ATMEL AT91SAM7A3-AJ At91 arm thumb-based microcontroller Datasheet

Features
• Incorporates the ARM7TDMI ® ARM® Thumb® Processor
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– High-performance 32-bit RISC Architecture
– High-density 16-bit Instruction Set
– Leader in MIPS/Watt
Embedded ICE In-circuit Emulation, Debug Communication Channel Support
256 Kbytes of Internal High-speed Flash, Organized in 1024 Pages of 256 Bytes
– Single Cycle Access at Up to 30 MHz in Worst Case Conditions
– Prefetch Buffer Optimizing Thumb Instruction Execution at Maximum Speed
– Page Programming Time: 4 ms, Including Page Auto-erase, Full Erase Time: 10 ms
– 10,000 Write Cycles, 10-year Data Retention Capability, Sector Lock Capabilities
32K Bytes of Internal High-speed SRAM, Single-cycle Access at Maximum Speed
Memory Controller (MC)
– Embedded Flash Controller, Abort Status and Misalignment Detection
– Memory Protection Unit
Reset Controller (RSTC)
– Based on Three Power-on Reset Cells
– Provides External Reset Signal Shaping and Reset Sources Status
Clock Generator (CKGR)
– Low-power RC Oscillator, 3 to 20 MHz On-chip Oscillator and One PLL
Power Management Controller (PMC)
– Power Optimization Capabilities, including Slow Clock Mode (Down to 500 Hz), Idle
Mode, Standby Mode and Backup Mode
– Four Programmable External Clock Signals
Advanced Interrupt Controller (AIC)
– Individually Maskable, Eight-level Priority, Vectored Interrupt Sources
– Four External Interrupt Sources and One Fast Interrupt Source, Spurious Interrupt
Protected
Debug Unit (DBGU)
– 2-wire UART and Support for Debug Communication Channel interrupt,
Programmable ICE Access Prevention
Periodic Interval Timer (PIT)
– 20-bit Programmable Counter plus 12-bit Interval Counter
Windowed Watchdog (WDT)
– 12-bit key-protected Programmable Counter
– Provides Reset or Interrupt Signal to the System
– Counter May Be Stopped While the Processor is in Debug Mode or in Idle State
Real-time Timer (RTT)
– 32-bit Free-running Counter with Alarm
– Runs Off the Internal RC Oscillator
Two Parallel Input/Output Controllers (PIO)
– Sixty-two 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
Shutdown Controller (SHDWC)
– Programmable Shutdown Pin and Wake-up Circuitry
Four 32-bit Battery Backup Registers for a Total of 16 Bytes
One 8-channel 20-bit PWM Controller (PMWC)
One USB 2.0 Full Speed (12 Mbits per Second) Device Port
– On-chip Transceiver, 2-Kbyte Configurable Integrated FIFOs
Nineteen Peripheral Data Controller (PDC) Channels
Two CAN 2.0B Active Controllers, Supporting 11-bit Standard and 29-bit Extended
Identifiers
– 16 Fully Programmable Message Object Mailboxes, 16-bit Time Stamp Counter
Two 8-channel 10-bit Analog-to-Digital Converter
AT91 ARM®
Thumb®-based
Microcontrollers
AT91SAM7A3
Preliminary
6042A–ATARM–23-Dec-04
Preliminary
• Three Universal Synchronous/Asynchronous Receiver Transmitters (USART)
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– Individual Baud Rate Generator, IrDA Infrared Modulation/Demodulation
– Support for ISO7816 T0/T1 Smart Card, Hardware Handshaking, RS485 Support
Two Master/Slave Serial Peripheral Interfaces (SPI)
– 8- to 16-bit Programmable Data Length, Four External Peripheral Chip Selects
Three 3-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
Two Synchronous Serial Controllers (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
One Two-wire Interface (TWI)
– Master Mode Support Only, All Two-wire Atmel EEPROM’s Supported
Multimedia Card Interface (MCI)
– Compliant with Multimedia Cards and SD Cards
– Automatic Protocol Control and Fast Automatic Data Transfers with PDC, MMC and SDCard Compliant
IEEE 1149.1 JTAG Boundary Scan on All Digital Pins
Required Power Supplies:
– Embedded 1.8V Regulator, Drawing up to 100 mA for the Core and the External Components, Enables 3.3V Single Supply
Mode
– 3.3 VDDIO I/O Lines and Flash Power Supply
– 1.8V VDDCORE Core Power Supply
– 3V to 3.6V VDDANA Analog Power Supply
– 3V to 3.6V VDDBU Backup Power Supply
5V-tolerant I/Os
Fully Static Operation: 0 Hz to 60 MHz at 1.65V and 85°C Worst Case Conditions
Available in a 100-lead LQFP Package
Description
The AT91SAM7A3 is a member of a series of 32-bit ARM7® microcontrollers with an
integrated CAN controller. It features a 256-Kbyte high-speed Flash and 32-Kbyte
SRAM, a large set of peripherals, including two 2.0B full CAN controllers, and a complete set of system functions minimizing the number of external components. The
device is an ideal migration path for 8-bit microcontroller users looking for additional performance and extended memory.
The embedded Flash memory can be programmed in-system via the JTAG-ICE interface. Built-in lock bits protect the firmware from accidental overwrite.
The AT91SAM7A3 integrates a complete set of features facilitating debug, including a
JTAG In-Circuit-Emulation interface, misalignment detector, interrupt driven debug communication channel for user configurable trace on a console, and JTAG boundary scan
for board level debug and test.
By combining a high-performance 32-bit RISC processor with a high-density 16-bit
instruction set, Flash and SRAM memory, a wide range of peripherals including CAN
controllers, 10-bit ADC, Timers and serial communication channels, on a monolithic
chip, the AT91SAM7A3 is ideal for many compute-intensive embedded control applications in the automotive, medical and industrial world.
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AT91SAM7A3 Preliminary
6042A–ATARM–23-Dec-04
AT91SAM7A3 Preliminary
Block Diagram
Figure 1. AT91SAM7A3 Block Diagram
TDI
TDO
TMS
TCK
JTAG
SCAN
ARM7TDMI
Processor
ICE
1.8 V
Voltage
Regulator
JTAGSEL
TST
FIQ
System Controller
VDDIN
GND
VDDOUT
AIC
DRXD
DTXD
PIO
IRQ0-IRQ3
PDC
Embedded
Flash
Controller
FLASH
256K Bytes
DBGU
PDC
Memory
Protection
Unit
PCK0-PCK3
PLLRC
PLL
XIN
XOUT
OSC
GNDBU
VDDBU
Memory
Controller
PMC
Address
Decoder
SRAM
32K Bytes
GPBR
RCOSC
FWKUP
WKUP0
WKUP1
SHDW
RTT
Shutdown
Controller
Peripheral Bridge
Abort
Status
Peripheral Data
Controller
Misalignment
Detection
POR
VDDIO
POR
VDDCORE
POR
Reset
Controller
APB
FIFO
USB Device
NRST
Transceiver
19 channels
VDDBU
PIT
TWI
WDT
PIOA
CAN1
PDC
PWMC
USART0
PDC
PDC
USART1
SSC0
PDC
PDC
PDC
USART2
PDC
PDC
SPI0
SSC1
PDC
Timer Counter
PDC
PDC
SPI1
TC0
TC1
PDC
PDC
MCI
PDC
TC2
Timer Counter
TC3
TC4
ADC0
TC5
PDC
Timer Counter
TC6
ADC1
TC7
TC8
PIO
PDC
PDC
PIO
RXD0
TXD0
SCK0
RTS0
CTS0
RXD1
TXD1
SCK1
RTS1
CTS1
RXD2
TXD2
SCK2
RTS2
CTS2
NPCS00
NPCS01
NPCS02
NPCS03
MISO0
MOSI0
SPCK0
NPCS10
NPCS11
NPCS12
NPCS13
MISO1
MOSI1
SPCK1
MCCK
MCCDA
MCDA0-MCDA3
AD00
AD01
AD02
AD03
AD04
AD05
AD06
AD07
ADTRG0
ADVREFP
VDDANA
GNDANA
AD10
AD11
AD12
AD13
AD14
AD15
AD16
AD17
ADTRG1
CAN0
PIOB
DDM
DDP
TWD
TWCK
CANRX0
CANTX0
CANRX1
CANTX1
PWM0
PWM1
PWM2
PWM3
PWM4
PWM5
PWM6
PWM7
TF0
TK0
TD0
RD0
RK0
RF0
TF1
TK1
TD1
RD1
RK1
RF1
TCLK0
TCLK1
TCLK2
TIOA0
TIOB0
TIOA1
TIOB1
TIOA2
TIOB2
TCLK3
TCLK4
TCLK5
TIOA3
TIOB3
TIOA4
TIOB4
TIOA5
TIOB5
TCLK6
TCLK7
TCLK8
TIOA6
TIOB6
TIOA7
TIOB7
TIOA8
TIOB8
Preliminary
6042A–ATARM–23-Dec-04
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Preliminary
Signal Description
Table 1. Signal Description
Signal Name
Function
Type
Active
Level
Comments
Power
VDDIN
1.8V Voltage Regulator Power Supply
Power
2.7V to 3.6V
VDDIO
I/O Lines and Flash Power Supply
Power
3V to 3.6V
VDDBU
Backup I/O Lines Power Supply
Power
3V to 3.6V
VDDANA
Analog Power Supply
Power
3V to 3.6V
VDDOUT
1.8V Voltage Regulator Output
Power
1.85V typical
VDDCORE
1.8V Core Power Supply
Power
1.65V to 1.95V
VDDPLL
1.8V PLL Power Supply
Power
1.65V to 1.95V
GND
Ground
Ground
GNDANA
Analog Ground
Ground
GNDBU
Backup Ground
Ground
GNDPLL
PLL Ground
Ground
Clocks, Oscillators and PLLs
XIN
Main Oscillator Input
Input
XOUT
Main Oscillator Output
PLLRC
PLL Filter
PCK0 - PCK3
Programmable Clock Output
Output
SHDW
Shut-Down Control
Output
Driven at 0V only. Do not tie over
VDDBU
WKUP0 - WKUP1
Wake-Up Inputs
Input
Accept between 0V and VDDBU
FWKUP
Force Wake Up
Input
Accept between 0V and VDDBU
Output
Input
ICE and JTAG
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
Output
Reset/Test
NRST
Microcontroller Reset
TST
Test Mode Select
I/O
Input
Low
Pull-down resistor
Debug Unit
DRXD
Debug Receive Data
Input
DTXD
Debug Transmit Data
Output
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AT91SAM7A3 Preliminary
6042A–ATARM–23-Dec-04
AT91SAM7A3 Preliminary
Table 1. Signal Description (Continued)
Signal Name
Function
Type
Active
Level
Comments
AIC
IRQ0 - IRQ3
External Interrupt Inputs
Input
FIQ
Fast Interrupt Input
Input
PIO
PA0 - PA31
Parallel IO Controller A
I/O
Pulled-up input at reset
PB0 - PB29
Parallel IO Controller B
I/O
Pulled-up input at reset
Multimedia Card Interface
MCCK
Multimedia Card Clock
Output
MCCDA
Multimedia Card A Command
I/O
MCDA0 - MCDA3
Multimedia Card A Data
I/O
USB Device Port
DDM
USB Device Port Data -
Analog
DDP
USB Device Port Data +
Analog
USART
SCK0 - SCK1 - SCK2
Serial Clock
I/O
TXD0 - TXD1 - TXD2
Transmit Data
I/O
RXD0 - RXD1 RXD2
Receive Data
Input
RTS0 - RTS1 - RTS2
Request To Send
CTS0 - CTS1 - CTS2
Clear To Send
Output
Input
Synchronous Serial Controller
TD0 - TD1
Transmit Data
Output
RD0 - RD1
Receive Data
Input
TK0 - TK1
Transmit Clock
I/O
RK0 - RK1
Receive Clock
I/O
TF0 - TF1
Transmit Frame Sync
I/O
RF0 - RF1
Receive Frame Sync
I/O
Timer/Counter
TCLK0 - TCLK8
External Clock Input
Input
TIOA0 - TIOA8
I/O Line A
I/O
TIOB0 - TIOB8
I/O Line B
I/O
PWM Controller
PWM0 - PWM7
PWM Channels
Output
Preliminary
6042A–ATARM–23-Dec-04
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Preliminary
Table 1. Signal Description (Continued)
Signal Name
Function
Type
Active
Level
Comments
SPI
MISO0-MISO1
Master In Slave Out
I/O
MOSI0-MOSI1
Master Out Slave In
I/O
SPCK0-SPCK1
SPI Serial Clock
I/O
NPCS00-NPCS10
SPI Peripheral Chip Select 0
I/O
Low
NPCS01 - NPCS03
NPCS11 - NPCS13
SPI Peripheral Chip Select
Output
Low
Two-wire Interface
TWD
Two-wire Serial Data
I/O
TWCK
Two-wire Serial Clock
I/O
Analog-to-Digital Converter
AD00-AD07
AD10-AD17
Analog Inputs
Analog
ADVREFP
Analog Positive Reference
Analog
ADTRG0 - ADTRG1
ADC Trigger
Digital pulled-up inputs at reset
Input
CAN Controller
CANRX0-CANRX1
CAN Inputs
CANTX0-CANTX1
CAN Outputs
6
Input
Output
AT91SAM7A3 Preliminary
6042A–ATARM–23-Dec-04
AT91SAM7A3 Preliminary
Package and Pinout
100-lead LQFP
Mechanical Overview
Figure 2 shows the orientation of the 100-lead LQFP package. A detailed mechanical
description is given in “AT91SAM7A3 Mechanical Characteristics” on page 553.
Figure 2. 100-lead LQFP Pinout (Top View)
51
75
76
50
100
26
25
1
Pinout
Table 2. Pinout in 100-lead LQFP Package
1
GND
26
VDDBU
51
PA20
76
PLLRC
2
NRST
27
FWKUP
52
PA21
77
VDDANA
3
TST
28
WKUP0
53
PA22
78
ADVREFP
4
PB13
29
WKUP1
54
PA23
79
GNDANA
5
PB12
30
SHDW
55
PA24
80
PB14/AD00
6
PB11
31
GNDBU
56
PA25
81
PB15/AD01
7
PB10
32
PA4
57
PA26
82
PB16/AD02
8
PB9
33
PA5
58
PA27
83
PB17/AD03
9
PB8
34
PA6
59
VDDCORE
84
PB18/AD04
10
PB7
35
PA7
60
GND
85
PB19/AD05
11
PB6
36
PA8
61
VDDIO
86
PB20/AD06
12
PB5
37
PA9
62
PA28
87
PB21/AD07
13
PB4
38
VDDIO
63
PA29
88
VDDIO
14
PB3
39
GND
64
PA30
89
PB22/AD10
15
VDDIO
40
VDDCORE
65
PA31
90
PB23/AD11
16
GND
41
PA10
66
JTAGSEL
91
PB24/AD12
17
VDDCORE
42
PA11
67
TDI
92
PB25/AD13
18
PB2
43
PA12
68
TMS
93
PB26/AD14
19
PB1
44
PA13
69
TCK
94
PB27/AD15
20
PB0
45
PA14
70
TDO
95
PB28/AD16
21
PA0
46
PA15
71
GND
96
PB29/AD17
22
PA1
47
PA16
72
VDDPLL
97
DDM
23
PA2
48
PA17
73
XOUT
98
DDP
24
PA3
49
PA18
74
XIN
99
VDDOUT
25
GND
50
PA19
75
GNDPLL
100
VDDIN
Preliminary
6042A–ATARM–23-Dec-04
7
Preliminary
Power Considerations
Power Supplies
The AT91SAM7A3 has seven types of power supply pins:
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VDDIN pin. It powers the voltage regulator; voltage ranges from 2.7V to 3.6V, 3.3V
nominal. If the voltage regulator is not used, VDDIN should be connected to GND.
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VDDIO pin. It powers the I/O lines, the Flash and the USB transceivers; voltage
ranges from 3.0V to 3.6V, 3.3V nominal.
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VDDOUT pin. It is the output of the 1.8V voltage regulator.
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VDDCORE pins. They power the logic of the device; voltage ranges from 1.65V to
1.95V, 1.8V typical. It might be connected to the VDDOUT pin with decoupling
capacitor. VDDCORE is required for the device, including its embedded Flash, to
operate correctly.
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VDDPLL pins. They power the PLL; voltage ranges from 1.65V to 1.95V, 1.8V
typical. They can be connected to the VDDOUT pin with decoupling capacitor.
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VDDBU pin. It powers the Slow Clock oscillator and the Real Time Clock, as well as
a part of the System Controller; ranges from 3.0V and 3.6V, 3.3V nominal.
•
VDDANA pin. It powers the ADC; ranges from 3.0V and 3.6V, 3.3V nominal.
Separated ground pins are provided for VDDPLL, VDDIO, VDDBU and VDDANA. The
ground pins are respectively GNDPLL, GND, GNDBU and GNDANA.
Voltage Regulator
The AT91SAM7A3 embeds a voltage regulator that consumes less than 120 µA static
current and draws up to 100 mA of output current.
Adequate output supply decoupling is mandatory for VDDOUT to reduce ripple and
avoid oscillations. The best way to achieve this is to use two capacitors in parallel: one
external 470 pF (or 1 nF) NPO capacitor must be connected between VDDOUT and
GND as close to the chip as possible. One external 3.3 µF (or 4.7 µF) X7R capacitor
must be connected between VDDOUT and GND.
Adequate input supply decoupling is mandatory for VDDIN in order to improve startup
stability and reduce source voltage drop. The input decoupling capacitor should be
placed close to the chip. For example, two capacitors can be used in parallel: 100 nF
NPO and 4.7 µF X7R.
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AT91SAM7A3 Preliminary
6042A–ATARM–23-Dec-04
AT91SAM7A3 Preliminary
Typical Powering
Schematics
3.3V Single Supply
The AT91SAM7A3 supports a 3.3V single supply mode. The internal regulator is connected to the 3.3V source and its output feeds VDDCORE and VDDPLL. Figure 3
shows the power schematics to be used for USB bus-powered systems.
Figure 3. 3.3V System Single Power Supply Schematics
VDDBU
VDDANA
DC/DC Converter
USB Connector
up to 5.5V
VDDIO
VDDIN
Voltage
Regulator
3.3V
VDDOUT
VDDCORE
VDDPLL
Preliminary
6042A–ATARM–23-Dec-04
9
Preliminary
I/O Lines Considerations
JTAG Port Pins
TMS, TDI and TCK are schmitt trigger inputs. TMS and TCK are 5V-tolerant, TDI is not.
TMS, TDI and TCK do not integrate any resistors and have to be pulled-up externally.
TDO is an output, driven at up to VDDIO.
The JTAGSEL pin is used to select the JTAG boundary scan when asserted at a high
level.
The JTAGSEL pin integrates a permanent pull-down resistor so that it can be left unconnected for normal operations.
Test Pin
The TST pin is used for manufacturing tests and integrates a pull-down resistor so that it
can be left unconnected for normal operations. Driving this line at a high level leads to
unpredictable results.
Reset Pin
The NRST pin is bidirectional. It is handled by the on-chip reset controller and can be
driven low to provide a reset signal to the external components or asserted low externally to reset the microcontroller. There is no constraint on the length of the reset pulse,
and the reset controller can guarantee a minimum pulse length. This allows connection
of a simple push-button on the NRST pin as system user reset, and the use of the NRST
signal to reset all the components of the system.
PIO Controller A and B
Lines
All the I/O lines PA0 to PA31 and PB0 to PB29 are 5V-tolerant and all integrate a programmable pull-up resistor. Programming of this pull-up resistor is performed
independently for each I/O line through the PIO Controllers.
5V-tolerant means that the I/O lines can drive voltage level according to VDDIO, but can
be driven with a voltage at up to 5.5V. However, driving an I/O line with a voltage over
VDDIO while the programmable pull-up resistor is enabled can lead to unpredictable
results. Care should be taken, especially at reset, as all the I/O lines default as inputs
with pull-up resistor enabled at reset.
Shutdown Logic Pins
The SHDW pin is an open drain output. It can be tied to VDDBU with an external pull-up
resistor.
The FWUP, WKUP0 and WKUP1 pins are input-only. They can accept voltages only
between 0V and VDDBU. It is recommended to tie these pins either to GND or to
VDDBU with an external resistor.
I/O Line Drive Levels
10
All the I/O lines can draw up to 2 mA.
