out Access time after SDCK rising
5.4
Data Out change time after SDCK rising
ns
3.0
ns
Table 41-34. Mobile Characteristics
Parameter
Min
Max
1.8V Supply
1.8V Supply
Units
133/100 (3)
MHz
SDRAM Controller Clock Frequency
Control/Address/Data In Setup(1)(2)
(1)(2)
Control/Address/Data In Hold
2.0
1.0
Data Out Access time after SDCK rising
Data Out change time after SDCK rising
Notes:
ns
ns
6.0 / 8.0
3.0
(3)
ns
ns
1. Control is the set of following signals: SDCKE, SDCS, RAS, CAS, SDA10, BAx, DQMx, and
SDWE.
2. Address is the set of A0-A9, A11-A13.
3. 133 MHz with CL = 3, 100 MHz with CL = 2.
783
6384E–ATARM–05-Feb-10
41.11 Peripheral Timings
41.11.1
EMAC
Timings are given assuming a capacitance load on data and clock:
Table 1. Capacitance Load on data, clock pads
Corner
IO Supply
MAX
3.3V
20pf
1.8V
20pf
The Ethernet controller satisfies the timings of standard in MAX corner.
Table 41-35. EMAC Signals Relative to EMDC
Symbol
Parameter
EMAC1
Setup for EMDIO from EMDC rising
10 ns
EMAC2
Hold for EMDIO from EMDC rising
10 ns
EMAC3
EMDIO toggling from EMDC rising
0 ns
300 ns
Min (ns)
Max (ns)
41.11.1.1
Min (ns)
Max (ns)
MII Mode
Table 41-36. EMAC MII Specific Signals
Symbol
Parameter
EMAC4
Setup for ECOL from ETXCK rising
10
EMAC5
Hold for ECOL from ETXCK rising
10
EMAC6
Setup for ECRS from ETXCK rising
10
EMAC7
Hold for ECRS from ETXCK rising
10
EMAC8
ETXER toggling from ETXCK rising
10
25
EMAC9
ETXEN toggling from ETXCK rising
10
25
EMAC10
ETX toggling from ETXCK rising
10
25
EMAC11
Setup for ERX from ERXCK
10
EMAC12
Hold for ERX from ERXCK
10
EMAC13
Setup for ERXER from ERXCK
10
EMAC14
Hold for ERXER from ERXCK
10
EMAC15
Setup for ERXDV from ERXCK
10
EMAC16
Hold for ERXDV from ERXCK
10
Note:
784
1. VDDIO from 3.0V to 3.6V, maximum external capacitor = 20 pF
AT91SAM9G20
6384E–ATARM–05-Feb-10
AT91SAM9G20
Figure 41-5. EMAC MII Mode
EMDC
EMAC1
EMAC3
EMAC2
EMDIO
EMAC4
EMAC5
EMAC6
EMAC7
ECOL
ECRS
ETXCK
EMAC8
ETXER
EMAC9
ETXEN
EMAC10
ETX[3:0]
ERXCK
EMAC11
EMAC12
ERX[3:0]
EMAC13
EMAC14
EMAC15
EMAC16
ERXER
ERXDV
Table 41-37. RMII Mode
Symbol
Parameter
Min (ns)
Max (ns)
EMAC21
ETXEN toggling from EREFCK rising
2
16
EMAC22
ETX toggling from EREFCK rising
2
16
EMAC23
Setup for ERX from EREFCK rising
4
EMAC24
Hold for ERX from EREFCK rising
2
EMAC25
Setup for ERXER from EREFCK rising
4
785
6384E–ATARM–05-Feb-10
Table 41-37. RMII Mode
Symbol
Parameter
Min (ns)
EMAC26
Hold for ERXER from EREFCK rising
2
EMAC27
Setup for ECRSDV from EREFCK rising
4
EMAC28
Hold for ECRSDV from EREFCK rising
2
Max (ns)
Figure 41-6. EMAC RMII Timings
EREFCK
EMAC21
ETXEN
EMAC22
ETX[1:0]
EMAC23
EMAC24
ERX[1:0]
EMAC25
EMAC26
EMAC27
EMAC28
ERXER
ECRSDV
41.11.2
SPI
SPI timings are given assuming a capacitance load on MISO, SPCK and MOSI:
Table 41-38. Capacitance Load for MISO, SPCK and MOSI
Corner
Supply
MAX
1.8V
20 pF
Figure 41-7. SPI Master Mode 1 and 2
SPCK
SPI0
SPI1
MISO
SPI2
MOSI
786
AT91SAM9G20
6384E–ATARM–05-Feb-10
AT91SAM9G20
Figure 41-8. SPI Master Mode 0 and3
SPCK
SPI3
SPI4
MISO
SPI5
MOSI
Figure 41-9. SPI Slave Mode 0 and 3
SPCK
SPI6
MISO
SPI7
SPI8
SPI10
SPI11
MOSI
Figure 41-10. SPI Slave Mode 1 and 2
SPCK
SPI9
MISO
MOSI
787
6384E–ATARM–05-Feb-10
Figure 41-11. SPI Slave Mode - NPCS Timings
SPI15
SPI14 SPI6
SPCK
(CPOL = 0)
SPI12
SPI13
SPI9
SPCK
(CPOL = 1)
SPI16
MISO
Table 41-39. SPI Timings
Symbol
Parameter
Conditions
Min
Max
Units
Master Mode
SPI0
MISO Setup time before SPCK rises
MAX corner, VDDIOP in 1.8V range
14.5 + 0.5*tCPMCK
ns
SPI1
MISO Hold time after SPCK rises