AT91SAM7A3 Preliminary
6042A–ATARM–23-Dec-04
AT91SAM7A3 Preliminary
Processor and Architecture
ARM7TDMI Processor
•
RISC Processor Based on ARMv4T Von Neumann Architecture
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•
•
Debug and Test Features •
•
Memory Controller
Runs at up to 60 MHz, providing 0.9 MIPS/MHz
Two instruction sets
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ARM high-performance 32-bit Instruction Set
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Thumb high code density 16-bit Instruction Set
Three-stage pipeline architecture
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Instruction Fetch (F)
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Instruction Decode (D)
–
Execute (E)
Integrated embedded in-circuit emulator
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Two watchpoint units
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Test access port accessible through a JTAG protocol
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Debug communication channel
Debug Unit
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Two-pin UART
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Debug communication channel interrupt handling
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Chip ID Register
•
IEEE1149.1 JTAG Boundary-scan on all digital pins
•
Bus Arbiter
–
•
•
•
•
•
•
Handles requests from the ARM7TDMI and the Peripheral Data Controller
Address Decoder Provides Selection Signals for
–
Three internal 1Mbyte memory areas
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One 256 Mbyte embedded peripheral area
Abort Status Registers
–
Source, Type and all parameters of the access leading to an abort are saved
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Facilitates debug by detection of bad pointers
Misalignment Detector
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Alignment checking of all data accesses
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Abort generation in case of misalignment
Remap Command
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Remaps the Internal SRAM in place of the embedded non-volatile memory
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Allows handling of dynamic exception vectors
16-area Memory Protection Unit
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Individually programmable size between 1K Bytes and 1M Bytes
–
Individually programmable protection against write and/or user access
–
Peripheral protection against write and/or user access
Embedded Flash Controller
–
Embedded Flash interface, up to three programmable wait states
Preliminary
6042A–ATARM–23-Dec-04
11
Preliminary
Peripheral Data
Controller
Read-optimized interface, buffering and anticipating the 16-bit requests,
reducing the required wait states
–
Password-protected program, erase and lock/unlock sequencer
–
Automatic consecutive programming, erasing and locking operations
–
Interrupt generation in case of forbidden operation
•
Handles data transfer between peripherals and memories
•
Nineteen Channels
•
•
12
–
–
Two for each USART
–
Two for the Debug Unit
–
Two for each Serial Synchronous Controller
–
Two for each Serial Peripheral Interface
–
One for the Multimedia Card Interface
–
One for each Analog-to-Digital Converter
Low bus arbitration overhead
–
One Master Clock cycle needed for a transfer from memory to peripheral
–
Two Master Clock cycles needed for a transfer from peripheral to memory
Next Pointer management for reducing interrupt latency requirements
AT91SAM7A3 Preliminary
6042A–ATARM–23-Dec-04
AT91SAM7A3 Preliminary
Memory
Embedded Memories
•
•
256 Kbytes of Flash Memory
–
1024 pages of 256 bytes.
–
Fast access time, 30 MHz single cycle access in worst case conditions.
–
Page programming time: 4 ms, including page auto-erase
–
Full erase time: 10 ms
–
10,000 write cycles, 10-year data retention capability
–
16 lock bits, each protecting 64 pages
32 Kbytes of Fast SRAM
–
Single-cycle access at full speed
Memory Mapping
Internal RAM
The AT91SAM7A3 embeds a high-speed 32-Kbyte SRAM bank. After reset and until the
Remap Command is performed, the SRAM is only accessible at address 0x0020 0000.
After Remap, the SRAM also becomes available at address 0x0.
Internal Flash
The AT91SAM7A3 features one bank of 256 Kbytes of Flash. The Flash is mapped to
address 0x0010 0000. It is also accessible at address 0x0 after the reset and before the
Remap Command.
Figure 4. Internal Memory Mapping
0x0000 0000
0x000F FFFF
Flash Before Remap
SRAM After Remap
1M Bytes
0x0010 0000
Internal Flash
1M Bytes
Internal SRAM
1M Bytes
0x001F FFFF
0x0020 0000
256M Bytes
0x002F FFFF
0x0030 0000
Undefined Areas
(Abort)
253M Bytes
0x0FFF FFFF
Preliminary
6042A–ATARM–23-Dec-04
13
Preliminary
Embedded Flash
Flash Organization
The Flash block of the AT91SAM7A3 is organized in 1024 pages of 256 bytes. It reads
as 65,536 32-bit words.
The Flash block contains a 256-byte write buffer, accessible through a 32-bit interface.
Embedded Flash Controller
The Embedded Flash Controller (EFC) manages accesses performed by the masters of
the system. It enables reading the Flash and writing the write buffer. It also contains a
User Interface mapped within the Memory Controller on the APB. The User Interface
allows:
•
programming of the access parameters of the Flash (number of wait states, timings,
etc.)
•
starting commands such as full erase, page erase, page program, NVM bit set,
NVM bit clear, etc.
•
getting the end status of the last command
•
getting error status
•
programming interrupts on the end of the last commands or on errors
The Embedded Flash Controller also provides a dual 32-bit Prefetch Buffer that optimizes 16-bit access to the Flash. This is particularly efficient when the processor is
running in Thumb mode.
Lock Regions
The Embedded Flash Controller manages 16 lock bits to protect 16 regions of the Flash
against inadvertent Flash erasing or programming commands.
The AT91SAM7A3 has 16 lock regions. Each lock region contains 64 pages of 256
bytes.
Each lock region has a size of 16 kbytes.
The 16 NVM bits are software programmable through the EFC User Interface. The command “Set Lock Bit” enables the protection. The command “Clear Lock Bit” unlocks the
lock region.
14
AT91SAM7A3 Preliminary
6042A–ATARM–23-Dec-04
AT91SAM7A3 Preliminary
System Controller
The System Controller manages all vital blocks of the microcontroller: interrupts, clocks,
power, time, debug and reset.
Figure 5. System Controller Block Diagram
jtag_nreset
System Controller
Boundary Scan
TAP Controller
nirq
irq0-irq1-irq2-irq3
nfiq
fiq
Advanced
Interrupt
Controller
periph_irq[2..27]
pit_irq
rtt_irq
wdt_irq
dbgu_irq
pmc_irq
rstc_irq
proc_nreset
PCK
int
debug
ARM7TDMI
ice_nreset
dbgu_irq
MCK
periph_nreset
Debug
Unit
force_ntrst
force_ntrst
dbgu_txd
dbgu_rxd
wdt_fault
WDRPROC
VDDIO
POR
periph_nreset
ice_nreset
jtag_nreset
VDDCORE
POR
flash_poe
proc_nreset
Reset
Controller
proc_nreset
Embedded Flash
rstc_irq
NRST
VDDBU
POR
SLCK
VDDCORE Powered
Real-Time
Timer
SLCK
periph_nreset
rtt_irq
MCK
FWKUP
proc_nreset
WKUP0
Memory
Controller
Shutdown
Controller
WKUP1
SHDW
VDDBU Powered
RCOSC
XIN
XOUT
PLLRC
MAIN
OSC
4 General-Purpose
Backup Regs
SLCK
MAINCK
periph_clk[2..27]
pck[0-3]
PLL
PLLCK
Power
Management
Controller
PCK
UDPCK
MCK
pmc_irq
int
periph_nreset
UDPCK
periph_clk[27]
periph_nreset
USB Device
Port
periph_irq[27]
idle
MCK
debug
periph_nreset
SLCK
debug
idle
proc_nreset
PB0-PB29
Watchdog
Timer
pit_irq
wdt_irq
wdt_fault
WDRPROC
periph_nreset
periph_irq{2..3]
periph_clk[2..3]
irq0-irq1-irq2-irq3
dbgu_rxd
PA0-PA31
Periodic
Interval
Timer
PIOs
Controller
periph_clk[4..26]
periph_nreset
periph_irq[4..26]
Embedded
Peripherals
fiq
dbgu_txd
in
out
enable
Preliminary
6042A–ATARM–23-Dec-04
15
Preliminary
System Controller
Mapping
The System Controller peripherals are all mapped to the highest 4K bytes of address
space, between addresses 0xFFFF F000 and 0xFFFF FFFF. Each peripheral has an
address space of 256 or 512 Bytes, representing 64 or 128 registers.
Figure 6 shows the mapping of the System Controller and of the Memory Controller
Figure 6. System Controller Mapping
Address
Peripheral
Peripheral Name
Size
0xFFFF F000
AIC
Advanced Interrupt Controller
512 Bytes/128 registers
0xFFFF F1FF
0xFFFF F200
DBGU
Debug Unit
512 Bytes/128 registers
PIOA
PIO Controller A
512 Bytes/128 registers
0xFFFF F3FF
0xFFFF F400
0xFFFF F5FF
0xFFFF F600
PIOB
PIO Controller B
512 Bytes/128 registers
0xFFFF F5FF
0xFFFF F800
Reserved
0xFFFF FBFF
0xFFFF FC00
0xFFFF FCFF
0xFFFF FD00
0xFFFF FD0F
0xFFFF FD10
0xFFFF FC1F
0xFFFF FD20
0xFFFF FC2F
0xFFFF FD30
0xFFFF FC3F
0xFFFF FD40
0xFFFF FD4F
PMC
Power Management Controller
256 Bytes/64 registers
RSTC
Reset Controller
16 Bytes/4 registers
Shutdown Controller
16 Bytes/4 registers
RTT
Real-time Timer
16 Bytes/4 registers
PIT
Periodic Interval Timer
16 Bytes/4 registers
Watchdog Timer
16 Bytes/4 registers
General Purpose Backup Registers
16 Bytes/4 registers
Memory Controller
256 Bytes/64 registers
SHDWC
WDT
Reserved
0xFFFF FD60
0xFFFF FC6F
0xFFFF FD70
Reserved
GPBR
0xFFFF FD80
Reserved
0xFFFF FF00
MC
0xFFFF FFFF
16
AT91SAM7A3 Preliminary
6042A–ATARM–23-Dec-04
AT91SAM7A3 Preliminary
Reset Controller
The Reset Controller is based on three power-on reset cells. It gives the status of the
last reset, indicating whether it is a general reset, a wake-up reset, a software reset, a
user reset or a watchdog reset. In addition, it controls the internal resets and the NRST
pin output. It shapes a signal on the NRST line, guaranteeing that the length of the pulse
meets any requirement.
Clock Generator
The Clock Generator embeds one low-power RC Oscillator, one Main Oscillator and
one PLL with the following characteristics:
–
RC Oscillator ranges between 22 KHz and 42 KHz
–
Main Oscillator frequency ranges between 3 and 20 MHz
–
Main Oscillator can be bypassed
–
PLL output ranges between 80 and 220 MHz
It provides SLCK, MAINCK and PLLCK.
Figure 7. Clock Generator Block Diagram
Clock Generator
XIN
Embedded
RC
Oscillator
Slow Clock
SLCK
Main
Oscillator
Main Clock
MAINCK
PLL and
Divider
PLL Clock
PLLCK
XOUT
PLLRC
Status
Control
Power
Management
Controller
Preliminary
6042A–ATARM–23-Dec-04
17
Preliminary
Power Management
Controller
The Power Management Controller uses the Clock Generator outputs to provide:
–
the Processor Clock PCK
–
the Master Clock MCK
–
the USB Clock UDPCK
–
all the peripheral clocks, independently controllable
–
four programmable clock outputs
The Master Clock (MCK) is programmable from a few hundred Hz to the maximum
operating frequency of the device.
The Processor Clock (PCK) switches off when entering processor idle mode, thereby
reducing power consumption while waiting an interrupt.
Figure 8. Power Management Controller Block Diagram
Processor
Clock
Controller
Master Clock Controller
SLCK
MAINCK
PLLCK
PCK
int
Idle Mode
Prescaler
/1,/2,/4,...,/64
MCK
Peripherals
Clock Controller
periph_clk[2..26]
ON/OFF
Programmable Clock Controller
SLCK
MAINCK
PLLCK
Prescaler
/1,/2,/4,...,/64
pck[0..3]
USB Clock Controller
ON/OFF
PLLCK
Advanced Interrupt
Controller
UDPCK
•
Controls the interrupt lines (nIRQ and nFIQ) of the ARM Processor
•
Individually maskable and vectored interrupt sources
•
•
–
Source 0 is reserved for the Fast Interrupt Input (FIQ)
–
Source 1 is reserved for system peripherals (ST, PMC, DBGU, etc.)
–
Other sources control the peripheral interrupts or external interrupts
–
Programmable edge-triggered or level-sensitive internal sources
–
Programmable positive/negative edge-triggered or high/low level-sensitive
external sources
8-level Priority Controller
–
Drives the normal interrupt nIRQ of the processor
–
Handles priority of the interrupt sources
–
Higher priority interrupts can be served during service of a lower priority
interrupt
Vectoring
–
18
Divider
/1,/2,/4
Optimizes interrupt service routine branch and execution
AT91SAM7A3 Preliminary
6042A–ATARM–23-Dec-04
AT91SAM7A3 Preliminary
•
–
One 32-bit vector register per interrupt source
–
Interrupt vector register reads the corresponding current interrupt vector
Protect Mode
–
•
–
•
•
•
–
One two-pin UART
–
One interface for the Debug Communication Channel (DCC) support
–
One set of chip ID registers
–
One interface allowing ICE access prevention
Two-pin UART
USART-compatible user interface
–
Programmable baud rate generator
–
Parity, framing and overrun error
–
Automatic Echo, Local Loopback and Remote Loopback Channel Modes
Debug Communication Channel Support
–
•
Provides processor synchronization on events without triggering an interrupt
Comprises
–
•
Permits redirecting any interrupt source on the fast interrupt
General Interrupt Mask
–
Debug Unit
Easy debugging by preventing automatic operations
Fast Forcing
Offers visibility of COMMRX and COMMTX signals from the ARM Processor
Chip ID Registers
–
Identification of the device revision, sizes of the embedded memories, set of
peripherals
–
Chip ID is 0x170A0940 (Version 0)
Period Interval Timer
•
20-bit programmable counter plus 12-bit interval counter
Watchdog Timer
•
12-bit key-protected Programmable Counter running on prescaled SLCK
•
Provides reset or interrupt signals to the system
•
Counter may be stopped while the processor is in debug state or in idle mode
•
32-bit free-running counter with alarm
•
Programmable 16-bit prescaler for SCLK accuracy compensation
•
Software programmable assertion of the SHDW open-drain pin
•
De-assertion programmable with the pins WKUP0, WKUP1 and FWKUP
•
The PIO Controllers A and B respectively control 32 and 30 programmable I/O Lines
•
Fully programmable through Set/Clear Registers
•
Multiplexing of two peripheral functions per I/O Line
•
For each I/O Line (whether assigned to a peripheral or used as general purpose I/O)
Real-time Timer
Shutdown Controller
PIO Controllers A and B
–
Input change interrupt
–
Half a clock period Glitch filter
Preliminary
6042A–ATARM–23-Dec-04
19
Preliminary
•
20
–
Multi-drive option enables driving in open drain
–
Programmable pull up on each I/O line
–
Pin data status register, supplies visibility of the level on the pin at any time
Synchronous output, provides Set and Clear of several I/O lines in a single write
AT91SAM7A3 Preliminary
6042A–ATARM–23-Dec-04
AT91SAM7A3 Preliminary
Peripherals
Peripheral Mapping
Each User Peripheral is allocated 16K bytes of address space.
Figure 9. User Peripherals Mapping
Address
Peripheral Name
Size
CAN0
CAN Controller 0
16K Bytes
CAN1
CAN Controller 1
16K Bytes
TC0, TC1, TC2
Timer/Counter 0, 1 and 2
16K Bytes
TC3, TC4, TC5
Timer/Counter 3, 4 and 5
16K Bytes
TC6, TC7, TC8
Timer/Counter 6, 7 and 8
16K Bytes
MCI
Multimedia Card Interface
16K Bytes
UDP
USB Device Port
16K Bytes
Two-Wire Interface
16K Bytes
USART0
Universal Synchronous Asynchronous
Receiver Transmitter 0
16K Bytes
USART1
Universal Synchronous Asynchronous
Receiver Transmitter 1
16K Bytes
USART2
Universal Synchronous Asynchronous
Receiver Transmitter 1
16K Bytes
PWMC
PWM Controller
16K Bytes
SSC0
Serial Synchronous Controller 0
16K Bytes
SSC1
Serial Synchronous Controller 1
16K Bytes
ADC0
Analog-to-Digital Converter 0
16K Bytes
ADC1
Analog-to-Digital Converter 1
16K Bytes
SPI0
Serial Peripheral Interface 0
SPI1
Serial Peripheral Interface 1
Peripheral
0xF000 0000
Reserved
0xFFF7 FFFF
0xFFF8 0000
0xFFF8 3FFF
0xFFF8 4000
0xFFF8 7FFF
0xFFF8 8000
Reserved
0xFFF9 FFFF
0xFFFA 0000
0xFFFA 3FFF
0xFFFA 4000
0xFFFA 7FFF
0xFFFA 8000
0xFFFA BFFF
0xFFFA C000
0xFFFA FFFF
0xFFFB 0000
0xFFFB 3FFF
0xFFFB 4000
Reserved
0xFFFB 7FFF
0xFFFB 8000
TWI
0xFFFB BFFF
0xFFFB C000
Reserved
0xFFFB FFFF
0xFFFC 0000
0xFFFC 3FFF
0xFFFC 4000
0xFFFC 7FFF
0xFFFC 8000
0xFFFC BFFF
0xFFFC C000
0xFFFC FFFF
0xFFFD 0000
0xFFFD 3FFF
0xFFFD 4000
0xFFFD 7FFF
0xFFFD 8000
0xFFFD BFFF
0xFFFD C000
0xFFFD FFFF
0xFFFE 0000
16K Bytes
0xFFFE 3FFF
0xFFFE 4000
16K Bytes
0xFFFE 7FFF
0xFFFE 8000
Reserved
0xFFFE FFFF
Preliminary
6042A–ATARM–23-Dec-04
21
Preliminary
Peripheral Multiplexing
on PIO Lines
The AT91SAM7A3 features two PIO controllers, PIOA and PIOB, which multiplex the
I/O lines of the peripheral set.
PIO Controllers A and B control respectively 32 and 30 lines. Each line can be assigned
to one of two peripheral functions, A or B. Some of them can also be multiplexed with
Analog Input of both ADC Controllers.
Table 3 on page 23 and Table 4 on page 24 define how the I/O lines of the peripherals
A, B or Analog Input are multiplexed on the PIO Controllers A and B. The two columns
“Function” and “Comments” have been inserted for the user’s own comments; they may
be used to track how pins are defined in an application.
Note that some peripheral functions that are output only may be duplicated within both
tables.
At reset, all I/O lines are automatically configured as input with the programmable pullup enabled, so that the device is maintained in a static state as soon as a reset occurs.
22
AT91SAM7A3 Preliminary
6042A–ATARM–23-Dec-04
AT91SAM7A3 Preliminary
PIO Controller A Multiplexing
Table 3. Multiplexing on PIO Controller A
PIO Controller A
I/O Line
Peripheral A
Peripheral B
PA0
TWD
ADTRG0
PA1
TWCK
ADTRG1
PA2
RXD0
PA3
TXD0
PA4
SCK0
NPSC10
PA5
RTS0
NPCS11
PA6
CTS0
NPCS12
PA7
RXD1
NPCS13
PA8
TXD1
MISO1
PA9
RXD2
MOSI1
PA10
TXD2
SPCK1
PA11
NPCS00
PA12
NPCS01
MCDA1
PA13
NPCS02
MCDA2
PA14
NPCS03
MCDA3
PA15
MISO0
MCDA0
PA16
MOSI0
MCCDA
PA17
SPCK0
MCCK
PA18
PWM0
PCK0
PA19
PWM1
PCK1
PA20
PWM2
PCK2
PA21
PWM3
PCK3
PA22
PWM4
IRQ0
PA23
PWM5
IRQ1
PA24
PWM6
TCLK4
PA25
PWM7
TCLK5
PA26
CANRX0
PA27
CANTX0
PA28
CANRX1
TCLK3
PA29
CANTX1
TCLK6
PA30
DRXD
TCLK7
PA31
DTXD
TCLK8
Application Usage
Comment
Function
Comments
Preliminary
6042A–ATARM–23-Dec-04
23
Preliminary
PIO Controller B Multiplexing
Table 4. Multiplexing on PIO Controller B
PIO Controller B
24
Application Usage
I/O Line
Peripheral A
Peripheral B
Comment
PB0
IRQ2
PWM5
PB1
IRQ3
PWM6
PB2
TF0
PWM7
PB3
TK0
PCK0
PB4
TD0
PCK1
PB5
RD0
PCK2
PB6
RK0
PCK3
PB7
RF0
CANTX1
PB8
FIQ
TF1
PB9
TCLK0
TK1
PB10
TCLK1
RK1
PB11
TCLK2
RF1
PB12
TIOA0
TD1
PB13
TIOB0
RD1
PB14
TIOA1
PWM0
AD00
PB15
TIOB1
PWM1
AD01
PB16
TIOA2
PWM2
AD02
PB17
TIOB2
PWM3
AD03
PB18
TIOA3
PWM4
AD04
PB19
TIOB3
NPCS11
AD05
PB20
TIOA4
NPCS12
AD06
PB21
TIOB4
NPCS13
AD07
PB22
TIOA5
AD10
PB23
TIOB5
AD11
PB24
TIOA6
RTS1
AD12
PB25
TIOB6
CTS1
AD13
PB26
TIOA7
SCK1
AD14
PB27
TIOB7
RTS2
AD15
PB28
TIOA8
CTS2
AD16
PB29
TIOB8
SCK2
AD17
Function
Comments
AT91SAM7A3 Preliminary
6042A–ATARM–23-Dec-04
AT91SAM7A3 Preliminary
Peripheral Identifiers
The AT91SAM7A3 embeds a wide range of peripherals. Table 5 defines the Peripheral
Identifiers of the AT91SAM7A3. Unique peripheral identifiers are defined for both the
AIC and the PMC.
Table 5. Peripheral Identifiers
Peripheral
Peripheral
Peripheral
External
ID
Mnemonic
Name
Interrupt
0
AIC
Advanced Interrupt Controller
FIQ
(1)
1
SYSIRQ
2
PIOA
Parallel I/O Controller A
3
PIOB
Parallel I/O Controller B
4
CAN0
CAN Controller 0
5
CAN1
CAN Controller 1
6
US0
USART 0
7
US1
USART 1
8
US2
USART 2
9
MCI
Multimedia Card Interface
10
TWI
Two-wire Interface
11
SPI0
Serial Peripheral Interface 0
12
SPI1
Serial Peripheral Interface 1
13
SSC0
Synchronous Serial Controller 0
14
SSC1
Synchronous Serial Controller 1
15
TC0
Timer/Counter 0
16
TC1
Timer/Counter 1
17
TC2
Timer/Counter 2
18
TC3
Timer/Counter 3
19
TC4
Timer/Counter 4
20
TC5
Timer/Counter 5
21
TC6
Timer/Counter 6
22
TC7
Timer/Counter 7
23
TC8
Timer/Counter 8
ADC0
(1)
Analog-to Digital Converter 0
25
ADC1
(1)
Analog-to Digital Converter 1
26
PWMC
PWM Controller
27
UDP
USB Device Port
28
AIC
Advanced Interrupt Controller
IRQ0
29
AIC
Advanced Interrupt Controller
IRQ1
30
AIC
Advanced Interrupt Controller
IRQ2
31
AIC
Advanced Interrupt Controller
IRQ3
24
Note:
1. Setting SYSIRQ and ADC bits in the clock set/clear registers of the PMC has no
effect. The System Controller and ADC are continuously clocked.
Preliminary
6042A–ATARM–23-Dec-04
25
Preliminary
Serial Peripheral
Interface
•
•
Two-wire Interface
USART
Supports communication with external serial devices
–
Four chip selects with external decoder 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 per chip select between consecutive transfers
and between clock and data
–
Programmable delay between consecutive transfers
–
Selectable mode fault detection
–
Maximum frequency at up to Master Clock
•
Master Mode only
•
Compatibility with standard two-wire serial memories
•
One, two or three bytes for slave address
•
Sequential read/write operations
•
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
–
By 8 or by 16 over-sampling receiver frequency
–
Hardware handshaking RTS-CTS
–
Receiver time-out and transmitter timeguard
–
Optional Multi-drop Mode with address generation and detection
•
RS485 with driver control signal
•
ISO7816, T = 0 or T = 1 Protocols for interfacing with smart cards
–
•
–
•
26
Communication at up to 115.2 Kbps
Test Modes
–
Serial Synchronous
Controller
NACK handling, error counter with repetition and iteration limit
IrDA modulation and demodulation
Remote Loopback, Local Loopback, Automatic Echo
•
Provides serial synchronous communication links used in audio and telecom
applications
•
Contains an independent receiver and transmitter and a common clock divider
AT91SAM7A3 Preliminary
6042A–ATARM–23-Dec-04
AT91SAM7A3 Preliminary
Timer Counter
•
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
•
Three 16-bit Timer Counter Channels
•
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:
–
Three external clock inputs
–
Five internal clock inputs as defined in Table 6.
Table 6. Timer Counter Clock Assignment
PWM Controller
Clock
TIMER_CLOCK1
MCK/2
TIMER_CLOCK2
MCK/8
TIMER_CLOCK3
MCK/32
TIMER_CLOCK4
MCK/128
TIMER_CLOCK5
MCK/1024
–
Two multi-purpose input/output signals
–
Two global registers that act on all three TC Channels
•
Eight channels, one 20-bit counter per channel
•
Common clock generator, providing thirteen different clocks
•
USB Device Port
TC Clock input
–
A Modulo n counter providing eleven clocks
–
Two independent linear dividers working on modulo n counter outputs
Independent channel programming
–
Independent enable/disable commands
–
Independent clock selection
–
Independent period and duty cycle, with double buffering
–
Programmable selection of the output waveform polarity
–
Programmable center or left aligned output waveform
•
USB V2.0 full-speed compliant,12 Mbits per second.
•
Embedded USB V2.0 full-speed transceiver
•
Six endpoints
Preliminary
6042A–ATARM–23-Dec-04
27
Preliminary
•
–
Endpoint 0: 8 bytes
–
Endpoint 1 and 2: 64 bytes ping-pong
–
Endpoint 3: 64 bytes
–
Endpoint 4 and 5: 512 bytes ping-pong
Embedded 2,376-byte dual-port RAM for endpoints
–
Multimedia Card
Interface
•
Suspend/resume logic
•
Compatibility with MultiMedia card specification version 2.2
•
Compatibility with SD Memory card specification version 1.0
•
Cards clock rate up to Master Clock divided by 2
•
Embeds power management to slow down clock rate when not used
•
Supports up to sixteen slots (through multiplexing)
–
Analog-to-Digital
Converter
28
One slot for one MultiMedia card bus (up to 30 cards) or one SD memory
card
•
Supports stream, block and multi-block data read and write
•
Supports connection to Peripheral Data Controller
–
CAN Controller
Ping-pong Mode (two memory banks) for isochronous and bulk endpoints
Minimizes processor intervention for large buffer transfers
•
Fully compliant with CAN 2.0B active controllers
•
Bit rates up to 1Mbit/s
•
16 object-oriented mailboxes, each with the following properties:
–
CAN specification 2.0 Part A or 2.0 Part B programmable for each message
–
Object-configurable as receive (with overwrite or not) or transmit
–
Local tag and mask filters up to 29-bit identifier/channel
–
32-bit access to data registers for each mailbox data object
–
Uses a 16-bit time stamp on receive and transmit messages
–
Hardware concatenation of ID unmasked bit fields to speed up family ID
processing
–
16-bit internal timer for Time Stamping and Network synchronization
–
Programmable reception buffer length up to 16 mailbox object
–
Priority management between transmission mailboxes
–
Autobaud and listening mode
–
Low power mode and programmable wake-up on bus activity or by the
application
–
Data, remote, error and overload frame handling
•
8-channel ADC
•
10-bit 384K samples/sec Successive Approximation Register ADC
•
-2/+2 LSB Integral Non Linearity, -1/+2 LSB Differential Non Linearity
•
Integrated 8-to-1 multiplexer, offering eight independent 3.3V analog inputs
•
Individual enable and disable of each channel
•
External voltage reference for better accuracy on low-voltage inputs
AT91SAM7A3 Preliminary
6042A–ATARM–23-Dec-04
AT91SAM7A3 Preliminary
•
•
Multiple trigger sources
–
Hardware or software trigger
–
External pins: ADTRG0 and ADTRG1
–
Timer Counter 0 to 5 outputs: TIOA0 to TIOA5
Sleep Mode and conversion sequencer
–
•
Automatic wakeup on trigger and back to sleep mode after conversions of all
enabled channels
All analog inputs are shared with digital signals
Preliminary
6042A–ATARM–23-Dec-04
29
Preliminary
30
AT91SAM7A3 Preliminary
6042A–ATARM–23-Dec-04
AT91SAM7A3 Preliminary
ARM7TDMI Processor Overview
Overview
The ARM7TDMI core executes both the 32-bit ARM and 16-bit Thumb instruction sets, allowing the user to trade off between high performance and high code density. The ARM7TDMI
processor implements Von Neuman architecture, using a three-stage pipeline consisting of
Fetch, Decode, and Execute stages.
The main features of the ARM7TDMI processor are:
•
ARM7TDMI Based on ARMv4T Architecture
•
Two Instruction Sets
•
–
ARM High-performance 32-bit Instruction Set
–
Thumb High Code Density 16-bit Instruction Set
Three-Stage Pipeline Architecture
–
Instruction Fetch (F)
–
Instruction Decode (D)
–
Execute (E)
31
6042A–ATARM–23-Dec-04
ARM7TDMI Processor
For further details on ARM7TDMI, refer to the following ARM documents:
ARM Architecture Reference Manual (DDI 0100E)
ARM7TDMI Technical Reference Manual (DDI 0210B)
Instruction Type
Instructions are either 32 bits long (in ARM state) or 16 bits long (in THUMB state).
Data Type
ARM7TDMI supports byte (8-bit), half-word (16-bit) and word (32-bit) data types. Words must
be aligned to four-byte boundaries and half words to two-byte boundaries.
Unaligned data access behavior depends on which instruction is used where.
ARM7TDMI
Operating Mode
The ARM7TDMI, based on ARM architecture v4T, supports seven processor modes:
User: The normal ARM program execution state
FIQ: Designed to support high-speed data transfer or channel process
IRQ: Used for general-purpose interrupt handling
Supervisor: Protected mode for the operating system
Abort mode: Implements virtual memory and/or memory protection
System: A privileged user mode for the operating system
Undefined: Supports software emulation of hardware coprocessors
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, or privileged modes, are entered in order to service interrupts or exceptions,
or to access protected resources.
ARM7TDMI
Registers
The ARM7TDMI processor has a total of 37registers:
•
31 general-purpose 32-bit registers
•
6 status registers
These registers are not accessible at the same time. The processor state and operating mode
determine which registers are available to the programmer.
At any one time 16 registers are visible to the user. The remainder are synonyms used to
speed up exception processing.
Register 15 is the Program Counter (PC) and can be used in all instructions to reference data
relative to the current instruction.
R14 holds the return address after a subroutine call.
R13 is used (by software convention) as a stack pointer
32
AT91SAM7A3 Preliminary
6042A–ATARM–23-Dec-04
AT91SAM7A3 Preliminary
.
Table 7. ARM7TDMI ARM Modes and Registers Layout
Abort Mode
Undefined
Mode
Interrupt
Mode
Fast
Interrupt
Mode
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
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_ABORT
SPSR_UNDEF
SPSR_IRQ
SPSR_FIQ
User and
System
Mode
Supervisor
Mode
R0
Mode-specific banked registers
Registers R0 to R7 are unbanked registers. This means that each of them refers to the same
32-bit physical register in all processor modes. They are general-purpose registers, with no
special uses managed by the architecture, and can be used wherever an instruction allows a
general-purpose register to be specified.
Registers R8 to R14 are banked registers. This means that each of them depends on the current mode of the processor.
Modes and Exception
Handling
All exceptions have banked registers for R14 and R13.
After an exception, R14 holds the return address for exception processing. This address is
used to return after the exception is processed, as well as to address the instruction that
caused the exception.
R13 is banked across exception modes to provide each exception handler with a private stack
pointer.
The fast interrupt mode also banks registers 8 to 12 so that interrupt processing can begin
without having to save these registers.
33
6042A–ATARM–23-Dec-04
A seventh processing mode, System Mode, does not have any banked registers. It uses the
User Mode registers. System Mode runs tasks that require a privileged processor mode and
allows them to invoke all classes of exceptions.
Status Registers
All other processor states are held in status registers. The current operating processor status
is in the Current Program Status Register (CPSR). The CPSR holds:
•
four ALU flags (Negative, Zero, Carry, and Overflow)
•
two interrupt disable bits (one for each type of interrupt)
•
one bit to indicate ARM or Thumb execution
•
five bits to encode the current processor mode
All five exception modes also have a Saved Program Status Register (SPSR) that holds the
CPSR of the task immediately preceding the exception.
Exception Types
The ARM7TDMI supports five types of exception and a privileged processing mode for each
type. The types of exceptions are:
•
fast interrupt (FIQ)
•
normal interrupt (IRQ)
•
memory aborts (used to implement memory protection or virtual memory)
•
attempted execution of an undefined instruction
•
software interrupts (SWIs)
Exceptions are generated by internal and external sources.
More than one exception can occur in the same time.
When an exception occurs, the banked version of R14 and the SPSR for the exception mode
are used to save state.
To return after handling the exception, the SPSR is moved to the CPSR, and R14 is moved to
the PC. This can be done in two ways:
ARM Instruction
Set Overview
•
by using a data-processing instruction with the S-bit set, and the PC as the destination
•
by using the Load Multiple with Restore CPSR instruction (LDM)
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 (bit[31:28]).
Table 8 gives the ARM instruction mnemonic list.
34
AT91SAM7A3 Preliminary
6042A–ATARM–23-Dec-04
AT91SAM7A3 Preliminary
Table 8. ARM Instruction Mnemonic List
Mnemonic
Operation
Mnemonic
Operation
MOV
Move
CDP
Coprocessor Data Processing
ADD
Add
MVN
Move Not
SUB
Subtract
ADC
Add with Carry
RSB
Reverse Subtract
SBC
Subtract with Carry
CMP
Compare
RSC
Reverse Subtract with Carry
TST
Test
CMN
Compare Negated
AND
Logical AND
TEQ
Test Equivalence
EOR
Logical Exclusive OR
BIC
Bit Clear
MUL
Multiply
ORR
Logical (inclusive) OR
SMULL
Sign Long Multiply
MLA
Multiply Accumulate
SMLAL
Signed Long Multiply Accumulate
UMULL
Unsigned Long Multiply
MSR
Move to Status Register
UMLAL
Unsigned Long Multiply Accumulate
MRS
Move From Status Register
B
Thumb Instruction
Set Overview
Branch
BX
Branch and Exchange
BL
Branch and Link
LDR
Load Word
SWI
Software Interrupt
LDRSH
Load Signed Halfword
STR
Store Word
LDRSB
Load Signed Byte
STRH
Store Half Word
LDRH
Load Half Word
STRB
Store Byte
LDRB
Load Byte
STRBT
Store Register Byte with Translation
LDRBT
Load Register Byte with Translation
STRT
Store Register with Translation
LDRT
Load Register with Translation
STM
Store Multiple
LDM
Load Multiple
SWPB
Swap Byte
SWP
Swap Word
MRC
Move From Coprocessor
MCR
Move To Coprocessor
STC
Store From Coprocessor
LDC
Load To Coprocessor
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
•
Exception-generating instruction
In Thumb mode, eight general-purpose registers, R0 to R7, are available that are the same
physical registers as R0 to R7 when executing ARM instructions. Some Thumb instructions
also access to the Program Counter (ARM Register 15), the Link Register (ARM Register 14)
35
6042A–ATARM–23-Dec-04
and the Stack Pointer (ARM Register 13). Further instructions allow limited access to the ARM
registers 8 to 15.
Table 9 gives the Thumb instruction mnemonic list.
Table 9. Thumb Instruction Mnemonic List
36
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
B
Branch
BL
Branch and Link
BX
Branch and Exchange
SWI
Software Interrupt
LDR
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
AT91SAM7A3 Preliminary
6042A–ATARM–23-Dec-04
AT91SAM7A3 Preliminary
AT91SAM7A3 Debug and Test Features
Overview
The AT91SAM7A3 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.
Block Diagram
Figure 10. Debug and Test Block Diagram
TMS
TCK
TDI
ICE/JTAG
TAP
Boundary
TAP
JTAGSEL
TDO
ICE
POR
Reset
and
Test
TST
PIO
ARM7TDMI
PDC
DTXD
DBGU
DRXD
37
6042A–ATARM–23-Dec-04
Application Examples
Debug Environment
Figure 11 on page 38 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.
Figure 11. Application Debug Environment Example
Host Debugger
ICE/JTAG
Interface
ICE/JTAG
Connector
AT91SAM7A3
RS232
Connector
Terminal
AT91SAM7A3-based Application Board
38
AT91SAM7A3 Preliminary
6042A–ATARM–23-Dec-04
AT91SAM7A3 Preliminary
Test
Environment
Figure 12 on page 39 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. Application Test Environment Example
Test Adaptor
Tester
JTAG
Interface
ICE/JTAG
Connector
Chip n
AT91SAM7A3
Chip 2
Chip 1
AT91SAM7A3-based Application Board In Test
Debug and Test
Pin Description
Table 10. Debug and Test Pin List
Pin Name
Function
Type
Active Level
Input/Output
Low
Input
High
Reset/Test
NRST
Microcontroller Reset
TST
Test Mode Select
ICE and JTAG
TCK
Test Clock
Input
TDI
Test Data In
Input
TDO
Test Data Out
TMS
Test Mode Select
Input
JTAGSEL
JTAG Selection
Input
Output
Debug Unit
DRXD
Debug Receive Data
Input
DTXD
Debug Transmit Data
Output
39
6042A–ATARM–23-Dec-04
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.
Embedded Incircuit Emulator
The ARM7TDMI embedded In-circuit Emulator is supported via the ICE/JTAG port.The internal state of the ARM7TDMI is examined through an ICE/JTAG port.
The ARM7TDMI processor contains hardware extensions for advanced debugging features:
•
In halt mode, a store-multiple (STM) can be inserted into the instruction pipeline. This
exports the contents of the ARM7TDMI registers. This data can be serially shifted out
without affecting the rest of the system.
•
In monitor mode, the JTAG interface is used to transfer data between the debugger and a
simple monitor program running on the ARM7TDMI processor.
There are three scan chains inside the ARM7TDMI processor that support testing, debugging,
and programming of the Embedded ICE. The scan chains are controlled by the ICE/JTAG
port.
Embedded ICE 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 Embedded In-Circuit-Emulator, see the ARM7TDMI (Rev4) Technical Reference Manual (DDI0210B).
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.
The Debug Unit can be used to upload an application into the internal SRAM. It is activated by
the boot program when no valid application is detected. The protocol used to load the application is XMODEM.
A specific register, the Debug Unit Chip ID Register, gives information about the product version and its internal configuration.
The AT91SAM7A3 Debug Unit Chip ID value is 0x170a940 on 32-bit width
For further details on the Debug Unit, see the Debug Unit section.
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.
40
AT91SAM7A3 Preliminary
6042A–ATARM–23-Dec-04
AT91SAM7A3 Preliminary
A Boundary-scan Descriptor Language (BSDL) file is provided to set up test.
JTAG Boundary-scan
Register
The Boundary-scan Register (BSR) contains 186 bits that correspond to active pins and associated control signals.
Each AT91SAM7A3 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 11. AT91SAM7A3 JTAG Boundary Scan Register
Bit Number
Pin Name
Pin Type
185
184
Associated BSR
Cells
INPUT
PB13
IN/OUT
OUTPUT
183
CONTROL
182
INPUT
181
PB12
IN/OUT
OUTPUT
180
CONTROL
179
INPUT
178
PB11
IN/OUT
OUTPUT
177
CONTROL
176
INPUT
175
PB10
IN/OUT
OUTPUT
174
CONTROL
173
INPUT
172
PB9
IN/OUT
OUTPUT
171
CONTROL
170
INPUT
169
PB8
IN/OUT
OUTPUT
168
CONTROL
167
INPUT
166
PB7
IN/OUT
OUTPUT
165
CONTROL
164
INPUT
163
PB6
IN/OUT
OUTPUT
162
CONTROL
161
INPUT
160
159
PB5
IN/OUT
OUTPUT
CONTROL
41
6042A–ATARM–23-Dec-04
Table 11. AT91SAM7A3 JTAG Boundary Scan Register (Continued)
Bit Number
Pin Name
Pin Type
158
157
INPUT
PB4
IN/OUT
OUTPUT
156
CONTROL
155
INPUT
154
PB3
IN/OUT
OUTPUT
153
CONTROL
152
INPUT
151
PB2
IN/OUT
OUTPUT
150
CONTROL
149
INPUT
148
PB1
IN/OUT
OUTPUT
147
CONTROL
146
INPUT
145
PB0
IN/OUT
OUTPUT
144
CONTROL
143
INPUT
142
PA0
IN/OUT
OUTPUT
141
CONTROL
140
INPUT
139
PA1
IN/OUT
OUTPUT
138
CONTROL
137
INPUT
136
PA2
IN/OUT
OUTPUT
135
CONTROL
134
INPUT
133
PA3
IN/OUT
OUTPUT
132
CONTROL
131
INPUT
130
PA4
IN/OUT
OUTPUT
129
CONTROL
128
INPUT
127
126
42
Associated BSR
Cells
PA5
IN/OUT
OUTPUT
CONTROL
AT91SAM7A3 Preliminary
6042A–ATARM–23-Dec-04
AT91SAM7A3 Preliminary
Table 11. AT91SAM7A3 JTAG Boundary Scan Register (Continued)
Bit Number
Pin Name
Pin Type
125
124
Associated BSR
Cells
INPUT
PA6
IN/OUT
OUTPUT
123
CONTROL
122
INPUT
121
PA7
IN/OUT
OUTPUT
120
CONTROL
119
INPUT
118
PA8
IN/OUT
OUTPUT
117
CONTROL
116
INPUT
115
PA9
IN/OUT
OUTPUT
114
CONTROL
113
INPUT
112
PA10
IN/OUT
OUTPUT
111
CONTROL
110
INPUT
109
PA11
IN/OUT
OUTPUT
108
CONTROL
107
INPUT
106
PA12
IN/OUT
OUTPUT
105
CONTROL
104
INPUT
103
PA13
IN/OUT
OUTPUT
102
CONTROL
101
INPUT
100
PA14
IN/OUT
OUTPUT
99
CONTROL
98
INPUT
97
PA15
IN/OUT
OUTPUT
96
CONTROL
95
INPUT
94
93
PA16
IN/OUT
OUTPUT
CONTROL
43
6042A–ATARM–23-Dec-04
Table 11. AT91SAM7A3 JTAG Boundary Scan Register (Continued)
Bit Number
Pin Name
Pin Type
92
91
INPUT
PA17
IN/OUT
OUTPUT
90
CONTROL
89
INPUT
88
PA18
IN/OUT
OUTPUT
87
CONTROL
86
INPUT
85
PA19
IN/OUT
OUTPUT
84
CONTROL
83
INPUT
82
PA20
IN/OUT
OUTPUT
81
CONTROL
80
INPUT
79
PA21
IN/OUT
OUTPUT
78
CONTROL
77
INPUT
76
PA22
IN/OUT
OUTPUT
75
CONTROL
74
INPUT
73
PA23
IN/OUT
OUTPUT
72
CONTROL
71
INPUT
70
PA24
IN/OUT
OUTPUT
69
CONTROL
68
INPUT
67
PA25
IN/OUT
OUTPUT
66
CONTROL
65
INPUT
64
PA26
IN/OUT
OUTPUT
63
CONTROL
62
INPUT
61
60
44
Associated BSR
Cells
PA27
IN/OUT
OUTPUT
CONTROL
AT91SAM7A3 Preliminary
6042A–ATARM–23-Dec-04
AT91SAM7A3 Preliminary
Table 11. AT91SAM7A3 JTAG Boundary Scan Register (Continued)
Bit Number
Pin Name
Pin Type
59
58
Associated BSR
Cells
INPUT
PA28
IN/OUT
OUTPUT
57
CONTROL
56
INPUT
55
PA29
IN/OUT
OUTPUT
54
CONTROL
53
INPUT
52
PA30
IN/OUT
OUTPUT
51
CONTROL
50
INPUT
49
PA31
IN/OUT
OUTPUT
48
CONTROL
47
INPUT
46
PB14
IN/OUT
OUTPUT
45
CONTROL
44
INPUT
43
PB15
IN/OUT
OUTPUT
42
CONTROL
41
INPUT
40
PB16
IN/OUT
OUTPUT
39
CONTROL
38
INPUT
37
PB17
IN/OUT
OUTPUT
36
CONTROL
35
INPUT
34
PB18
IN/OUT
OUTPUT
33
CONTROL
32
INPUT
31
PB19
IN/OUT
OUTPUT
30
CONTROL
29
INPUT
28
27
PB20
IN/OUT
OUTPUT
CONTROL
45
6042A–ATARM–23-Dec-04
Table 11. AT91SAM7A3 JTAG Boundary Scan Register (Continued)
Bit Number
Pin Name
Pin Type
26
25
INPUT
PB21
IN/OUT
OUTPUT
24
CONTROL
23
INPUT
22
PB22
IN/OUT
OUTPUT
21
CONTROL
20
INPUT
19
PB23
IN/OUT
OUTPUT
18
CONTROL
17
INPUT
16
PB24
IN/OUT
OUTPUT
15
CONTROL
14
INPUT
13
PB25
IN/OUT
OUTPUT
12
CONTROL
11
INPUT
10
PB26
IN/OUT
OUTPUT
9
CONTROL
8
INPUT
7
PB27
IN/OUT
OUTPUT
6
CONTROL
5
INPUT
4
PB28
IN/OUT
OUTPUT
3
CONTROL
2
INPUT
1
0
46
Associated BSR
Cells
PB29
IN/OUT
OUTPUT
CONTROL
AT91SAM7A3 Preliminary
6042A–ATARM–23-Dec-04
AT91SAM7A3 Preliminary
ID 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 0x1.