MAX corner, VDDIOP in 1.8V range
-11.6 - 0.5* tCPMCK
ns
SPI2
SPCK rising to MOSI
MAX corner, VDDIOP in 1.8V range
-0.6
ns
SPI3
MISO Setup time before SPCK falls
MAX corner, VDDIOP in 1.8V range
14.7 + 0.5*tCPMCK
ns
SPI4
MISO Hold time after SPCK falls
MAX corner, VDDIOP in 1.8V range
-11.7 - 0.5* tCPMCK
ns
SPI5
SPCK falling to MOSI
MAX corner, VDDIOP in 1.8V range
-0.7
ns
Slave Mode
SPI6
SPCK falling to MISO
MAX corner, VDDIOP in 1.8V range
14.7
ns
SPI7
MOSI Setup time before SPCK rises
MAX corner, VDDIOP in 1.8V range
5.8
ns
SPI8
MOSI Hold time after SPCK rises
MAX corner, VDDIOP in 1.8V range
-2.7
ns
SPI9
SPCK rising to MISO
MAX corner, VDDIOP in 1.8V range
14.7
ns
SPI10
MOSI Setup time before SPCK falls
MAX corner, VDDIOP in 1.8V range
23.8
ns
SPI11
MOSI Hold time after SPCK falls
MAX corner, VDDIOP in 1.8V range
15.3
ns
SPI12
NPCS0 setup to SPCK rising
MAX corner, VDDIOP in 1.8V range
-8.3
ns
SPI13
NPCS0 hold after SPCK falling
MAX corner, VDDIOP in 1.8V range
10.9
ns
SPI14
NPCS0 setup to SPCK falling
MAX corner, VDDIOP in 1.8V range
-8.3
ns
SPI15
NPCS0 hold after SPCK rising
MAX corner, VDDIOP in 1.8V range
10.9
ns
SPI16
NPCS0 falling to MISO valid
MAX corner, VDDIOP in 1.8V range
14.7
Note:
788
10.7
ns
1. CLOAD is 8 pF for MISO and 6 pF for SPCK and MOSI.
AT91SAM9G20
6384E–ATARM–05-Feb-10
AT91SAM9G20
41.11.3
SSC
Timings are given assuming a capacitance load on clock and data signals.
Table 41-40. Capacitance Load
Corner
Supply
MAX
3.3V
30pF
1.8V
20pF
Figure 41-12. SSC Transmitter, TK and TF in Output
TK (CKI =1)
TK (CKI =0)
SSC0
TF/TD
Figure 41-13. SSC Transmitter, TK in Input and TF in Output
TK (CKI =1)
TK (CKI =0)
SSC1
TF/TD
789
6384E–ATARM–05-Feb-10
Figure 41-14. SSC Transmitter, TK in Output and TF in Input
TK (CKI=1)
TK (CKI=0)
SSC2
SSC3
TF
SSC0
TD
Figure 41-15. SSC Transmitter, TK and TF in Input
TK (CKI=1)
TK (CKI=0)
SSC4
SSC5
TF
SSC3
TD
Figure 41-16. SSC Receiver RK and RF in Input
RK (CKI=0)
RK (CKI=1)
SSC6
SSC7
RF/RD
790
AT91SAM9G20
6384E–ATARM–05-Feb-10
AT91SAM9G20
Figure 41-17. SSC Receiver, RK in input and RF in Output
RK (CKI=1)
RK (CKI=0)
SSC6
SSC7
RD
SSC8
RF
Figure 41-18. SSC Receiver, RK and RF in Output
RK (CKI=1)
RK (CKI=0)
SSC9
SSC10
RD
SSC11
RF
Figure 41-19. SSC Receiver, RK in Output and RF in Input
RK (CKI=0)
RK (CKI=1)
SSC9
SSC10
RF/RD
791
6384E–ATARM–05-Feb-10
Table 41-41. SSC Timings
Symbol
Parameter
Conditions
Min
Max
Units
MAX corner, VDDIO = 1.8V
-3.2 ((2)
4.2 (2)
ns
MAX corner, VDDIO = 3.3V
-2.7
(2)
3.7
(2)
ns
-3.2
(2)
4.2
(2)
ns
-2.7
(2)
3.7
(2)
ns
Transmitter
SSC0
TK edge to TF/TD (TK output, TF output)
MAX corner, VDDIO = 1.8V
SSC1
TK edge to TF/TD (TK input, TF output)
SSC2
TF setup time before TK edge (TK output)
SSC3
TF hold time after TK edge (TK output)
MAX corner, VDDIO = 3.3V
SSC4 (1)
21.2 - tCPMCK
ns
MAX corner, VDDIO = 3.3V
15.5 - tCPMCK
ns
MAX corner, VDDIO = 1.8V
tCPMCK - 13.4
ns
MAX corner, VDDIO = 3.3V
tCPMCK - 9.5
ns
MAX corner, VDDIO = 1.8V
-3.1(1)(2)
2 * tCPMCK +
4.3 (1)(2)
ns
MAX corner, VDDIO = 3.3V
-2.6(1)(2)
2 * tCPMCK +
3.8 (1)(2)
ns
MAX corner, VDDIO = 1.8V
7.4 - tCPMCK
ns
MAX corner, VDDIO = 3.3V
6.0 - tCPMCK
ns
MAX corner, VDDIO = 1.8V
tCPMCK - 0.7
ns
MAX corner, VDDIO = 3.3V
tCPMCK - 2.0
ns
MAX corner, VDDIO = 1.8V
11.6(1)
3 * tCPMCK +
17.0(1)
ns
MAX corner, VDDIO = 3.3V
7.7(1)
3 * tCPMCK +
11.3(1)
ns
TK edge to TF/TD (TK output, TF input)
SSC5
TF setup time before TK edge (TK input)
SSC6
TF hold time after TK edge (TK input)
SSC7(1)
MAX corner, VDDIO = 1.8V