PART NUMBER[27:12]: Product Part Number
Product part Number is 0x5B05
MANUFACTURER IDENTITY[11:1]
Set to 0x01F.
Bit[0] Required by IEEE Std. 1149.1.
Set to 0x1.
JTAG ID Code value is 0x05B0503F
47
6042A–ATARM–23-Dec-04
48
AT91SAM7A3 Preliminary
6042A–ATARM–23-Dec-04
AT91SAM7A3 Preliminary
Reset Controller (RSTC)
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.
Block Diagram
Figure 13. 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
49
6042A–ATARM–23-Dec-04
Functional
Description
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 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.
NRST Manager
The NRST Manager samples the NRST input pin and drives this pin low when required by the
Reset State Manager. Figure 14 shows the block diagram of the NRST Manager.
Figure 14. 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
NRST Signal or
Interrupt
External Reset Timer
exter_nreset
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.
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.
NRST External Reset
Control
50
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.
AT91SAM7A3 Preliminary
6042A–ATARM–23-Dec-04
AT91SAM7A3 Preliminary
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.
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.
General Reset
A general reset occurs when VDDBU is 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 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 remains
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 shut down.
Figure 15 shows how the General Reset affects the reset signals.
Figure 15. General Reset State
SLCK
Any
Freq.
MCK
Backup Supply
POR output
Startup Time
backup_nreset
Processor Startup
= 3 cycles
proc_nreset
RSTTYP
XXX
0x0 = General Reset
XXX
periph_nreset
NRST
(nrst_out)
EXTERNAL RESET LENGTH
= 2 cycles
51
6042A–ATARM–23-Dec-04
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 reenabled 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 16. 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)
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 threecycle processor startup. The processor clock is re-enabled as soon as NRST is confirmed
high.
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.
Th e NR ST Man age r gua rante es th at the NR ST line is asser te d for
EXTERNAL_RESET_LENGTH Slow Clock cycles, as programmed in the field ERSTL. How-
52
AT91SAM7A3 Preliminary
6042A–ATARM–23-Dec-04
AT91SAM7A3 Preliminary
ever, 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 17. User Reset State
SLCK
Any
Freq.
MCK
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
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.
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
53
6042A–ATARM–23-Dec-04
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 18. 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
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.
When the WDRSTEN in WDT_MR bit is reset, the watchdog fault has no impact on the reset
controller.
54
AT91SAM7A3 Preliminary
6042A–ATARM–23-Dec-04
AT91SAM7A3 Preliminary
Figure 19. 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)
55
6042A–ATARM–23-Dec-04
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:
•
•
•
Reset Controller
Status Register
56
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.
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 20). 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.
AT91SAM7A3 Preliminary
6042A–ATARM–23-Dec-04
AT91SAM7A3 Preliminary
Figure 20. 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)
57
6042A–ATARM–23-Dec-04
Reset Controller (RSTC) User Interface
Table 12. Reset Controller (RSTC) Register Mapping
Offset
Register
Name
0x00
Control Register
0x04
0x08
Note:
58
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.
AT91SAM7A3 Preliminary
6042A–ATARM–23-Dec-04
AT91SAM7A3 Preliminary
Reset Controller Control Register
Register Name: 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.
59
6042A–ATARM–23-Dec-04
Reset Controller Status Register
Register Name: 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.
60
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6042A–ATARM–23-Dec-04
AT91SAM7A3 Preliminary
Reset Controller Mode Register
Register Name: RSTC_MR
Access Type:
Read/Write
31
30
29
28
27
26
25
24
17
–
16
–
9
8
1
–
0
URSTEN
KEY
23
–
22
–
21
–
20
–
19
–
18
–
15
–
14
–
13
–
12
–
11
10
7
–
6
–
5
–
4
URSTIEN
3
–
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.
61
6042A–ATARM–23-Dec-04
62
AT91SAM7A3 Preliminary
6042A–ATARM–23-Dec-04
AT91SAM7A3 Preliminary
Real-time Timer (RTT)
Overview
The Real-time Timer is built around a 32-bit counter and used to count elapsed seconds. It
generates a periodic interrupt or/and triggers an alarm on a programmed value.
Block Diagram
Figure 21. 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
ALMV
63
6042A–ATARM–23-Dec-04
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 reached by writing RTPRES at 1. In this case, the period of the signal provided to the Real-time Timer counter is 30.52 µs (when Slow Clock is 32.768 Hz) and the
maximum the Real-time Timer can cover is 131072 seconds, corresponding to more than 36
days.
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 reg ister is se t to its ma ximum value, co rrespo nding 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.
64
AT91SAM7A3 Preliminary
6042A–ATARM–23-Dec-04
AT91SAM7A3 Preliminary
Figure 22. 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
65
6042A–ATARM–23-Dec-04
Real-time Timer (RTT) User Interface
Table 13. Real-time Timer Register Mapping
Offset
Register
Name
Access
Reset Value
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
66
AT91SAM7A3 Preliminary
6042A–ATARM–23-Dec-04
AT91SAM7A3 Preliminary
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.
67
6042A–ATARM–23-Dec-04
Real-time Timer Alarm Register
Register Name: RTT_AR
Access Type:
31
Read/Write
30
29
28
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.
68
AT91SAM7A3 Preliminary
6042A–ATARM–23-Dec-04
AT91SAM7A3 Preliminary
Real-time Timer Value Register
Register Name: RTT_VR
Access Type:
Read-only
31
30
29
28
27
26
25
24
19
18
17
16
11
10
9
8
3
2
1
0
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.
69
6042A–ATARM–23-Dec-04
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.
70
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6042A–ATARM–23-Dec-04
AT91SAM7A3 Preliminary
Periodic Interval Timer (PIT)
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.
Block Diagram
Figure 23. Periodic Interval Timer
PIT_MR
PIV
=?
PIT_MR
PITIEN
set
0
PIT_SR
PITS
pit_irq
reset
0
MCK
Prescaler
0
0
1
12-bit
Adder
1
read PIT_PIVR
20-bit
Counter
MCK/16
CPIV
PIT_PIVR
CPIV
PIT_PIIR
PICNT
PICNT
71
6042A–ATARM–23-Dec-04
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).
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 24 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.
72
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6042A–ATARM–23-Dec-04
AT91SAM7A3 Preliminary
Figure 24. Enabling/Disabling PIT with PITEN
APB cycle
APB cycle
MCK
15
restarts MCK Prescaler
MCK Prescaler 0
PITEN
CPIV
PICNT
0
1
PIV - 1
0
PIV
1
0
1
0
PITS (PIT_SR)
APB Interface
read PIT_PIVR
73
6042A–ATARM–23-Dec-04
Periodic Interval Timer (PIT) User Interface
Table 14. Periodic Interval Timer (PIT) Register Mapping
Offset
Register
Name
Access
Reset Value
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
74
AT91SAM7A3 Preliminary
6042A–ATARM–23-Dec-04
AT91SAM7A3 Preliminary
Periodic Interval Timer Mode Register
Register Name: PIT_MR
Access Type:
Read/Write
31
–
30
–
29
–
28
–
27
–
26
–
23
–
22
–
21
–
20
–
19
18
15
14
13
12
25
PITIEN
24
PITEN
17
16
PIV
11
10
9
8
3
2
1
0
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.
75
6042A–ATARM–23-Dec-04
Periodic Interval Timer Status Register
Register Name: PIT_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
–
0
PITS
• 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.
76
AT91SAM7A3 Preliminary
6042A–ATARM–23-Dec-04
AT91SAM7A3 Preliminary
Periodic Interval Timer Value Register
Register Name: PIT_PIVR
Access Type:
Read-only
31
30
29
28
27
26
19
18
25
24
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
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.
77
6042A–ATARM–23-Dec-04
Periodic Interval Timer Image Register
Register Name: PIT_PIIR
Access Type:
Read-only
31
30
29
28
27
26
19
18
25
24
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.
78
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AT91SAM7A3 Preliminary
Watchdog Timer (WDT)
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.
Block Diagram
Figure 25. Watchdog Timer Block Diagram
write WDT_MR
WDT_MR
WV
WDT_CR
WDRSTT
reload
1
0
12-bit Down
Counter
WDT_MR
reload
Current
Value
WDD
1/128
SLCK
<= WDD
WDT_MR
WDRSTEN
= 0
wdt_fault
(to Reset Controller)
set
WDUNF
set
wdt_int
reset
WDERR
read WDT_SR
or
reset
reset
WDFIEN
WDT_MR
79
6042A–ATARM–23-Dec-04
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 WV 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 WV 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 in a window defined by 0 and WDD in the WDT_MR:
0 ≤WDT ≤WDD; writing WDRSTT restarts the Watchdog Timer.
Any attempt to restart the Watchdog Timer in the range [WDV; 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.
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AT91SAM7A3 Preliminary
Figure 26. 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
81
6042A–ATARM–23-Dec-04
Watchdog Timer (WDT) User Interface
Table 15. Watchdog Timer (WDT) Register Mapping
Offset
82
Register
Name
Access
Reset Value
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
AT91SAM7A3 Preliminary
6042A–ATARM–23-Dec-04
AT91SAM7A3 Preliminary
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.
83
6042A–ATARM–23-Dec-04
Watchdog Timer Mode Register
Register Name: WDT_MR
Access Type:
31
Read / Write Once
30
23
29
WDIDLEHLT
28
WDDBGHLT
27
21
20
19
18
11
10
22
26
25
24
17
16
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.
84
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AT91SAM7A3 Preliminary
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.
85
6042A–ATARM–23-Dec-04
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AT91SAM7A3 Preliminary
Shutdown Controller (SHDWC)
Description
The Shutdown Controller controls the power supplies VDDIO and VDDCORE and the wakeup detection on debounced input lines. A dedicated input, Force Wake Up, is also available.
Block Diagram
Figure 27. Shutdown Controller Block Diagram
SLCK
Shutdown Controller
SYSC_SHMR
CPTWK0
CPTWK1
WKMODE0
WKMODE1
read SYSC_SHSR
reset
WAKEUP0 SYSC_SHSR
WKUP0
set
event0
read SYSC_SHSR
Event
Detector
reset
WAKEUP1
WKUP1
SYSC_SHSR
set
event1
Wake-up
read SYSC_SHSR
Shutdown
Output
Controller
reset
RTTWKEN
SYSC_SHMR
RTT Alarm
RTTWK
SYSC_SHSR
SYSC_SHCR
set
SHDW
read SYSC_SHSR
RTC Alarm
SYSC_SHMR
RTCWK
Shut-down
read SYSC_SHSR
reset
RTCWKEN
SHDW
reset
SYSC_SHSR
FWKUP
set
SYSC_SHSR
set
FWKUP
87
6042A–ATARM–23-Dec-04
I/O Lines Description
Table 16. I/O Lines Description
Name
Description
Type
FWKUP
Force Wake Up input for the Shutdown Controller
Input
WKUP0
Wake-up 0 input
Input
WKUP1
Wake-up 1input
Input
SHDW
Shutdown output
Output
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.
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, SHDW.
A typical application connects the pin SHDW 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, WKUP1, FWKUP) connect to any push-buttons or signal that
wake up the system.
The software is able to control the pin SHDW by writing the Shutdown Control Register
(SHDW_CR) with the bit SHDW at 1. 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 pins WKUP0 or WKUP1 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 the pins WKUP0 and WKUP1.
The detection can also be disabled. Programming is performed by defining the fields
WKMODE0 and WKMODE1.
Moreover, a debouncing circuit can be programmed for the pin WKUP0 or WKUP1. The
debouncing circuit filters pulses on WKUP0 or WKUP1 shorter than the programmed number
of 16 SLCK cycles in CPTWK0 or CPTWK1 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 or CPTWK1, the SHDW pin is released. If a
new input change is detected before the counter reaches the corresponding value, the counter
is stopped and cleared. The field WAKEUP0 and/or WAKEUP1 of the Status Register
(SHDW_SR) reports the detection of the programmed events on WKUP0 or WKUP1. These
fields are reset after the read of SHDW_SR.
The pin FWKUP is treated differently and a low level on this pin forces a de-assertion of the
SHDW pin, regardless of the presence of the Slow Clock. The bit FWKUP in the status register
reports a Forced Wakeup Event after internal resynchronization of the event with the Slow
Clock.
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Shutdown Controller (SHDWC) User Interface
Table 17. Shutdown Controller (SHDWC) Register Mapping
Access
Reset Value (1)
SHDW_CR
Write-only
-
Shutdown Mode Register
SHDW_MR
Read-Write
0x0000_0303
Shutdown Status Register
SHDW_SR
Read-only
0x0000_0000
Offset
Register
Name
0x00
Shutdown Control Register
0x04
0x18
89
6042A–ATARM–23-Dec-04
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: Shut Down Command
0 = No effect.
1 = If KEY is correct, asserts the SHDW pin.
• KEY: Password
Should be written at value 0xA5. Writing any other value in this field aborts the write operation.
90
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AT91SAM7A3 Preliminary
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
15
14
13
12
11
–
10
–
9
3
–
2
–
1
CPTWK1
7
6
5
4
CPTWK0
8
WKMODE1
0
WKMODE0
• WKMODE0: Wake-up Mode 0
• WKMODE1: Wake-up Mode 1
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
• CPTWK1: Counter on Wake-up 1
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 or WKUP1, the SHDW pin is released
(CPTWK x 16 + 2) Slow Clock cycles after the event on WKUP.
91
6042A–ATARM–23-Dec-04
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
15
–
14
–
13
–
12
–
11
–
10
–
9
–
8
–
7
–
6
–
5
–
4
–
3
–
2
FWKUP
1
WAKEUP1
0
WAKEUP0
• WAKEUP0: Wake-up 0 Status
• WAKEUP1: Wake-up 1 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.
• FWKUP: Force Wake Up Status
0 = No wake-up event occurred on the Force Wake Up input since the last read of SHDW_SR.
1 = At least one wake-up event occurred on the Force Wake Up input since the last read of SHDW_SR.
92
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AT91SAM7A3 Preliminary
Memory Controller
Overview
The Memory Controller (MC) manages the ASB bus and controls accesses requested by the
masters, typically the ARM7TDMI processor and the Peripheral Data Controller. It features a
simple bus arbiter, an address decoder, an abort status, a misalignment detector and an
Embedded Flash Controller. In addition, the MC contains a Memory Protection Unit (MPU)
consisting of 16 areas that can be protected against write and/or user accesses. Access to
peripherals can be protected in the same way.
Block Diagram
Figure 28. Memory Controller Block Diagram
Memory Controller
ASB
ARM7TDMI
Processor
Embedded
Flash
Controller
Abort
Internal
Flash
Abort
Status
Internal
RAM
Bus
Arbiter
Misalignment
Detector
Address
Decoder
Memory
Protection
Unit
User
Interface
Peripheral
Data
Controller
APB
Bridge
Peripheral 0
Peripheral 1
APB
From Master
to Slave
Peripheral N
93
6042A–ATARM–23-Dec-04
Functional
Description
The Memory Controller handles the internal ASB bus and arbitrates the accesses of both
masters.
It is made up of:
•
A bus arbiter
•
An address decoder
•
An abort status
•
A misalignment detector
•
A memory protection unit
•
An Embedded Flash Controller
The MC handles only little-endian mode accesses. The masters work in little-endian mode
only.
Bus Arbiter
The Memory Controller has a simple, hard-wired priority bus arbiter that gives the control of
the bus to one of the two masters. The Peripheral Data Controller has the highest priority; the
ARM processor has the lowest one.
Address Decoder
The Memory Controller features an Address Decoder that first decodes the four highest bits of
the 32-bit address bus and defines three separate areas:
•
One 256-Mbyte address space for the internal memories
•
One 256-Mbyte address space reserved for the embedded peripherals
•
An undefined address space of 3584M bytes representing fourteen 256-Mbyte areas that
return an Abort if accessed
Figure 29 shows the assignment of the 256-Mbyte memory areas.
Figure 29. Memory Areas
256M Bytes
0x0000 0000
Internal Memories
0x0FFF FFFF
0x1000 0000
14 x 256MBytes
3,584 Mbytes
Undefined
(Abort)
0xEFFF FFFF
256M Bytes
0xF000 0000
Peripherals
0xFFFF FFFF
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Internal Memory
Mapping
Within the Internal Memory address space, the Address Decoder of the Memory Controller
decodes eight more address bits to allocate 1-Mbyte address spaces for the embedded
memories.
The allocated memories are accessed all along the 1-Mbyte address space and so are
repeated n times within this address space, n equaling 1M bytes divided by the size of the
memory.
When the address of the access is undefined within the internal memory area, the Address
Decoder returns an Abort to the master.
Figure 30. Internal Memory Mapping
0x0000 0000
Internal Memory Area 0
1M Bytes
Internal Memory Area 1
Internal Flash
1M Bytes
Internal Memory Area 2
Internal SRAM
1M Bytes
0x000F FFFF
0x0010 0000
0x001F FFFF
0x0020 0000
256M Bytes
0x002F FFFF
0x0030 0000
Undefined Areas
(Abort)
253M bytes
0x0FFF FFFF
Internal Memory
Area 0
The first 32 bytes of Internal Memory Area 0 contain the ARM processor exception vectors, in
particular, the Reset Vector at address 0x0.
Before execution of the remap command, the on-chip Flash is mapped into Internal Memory
Area 0, so that the ARM7TDMI reaches an executable instruction contained in Flash. After the
remap command, the internal SRAM at address 0x0020 0000 is mapped into Internal Memory
Area 0. The memory mapped into Internal Memory Area 0 is accessible in both its original
location and at address 0x0.
Remap Command
After execution, the Remap Command causes the Internal SRAM to be accessed through the
Internal Memory Area 0.
As the ARM vectors (Reset, Abort, Data Abort, Prefetch Abort, Undefined Instruction, Interrupt, and Fast Interrupt) are mapped from address 0x0 to address 0x20, the Remap
Command allows the user to redefine dynamically these vectors under software control.
The Remap Command is accessible through the Memory Controller User Interface by writing
the MC_RCR (Remap Control Register) RCB field to one.
The Remap Command can be cancelled by writing the MC_RCR RCB field to one, which acts
as a toggling command. This allows easy debug of the user-defined boot sequence by offering
a simple way to put the chip in the same configuration as after a reset.
95
6042A–ATARM–23-Dec-04
Abort Status
There are three reasons for an abort to occur:
•
access to an undefined address
•
access to a protected area without the permitted state
•
an access to a misaligned address.
When an abort occurs, a signal is sent back to all the masters, regardless of which one has
generated the access. However, only the ARM7TDMI can take an abort signal into account,
and only under the condition that it was generating an access. The Peripheral Data Controller
does not handle the abort input signal. Note that the connection is not represented in Figure
28.
To facilitate debug or for fault analysis by an operating system, the Memory Controller integrates an Abort Status register set.
The full 32-bit wide abort address is saved in MC_AASR. Parameters of the access are saved
in MC_ASR and include:
•
the size of the request (field ABTSZ)
•
the type of the access, whether it is a data read or write, or a code fetch (field ABTTYP)
•
whether the access is due to accessing an undefined address (bit UNDADD), a misaligned
address (bit MISADD) or a protection violation (bit MPU)
•
the source of the access leading to the last abort (bits MST0 and MST1)
•
whether or not an abort occurred for each master since the last read of the register (bit
SVMST0 and SVMST1) unless this information is loaded in MST bits
In the case of a Data Abort from the processor, the address of the data access is stored. This
is useful, as searching for which address generated the abort would require disassembling the
instructions and full knowledge of the processor context.
In the case of a Prefetch Abort, the address may have changed, as the prefetch abort is pipelined in the ARM processor. The ARM processor takes the prefetch abort into account only if
the read instruction is executed and it is probable that several aborts have occurred during this
time. Thus, in this case, it is preferable to use the content of the Abort Link register of the ARM
processor.
Memory
Protection Unit
The Memory Protection Unit allows definition of up to 16 memory spaces within the internal
memories.
After reset, the Memory Protection Unit is disabled. Enabling it requires writing the Protection
Unit Enable Register (MC_PUER) with the PUEB at 1.
Programmming of the 16 memory spaces is done in the registers MC_PUIA0 to MC_PUIA15.
The size of each of the memory spaces is programmable by a power of 2 between 1K bytes
and 4M bytes. The base address is also programmable on a number of bits according to the
size.
The Memory Protection Unit also allows the protection of the peripherals by programming the
Protection Unit Peripheral Register (MC_PUP) with the field PROT at the appropriate value.
The peripheral address space and each internal memory area can be protected against write
and non-privileged access of one of the masters. When one of the masters performs a forbidden access, an Abort is generated and the Abort Status traces what has happened.
There is no priority in the protection of the memory spaces. In case of overlap between several
memory spaces, the strongest protection is taken into account. If an access is performed to an
address which is not contained in any of the 16 memory spaces, the Memory Protection Unit
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AT91SAM7A3 Preliminary
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AT91SAM7A3 Preliminary
generates an abort. To prevent this, the user can define a memory space of 4M bytes starting
at 0 and authorizing any access.
Embedded Flash
Controller
The Embedded Flash Controller is added to the Memory Controller and ensures the interface
of the flash block with the 32-bit internal bus. It allows an increase of performance in Thumb
Mode for Code Fetch with its system of 32-bit buffers. It also manages with the programming,
erasing, locking and unlocking sequences thanks to a full set of commands.
Misalignment
Detector
The Memory Controller features a Misalignment Detector that checks the consistency of the
accesses.
For each access, regardless of the master, the size of the access and the bits 0 and 1 of the
address bus are checked. If the type of access is a word (32-bit) and the bits 0 and 1 are not 0,
or if the type of the access is a half-word (16-bit) and the bit 0 is not 0, an abort is returned to
the master and the access is cancelled. Note that the accesses of the ARM processor when it
is fetching instructions are not checked.
The misalignments are generally due to software bugs leading to wrong pointer handling.
These bugs are particularly difficult to detect in the debug phase.
As the requested address is saved in the Abort Status Register and the address of the instruction generating the misalignment is saved in the Abort Link Register of the processor,
detection and fix of this kind of software bugs is simplified.
97
6042A–ATARM–23-Dec-04
Memory Controller (MC) User Interface
Base Address: 0xFFFFFF00
Table 18. Memory Controller (MC) Memory Mapping
Offset
Register
Name
Access
0x00
MC Remap Control Register
MC_RCR
Write-only
0x04
MC Abort Status Register
MC_ASR
Read-only
0x0
0x08
MC Abort Address Status Register
MC_AASR
Read-only
0x0
0x0C
Reserved
0x10
MC Protection Unit Area 0
MC_PUIA0
Read/Write
0x0
0x14
MC Protection Unit Area 1
MC_PUIA1
Read/Write
0x0
0x18
MC Protection Unit Area 2
MC_PUIA2
Read/Write
0x0
0x1C
MC Protection Unit Area 3
MC_PUIA3
Read/Write
0x0
0x20
MC Protection Unit Area 4
MC_PUIA4
Read/Write
0x0
0x24
MC Protection Unit Area 5
MC_PUIA5
Read/Write
0x0
0x28
MC Protection Unit Area 6
MC_PUIA6
Read/Write
0x0
0x2C
MC Protection Unit Area 7
MC_PUIA7
Read/Write
0x0
0x30
MC Protection Unit Area 8
MC_PUIA8
Read/Write
0x0
0x34
MC Protection Unit Area 9
MC_PUIA9
Read/Write
0x0
0x38
MC Protection Unit Area 10
MC_PUIA10
Read/Write
0x0
0x3C
MC Protection Unit Area 11
MC_PUIA11
Read/Write
0x0
0x40
MC Protection Unit Area 12
MC_PUIA12
Read/Write
0x0
0x44
MC Protection Unit Area 13
MC_PUIA13
Read/Write
0x0
0x48
MC Protection Unit Area 14
MC_PUIA14
Read/Write
0x0
0x4C
MC Protection Unit Area 15
MC_PUIA15
Read/Write
0x0
0x50
MC Protection Unit Peripherals
MC_PUP
Read/Write
0x0
0x54
MC Protection Unit Enable Register
MC_PUER
Read/Write
0x0
0x60
EFC Configuration Registers
98
Reset State
See EFC Part
AT91SAM7A3 Preliminary
6042A–ATARM–23-Dec-04
AT91SAM7A3 Preliminary
MC Remap Control Register
Register Name:
MC_RCR
Access Type:
Write-only
Absolute Address:
0xFFFF FF00
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
–
–
–
–
–
–
–
RCB
• RCB: Remap Command Bit
0: No effect.
1: This Command Bit acts on a toggle basis: writing a 1 alternatively cancels and restores the remapping of the page zero
memory devices.
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6042A–ATARM–23-Dec-04
MC Abort Status Register
Register Name:
MC_ASR
Access Type:
Read-only
Reset Value:
0x0
Absolute Address:
0xFFFF FF04
31
30
29
28
27
26
25
24
–
–
–
–
–
–
SVMST1
SVMST0
23
22
21
20
19
18
17
16
–
–
–
–
–
–
MST1
MST0
15
14
13
12
11
10
9
–
–
–
–
7
6
5
4
3
2
1
0
–
–
–
–
–
MPU
MISADD
UNDADD
8
ABTTYP
ABTSZ
• UNDADD: Undefined Address Abort Status
0: The last abort was not due to the access of an undefined address in the address space.
1: The last abort was due to the access of an undefined address in the address space.
• MISADD: Misaligned Address Abort Status
0: The last aborted access was not due to an address misalignment.
1: The last aborted access was due to an address misalignment.
• MPU: Memory Protection Unit Abort Status
0: The last aborted access was not due to the Memory Protection Unit.
1: The last aborted access was due to the Memory Protection Unit.
• ABTSZ: Abort Size Status
ABTSZ
Abort Size
0
0
Byte
0
1
Half-word
1
0
Word
1
1
Reserved
• ABTTYP: Abort Type Status
ABTTYP
100
Abort Type
0
0
Data Read
0
1
Data Write
1
0
Code Fetch
1
1
Reserved
AT91SAM7A3 Preliminary
6042A–ATARM–23-Dec-04
AT91SAM7A3 Preliminary
• MST0: ARM7TDMI Abort Source
0: The last aborted access was not due to the ARM7TDMI.
1: The last aborted access was due to the ARM7TDMI.
• MST1: PDC Abort Source
0: The last aborted access was not due to the PDC.
1: The last aborted access was due to the PDC.
• SVMST0: Saved ARM7TDMI Abort Source
0: No abort due to the ARM7TDMI occurred since the last read of MC_ASR or it is notified in the bit MST0.
1: At least one abort due to the ARM7TDMI occurred since the last read of MC_ASR.
• SVMST1: Saved PDC Abort Source
0: No abort due to the PDC occurred since the last read of MC_ASR or it is notified in the bit MST1.
1: At least one abort due to the PDC occurred since the last read of MC_ASR.
MC Abort Address Status Register
Register Name:
MC_AASR
Access Type:
Read-only
Reset Value:
0x0
Absolute Address:
0xFFFF FF08
31
30
29
28
27
26
25
24
19
18
17
16
11
10
9
8
3
2
1
0
ABTADD
23
22
21
20
ABTADD
15
14
13
12
ABTADD
7
6
5
4
ABTADD
• ABTADD: Abort Address
This field contains the address of the last aborted access.
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6042A–ATARM–23-Dec-04
MC Protection Unit Area 0 to 15 Registers
Register Name:
MC_PUIA0 - MC_PUIA15
Access Type:
Read/Write
Reset Value:
0x0
Absolute Address:
0xFFFFFF10 - 0xFFFFFF4C
31
30
29
28
27
26
25
24
–
–
–
–
–
–
–
–
23
22
21
20
19
18
17
16
–
–
15
14
BA
13
12
11
10
BA
7
6
5
4
SIZE
3
2
–
–
9
8
–
–
1
0
PROT
• PROT: Protection :
Processor Mode
PROT
Privilege
User
0
0
No access
No access
0
1
Read/Write
No access
1
0
Read/Write
Read-only
1
1
Read/Write
Read/Write
• SIZE: Internal Area Size
SIZE
Area Size
LSB of BA
0
0
0
0
1 KB
10
0
0
0
1
2 KB
11
0
0
1
0
4 KB
12
0
0
1
1
8 KB
13
0
1
0
0
16 KB
14
0
1
0
1
32 KB
15
0
1
1
0
64 KB
16
0
1
1
1
128 KB
17
1
0
0
0
256 KB
18
1
0
0
1
512 KB
19
1
0
1
0
1 MB
20
1
0
1
1
2 MB
21
1
1
0
1
4 MB
22
• BA: Internal Area Base Address
These bits define the Base Address of the area. Note that only the most significant bits of BA are significant. The number of
significant bits are in respect with the size of the area.
102
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MC Protection Unit Peripheral
Register Name:
MC_PUP
Access Type:
Read/Write
Reset Value:
0x000000000
Absolute Address:
0xFFFFFF50
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
PROT
• PROT: Protection :
Processor Mode
PROT
Privilege
User
0
0
Read/Write
No access
0
1
Read/Write
No access
1
0
Read/Write
Read-only
1
1
Read/Write
Read/Write
MC Protection Unit Enable Register
Register Name:
MC_PUER
Access Type:
Read/Write
Reset Value:
0x000000000
Absolute Address:
0xFFFFFF54
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
–
–
–
–
–
–
–
PUEB
• PUEB: Protection Unit Enable Bit
0: The Memory Controller Protection Unit is disabled.
1: The Memory Controller Protection Unit is enabled.
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AT91SAM7A3 Preliminary
Embedded Flash Controller (EFC)
Description
The Embedded Flash Controller is added to the Memory Controller and ensures the interface
of the Flash block with the 32-bit internal bus. It increases performance in Thumb Mode for
Code Fetch with its system of 32-bit buffers. It also manages the programming, erasing, locking and unlocking sequences using a full set of commands.
Functional
Description
Embedded Flash
Organization
The Embedded Flash interfaces directly to the 32-bit internal bus. It is composed of several
interfaces:
•
One memory plane organized in several pages of the same size.
•
Two 32-bit read buffers used for code read optimization (see “Read Operations” on page
106).
•
One write buffer that manages page programming. The write buffer size is equal to the
page size. This buffer is write-only and accessible all along the 1 MByte address space, so
that each word can be written to its final address (see “Write Operations” on page 108).
•
Several lock bits used to protect write and erase operations on lock regions. A lock region
is composed of several consecutive pages, and each lock region has its associated lock
bit.
The Embedded Flash size, the page size and the lock region organization are described in the
product definition section.
105
6042A–ATARM–23-Dec-04
Figure 31. Embedded Flash Memory Mapping
Page 0
Start Address
Lock Region 0
Lock Bit 0
Lock Region 1
Lock Bit 1
Lock Region (n-1)
Lock Bit n-1
Page (m-1)
Flash Memory
Page ( (n-1)*m )
Page (n*m-1)
Read Operations
An optimized controller manages embedded Flash reads. A system of 2 x 32-bit buffers is
added in order to start access at following address during the second read, thus increasing
performance when the processor is running in Thumb mode (16-bit instruction set). See Figure 32, Figure 33 and Figure 34.
This optimization concerns only Code Fetch and not Data.
The read operations can be performed with or without wait state. Up to 3 wait states can be
programmed in the field FWS (Flash Wait State) in the Flash Mode Register MC_FMR (see
“MC Flash Mode Register” on page 113). Defining FWS to be 0 enables the single-cycle
access of the embedded Flash.
The Flash memory is accessible through 8-, 16- and 32-bit reads.
As the Flash block size is smaller than the address space reserved for the internal memory
area, the embedded Flash wraps around the address space and appears to be repeated
within it.
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AT91SAM7A3 Preliminary
Figure 32. Code Read Optimization in Thumb Mode for FWS = 0
Master Clock
ARM Request (16-bit)
Code Fetch
@Byte 0
Flash Access
@Byte 2
@Byte 4
Bytes 0-3
Bytes 4-7
Buffer (32 bits)
Bytes 0-1
@Byte 10
@Byte 8
Bytes 4-7
Bytes 2-3
Bytes 4-5
@Byte 12
Bytes 8-9
@Byte 16
Bytes 16-19
Bytes 12-15
Bytes 8-11
Bytes 6-7
@Byte 14
Bytes 12-15
Bytes 8-11
Bytes 0-3
Data To ARM
Note:
@Byte 6
Bytes 10-11
Bytes 12-13
Bytes 14-15
When FWS is equal to 0, all accesses are performed in a single-cycle access.
Figure 33. Code Read Optimization in Thumb Mode for FWS = 1
1 Wait State Cycle
1 Wait State Cycle
1 Wait State Cycle
1 Wait State Cycle
Master Clock
ARM Request (16-bit)
Code Fetch
@Byte 0
Flash Access
@Byte 2
Bytes 0-3
Buffer (32 bits)
Data To ARM
Note:
Bytes 0-1
@Byte 4
@Byte 6
@Byte 8
@Byte 10
@Byte 12
@Byte 14
Bytes 4-7
Bytes 8-11
Bytes 12-15
Bytes 0-3
Bytes 4-7
Bytes 8-11
Bytes 2-3
Bytes 4-5
Bytes 6-7
Bytes 8-9
Bytes 10-11
Bytes 12-13
When FWS is equal to 1, in case of sequential reads, all the accesses are performed in a single-cycle access (except for the
first one).
107
6042A–ATARM–23-Dec-04
Figure 34. Code Read Optimization in Thumb Mode for FWS = 3
3 Wait State Cycles
3 Wait State Cycles
3 Wait State Cycles
3 Wait State Cycles
Master Clock
ARM Request (16-bit)
Code Fetch
@2
@Byte 0
Flash Access
Bytes 0-3
Buffer (32 bits)
Data To ARM
Note:
0-1
@6
@4
@10
@8
@12
Bytes 4-7
Bytes 8-11
Bytes 12-15
Bytes 0-3
Bytes 4-7
Bytes 8-11
2-3
4-5
8-9 10-11
6-7
12-13
When FWS is equal to 2 or 3, in case of sequential reads, the first access takes FWS cycles, the second access one cycle, the
third access FWS cycles, the fourth access one cycle, etc.
Write Operations
The internal memory area reserved for the Embedded Flash can also be written through a
write-only latch buffer. Write operations take into account only the 8 lowest address bits and
thus wrap around within the internal memory area address space and appear to be repeated
1024 times within it.
Write operations might be prevented by programming the Memory Protection Unit of the
product.
Writing of 8-bit and 16-bit data is not allowed and may lead to unpredictable data
corruption.
Write operations are performed in the number of wait states equal to the number of wait states
for read operations + 1, except for FWS = 3 (see “MC Flash Mode Register” on page 113).
Flash Commands
The Embedded Flash Controller offers a command set to manage programming the memory
flash, locking and unlocking lock regions, consecutive programming and locking, and full Flash
erasing.
Table 19. Set of Commands
Command
Value
Mnemonic
Write page
0x01
WP
Set Lock Bit
0x02
SLB
Write Page and Lock
0x03
WPL
Clear Lock Bit
0x04
CLB
Erase all
0x08
EA
In order to perform one of these commands, the Flash Command Register (MC_FCR) has to
be written with the correct command using to the field FCMD (see “MC Flash Command Register” on page 115).
All the commands are protected by the same keyword, which has to be written in the eight
highest bits of the MC_FCR register.
108
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AT91SAM7A3 Preliminary
Writing MC_FCR with data that does not contain the correct key and/or with an invalid command has no effect on the memory plane; however, the PROGE flag is set in the MC_FSR
register. This flag is automatically cleared by a read access to the MC_FSR register.
When the current command writes or erases a page in a locked region, the command has no
effect on the whole memory plane; however, the LOCKE flag is set in the MC_FSR register.
This flag is automatically cleared by a read access to the MC_FSR register.
In order to guarantee valid operations on the Flash memory, the field Flash Microsecond Cycle Number (FMCN) in the Flash Mode Register MC_FMR must be correctly
programmed (see “MC Flash Mode Register” on page 113).
Note:
Programming
This field defines the number of Master Clock cycles in 1 microsecond that allow some necessary internal timings to be computed.
The programming is done by writing data into the latch buffer and then triggering a programming command that corresponds to the Write Page Command (WP) in the Flash Command
Register MC_FCR. The sequence is as follows:
•
Write the full page, at any page address, within the internal memory area address space
using only 32-bit access.
•
If not already done, set the bit EOP (End of Programming) in the Flash Mode Register,
depending on whether an interrupt is required or not at the end of programming.
•
Write in the field PAGEN of the Flash Command Register (MC_FCR) the Page Number to
be programmed.
•
Clear the bit NEBP (No Erase Before Programming) in MC_FMR, if an erase before
programming is required.
•
Start the programming by writting the Flash Command Register with the Write Page
Command.
•
The page defined by PAGEN is first erased if the bit NEBP is set to 0 and then
programmed with the data written in the buffer.
•
When the programming completes, the bit EOP in the Flash Programming Status Register
raises. If an interrupt has been enabled by setting the bit EOP in MC_FMR, the interrupt
line of the Memory Controller is activated.
Figure 35. State of the EOP Bit in MC_FSR
Write the MC_FCR with WP or WPL command
Read the MC_FSR
EOP
Programming Time
When the software reads the Flash Status Register (MC_FSR), the EOP bit is automatically
cleared and the interrupt line is deactivated.
109
6042A–ATARM–23-Dec-04
Two errors can be detected in the MC_FSR register after a programming sequence:
•
Programming Error: A bad keyword and/or an invalid command have been written in the
MC_FCR register.
•
Lock Error: The page to be programmed belongs to a locked region. A command must be
previously run to unlock the corresponding region.
The Flash technology requires that an erase must be done before programming. The entire
memory plane can be erased at the same time, or a page can be automatically erased by
clearing the NEBP bit in the MC_FMR register before writing the command in the MC_FCR
register.
By setting the NEBP bit in the MC_FMR register, a page can be programmed in several steps
if it has been erased before (see Figure 36).
Figure 36. Example of Partial Page Programming
32 bits wide
32 bits wide
16 words
16 words
FF
FF
FF
FF
FF
FF
FF
FF
FF
FF
16 words
FF
FF
FF
16 words
FF
FF
FF
FF
FF
FF
FF
FF
FF
FF
FF
FF
FF
FF
FF FF
...
FF FF
FF FF
FF
CA
FE
FF
FF
CA
CA
FE
FE
FF FF
...
FF FF
FF FF
FF
FF
FF
FF
FF
FF
FF
FF
FF
FF FF
...
FF FF
FF FF
FF
FF
FF
FF
FF
FF
FF
FF
FF
...
Step 1.
Erase All Flash
Page 7 erased
Lock and Unlock
Operations
...
...
...
...
32 bits wide
FF
FF
FF
FF
FF
FF
FF
FF
FF
FF
FF
FF
CA
FE
CA
FE
CA
CA
FE
FE
CA
CA
FE
FE
FF
FF
DE
CA
FF
FF
FF
FF
DE
DE
CA
CA
FF
FF
FF
FF
FF
FF
FF
FF
FF
FF
FF
FF
Step 2.
Programming of the second part of Page 7
(NEBP = 1)
FF
...
FF
FF
FF
CA
FE
CA
CA
FE
FE
DE
CA
DE
DE
CA
CA
FF
FF
FF
FF
FF
FF
FF
FF
...
...
...
Step 3.
Programming of the third part of Page 7
(NEBP = 1)
Lock bits are associated with several pages in the embedded Flash memory plane. This
defines lock regions in the embedded Flash memory plane. They prevent writing/erasing protected pages.
Each lock region has its own lock bit that is readable in the highest bits of the Flash Status
Register (MC_FSR).
After production, the device may have some embedded Flash lock regions locked. These
locked regions are reserved for a default application. Refer to the product definition section for
the default embedded Flash mapping. Locked lock regions can be unlocked to be erased and
then programmed with another application or other data.