TK edge to TF/TD (TK input, TF input)
Receiver
SSC8
RF/RD setup time before RK edge (RK input)
SSC9
RF/RD hold time after RK edge (RK input)
MAX corner, VDDIO = 1.8V
7.4 - tCPMCK
ns
MAX corner, VDDIO = 3.3V
6.2 - tCPMCK
ns
MAX corner, VDDIO = 1.8V
tCPMCK +7.4
ns
MAX corner, VDDIO = 3.3V
tCPMCK +6.1
MAX corner, VDDIO = 1.8V
SSC10
RK edge to RF (RK input)
SSC11
RF/RD setup time before RK edge (RK output)
SSC12
RF/RD hold time after RK edge (RK output)
MAX corner, VDDIO = 3.3V
Notes:
11.3
(2)
7.3
ns
(2)
ns
(2)
ns
22.3
16.5
MAX corner, VDDIO = 1.8V
21.6 - tCPMCK
ns
MAX corner, VDDIO = 3.3V
15.9 - tCPMCK
ns
MAX corner, VDDIO = 1.8V
tCPMCK - 10.5
ns
MAX corner, VDDIO = 3.3V
tCPMCK - 6.5
ns
MAX corner, VDDIO = 1.8V
SSC13
(2)
RK edge to RF (RK output)
MAX corner, VDDIO = 3.3V
(2)
ns
(2)
ns
-3.2
-2.8
1. Timings SSC4 and SSC7 depend on the start condition. When STTDLY = 0 (Receive start delay) and START = 4, or 5 or 7
(Receive Start Selection), two periods of the MCK must be added to timings.
2. For output signals (TF, TD, RF), Min and Max access times are defined. The Min access time is the time between the TK (or
RK) edge and the signal change. The Max access timing is the time between the TK edge and the signal stabilization. Figure
41-20 illustrates Min and Max accesses for SSC0. The same appliess for SSC1, SSC4, and SSC7, SSC10 and SSC13.
792
AT91SAM9G20
6384E–ATARM–05-Feb-10
AT91SAM9G20
Figure 41-20. Min and Max Access for SSC0
TK (CKI =1)
TK (CKI =0)
SSC0min
SSC0max
TF/TD
41.11.4
ISI
Timings are given assuming a capacitance load on clock and data signals.
Table 41-42. Capacitance Load
Corner
Supply
MAX
3.3V
30pF
1.8V
20pF
Figure 41-21. ISI Timing Diagram
PIXCLK
3
DATA[7:0]
VSYNC
HSYNC
Valid Data
1
Valid Data
Valid Data
2
Table 41-43. ISI Timings with Peripheral Supply 3.3V
Symbol
Parameter
Min
Max
Units
ISI1
DATA/VSYNC/HSYNC setup time
4.5
ns
ISI2
DATA/VSYNC/HSYNC hold time
1.3
ns
ISI3
PIXCLK frequency
TBD
MHz
Max
Units
Table 41-44. ISI Timings with Peripheral Supply 1.8V
Symbol
Parameter
Min
ISI1
DATA/VSYNC/HSYNC setup time
2.0
ns
ISI2
DATA/VSYNC/HSYNC hold time
6.4
ns
ISI3
PIXCLK frequency
TBD
MHz
793
6384E–ATARM–05-Feb-10
41.11.5
MCI
Capacitance loads on data and clock are given in Table 41-45.
Figure 41-22. MCI Timings
MCI1
CLK
MCI2
MCI3
MCI4
MCI5
CMD_DAT Input
CMD_DAT Output
Shaded areas are not valid
Table 41-45. MCI Timings
Symbol
MCI1
Parameter
CLK frequency at Data transfer Mode
CLoad
Min
Max
Units
C = 25 pf
25
MHz
C= 100 pf
20
MHz
C= 250 pf
20
MHz
400
kHz
CLK frequency at Identification Mode
CLK Low time
C= 100 pf
10
ns
CLK High time
C= 100 pf
10
ns
CLK Rise time
C= 100 pf
10
ns
CLK Fall time
C= 100 pf
10
ns
CLK Low time
C= 250 pf
50
ns
CLK High time
C= 250 pf
50
ns
CLK Rise time
C= 250 pf
50
ns
CLK Fall time
C= 250 pf
50
ns
MCI2
Input hold time
3
ns
MCI3
Input setup time
3
ns
MCI4
Output change after CLK rising
5
ns
MCI5
Output valid before CLK rising
5
ns
794
AT91SAM9G20
6384E–ATARM–05-Feb-10
AT91SAM9G20
41.11.6
UDP
Figure 41-23. USB Data Signal Rise and Fall Times
Rise Time
Fall Time
90%
VCRS
10%
Differential
Data Lines
10%
tR
tF
(a)
REXT=27 ohms
Fosc = 6 MHz/750 kHz
Cload
Buffer
(b)
Table 41-46. In Full Speed
Symbol
Parameter
Conditions
tFR
Transition Rise Time
CLOAD = 50 pF
tFE
Transition Fall Time
CLOAD = 50 pF
tFRFM
Rise/Fall time Matching
Min
Typ
Max
Unit
4
20
ns
4
20
ns
90
111.11
%
795
6384E–ATARM–05-Feb-10
42. AT91SAM9G20 Mechanical Characteristics
42.1
217-ball LFBGA Package Drawing
Figure 42-1. 217-ball LFBGA Package Drawing
Table 42-1.