The lock and unlock commands are performed by defining the PAGEN field and by writing the
appropriate command (Set Lock Bit Command (SLB) or Clear Lock Bit Command (CLB))
in the Flash Command Register (MC_FCR) . PAGEN defines one page number of the lock
region to be locked or unlocked. Writing in all the other bits of PAGEN has no effect.
The Clear Lock Bit command programs the lock bit to 1; the corresponding bit LOCKSx in
MC_FSR reads 0. The Set Lock Bit command programs the lock bit to 0; the corresponding bit
LOCKSx in MC_FSR reads 1.
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AT91SAM7A3 Preliminary
When the Set Lock Bit or Clear Lock Bit command is triggered, the programming or erasing
operation of the lock bit is performed. When it completes, the bit EOL is set.
No access to the Flash is permitted when a Set Lock Bit or Clear Lock Bit command is
performed.
A programming error, where a bad keyword and/or an invalid command have been written in
the MC_FCR register, may be detected in the MC_FSR register after a programming
sequence.
Figure 37. State of the EOL Bit in MC_FSR
Write the MC_FCR with SLB, CLB or WPL command
Read the MC_FSR
EOL
Locking or unlocking Time Sequence
Lock Protection
When a programming command is performed with PAGEN defining a locked lock region, the
bit LOCKE in MC_FSR rises. If the bit LOCKE has been written at 1 in MC_FMR, the interrupt
line rises. Reading MC_FSR automatically clears the bit LOCKE in MC_FSR and thus deactivates the interrupt line.
Write Page and Lock
The user can perform consecutively the programming of the page and the lock of the lock
region (Write Page and Lock Command (WPL) in the FCMD field of the Flash Command
Register MC_FCR), both defined by PAGEN.
Only one or both end of programming or end of lock interrupts may be enabled to trigger an
interrupt when the operations completes.
Erase All Flash
The entire memory can be erased if the Erase All Command (EA) in the Flash Command
Register MC_FCR is written.
Erase All operation is allowed only if there are no lock bits set. Thus, if at least one lock region
is locked, the bit LOCKE in MC_FSR rises and the command is cancelled. If the bit LOCKE
has been written at 1 in MC_FMR, the interrupt line rises (see “Lock Protection” on page 111).
If not already done, set the bit EOP (End of Programming) in the Flash Mode Register,
depending on whether an interrupt is required or not at the end of the erase.
When the Flash erase is complete, the bit EOP in the Flash Programming Status Register
rises. If an interrupt has been enabled by setting the bit EOP in MC_FMR, the interrupt line of
the Memory Controller is activated.
When the software reads the Flash Status Register (MC_FSR), the EOP bit is automatically
cleared and the interrupt line is deactivated.
Two errors can be detected in the MC_FSR register after a programming sequence:
•
Programming Error: A bad keyword and/or an invalid command have been written in the
MC_FCR register.
•
Lock Error: At least one lock region to be erased is protected. The erase command has
been refused and no page has been erased. A Clear Lock Bit command must be executed
previously to unlock the corresponding lock regions.
111
6042A–ATARM–23-Dec-04
Embedded Flash Controller (EFC) User Interface
The User Interface of the Embedded Flash Controller is integrated within the Memory Controller with base address:
0xFFFF FF00.
Table 20. Embedded Flash Controller (EFC) Register Mapping
Offset
Register
Name
Access
Reset State
0x60
MC Flash Mode Register
MC_FMR
Read/Write
0x0
0x64
MC Flash Command Register
MC_FCR
Write-only
–
0x68
MC Flash Status Register
MC_FSR
Read-only
–
0x6C
Reserved
–
–
–
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AT91SAM7A3 Preliminary
MC Flash Mode Register
Register Name:
MC_FMR
Access Type:
Read/Write
Offset:
0x60
31
–
30
–
29
–
28
–
27
–
26
–
25
–
24
–
23
22
21
20
19
18
17
16
FMCN
15
–
14
–
13
–
12
–
11
–
10
–
9
7
NEBP
6
–
5
–
4
–
3
PROGE
2
LOCKE
1
EOL
8
FWS
0
EOP
• EOP: End of Programming Interrupt Enable
0: End of Programming (page programming or erase all flash) does not generate an interrupt.
1: End of Programming (page programming or erase all flash) generates an interrupt.
• EOL: End of Lock/Unlock Interrupt Enable
0: End of Lock or End of Unlock does not generate an interrupt.
1: End of Lock or End of Unlock generates an interrupt.
• LOCKE: Lock Error Interrupt Enable
0: Lock Error does not generate an interrupt.
1: Lock Error generates an interrupt.
• PROGE: Programming Error Interrupt Enable
0: Programming Error does not generate an interrupt.
1: Programming Error generates an interrupt.
• NEBP: No Erase Before Programming
0: A page erase is performed before programming.
1: No erase is performed before programming.
• FWS: Flash Wait State
This field defines the number of wait states for read and write operations:
FWS
Read Operations
Write Operations
0
1 cycle
2 cycles
1
2 cycles
3 cycles
2
3 cycles
4 cycles
3
4 cycles
4 cycles
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• FMCN: Flash Microsecond Cycle Number
This field defines the number of Master Clock cycles in 1 microsecond.
Warning: The value 0 is only allowed for a master clock period superior to 30 microseconds.
Warning: In order to guarantee valid operations on the flash memory, the field Flash Microsecond Cycle Number (FMCN)
must be correctly programmed.
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MC Flash Command Register
Register Name:
MC_FCR
Access Type:
Write only
Offset:
0x64
31
30
29
28
27
26
25
24
19
–
18
–
17
16
11
10
9
8
3
2
1
0
KEY
23
–
22
–
21
–
20
–
15
14
13
12
PAGEN
PAGEN
7
–
6
–
5
–
4
–
FCMD
• FCMD: Flash Command
This field defines the Flash commands:
FCMD
Operations
0000
No command.
Does not raise the Programming Error Status flag in the Flash Status Register MC_FSR.
0001
Write Page Command (WP):
Starts the programming of the page specified in the PAGEN field.
0010
Set Lock Bit Command (SLB):
Starts a set lock bit sequence of the lock region specified in the PAGEN field.
0011
Write Page and Lock Command (WPL):
The lock sequence of the lock region associated with the page specified in the field PAGEN
occurs automatically after completion of the programming sequence.
0100
Clear Lock Bit Command (CLB):
Starts a clear lock bit sequence of the lock region specified in the PAGEN field.
1000
Erase All Command (EA):
Starts the erase of the entire Flash.
If at least one page is locked, the command is cancelled.
Others
Reserved.
Raises the Programming Error Status flag in the Flash Status Register MC_FSR.
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• PAGEN: Page Number
Command
PAGEN Description
Write Page Command
PAGEN defines the page number to be written.
Write Page and Lock Command
PAGEN defines the page number to be written and its associated
lock region.
Erase All Command
This field is meaningless
Set/Clear Lock Bit Command
PAGEN defines one page number of the lock region to be locked or
unlocked.
Note:
Depending on the command, all the possible unused bits of PAGEN are meaningless.
• KEY: Writing Protection Key
This field should be written with the value 0x5A to enable the command defined by the bits of the register. If the field is written with a different value, the write is actually not performed and no action is started.
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MC Flash Status Register
Register Name:
MC_FSR
Access Type:
Read only
Offset:
0x68
31
LOCKS15
30
LOCKS14
29
LOCKS13
28
LOCKS12
27
LOCKS11
26
LOCKS10
25
LOCKS9
24
LOCKS8
23
LOCKS7
22
LOCKS6
21
LOCKS5
20
LOCKS4
19
LOCKS3
18
LOCKS2
17
LOCKS1
16
LOCKS0
15
–
14
–
13
–
12
–
11
–
10
–
9
–
8
–
7
–
6
–
5
–
4
–
3
PROGE
2
LOCKE
1
EOL
0
EOP
• EOP: End of Programming Status
0: The programming sequence (page programming or erase all Flash) triggered by the last write in MC_FCR is not yet completed, or FMC_FSR has been read.
1: The programming sequence (page programming or erase all Flash) triggered by the last write in MC_FCR is completed
and MC_FSR has not been read yet.
• EOL: End of Lock Status
0: The lock or unlock sequence triggered by the last write in MC_FCR is not yet completed, or FMC_FSR has been read.
1: The lock or unlock sequence triggered by the last write in MC_FCR is completed and MC_FSR has not been read yet.
• LOCKE: Lock Error Status
0: No programming of at least one locked lock region has happened since the last read of MC_FSR.
1: Programming of at least one locked lock region has happened since the last read of MC_FSR.
• PROGE: Programming Error Status
0: No invalid commands and no bad key-words were written in the Flash Command Register MC_FCR.
1: An invalid command and/or a bad key-word was/were written in the Flash Command Register MC_FCR.
• LOCKSx: Lock Region x Lock Status
0: The corresponding lock region is not locked.
1: The corresponding lock region is locked.
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Peripheral Data Controller (PDC)
Overview
The Peripheral Data Controller (PDC) transfers data between on-chip serial peripherals such
as the UART, USART, SSC, SPI, MCI and the on- and off-chip memories. Using the Peripheral Data Contoller avoids processor intervention and removes the processor interrupthandling overhead. This significantly reduces the number of clock cycles required for a data
transfer and, as a result, improves the performance of the microcontroller and makes it more
power efficient.
The PDC channels are implemented in pairs, each pair being dedicated to a particular peripheral. One channel in the pair is dedicated to the receiving channel and one to the transmitting
channel of each UART, USART, SSC and SPI.
The user interface of a PDC channel is integrated in the memory space of each peripheral. It
contains:
•
A 32-bit memory pointer register
•
A 16-bit transfer count register
•
A 32-bit register for next memory pointer
•
A 16-bit register for next transfer count
The peripheral triggers PDC transfers using transmit and receive signals. When the programmed data is transferred, an end of transfer interrupt is generated by the corresponding
peripheral.
Block Diagram
Figure 38. Block Diagram
Peripheral
Peripheral Data Controller
THR
PDC Channel 0
RHR
PDC Channel 1
Control
Control
Memory
Controller
Status & Control
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6042A–ATARM–23-Dec-04
Functional Description
Configuration
The PDC channels user interface enables the user to configure and control the data transfers
for each channel. The user interface of a PDC channel is integrated into the user interface of
the peripheral (offset 0x100), which it is related to.
Per peripheral, it contains four 32-bit Pointer Registers (RPR, RNPR, TPR, and TNPR) and
four 16-bit Counter Registers (RCR, RNCR, TCR, and TNCR).
The size of the buffer (number of transfers) is configured in an internal 16-bit transfer counter
register, and it is possible, at any moment, to read the number of transfers left for each
channel.
The memory base address is configured in a 32-bit memory pointer by defining the location of
the first address to access in the memory. It is possible, at any moment, to read the location in
memory of the next transfer and the number of remaining transfers. 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 peripheral status register. Transfers can be enabled
and/or disabled by setting TXTEN/TXTDIS and RXTEN/RXTDIS in PDC Transfer Control
Register. These control bits enable reading the pointer and counter registers safely without
any risk of their changing between both reads.
The PDC sends status flags to the peripheral visible in its status-register (ENDRX, ENDTX,
RXBUFF, and TXBUFE).
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.
Memory Pointers
Each peripheral is connected to the PDC by a receiver data channel and a transmitter data
channel. Each channel has an internal 32-bit memory pointer. Each memory pointer points to
a location anywhere in the memory space (on-chip memory or external bus interface memory).
Depending on the type of transfer (byte, half-word or word), the memory pointer is incremented by 1, 2 or 4, respectively for peripheral transfers.
If a memory pointer is reprogrammed while the PDC is in operation, the transfer address is
changed, and the PDC performs transfers using the new address.
Transfer Counters
There is one internal 16-bit transfer counter for each channel used to count the size of the
block already transferred by its associated channel. These counters are decremented after
each data transfer. When the counter reaches zero, the transfer is complete and the PDC
stops transferring data.
If the Next Counter Register is equal to zero, the PDC disables the trigger while activating the
related peripheral end flag.
If the counter is reprogrammed while the PDC is operating, the number of transfers is updated
and the PDC counts transfers from the new value.
Programming the Next Counter/Pointer registers chains the buffers. The counters are decremented after each data transfer as stated above, but when the transfer counter reaches zero,
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the values of the Next Counter/Pointer are loaded into the Counter/Pointer registers in order to
re-enable the triggers.
For each channel, two status bits indicate the end of the current buffer (ENDRX, ENTX) and
the end of both current and next buffer (RXBUFF, TXBUFE). These bits are directly mapped to
the peripheral status register and can trigger an interrupt request to the AIC.
The peripheral end flag is automatically cleared when one of the counter-registers (Counter or
Next Counter Register) is written.
Note: When the Next Counter Register is loaded into the Counter Register, it is set to zero.
Data Transfers
The peripheral triggers PDC transfers using transmit (TXRDY) and receive (RXRDY) signals.
When the peripheral receives an external character, it sends a Receive Ready signal to the
PDC which then requests access to the system bus. When access is granted, the PDC starts
a read of the peripheral Receive Holding Register (RHR) and then triggers a write in the
memory.
After each transfer, the relevant PDC memory pointer is incremented and the number of transfers left is decremented. When the memory block size is reached, a signal is sent to the
peripheral and the transfer stops.
The same procedure is followed, in reverse, for transmit transfers.
Priority of PDC
Transfer Requests
The Peripheral Data Controller handles transfer requests from the channel according to priorities fixed for each product.These priorities are defined in the product datasheet.
If simultaneous requests of the same type (receiver or transmitter) occur on identical peripherals, the priority is determined by the numbering of the peripherals.
If transfer requests are not simultaneous, they are treated in the order they occurred.
Requests from the receivers are handled first and then followed by transmitter requests.
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Peripheral Data Controller (PDC) User Interface
Table 21. Peripheral Data Controller (PDC) Register Mapping
Offset
Register
Register Name
Read/Write
Reset
0x100
Receive Pointer Register
PERIPH (1)_RPR
Read/Write
0x0
0x104
Receive Counter Register
PERIPH_RCR
Read/Write
0x0
0x108
Transmit Pointer Register
PERIPH_TPR
Read/Write
0x0
0x10C
Transmit Counter Register
PERIPH_TCR
Read/Write
0x0
0x110
Receive Next Pointer Register
PERIPH_RNPR
Read/Write
0x0
0x114
Receive Next Counter Register
PERIPH_RNCR
Read/Write
0x0
0x118
Transmit Next Pointer Register
PERIPH_TNPR
Read/Write
0x0
0x11C
Transmit Next Counter Register
PERIPH_TNCR
Read/Write
0x0
0x120
PDC Transfer Control Register
PERIPH_PTCR
Write-only
-
0x124
PDC Transfer Status Register
PERIPH_PTSR
Read-only
0x0
Note:
122
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).
AT91SAM7A3 Preliminary
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PDC Receive Pointer Register
Register Name: PERIPH_RPR
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
RXPTR
23
22
21
20
RXPTR
15
14
13
12
RXPTR
7
6
5
4
RXPTR
• RXPTR: Receive Pointer Address
Address of the next receive transfer.
PDC Receive Counter Register
Register Name: PERIPH_RCR
Access Type:
Read/Write
31
30
29
28
-23
22
21
20
-15
14
13
12
RXCTR
7
6
5
4
RXCTR
• RXCTR: Receive Counter Value
Number of receive transfers to be performed.
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PDC 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
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 Pointer Address
Address of the transmit buffer.
PDC Transmit Counter Register
Register Name: PERIPH_TCR
Access Type:
31
Read/Write
30
29
28
-23
22
21
20
-15
14
13
12
TXCTR
7
6
5
4
TXCTR
• TXCTR: Transmit Counter Value
TXCTR is the size of the transmit transfer to be performed. At zero, the peripheral data transfer is stopped.
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PDC Receive Next Pointer Register
Register Name: PERIPH_RNPR
Access Type:
Read/Write
31
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 Address
RXNPTR is the address of the next buffer to fill with received data when the current buffer is full.
PDC Receive Next Counter Register
Register Name: PERIPH_RNCR
Access Type:
Read/Write
31
30
29
28
27
26
25
24
19
18
17
16
11
10
9
8
3
2
1
0
-23
22
21
20
-15
14
13
12
RXNCR
7
6
5
4
RXNCR
• RXNCR: Receive Next Counter Value
RXNCR is the size of the next buffer to receive.
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PDC 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 Address
TXNPTR is the address of the next buffer to transmit when the current buffer is empty.
PDC Transmit Next Counter Register
Register Name:
Access Type:
31
PERIPH_TNCR
Read/Write
30
29
28
27
26
25
24
19
18
17
16
11
10
9
8
3
2
1
0
-23
22
21
20
-15
14
13
12
TXNCR
7
6
5
4
TXNCR
• TXNCR: Transmit Next Counter Value
TXNCR is the size of the next buffer to transmit.
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PDC 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
8
–
–
–
–
–
–
TXTDIS
TXTEN
7
6
5
4
3
2
1
0
–
–
–
–
–
–
RXTDIS
RXTEN
• RXTEN: Receiver Transfer Enable
0 = No effect.
1 = Enables the receiver PDC transfer requests if RXTDIS is not set.
• RXTDIS: Receiver Transfer Disable
0 = No effect.
1 = Disables the receiver PDC transfer requests.
• TXTEN: Transmitter Transfer Enable
0 = No effect.
1 = Enables the transmitter PDC transfer requests.
• TXTDIS: Transmitter Transfer Disable
0 = No effect.
1 = Disables the transmitter PDC transfer requests
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6042A–ATARM–23-Dec-04
PDC 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 = Receiver PDC transfer requests are disabled.
1 = Receiver PDC transfer requests are enabled.
• TXTEN: Transmitter Transfer Enable
0 = Transmitter PDC transfer requests are disabled.
1 = Transmitter PDC transfer requests are enabled.
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Advanced Interrupt Controller (AIC)
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.
Block Diagram
Figure 39. Block Diagram
FIQ
AIC
IRQ0-IRQn
Embedded
PeripheralEE
Embedded
ARM
Processor
Up to
Thirty-two
Sources
nFIQ
nIRQ
Peripheral
Embedded
Peripheral
APB
Application
Block Diagram
Figure 40. 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
Embedded Peripherals
External Peripherals
(External Interrupts)
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AIC Detailed
Block Diagram
Figure 41. 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
I/O Line Description
Table 22. I/O Line Description
Pin Name
Pin Description
Type
FIQ
Fast Interrupt
Input
IRQ0 - IRQn
Interrupt 0 - Interrupt n
Input
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.
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.
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, such as the System Timer, the Real Time Clock,
the Power Management Controller and the Memory Controller. When a system interrupt
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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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6042A–ATARM–23-Dec-04
Functional Description
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 levelsensitive modes, or in positive edge-triggered or negative edge-triggered modes.
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.
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 135.) 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 139.)
The automatic clear of the interrupt source 0 is performed when AIC_FVR is read.
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 135) 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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Internal Interrupt
Source Input Stage
Figure 42. Internal Interrupt Source Input Stage
AIC_SMRI
(SRCTYPE)
AIC_IPR
Level/
Edge
Source i
AIC_IMR
Fast Interrupt Controller
or
Priority Controller
Edge
AIC_IECR
Detector
Set Clear
FF
AIC_ISCR
AIC_ICCR
AIC_IDCR
External Interrupt
Source Input Stage
Figure 43. External Interrupt Source Input Stage
High/Low
AIC_SMRi
SRCTYPE
Level/
Edge
Source i
AIC_IPR
AIC_IMR
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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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.
External Interrupt
Edge Triggered
Source
Figure 44. 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
External Interrupt
Level Sensitive Source
Figure 45. 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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Internal Interrupt Edge
Triggered Source
Figure 46. Internal Interrupt Edge Triggered Source
MCK
nIRQ
Maximum IRQ Latency = 4.5 Cycles
Peripheral Interrupt
Becomes Active
Internal Interrupt Level
Sensitive Source
Figure 47. Internal Interrupt Level Sensitive Source
MCK
nIRQ
Maximum IRQ Latency = 3.5 Cycles
Peripheral Interrupt
Becomes Active
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_SVR
(Source Vector 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 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.
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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.
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.
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:
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
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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).
Fast Interrupt
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.
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
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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.
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.
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 automatically 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
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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.
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 Fast Interrupt 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).
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.
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Figure 48. 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
nIRQ
AIC_IMR
Read IVR if Source n is the current interrupt
and if Fast Forcing is disabled on Source n.
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 DBGM 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.
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.
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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.
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.
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.
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Advanced Interrupt Controller (AIC) User Interface
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 an ± 4-Kbyte offset.