Soldering Informations
Ball Land
0.43 mm +/- 0.05
Soldering Mask Opening
0.30 mm +/- 0.05
Table 42-2.
Device and 217-ball LFBGA Package Maximum Weight
450
mg
Table 42-3.
217-ball LFBGA Package Characteristics
Moisture Sensitivity Level
796
3
AT91SAM9G20
6384E–ATARM–05-Feb-10
AT91SAM9G20
Table 42-4.
Package Reference
JEDEC Drawing Reference
MO-205
JESD97 Classification
e1
42.1.1
Soldering Profile
Table 42-5 gives the recommended soldering profile from J-STD-20.
Table 42-5.
Soldering Profile
Profile Feature
BGA217 green compliant Package
BGA247 green compliant Package
Average Ramp-up Rate (217°C to Peak)
3° C/sec. max.
3° C/sec. max.
Preheat Temperature 175°C ±25°C
180 sec. max.
180 sec. max.
Temperature Maintained Above 217°C
60 sec. to 150 sec.
60 sec. to 150 sec.
Time within 5° C of Actual Peak Temperature
20 sec. to 40 sec.
20 sec. to 40 sec.
Peak Temperature Range
260 +0 ° C
260 +0 ° C
Ramp-down Rate
6° C/sec. max.
6° C/sec. max.
Time 25° C to Peak Temperature
8 min. max.
8 min. max.
Note:
It is recommended to apply a soldering temperature higher than 250°C
A maximum of three reflow passes is allowed per component.
797
6384E–ATARM–05-Feb-10
42.2
247-ball TFBGA Package Drawing
Figure 42-2. 247-ball TFBGA Drawing
Table 42-6.
Ball Information
Ball Pitch
0.50 mm ± 0.05
Ball Diameter
0.30 mm ± 0.05
798
AT91SAM9G20
6384E–ATARM–05-Feb-10
AT91SAM9G20
Table 42-7.
Soldering Information
Ball Land
0.35 mm ± 0.05
Solder Mask Opening
0.27 mm ± 0.05
Table 42-8.
Device and 247-ball TFBGA Package Maximum Weight
177
mg
Table 42-9.
247-ball TFBGA Package Characteristics
Moisture Sensitivity Level
3
Table 42-10. Package Reference
JEDEC Drawing Reference
none
JESD97 Classification
e1
42.2.1
Soldering Profile
Table 42-5 gives the recommended soldering profile from J-STD-20.
Table 42-11. Soldering Profile
Profile Feature
Green Package
Average Ramp-up Rate (217°C to Peak)
3° C/sec. max.
Preheat Temperature 175°C ±25°C
180 sec. max.
Temperature Maintained Above 217°C
60 sec. to 150 sec.
Time within 5° C of Actual Peak Temperature
20 sec. to 40 sec.
Peak Temperature Range
260 +0 ° C
Ramp-down Rate
6° C/sec. max.
Time 25° C to Peak Temperature
8 min. max.
Note:
It is recommended to apply a soldering temperature higher than 250°C. A maximum of three
reflow passes is allowed per component.
799
6384E–ATARM–05-Feb-10
43. AT91SAM9G20 Ordering Information
Table 43-1.
AT91SAM9G20 Ordering Information
MRL A Ordering Code
MRL B Ordering Code
Package
Package Type
Temperature Operating Range
AT91SAM9G20-CU
AT91SAM9G20B-CU
BGA217
Green
Industrial -40°C to 85°C
–
AT91SAM9G20B-CFU
BGA247
Green
Industrial -40°C to 85°C
800
AT91SAM9G20
6384E–ATARM–05-Feb-10
AT91SAM9G20
44. AT91SAM9G20 Errata
44.1
Marking
All devices are marked with the Atmel logo and the ordering code.
Additional marking has the following format:
YYWW
V
XXXXXXXXX
ARM
where
• “YY”: manufactory year
• “WW”: manufactory week
• “V”: revision
• “XXXXXXXXX”: lot number
801
6384E–ATARM–05-Feb-10
44.2
AT91SAM9G20 Errata - Revision “A” Parts
Refer to Section 44.1 “Marking” on page 801.
44.2.1
44.2.1.1
Analog-to-digital Converter (ADC)
ADC: Sleep Mode
If Sleep mode is activated while there is no activity (no conversion is being performed), it will
take effect only after a conversion occurs.
Problem Fix/Workaround
To activate sleep mode as soon as possible, it is recommended to write successively, ADC
Mode Register (SLEEP) then ADC Control Register (START bit field); to start an analog-to-digital conversion, in order put ADC into sleep mode at the end of this conversion.
44.2.2
44.2.2.1
Boot ROM
Boot ROM: ROM Code, Internal RC Usage with SAM-BA Boot through USB
Booting from the internal RC oscillator (OSCSEL = 0) prevents using SAM-BA Boot through the
USB device interface.
Problem Fix/Workaround
Use SAM-BA Boot through DBGU (or AT91SAM-ICE JTAG-ICE interface with SAM-BA GUI) if
the internal RC oscillator must be used.
Boot from the 32 kHz external oscillator (OSCEL =1) to use SAM-BA Boot through the USB.
44.2.2.2
Boot ROM: MCCK Remains Active
The ROM boot sequence is as follows;
– DataFlash on SPI0 NPCS0
– DataFlash on SPI0 NPCS1
– NAND FLash
– SDCard
– TWI
– SAM-BA Boot
MCCK is not disabled after SDCard boot program. This does not affect the TWI boot program
but must be considered by any applications using SAM-BA boot.
Problem Fix/Workaround
None.
44.2.3
44.2.3.1
Error Corrected Code Controller (ECC)
ECC: 1-bit ECC per 512 Words
1-bit ECC per 512 words is not functional.
Problem Fix/Workaround
Perform the ECC computation by software.
802
AT91SAM9G20
6384E–ATARM–05-Feb-10
AT91SAM9G20
44.2.4
44.2.4.1
MCI
MCI: Busy Signal of R1b responses is not taken in account
The busy status of the card during the response (R1b) is ignored for the commands CMD7,
CMD28, CMD29, CMD38, CMD42, CMD56. Additionally, for commands CMD42 and CMD56 a
conflict can occur on data line0 if the MCI sends data to the card while the card is still busy.The
behavior is correct for CMD12 command (STOP_TRANSFER).
Problem Fix/Workaround
None.
44.2.4.2
MCI: SDIO Interrupt does not work with slots other than A
If there is 1-bit data bus width on slots other than slot A, the SDIO interrupt can not be captured.
The sample is made on the wrong data line.
Problem Fix/Workaround
None
44.2.4.3
MCI: Data Timeout Error Flag
As the data Timeout error flag checking the Naac timing cannot rise, the MCI can be stalled waiting indefinitely the Data start bit.
Problem Fix/Workaround
A STOP command must be sent with a software timeout.
44.2.4.4
MCI: Data Write Operation and number of bytes
The Data Write operation with a number of bytes less than 12 is impossible.
Problem Fix/Workaround
The PDC counters must always be equal to 12 bytes for data transfers lower than 12 bytes. The
BLKLEN or BCNT field are used to specify the real count number.
44.2.4.5
MCI: Flag Reset is not correct in half duplex mode
In half duplex mode, the reset of the flags ENDRX, RXBUFF, ENDTX and TXBUFE can be
incorrect. These flags are reset correctly after a PDC channel enable.
Problem Fix/Workaround
Enable the interrupts related to ENDRX, ENDTX, RXBUFF and TXBUFE only after enabling the
PDC channel by writing PDC_TXTEN or PDC_RXTEN.
803
6384E–ATARM–05-Feb-10
44.2.5
44.2.5.1
Reset Controller (RSTC)
RSTC: Reset During SDRAM Accesses
When a User Reset occurs during SDRAM read access, the SDRAM clock is turned off while
data are ready to be read on the data bus. The SDRAM maintains the data until the clock
restarts.
If the user Reset is programmed to assert a general reset, the data maintained by the SDRAM
leads to a data bus conflict and adversely affects the boot memories connected on the EBI:
• NAND Flash boot functionality, if the system boots out of internal ROM.
• NOR Flash boot, if the system boots on an external memory connected on the EBI CS0.
Problem Fix/Workaround
1. Avoid User Reset to generate a system reset.
2. Trap the User Reset with an interrupt.
In the interrupt routine, Power Down SDRAM properly and perform Peripheral and Processor
Reset with software in assembler.
Example with libV3.
• The main code:
//user reset interrupt setting
// Configure AIC controller to handle System peripheral interrupts
AT91F_AIC_ConfigureIt (
AT91C_BASE_AIC,
AT91C_ID_SYS,
AT91C_AIC_PRIOR_HIGHEST,
// AIC base address
// System peripheral ID
// Max priority
AT91C_AIC_SRCTYPE_INT_EDGE_TRIGGERED, // Level sensitive
sysc_handler );
// Enable SYSC interrupt in AIC
AT91F_AIC_EnableIt(AT91C_BASE_AIC, AT91C_ID_SYS);
*AT91C_RSTC_RMR = (0xA5<<24) | (0x4<<8) | AT91C_RSTC_URSTIEN;
• The C SYS handler:
extern void soft_user_reset(void);
void sysc_handler(void){
//check if interrupt comes from RSTC
if( (*AT91C_RSTC_RSR & AT91C_RSTC_URSTS ) == AT91C_RSTC_URSTS){
soft_user_reset();
//never reached
while(1);
}
}
804
AT91SAM9G20
6384E–ATARM–05-Feb-10
AT91SAM9G20
• Assembly code is mandatory for the following sequence as ARM instructions need to be
pipelined.