Table 23. Advanced Interrupt Controller (AIC) Register Mapping
Offset
Access
Reset Value
Source Mode Register 0
AIC_SMR0
Read/Write
0x0
0x04
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
---
---
---
AIC_SVR31
Read/Write
0x0
---
142
Name
0000
---
Note:
Register
---
0xFC
Source Vector Register 31
0x100
Interrupt Vector Register
AIC_IVR
Read-only
0x0
0x104
Fast Interrupt Vector Register
AIC_FVR
Read-only
0x0
0x108
Interrupt Status Register
AIC_ISR
Read-only
0x0
0x10C
Interrupt Pending Register
AIC_IPR
Read-only
0x0(1)
0x110
Interrupt Mask Register
AIC_IMR
Read-only
0x0
0x114
Core Interrupt Status Register
AIC_CISR
Read-only
0x0
0x118
Reserved
---
---
---
0x11C
Reserved
---
---
---
0x120
Interrupt Enable Command Register
AIC_IECR
Write-only
---
0x124
Interrupt Disable Command Register
AIC_IDCR
Write-only
---
0x128
Interrupt Clear Command Register
AIC_ICCR
Write-only
---
0x12C
Interrupt Set Command Register
AIC_ISCR
Write-only
---
0x130
End of Interrupt Command Register
AIC_EOICR
Write-only
---
0x134
Spurious Interrupt Vector Register
AIC_SPU
Read/Write
0x0
0x138
Debug Control Register
AIC_DCR
Read/Write
0x0
0x13C
Reserved
---
---
---
0x140
Fast Forcing Enable Register
AIC_FFER
Write-only
---
0x144
Fast Forcing Disable Register
AIC_FFDR
Write-only
---
0x148
Fast Forcing Status Register
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.
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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
0
0
Level Sensitive
0
1
Edge Triggered
1
0
Level Sensitive
1
1
Edge Triggered
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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.
AIC Interrupt Vector Register
Register Name: AIC_IVR
Access Type:
Read-only
Reset Value:
0
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.
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AIC FIQ Vector Register
Register Name: AIC_FVR
Access Type:
Read-only
Reset Value:
0
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 Fast Interrupt Vector Register reads the value stored in AIC_SPU.
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AIC Interrupt Status Register
Register Name: AIC_ISR
Access Type:
Read-only
Reset Value:
0
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.
AIC Interrupt Pending Register
Register Name: AIC_IPR
Access Type:
Read-only
Reset Value:
0
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.
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AIC Interrupt Mask Register
Register Name: AIC_IMR
Access Type:
Read-only
Reset Value:
0
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.
AIC Core Interrupt Status Register
Register Name: AIC_CISR
Access Type:
Read-only
Reset Value:
0
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
NIFQ
• 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.
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6042A–ATARM–23-Dec-04
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-PID3: Interrupt Enable
0 = No effect.
1 = Enables corresponding interrupt.
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.
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AT91SAM7A3 Preliminary
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.
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.
149
6042A–ATARM–23-Dec-04
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.
AIC Spurious Interrupt Vector Register
Register Name: AIC_SPU
Access Type:
Read/Write
Reset Value:
0
31
30
29
28
27
26
25
24
19
18
17
16
11
10
9
8
3
2
1
0
SIQV
23
22
21
20
SIQV
15
14
13
12
SIQV
7
6
5
4
SIQV
• SIQV: 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.
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AT91SAM7A3 Preliminary
AIC Debug Control Register
Register Name: AIC_DEBUG
Access Type:
Read/Write
Reset Value:
0
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.
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.
151
6042A–ATARM–23-Dec-04
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.
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.
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AT91SAM7A3 Preliminary
Clock Generator
Description
The Clock Generator is made up of one PLL, a Main Oscillator and an RC 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
•
PLLCK is the output of the Divider and PLL block
The Clock Generator User Interface is embedded within the Power Management Controller
User Interface and is described in “Power Management Controller (PMC) User Interface” on
page 165. However, the Clock Generator registers are named CKGR_.
Slow Clock RC
Oscillator
The slow clock is the output of the RC Oscillator and is the only clock considered permanent in
a system that includes the Power Management Controller. It is mandatory in the operations of
the PMC.
The user has to take the possible drifts of the RC Oscillator into account. More details are
given in the DC Characteristics section of the product datasheet.
Main Oscillator
Figure 49 shows the Main Oscillator block diagram.
Figure 49. Main Oscillator Block Diagram
MOSCEN
XIN
XOUT
Main
Oscillator
MAINCK
Main Clock
OSCOUNT
SLCK
Slow Clock
Main
Oscillator
Counter
Main Clock
Frequency
Counter
Main Oscillator
Connections
MOSCS
MAINF
MAINRDY
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 50. The 1 kΩ resistor is
only required for crystals with frequencies lower than 8 MHz. The oscillator contains 25 pF
capacitors on each XIN and XOUT pin. Consequently, CL1 and CL2 can be removed when a
crystal with a load capacitance of 12.5 pF is used. For further details on the electrical characteristics of the Main Oscillator, see the DC Characteristics section of the product datasheet.
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6042A–ATARM–23-Dec-04
Figure 50. Typical Crystal Connection
XIN
XOUT
GND
1K
CL1
CL2
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.
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).
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.
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.
Main Oscillator
Bypass
154
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.
AT91SAM7A3 Preliminary
6042A–ATARM–23-Dec-04
AT91SAM7A3 Preliminary
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 51 shows the block diagram of the divider and PLL block.
Figure 51. Divider and PLL Block Diagram
DIV
MUL
Divider
MAINCK
OUT
PLLCK
PLL
PLLRC
PLLCOUNT
PLL
Counter
SLCK
PLL Filter
LOCK
The PLL requires connection to an external second-order filter through the PLLRC pin. Figure
52 shows a schematic of these filters.
Figure 52. PLL Capacitors and Resistors
PLLRC
PLL
R
C2
C1
GND
Values of R, C1 and C2 to be connected to the PLLRC pin must be calculated as a function of
the PLL input frequency, the PLL output frequency and the phase margin. A trade-off has to be
found between output signal overshoot and startup time.
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 0. 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 in
PMC_SR is automatically cleared. The values written in the PLLCOUNT field in CKGR_PLLR
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.
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6042A–ATARM–23-Dec-04
The initial state of the PLL and its target frequency can be calculated using a specific tool provided by Atmel.
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AT91SAM7A3 Preliminary
Power Management Controller (PMC)
Description
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:
Master Clock
Controller
•
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.
•
UDP Clock (UDPCK), required by USB Device Port operations.
•
Programmable Clock Outputs can be selected from the clocks provided by the clock
generator and driven on the PCKx pins.
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 PLL.
The Master Clock Controller is made up of a clock selector and a prescaler.
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.
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 highspeed clock to a lower one to inform the software when the change is actually done.
Figure 53. Master Clock Controller
PMC_MCKR
CSS
PMC_MCKR
PRES
SLCK
MAINCK
Master Clock
Prescaler
MCK
PLLCK
To the Processor
Clock Controller (PCK)
Processor Clock
Controller
The PMC features a Processor Clock Controller (PCK) that implements the Processor Idle
Mode. The Processor Clock can be enabled and disabled by writing the System Clock Enable
(PMC_SCER) and System Clock Disable Registers (PMC_SCDR). The status of this clock (at
least for debug purpose) can be read in the System Clock Status Register (PMC_SCSR).
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6042A–ATARM–23-Dec-04
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.
USB Clock
Controller
The USB Source Clock is the PLL output. If using the USB, the user must program the PLL to
generate a 48 MHz, a 96 MHz or a 192 MHz signal with an accuracy of ± 0.25% depending on
the USBDIV bit in CKGR_PLLR.
When the PLL output is stable, i.e., the LOCK bit is set:
•
The USB device clock can be enabled by setting the UDP bit in PMC_SCER. To save
power on this peripheral when it is not used, the user can set the UDP bit in PMC_SCDR.
The UDP bit in PMC_SCSR gives the activity of this clock. The USB device port require
both the 48 MHz signal and the Master Clock. The Master Clock may be controlled via the
Peripheral Clock Controller.
Figure 54. USB Clock Controller
USBDIV
USB
Source
Clock
Peripheral Clock
Controller
Divider
/1,/2,/4
UDP Clock (UDPCK)
UDP
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.
Programmable
Clock Output
Controller
The PMC controls 4 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 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).
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AT91SAM7A3 Preliminary
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.
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.
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 and divider:
All parameters needed to configure PLL and the divider are located in the CKGR_PLLR
register.
The DIV field is used to control divider itself. A value between 0 and 255 can be programmed. Divider output is divider input divided by DIV parameter. By default DIV
parameter is set to 0 which means that divider is turned off.
The OUT field is used to select the PLL B output frequency range.
The MUL field is the PLL multiplier factor. This parameter can be programmed between 0
and 2047. If MUL is set to 0, PLL will be turned off, otherwise the PLL output frequency is
PLL input frequency multiplied by (MUL + 1).
The PLLCOUNT field specifies the number of slow clock cycles before LOCK bit is set in
the PMC_SR register after CKGR_PLLR register has been written.
Once the PMC_PLL register has been written, the user must wait for the LOCK 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 LOCK has been enabled
in the PMC_IER register. All parameters in CKGR_PLLR can be programmed in a single
write operation. If at some stage one of the following parameters, MUL, DIV is modified,
LOCK bit will go low to indicate that PLL is not ready yet. When PLL is locked, LOCK will
be set again. The user is constrained to wait for LOCK bit to be set before using the PLL
output clock.
The USBDIV field is used to control the additional divider by 1, 2 or 4, which generates the
USB clock(s).
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6042A–ATARM–23-Dec-04
Code Example:
write_register(CKGR_PLLR,0x00040805)
If PLL and divider are enabled, the PLL input clock is the main clock. PLL output clock is
PLL input clock multiplied by 5. Once CKGR_PLLR has been written, LOCK bit will be set
after eight slow clock cycles.
4. 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 Master Clock divider source. By default, the selected
clock source is slow clock.
The PRES field is used to control the Master Clock prescaler. The user can choose
between different values (1, 2, 4, 8, 16, 32, 64). Master Clock output is prescaler input
divided by PRES parameter. By default, PRES parameter is set to 1 which means that
master clock is equal to slow clock.
Once 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.
All parameters in PMC_MCKR can be programmed in a single write operation. 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, the MCKRDY flag will go low while PLL is unlocked. Once PLL is locked again,
LOCK goes high and MCKRDY is set.
While PLL is unlocked, the Master Clock selection is automatically changed to Main Clock. For
further information, see Section . “Clock Switching Waveforms” on page 162.
Code Example:
write_register(PMC_MCKR,0x00000011)
The Master Clock is main clock divided by 16.
The Processor Clock is the Master Clock.
5. 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, 4 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, PLLCK. 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.
160
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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.
6. 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, 20 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)
Peripheral clocks 4 and 8 are enabled.
write_register(PMC_PCDR,0x00000010)
Peripheral clock 4 is disabled.
161
6042A–ATARM–23-Dec-04
Clock Switching
Details
Master Clock
Switching Timings
Table 24 gives the worst case timing 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 24. 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
To
Main Clock
SLCK
0.5 x Main Clock +
4.5 x SLCK
PLL Clock
Clock Switching
Waveforms
0.5 x Main Clock +
4 x SLCK +
PLLCOUNT x SLCK +
2.5 x PLLx Clock
–
3 x PLL Clock +
5 x SLCK
2.5 x PLL Clock +
5 x SLCK +
PLLCOUNT x SLCK
2.5 x PLL Clock +
4 x SLCK +
PLLCOUNT x SLCK
Figure 55. Switch Master Clock from Slow Clock to PLL Clock
Slow Clock
PLL Clock
LOCK
MCKRDY
Master Clock
Write PMC_MCKR
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Figure 56. Switch Master Clock from Main Clock to Slow Clock
Slow Clock
Main Clock
MCKRDY
Master Clock
Write PMC_MCKR
Figure 57. Change PLL Programming
Slow Clock
PLL Clock
LOCK
MCKRDY
Master Clock
Slow Clock
Write CKGR_PLLR
163
6042A–ATARM–23-Dec-04
Figure 58. Programmable Clock Output Programming
PLL Clock
PCKRDY
PCKx Output
Write PMC_PCKx
PLL Clock is selected
Write PMC_SCER
Write PMC_SCDR
164
PCKx is enabled
PCKx is disabled
AT91SAM7A3 Preliminary
6042A–ATARM–23-Dec-04
AT91SAM7A3 Preliminary
Power Management Controller (PMC) User Interface
Table 25. PMC Register Mapping
Offset
Register
Name
Access
Reset Value
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
0x01
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
Reserved
–
–
0x002C
PLL Register
CKGR_PLLR
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
...
...
0x0060
Interrupt Enable Register
PMC_IER
Write-only
--
0x0064
Interrupt Disable Register
PMC_IDR
Write-only
--
0x0068
Status Register
PMC_SR
Read-only
0x18
0x006C
Interrupt Mask Register
PMC_IMR
Read-only
0x0
–
–
...
0x0070 - 0x00FC
Reserved
–
–
–
...
–
...
165
6042A–ATARM–23-Dec-04
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
–
–
–
–
PCK3
PCK2
PCK1
PCK0
7
6
5
4
3
2
1
0
UDP
–
–
–
–
–
–
PCK
• PCK: Processor Clock Enable
0 = No effect.
1 = Enables the Processor clock.
• 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.
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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
–
–
–
–
PCK3
PCK2
PCK1
PCK0
7
6
5
4
3
2
1
0
UDP
–
–
–
–
–
–
PCK
• PCK: Processor Clock Disable
0 = No effect.
1 = Disables the Processor clock. This is used to enter teh processor in Idle Mode.
• 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.
167
6042A–ATARM–23-Dec-04
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
–
–
–
–
PCK3
PCK2
PCK1
PCK0
7
6
5
4
3
2
1
0
UDP
–
–
–
–
–
–
PCK
• PCK: Processor Clock Status
0 = The Processor clock is disabled.
1 = The Processor clock 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.
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AT91SAM7A3 Preliminary
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:
Programming the control bits of the Peripheral ID that are not implemented has no effect on the behavior of the PMC.
169
6042A–ATARM–23-Dec-04
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.
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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.
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.
• 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.
• OSCOUNT: Main Oscillator Start-up Time
Specifies the number of Slow Clock cycles multiplied by 8 for the Main Oscillator start-up time.
171
6042A–ATARM–23-Dec-04
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.
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PMC Clock Generator PLL Register
Register Name: CKGR_PLLR
Access Type:
Read/Write
31
–
30
–
29
23
22
21
28
27
–
26
25
MUL
24
20
19
18
17
16
10
9
8
2
1
0
USBDIV
MUL
15
14
13
12
11
OUT
PLLCOUNT
7
6
5
4
3
DIV
Possible limitations on PLL input frequencies and multiplier factors should be checked before using the PMC.
• DIV: Divider
DIV
Divider Selected
0
Divider output is 0
1
Divider is bypassed
2 - 255
Divider output is the selected clock divided by DIV.
• PLLCOUNT: PLL Counter
Specifies the number of slow clock cycles before the LOCK bit is set in PMC_SR after CKGR_PLLR is written.
• OUT: PLL Clock Frequency Range
OUT
PLL Clock Frequency Range
0
0
Refer to the DC Characteristics section of the product datasheet
0
1
Reserved
1
0
Refer to the DC Characteristics section of the product datasheet
1
1
Reserved
• MUL: PLL Multiplier
0 = The PLL is deactivated.
1 up to 2047 = The PLL Clock frequency is the PLL input frequency multiplied by MUL+ 1.
• USBDIV: Divider for USB Clock
USBDIV
Divider for USB Clock(s)
0
0
Divider output is PLL clock output.
0
1
Divider output is PLL clock output divided by 2.
1
0
Divider output is PLL clock output divided by 4.
1
1
Reserved.
173
6042A–ATARM–23-Dec-04
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
–
–
–
–
–
–
4
3
2
7
6
5
–
–
–
8
–
1
0
PRES
CSS
• CSS: Master Clock Selection
CSS
Clock Source Selection
0
0
Slow Clock is selected
0
1
Main Clock is selected
1
0
Reserved
1
1
PLL Clock is selected.
• PRES: Master Clock Prescaler
PRES
174
Master 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
AT91SAM7A3 Preliminary
6042A–ATARM–23-Dec-04
AT91SAM7A3 Preliminary
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
Master 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
175
6042A–ATARM–23-Dec-04
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
–
–
–
–
PCKRDY3
PCKRDY2
PCKRDY1
PCKRDY0
7
6
5
4
3
2
1
0
–
–
–
–
MCKRDY
LOCK
–
MOSCS
• MOSCS: Main Oscillator Status Interrupt Enable
• LOCK: PLL Lock Interrupt Enable
• MCKRDY: Master Clock Ready Interrupt Enable
• PCKRDYx: Programmable Clock Ready x Interrupt Enable
0 = No effect.
1 = Enables the corresponding interrupt.
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
–
–
–
–
PCKRDY3
PCKRDY2
PCKRDY1
PCKRDY0
7
6
5
4
3
2
1
0
–
–
–
–
MCKRDY
LOCK
–
MOSCS
• MOSCS: Main Oscillator Status Interrupt Disable
• LOCK: PLL Lock Interrupt Disable
• MCKRDY: Master Clock Ready Interrupt Disable
• PCKRDYx: Programmable Clock Ready x Interrupt Disable
0 = No effect.
1 = Disables the corresponding interrupt.
176
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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
–
–
–
–
PCKRDY3
PCKRDY2
PCKRDY1
PCKRDY0
7
6
5
4
3
2
1
0
–
–
–
–
MCKRDY
LOCK
–
MOSCS
• MOSCS: MOSCS Flag Status
0 = Main oscillator is not stabilized.
1 = Main oscillator is stabilized.
• LOCK: PLL Lock Status
0 = PLL is not locked
1 = PLL is locked.
• MCKRDY: Master Clock Status
0 = Master Clock is not ready.
1 = Master Clock is ready.
• PCKRDYx: Programmable Clock Ready Status
0 = Programmable Clock x is not ready.
1 = Programmable Clock x is ready.
177
6042A–ATARM–23-Dec-04
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
–
–
–
–
PCKRDY3
PCKRDY2
PCKRDY1
PCKRDY0
7
6
5
4
3
2
1
0
–
–
–
–
MCKRDY
LOCK
–
MOSCS
• MOSCS: Main Oscillator Status Interrupt Mask
• LOCK: PLL Lock Interrupt Mask
• MCKRDY: Master Clock Ready Interrupt Mask
• PCKRDYx: Programmable Clock Ready x Interrupt Mask
0 = The corresponding interrupt is enabled.
1 = The corresponding interrupt is disabled.
178
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AT91SAM7A3 Preliminary
Debug Unit (DBGU)
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. 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.
179
6042A–ATARM–23-Dec-04
Block Diagram
Figure 59. Debug Unit Functional Block Diagram
Peripheral
Bridge
Peripheral Data 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
force_ntrst
ice_nreset
Table 26. Debug Unit Pin Description
Pin Name
Description
Type
DRXD
Debug Receive Data
Input
DTXD
Debug Transmit Data
Output
Figure 60. Debug Unit Application Example
Boot Program
Debug Monitor
Trace Manager
Debug Unit
RS232 Drivers
Programming Tool
180
Debug Console
Trace Console
AT91SAM7A3 Preliminary
6042A–ATARM–23-Dec-04
AT91SAM7A3 Preliminary
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.
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.
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 59.
This sharing requires the programmer to determine the source of the interrupt when the
source 1 is triggered.
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.
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).
MCK
Baud Rate = ---------------------16 × CD
Figure 1. Baud Rate Generator
CD
CD
MCK
16-bit Counter
OUT
>1
1
0
Divide
by 16
Baud Rate
Clock
0
Receiver
Sampling Clock
181
6042A–ATARM–23-Dec-04
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.
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.
Figure 2. Start Bit Detection
Sampling Clock
DRXD
True Start
Detection
D0
Baud Rate
Clock
Figure 3. Character Reception
Example: 8-bit, parity enabled 1 stop
0.5 bit
period
1 bit
period
DRXD
Sampling
Receiver Ready
182
D0
D1
True Start Detection
D2
D3
D4
D5
D6
D7
Stop Bit
Parity Bit
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.
AT91SAM7A3 Preliminary
6042A–ATARM–23-Dec-04
AT91SAM7A3 Preliminary
Figure 4. 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
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 5. Receiver Overrun
DRXD
S
D0
D1
D2
D3
D4
D5
D6
D7
P
S
stop
D0
D1
D2
D3
D4
D5
D6
D7
P
stop
RXRDY
OVRE
RSTSTA
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 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 6. Parity Error
DRXD
S
D0
D1
D2
D3
D4
D5
D6
D7
P
stop
RXRDY
PARE
Wrong Parity Bit
Receiver Framing
Error
RSTSTA
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 7. Receiver Framing Error
DRXD
S
D0
D1
D2
D3
D4
D5
D6
D7
P
stop
RXRDY
FRAME
Stop Bit
Detected at 0
RSTSTA
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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.
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 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 8. Character Transmission
Example: Parity enabled
Baud Rate
Clock
DTXD
Start
Bit
Transmitter Control
D0
D1
D2
D3
D4
D5
D6
D7
Parity
Bit
Stop
Bit
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.
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AT91SAM7A3 Preliminary
Figure 9. 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
Peripheral Data
Controller
Write Data 1
in DBGU_THR
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.
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.
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.
185
6042A–ATARM–23-Dec-04
Figure 10. Test Modes
Automatic Echo
RXD
Receiver
Transmitter
Disabled
TXD
Local Loopback
Disabled
Receiver
RXD
VDD
Disabled
Transmitter
Remote Loopback
Receiver
Transmitter
Debug
Communication
Channel Support
TXD
VDD
Disabled
Disabled
RXD
TXD
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.
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.
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AT91SAM7A3 Preliminary
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 peripheral
•
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.
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.
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6042A–ATARM–23-Dec-04
Debug Unit (DBGU) User Interface
Table 27. Debug Unit (DBGU) Register Mapping
Offset
Register
Name
Access
Reset Value
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
–
–
–
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AT91SAM7A3 Preliminary
Debug Unit Control Register
Name:
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.