The assembler routine:
AREA
TEST, CODE
INCLUDEAT91SAM9xxx.inc
EXPORTsoft_user_reset
soft_user_reset
;disable IRQs
MRS r0, CPSR
ORR r0, r0, #0x80
MSR CPSR_c, r0
;change refresh rate to block all data accesses
LDR r0, =AT91C_SDRAMC_TR
LDR r1, =1
STR r1, [r0]
;prepare power down command
LDR r0, =AT91C_SDRAMC_LPR
LDR r1, =2
;prepare proc_reset and periph_reset
LDR r2, =AT91C_RSTC_RCR
LDR r3, =0xA5000005
;perform power down command
STR r1, [r0]
;perform proc_reset and periph_reset (in the ARM pipeline)
STR r3, [r2]
END
805
6384E–ATARM–05-Feb-10
44.2.6
44.2.6.1
Serial Peripheral Interface (SPI)
SPI: Bad Serial Clock Generation on second chip_select when SCBR = 1, CPOL = 1 and NCPHA = 0
If the SPI is used in the following configuration:
• master mode
• CPOL =1 and NCPHA = 0
• multiple chip selects used with one transfer with Baud rate (SCBR) equal to 1 (i.e., when
serial clock frequency equals the system clock frequency) and the other transfers set with
SCBR not equal to 1
• transmit with the slowest chip select and then with the fastest one
then an additional pulse will be generated on output PSCK during the second transfer.
Problem Fix/Workaround
Do not use a multiple Chip Select configuration where at least one SCRx register is configured
with SCBR = 1 and the others differ from 1 if CPHA = 0 and CPOL = 1.
If all chip selects are configured with Baudrate = 1, the issue does not appear.
44.2.6.2
SPI: Baudrate set to 1
When Baudrate is set to 1 (i.e., when serial clock frequency equals the system clock frequency),
and when the fields BITS (number of bits to be transmitted) equals an ODD value (in this case
9,11,13 or 15), an additional pulse is generated on output SPCK. No error occurs if BITS field
equals 8,10,12,14 or 16 and Baudrate = 1.
Problem Fix/Workaround
None.
44.2.7
44.2.7.1
Serial Synchronous Controller (SSC)
SSC: Unexpected RK clock cycle when RK outputs a clock during data transfer
When the SSC receiver is used in the following configuration:
• the internal clock divider is used (CKS =0 and DIV different from 0),
• RK pin set as output and provides the clock during data transfer (CKO=2)
• data sampled on RK falling edge (CKI =0)
then, at the end of the data, the RK pin is set in high impedance which may be interpreted as an
unexpected clock cycle.
Problem Fix/Workaround
Enable the pull-up on RK pin.
44.2.7.2
SSC: Incorrect first RK clock cycle when RK outputs a clock during data transfer
When the SSC receiver is used in the following configuration:
• RX clock is divided clock (CKS = 0 and DIV different from 0)
• RK pin set as output and provides the clock during data transfer (CKO = 2)
• data sampled on RK falling edge (CKI = 0)
then the first clock cycle time generated by the RK pin is equal to MCK/(2 x (DIV +1)) instead of
MCK/(2 x DIV).
Problem Fix/Workaround
806
AT91SAM9G20
6384E–ATARM–05-Feb-10
AT91SAM9G20
None.
44.2.7.3
SSC: Transmitter Limitations in Slave Mode
If TK is programmed as output and TF is programmed as input, it is impossible to emit data
when start of edge (rising or falling) of synchro with a Start Delay equal to zero.
Problem Fix/Workaround
None.
44.2.7.4
SSC: Periodic Transmission Limitations in Master Mode
If Last Significant Bit is sent first (MSBF = 0) the first TAG during the frame synchro is not sent.
Problem Fix/Workaround
None.
44.2.8
44.2.8.1
Shutdown Controller (SHDWC)
SHDWC: SHDN Signal may be Driven to Low Level Voltage During Device Power-on
If only VDDBU is powered during boot sequence (No VDDCORE), the SHDN signal may be
driven to low level voltage after a delay.This delay is linked to the startup time of the slow clock
selected by OSCSEL signal.
If SHDN pin is connected to the Enable pin (EN) of the VDDCORE regulator, VDDCORE establishment does not occur and the system does not start.
Problem Fix/Workaround
1. VDDCORE must be established within the delay corresponding to the startup time of
the slow clock selected by OSCSEL.
2. Add a glue logic to latch the rising edge of the SHDN signal. The reset of the latch output (EN_REG) can be connected to a PIO and used to enter the shutdown mode.
44.2.9
44.2.9.1
Static Memory Controller (SMC)
SMC: Chip Select Parameters Modification
The user must not change the configuration parameters of an SMC Chip Select (Setup, Pulse,
Cycle, Mode) if accesses are performed on this CS during the modification.
For example, the modification of the Chip Select 0 (CS0) parameters, while fetching the code
from a memory connected on this CS0, may lead to unpredictable behavior.
Problem Fix/Workaround
The code used to modify the parameters of an SMC Chip Select can be executed from the internal RAM or from a memory connected to another Chip Select
44.2.10
44.2.10.1
System Controller (SYSC)
SYSC: Possible Event Loss when reading RTT_SR
If an event (RTTINC or ALMS) occurs within the same slow clock cycle as when the RTT_SR is
read, the corresponding bit might be cleared. This can lead to the loss of this event.
Problem Fix/Workaround
The software must handle an RTT event as an interrupt and should not poll RTT_SR.
807
6384E–ATARM–05-Feb-10
44.2.11
44.2.11.1
Two-wire Interface (TWI)
TWI: RXRDY Flag is not reset by a SOFTWARE Reset
The RXRDY Flag is not reset when a Software reset is performed.
Problem Fix/Workaround
After a Software Reset, the Register TWI_RHR must be read.
44.2.12
44.2.12.1
UHP
UHP: Non-ISO IN Transfers
Conditions:
Consider the following sequence:
1. The Host controller issues an IN token.
2. The Device provides the IN data in a short packet.
3. The Host controller writes the received data to the system memory.
4. The Host controller is now supposed to carry out two Write transactions (TD status
write and TD retirement write) to the system memory in order to complete the status
update.
5. The Host controller raises the request for the first write transaction. By the time the
transaction is completed, a frame boundary is crossed.
6. After completing the first write transaction, the Host controller skips the second write
transaction.
Consequence: When this error occurs, the Host controller tries the same IN token again.
Problem Fix/Workaround
This problem can be avoided if the system guarantees that the status update can be completed
within the same frame.
44.2.12.2
UHP: ISO OUT transfers
Conditions:
Consider the following sequence:
1. The Host controller sends an ISO OUT token after fetching 16 bytes of data from the
system memory.
2. When the Host controller is sending the ISO OUT data, because of system latencies,
remaining bytes of the packet are not available. This results in a buffer underrun
condition.
3. While there is an underrun condition, if the Host controller is in the process of bit-stuffing, it causes the Host controller to hang.
Consequence: After the failure condition, the Host controller stops sending the SOF. This
causes the connected device to go into suspend state.
Problem Fix/Workaround
This problem can be avoided if the system can guarantee that no buffer underrun occurs during
the transfer.
808
AT91SAM9G20
6384E–ATARM–05-Feb-10
AT91SAM9G20
44.2.12.3
UHP: Remote Wakeup Event
Conditions:
When a Remote Wakeup event occurs on a downstream port, the OHCI Host controller begins
sending resume signaling to the device. The Host controller is supposed to send this resume
signaling for 20 ms. However, if the driver sets the HcControl.HCFS into USBOPERATIONAL
state during the resume event, then the Host controller terminates sending the resume signal
with an EOP to the device.
Consequence: If the Device does not recognize the resume (<20 ms) event then the Device
remains in suspend state.
Problem Fix/Workaround
Host stack can do a port resume after it sets the HcControl.HCFS to USBOPERATIONAL.
44.2.13
44.2.13.1
USART
USART: TXD Signal is floating in Modem and Hardware Handshaking mode.
TXD signal should be pulled up in Modem and Hardware Handshaking mode.
Problem Fix/Workaround
TXD is multiplexed with PIO which integrates a pull up resistor. This internal pull-up must be
enabled.
44.2.13.2
USART: DCD is Active High instead of Low
The DCD signal is active at High level in the USART Modem Mode .
DCD should be active at Low level.
Problem Fix/Workaround
Add an inverter.
809
6384E–ATARM–05-Feb-10
44.3
AT91SAM9G20 Errata - Revision “B” Parts
Refer to Section 44.1 “Marking” on page 801.
44.3.1
44.3.1.1
Analog-to-digital Converter (ADC)
ADC: Sleep Mode
If Sleep mode is activated while there is no activity (no conversion is being performed), it will
take effect only after a conversion occurs.
Problem Fix/Workaround
To activate sleep mode as soon as possible, it is recommended to write successively, ADC
Mode Register (SLEEP) then ADC Control Register (START bit field); to start an analog-to-digital conversion, in order put ADC into sleep mode at the end of this conversion.
44.3.2
44.3.2.1
Boot ROM
Boot ROM: ROM Code, Internal RC Usage with SAM-BA Boot through USB
Booting from the internal RC oscillator (OSCSEL = 0) prevents using SAM-BA Boot through the
USB device interface.
Problem Fix/Workaround
Use SAM-BA Boot through DBGU (or AT91SAM-ICE JTAG-ICE interface with SAM-BA GUI) if
the internal RC oscillator must be used.
Boot from the 32 kHz external oscillator (OSCEL =1) to use SAM-BA Boot through the USB.
44.3.2.2
Boot ROM: MCCK Remains Active
The ROM boot sequence is as follows;
– DataFlash on SPI0 NPCS0
– DataFlash on SPI0 NPCS1
– NAND FLash
– SDCard
– TWI
– SAM-BA Boot
MCCK is not disabled after SDCard boot program. This does not affect the TWI boot program
but must be considered by any applications using SAM-BA boot.
Problem Fix/Workaround
None.
44.3.3
44.3.3.1
Error Corrected Code Controller (ECC)
ECC: 1-bit ECC per 512 Words
1-bit ECC per 512 words is not functional.
Problem Fix/Workaround
Perform the ECC computation by software.
810
AT91SAM9G20
6384E–ATARM–05-Feb-10
AT91SAM9G20
44.3.4
44.3.4.1
MCI
MCI: Busy Signal of R1b responses is not taken in account
The busy status of the card during the response (R1b) is ignored for the commands CMD7,
CMD28, CMD29, CMD38, CMD42, CMD56. Additionally, for commands CMD42 and CMD56 a
conflict can occur on data line0 if the MCI sends data to the card while the card is still busy.The
behavior is correct for CMD12 command (STOP_TRANSFER).
Problem Fix/Workaround
None.
44.3.4.2
MCI: SDIO Interrupt does not work with slots other than A
If there is 1-bit data bus width on slots other than slot A, the SDIO interrupt can not be captured.
Th sample is made on the wrong data line.
Problem Fix/Workaround
None
44.3.4.3
MCI: Data Timeout Error Flag
As the data Timeout error flag checking the Naac timing cannot rise, the MCI can be stalled waiting indefinitely the Data start bit.
Problem Fix/Workaround
A STOP command must be sent with a software timeout.
44.3.4.4
MCI: Data Write Operation and number of bytes
The Data Write operation with a number of bytes less than 12 is impossible.
Problem Fix/Workaround
The PDC counters must always be equal to 12 bytes for data transfers lower than 12 bytes. The
BLKLEN or BCNT field are used to specify the real count number.
44.3.4.5
MCI: Flag Reset is not correct in half duplex mode
In half duplex mode, the reset of the flags ENDRX, RXBUFF, ENDTX and TXBUFE can be
incorrect. These flags are reset correctly after a PDC channel enable.
Problem Fix/Workaround
Enable the interrupts related to ENDRX, ENDTX, RXBUFF and TXBUFE only after enabling the
PDC channel by writing PDC_TXTEN or PDC_RXTEN.
811
6384E–ATARM–05-Feb-10
44.3.5
44.3.5.1
Reset Controller (RSTC)
RSTC: Reset During SDRAM Accesses
When a User Reset occurs during SDRAM read access, the SDRAM clock is turned off while
data are ready to be read on the data bus. The SDRAM maintains the data until the clock
restarts.
If the user Reset is programmed to assert a general reset, the data maintained by the SDRAM
leads to a data bus conflict and adversely affects the boot memories connected on the EBI:
• NAND Flash boot functionality, if the system boots out of internal ROM.
• NOR Flash boot, if the system boots on an external memory connected on the EBI CS0.
Problem Fix/Workaround
1. Avoid User Reset to generate a system reset.
2. Trap the User Reset with an interrupt.
In the interrupt routine, Power Down SDRAM properly and perform Peripheral and Processor
Reset with software in assembler.
Example with libV3.
• The main code:
//user reset interrupt setting
// Configure AIC controller to handle SSC interrupts
AT91F_AIC_ConfigureIt (
AT91C_BASE_AIC,
AT91C_ID_SYS,
AT91C_AIC_PRIOR_HIGHEST,
// AIC base address
// System peripheral ID
// Max priority
AT91C_AIC_SRCTYPE_INT_EDGE_TRIGGERED, // Level sensitive
sysc_handler );
// Enable SYSC interrupt in AIC
AT91F_AIC_EnableIt(AT91C_BASE_AIC, AT91C_ID_SYS);
*AT91C_RSTC_RMR = (0xA5<<24) | (0x4<<8) | AT91C_RSTC_URSTIEN;
• The C SYS handler:
extern void soft_user_reset(void);
void sysc_handler(void){
//check if interrupt comes from RSTC
if( (*AT91C_RSTC_RSR & AT91C_RSTC_URSTS ) == AT91C_RSTC_URSTS){
soft_user_reset();
//never reached
while(1);
}
}
812
AT91SAM9G20
6384E–ATARM–05-Feb-10
AT91SAM9G20
• Assembly code is mandatory for the following sequence as ARM instructions need to be
pipelined.
The assembler routine:
AREA
TEST, CODE
INCLUDEAT91SAM9xxx.inc
EXPORTsoft_user_reset
soft_user_reset
;disable IRQs
MRS r0, CPSR
ORR r0, r0, #0x80
MSR CPSR_c, r0
;change refresh rate to block all data accesses
LDR r0, =AT91C_SDRAMC_TR
LDR r1, =1
STR r1, [r0]
;prepare power down command
LDR r0, =AT91C_SDRAMC_LPR
LDR r1, =2
;prepare proc_reset and periph_reset
LDR r2, =AT91C_RSTC_RCR
LDR r3, =0xA5000005
;perform power down command
STR r1, [r0]
;perform proc_reset and periph_reset (in the ARM pipeline)
STR r3, [r2]
END
813
6384E–ATARM–05-Feb-10
44.3.6
44.3.6.1
Serial Peripheral Interface (SPI)
SPI: Bad Serial Clock Generation on second chip_select when SCBR = 1, CPOL = 1 and NCPHA = 0
If the SPI is used in the following configuration:
• master mode
• CPOL =1 and NCPHA = 0
• multiple chip selects used with one transfer with Baud rate (SCBR) equal to 1 (i.e., when
serial clock frequency equals the system clock frequency) and the other transfers set with
SCBR not equal to 1
• transmit with the slowest chip select and then with the fastest one
then an additional pulse will be generated on output PSCK during the second transfer.
Problem Fix/Workaround
Do not use a multiple Chip Select configuration where at least one SCRx register is configured
with SCBR = 1 and the others differ from 1 if CPHA = 0 and CPOL = 1.
If all chip selects are configured with Baudrate = 1, the issue does not appear.
44.3.6.2
SPI: Baudrate set to 1
When Baudrate is set to 1 (i.e., when serial clock frequency equals the system clock frequency),
and when the fields BITS (number of bits to be transmitted) equals an ODD value (in this case
9,11,13 or 15), an additional pulse is generated on output SPCK. No error occurs if BITS field
equals