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6042A–ATARM–23-Dec-04
Debug Unit Mode Register
Name:
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
Parity Type
PAR
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
190
Mode Description
0
0
Normal Mode
0
1
Automatic Echo
1
0
Local Loopback
1
1
Remote Loopback
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6042A–ATARM–23-Dec-04
AT91SAM7A3 Preliminary
Debug Unit Interrupt Enable Register
Name:
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.
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6042A–ATARM–23-Dec-04
Debug Unit Interrupt Disable Register
Name:
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.
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AT91SAM7A3 Preliminary
Debug Unit Interrupt Mask Register
Name:
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.
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6042A–ATARM–23-Dec-04
Debug Unit Status Register
Name:
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.
• 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.
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AT91SAM7A3 Preliminary
• 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.
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Debug Unit Receiver Holding Register
Name:
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.
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Debug Unit Transmit Holding Register
Name:
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.
Debug Unit Baud Rate Generator Register
Name:
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)
197
6042A–ATARM–23-Dec-04
Debug Unit Chip ID Register
Name:
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
• 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
198
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
AT91SAM7A3 Preliminary
6042A–ATARM–23-Dec-04
AT91SAM7A3 Preliminary
• 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
Reserved
0
1
0
0
Reserved
0
1
0
1
4K bytes
0
1
1
0
Reserved
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
1
1
0
0
128K bytes
1
1
0
1
256K bytes
1
1
1
0
96K bytes
1
1
1
1
512K bytes
199
6042A–ATARM–23-Dec-04
• ARCH: Architecture Identifier
ARCH
Hex
Bin
0x40
0100 0000
AT91x40 Series
Architecture
0x63
0110 0011
AT91x63 Series
0x55
0101 0101
AT91x55 Series
0x42
0100 0010
AT91x42 Series
0x92
1001 0010
AT91x92 Series
0x34
0011 0100
AT91x34 Series
0x70
0111 0000
AT91SAM7Sxx and AT91SAM7Axx Series
0x71
0111 0001
AT91SAM7Xxx Series
0x72
0111 0010
AT91SAM7Exx Series
0x73
0111 0011
AT91SAM7Lxx Series
0x19
0001 1001
AT91SAM9xx Series
• NVPTYP: Nonvolatile Program Memory Type
NVPTYP
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
• EXT: Extension Flag
0 = Chip ID has a single register definition without extension
1 = An extended Chip ID exists.
Debug Unit Chip ID Extension Register
Name:
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.
200
AT91SAM7A3 Preliminary
6042A–ATARM–23-Dec-04
AT91SAM7A3 Preliminary
Debug Unit Force NTRST Register
Name:
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 ice_nreset signal.
1 = NTRST of the ARM processor’s TAP controller is held low.
201
6042A–ATARM–23-Dec-04
202
AT91SAM7A3 Preliminary
6042A–ATARM–23-Dec-04
AT91SAM7A3 Preliminary
Parallel Input/Output Controller (PIO)
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 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.
203
6042A–ATARM–23-Dec-04
Block Diagram
Figure 11. 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
Application
Block Diagram
Figure 12. Application Block Diagram
On-Chip Peripheral Drivers
Keyboard Driver
Control & Command
Driver
On-Chip Peripherals
PIO Controller
Keyboard Driver
204
General Purpose I/Os
External Devices
AT91SAM7A3 Preliminary
6042A–ATARM–23-Dec-04
AT91SAM7A3 Preliminary
Product
Dependencies
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.
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.
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.
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.
205
6042A–ATARM–23-Dec-04
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 13. In this description each signal shown represents but one of up to 32 possible indexes.
Figure 13. 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
PIO_SODR[0]
1
PIO_ODSR[0]
1
Pad
PIO_CODR[0]
0
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_IER[0]
PIO_IFDR[0]
PIO_IMR[0]
PIO_IDR[0]
PIO_ISR[31]
PIO_IER[31]
PIO_IMR[31]
PIO_IDR[31]
Pull-up Resistor
Control
206
Each I/O line is designed with an embedded pull-up resistor. The value of this resistor is about
100 kΩ (see the product electrical characteristics for more details about this value). The pull-
AT91SAM7A3 Preliminary
6042A–ATARM–23-Dec-04
AT91SAM7A3 Preliminary
up resistor can be enabled or disabled by writing respectively PIO_PUER (Pull-up Enable
Register) and PIO_PUDR (Pull-up 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.
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.
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.
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_PDR (Output Disable
Register). 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
207
6042A–ATARM–23-Dec-04
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.
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_OSWSR (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.
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 (Multidriver 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.
Output Line
Timings
Figure 14 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 14 also shows when the feedback in PIO_PDSR is available.
Figure 14. 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
Inputs
208
The level on each I/O line can be read through PIO_PDSR (Peripheral 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.
AT91SAM7A3 Preliminary
6042A–ATARM–23-Dec-04
AT91SAM7A3 Preliminary
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.
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 15.
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.
Figure 15. 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
Input Change
Interrupt
up to 2.5 cycles
1 cycle
up to 2 cycles
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.
209
6042A–ATARM–23-Dec-04
Figure 16. Input Change Interrupt Timings
MCK
Pin Level
PIO_ISR
Read PIO_ISR
210
APB Access
APB Access
AT91SAM7A3 Preliminary
6042A–ATARM–23-Dec-04
AT91SAM7A3 Preliminary
I/O Lines
Programming
Example
The programing example as shown in Table 28 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), opendrain, with pull-up resistor
•
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 pullup 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 28. 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
211
6042A–ATARM–23-Dec-04
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. Parallel Input/Output Controller (PIO) Register Mapping
Offset
Register
Name
Access
Reset Value
0x0000
PIO Enable Register
PIO_PER
Write-only
–
0x0004
PIO Disable Register
PIO_PDR
Write-only
–
0x0008
PIO Status Register (1)
PIO_PSR
Read-only
0x0000 0000
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(2)
PIO_ODSR
Read-only
0x0000 0000
(3)
0x003C
Pin Data Status Register
PIO_PDSR
Read-only
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
PIO_ISR
Read-only
0x00000000
(4)
0x004C
Interrupt Status Register
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
212
AT91SAM7A3 Preliminary
6042A–ATARM–23-Dec-04
AT91SAM7A3 Preliminary
Table 29. Parallel Input/Output Controller (PIO) Register Mapping (Continued)
Offset
Register
0x0070
Name
(5)
(5)
Peripheral A Select Register
Access
Reset Value
PIO_ASR
Write-only
–
0x0074
Peripheral B Select Register
PIO_BSR
Write-only
–
0x0078
AB Status Register(5)
PIO_ABSR
Read-only
0x00000000
0x007C - 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 - 0x00FC
Reserved
Notes:
1.
2.
3.
4.
Reset value of PIO_PSR depends on the product implementation.
PIO_ODSR is Read-only or Read/Write depending on PIO_OWSR I/O lines.
Reset value of PIO_PDSR depends on the level of the I/O lines.
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.
213
6042A–ATARM–23-Dec-04
PIO Controller PIO Enable Register
Name:
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).
PIO Controller PIO Disable Register
Name:
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).
214
AT91SAM7A3 Preliminary
6042A–ATARM–23-Dec-04
AT91SAM7A3 Preliminary
PIO Controller PIO Status Register
Name:
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).
PIO Controller Output Enable Register
Name:
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.
215
6042A–ATARM–23-Dec-04
PIO Controller Output Disable Register
Name:
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.
PIO Controller Output Status Register
Name:
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.
216
AT91SAM7A3 Preliminary
6042A–ATARM–23-Dec-04
AT91SAM7A3 Preliminary
PIO Controller Input Filter Enable Register
Name:
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.
PIO Controller Input Filter Disable Register
Name:
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.
217
6042A–ATARM–23-Dec-04
PIO Controller Input Filter Status Register
Name:
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.
PIO Controller Set Output Data Register
Name:
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.
218
AT91SAM7A3 Preliminary
6042A–ATARM–23-Dec-04
AT91SAM7A3 Preliminary
PIO Controller Clear Output Data Register
Name:
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.
PIO Controller Output Data Status Register
Name:
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.
219
6042A–ATARM–23-Dec-04
PIO Controller Pin Data Status Register
Name:
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.
PIO Controller Interrupt Enable Register
Name:
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.
220
AT91SAM7A3 Preliminary
6042A–ATARM–23-Dec-04
AT91SAM7A3 Preliminary
PIO Controller Interrupt Disable Register
Name:
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.
PIO Controller Interrupt Mask Register
Name:
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.
221
6042A–ATARM–23-Dec-04
PIO Controller Interrupt Status Register
Name:
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.
PIO Multi-driver Enable Register
Name:
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.
222
AT91SAM7A3 Preliminary
6042A–ATARM–23-Dec-04
AT91SAM7A3 Preliminary
PIO Multi-driver Disable Register
Name:
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.
PIO Multi-driver Status Register
Name:
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.
223
6042A–ATARM–23-Dec-04
PIO Pull Up Disable Register
Name:
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.
PIO Pull Up Enable Register
Name:
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.
224
AT91SAM7A3 Preliminary
6042A–ATARM–23-Dec-04
AT91SAM7A3 Preliminary
PIO Pull Up Status Register
Name:
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.
PIO Peripheral A Select Register
Name:
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.
225
6042A–ATARM–23-Dec-04
PIO Peripheral B Select Register
Name:
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.
PIO Peripheral A B Status Register
Name:
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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PIO Output Write Enable Register
Name:
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.
PIO Output Write Disable Register
Name:
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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PIO Output Write Status Register
Name:
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.
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Serial Peripheral Interface (SPI)
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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Block Diagram
Figure 17. Block Diagram
PDC
APB
SPCK
MISO
PMC
MOSI
MCK
SPI Interface
PIO
NPCS0/NSS
NPCS1
DIV
NPCS2
MCK(1)
N
Interrupt Control
NPCS3
SPI Interrupt
Note:
1. N = 32
Application Block Diagram
Figure 18. Application Block Diagram: Single Master/Multiple Slave Implementation
SPI Master
SPCK
SPCK
MISO
MISO
MOSI
MOSI
NPCS0
NSS
Slave 0
SPCK
NPCS1
NPCS2
NC
NPCS3
MISO
Slave 1
MOSI
NSS
SPCK
MISO
Slave 2
MOSI
NSS
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Signal Description
Table 30. 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
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.
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.
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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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.
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 31 shows the four modes and corresponding parameter settings.
Table 31. SPI Bus Protocol Mode
SPI Mode
CPOL
CPHA
0
0
1
1
0
0
2
1
1
3
1
0
Figure 19 and Figure 20 show examples of data transfers.
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Figure 19. 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 20. 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.
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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)
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.
No transfer is started when writing into the SPI_TDR if the PCS field does not select a slave.
The PCS field is set by writing the SPI_TDR in variable mode, or the SPI_MR in fixed mode,
depending on the value of PCS field.
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, no data is loaded in
SPI_RDR. The user has to read the status register to clear the OVRES bit.
Figure 21 on page 237 shows a block diagram of the SPI when operating in Master Mode. Figure 22 on page 238 shows a flow chart describing how transfers are handled.
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Master Mode Block Diagram
Figure 21. Master Mode Block Diagram
FDIV
SPI_CSR0..3
SCBR
MCK
0
Baud Rate Generator
MCK/N
SPCK
1
SPI
Clock
SPI_CSR0..3
BITS
NCPHA
CPOL
LSB
MISO
SPI_RDR
RDRF
OVRES
RD
MSB
Shift Register
MOSI
SPI_TDR
TD
SPI_CSR0..3
CSAAT
TDRE
SPI_RDR
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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Master Mode Flow Diagram
Figure 22. Master Mode Flow Diagram S
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
PS ?
0
1
0
Fixed
peripheral
PS ?
1
Fixed
peripheral
0
CSAAT ?
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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Clock Generation
The SPI Baud rate clock is generated by dividing the Master Clock (MCK) or the Master Clock
divided by 32, by a value between 2 and 255. The selection between Master Clock or Master
Clock divided by N is done by the FDIV value set in the Mode Register
This allows a maximum operating baud rate at up to Master Clock/2 and a minimum operating
baud rate of MCK divided by 255*32.
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.
Transfer Delays
Figure 23 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 23. Programmable Delays
Chip Select 1
Chip Select 2
SPCK
DLYBCS
Peripheral Selection
DLYBS
DLYBCT
DLYBCT
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
•
Variable Peripheral Select: Data can be exchanged with more than one peripheral
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6042A–ATARM–23-Dec-04
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 fields of
the Chip Select Registers have 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.
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.
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.
Figure 24 shows different peripheral deselection cases and the effect of the CSAAT bit.
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Figure 24. Peripheral Deselection
CSAAT = 0
TDRE
NPCS[0..3]
CSAAT = 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
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. As this pin is generally configured in
open-drain, it is important that a pull up resistor is connected on the NPCS0 line, so that a high
level is guaranteed and no spurious mode fault is detected.
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).
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
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.
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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 RDRF is already high when the data is transferred, the Overrun bit
rises and the data transfer to SPI_RDR is aborted.
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 25 shows a block diagram of the SPI when operating in Slave Mode.
Figure 25. 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
FLOAD
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Serial Peripheral Interface (SPI) User Interface
Table 32. Serial Peripheral Interface (SPI) Register Mapping
Offset
Register
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 - 0x00FC
0x100 - 0x124
Reserved
Reserved for the PDC
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SPI Control Register
Name:
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.
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.
• 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.
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SPI Mode Register
Name:
SPI_MR
Access Type:
Read/Write
31
30
29
28
27
26
19
18
25
24
17
16
DLYBCS
23
22
21
20
–
–
–
–
15
14
13
12
11
10
9
8
–
–
–
–
–
–
–
–
PCS
7
6
5
4
3
2
1
0
LLB
–
–
MODFDIS
FDIV
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 16 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 15.
• FDIV: Clock Selection
0 = The SPI operates at MCK.
1 = The SPI operates at MCK/N.
• 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.
245
6042A–ATARM–23-Dec-04
• PCS: Peripheral Chip Select
This field is only used if Fixed Peripheral Select is active (PS = 0).
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 (or 6*N MCK periods if FDIV is set) will be inserted by default.
Otherwise, the following equation determines the delay:
If FDIV is 0:
DLYBCS
Delay Between Chip Selects = ----------------------MCK
If FDIV is 1:
DLYBCS × N
Delay Between Chip Selects = ---------------------------------MCK
246
AT91SAM7A3 Preliminary
6042A–ATARM–23-Dec-04
AT91SAM7A3 Preliminary
SPI Receive Data Register
Name:
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.
247
6042A–ATARM–23-Dec-04
SPI Transmit Data Register
Name:
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.
248
AT91SAM7A3 Preliminary
6042A–ATARM–23-Dec-04
AT91SAM7A3 Preliminary
SPI Status Register
Name:
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 or SPI_RNCR.
1 = The Receive Counter Register has reached 0 since the last write in SPI_RCR or SPI_RNCR.
• ENDTX: End of TX buffer
0 = The Transmit Counter Register has not reached 0 since the last write in SPI_TCR or SPI_TNCR.
1 = The Transmit Counter Register has reached 0 since the last write in SPI_TCR or SPI_TNCR.
• RXBUFF: RX Buffer Full
0 = SPI_RCR or SPI_RNCR has a value other than 0.
1 = Both SPI_RCR and SPI_RNCR has a value of 0.
• TXBUFE: TX Buffer Empty
0 = SPI_TCR or SPI_TNCR has a value other than 0.
1 = Both SPI_TCR and SPI_TNCR has a value of 0.
249
6042A–ATARM–23-Dec-04
• 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.
250
AT91SAM7A3 Preliminary
6042A–ATARM–23-Dec-04
AT91SAM7A3 Preliminary
SPI Interrupt Enable Register
Name:
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
• TXEMPTY: Transmission Registers Empty Enable
• NSSR: NSS Rising Interrupt Enable
0 = No effect.
1 = Enables the corresponding interrupt.
251
6042A–ATARM–23-Dec-04
SPI Interrupt Disable Register
Name:
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
• TXEMPTY: Transmission Registers Empty Disable
• NSSR: NSS Rising Interrupt Disable
0 = No effect.
1 = Disables the corresponding interrupt.
252
AT91SAM7A3 Preliminary
6042A–ATARM–23-Dec-04
AT91SAM7A3 Preliminary
SPI Interrupt Mask Register
Name:
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
• TXEMPTY: Transmission Registers Empty Mask
• NSSR: NSS Rising Interrupt Mask
0 = The corresponding interrupt is not enabled.
1 = The corresponding interrupt is enabled.
253
6042A–ATARM–23-Dec-04
SPI Chip Select Register
Name:
SPI_CSR0... SPI_CSR3
Access Type:
Read/Write
31
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
1100
254
Bits Per Transfer
8
9
10
11
12
13
14
15
16
Reserved
Reserved
Reserved
Reserved
AT91SAM7A3 Preliminary
6042A–ATARM–23-Dec-04
AT91SAM7A3 Preliminary
BITS
1101
1110
1111
Bits Per Transfer
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:
If FDIV is 0:
MCK
SPCK Baudrate = --------------SCBR
If FDIV is 1:
Note:
MCK
SPCK Baudrate = ------------------------------( N × SCBR )
N = 32
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:
If FDIV is 0:
DLYBS
Delay Before SPCK = ------------------MCK
If FDIV is 1:
Note:
N × DLYBS
Delay Before SPCK = -----------------------------MCK
N = 32
• 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:
If FDIV is 0:
255
6042A–ATARM–23-Dec-04
32 × DLYBCT SCBR
Delay Between Consecutive Transfers = ------------------------------------- + ----------------MCK
2MCK
If FDIV is 1:
Note:
256
32 × N × DLYBCT N × SCBR
Delay Between Consecutive Transfers = ------------------------------------------------- + -------------------------MCK
2MCK
N = 32
AT91SAM7A3 Preliminary
6042A–ATARM–23-Dec-04
AT91SAM7A3 Preliminary
Two-wire Interface (TWI)
Overview
The 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 byteoriented transfer format. It can be used with any Atmel two-wire bus Serial EEPROM. The TWI
is programmable as a master with sequential or single-byte access. A configurable baud rate
generator permits the output data rate to be adapted to a wide range of core clock
frequencies.
Block Diagram
Figure 26. Block Diagram
APB Bridge
TWCK
PIO
PMC
MCK
TWD
Two-wire
Interface
TWI
Interrupt
Application
Block Diagram
AIC
Figure 27. Application Block Diagram
VDD
R
Host with
TWI
Interface
R
TWD
TWCK
AT24LC16
U1
AT24LC16
U2
LCD Controller
U3
Slave 1
Slave 2
Slave 3
257
6042A–ATARM–23-Dec-04
Product Dependencies
I/O Lines
Description
Table 33. I/O Lines Description
Pin Name
Pin Description
Type
TWD
Two-wire Serial Data
Input/Output
TWCK
Two-wire Serial Clock
Input/Output
Both TWD and TWCK are bidirectional lines, connected to a positive supply voltage via a current source or pull-up resistor (see Figure 27 on page 257). When the bus is free, both lines
are high. The output stages of devices connected to the bus must have an open-drain or opencollector 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.
Power
Management
•
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.
258
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.
AT91SAM7A3 Preliminary
6042A–ATARM–23-Dec-04
AT91SAM7A3 Preliminary
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 29 on page 259).
Each transfer begins with a START condition and terminates with a STOP condition (see Figure 28 on page 259).
•
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.
Figure 28. START and STOP Conditions
TWD
TWCK
Start
Stop
Figure 29. Transfer Format
TWD
TWCK
Start
Modes of
Operation
Address
R/W
Ack
Data
Ack
Data
Ack
Stop
The TWI has two modes of operation:
•
Master transmitter mode
•
Master receiver mode
The TWI Control Register (TWI_CR) allows configuration of the interface in Master Mode. In
this mode, it generates the clock according to the value programmed in the Clock Waveform
Generator Register (TWI_CWGR). This register defines the TWCK signal completely,
enabling the interface to be adapted to a wide range of clocks.
Transmitting Data
After the master initiates a Start condition, 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 (write or read). If this bit is 0, it indicates a write
operation (transmit operation). If the bit is 1, it indicates a request for data read (receive
operation).
The TWI transfers require the slave to acknowledge each received byte. During the acknowledge clock 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 NAK bit 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). After writing in the transmit-holding register (TWI_THR), setting the START bit in
259
6042A–ATARM–23-Dec-04
the control register starts the transmission. The data is shifted in the internal shifter and when
an acknowledge is detected, the TXRDY bit is set until a new write in the TWI_THR (see Figure 31 below). The master generates a stop condition to end the transfer.
The read sequence begins by setting the START bit. 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.
The TWI interface performs various transfer formats (7-bit slave address, 10-bit slave
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, IADRSZ must be set to 0. 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).
Figure 30. 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
A
DATA
P
Two bytes internal address
S
TWD
DADR
P
One byte internal address
S
TWD
DADR
P
Figure 31. Master Write with One Byte Internal Address and Multiple Data Bytes
S
TWD
DADR
W
A
IADR(7:0)
DATA
A
A
DATA
DATA
A
A
P
TXCOMP
Write THR
TXRDY
Write THR
Write THR
Write THR
Figure 32. Master Read with One, Two or Three Bytes Internal Address and One Data Byte
Three bytes internal address
TWD
S
DADR
W
A
IADR(23:16)
A
IADR(15:8)
A
IADR(7:0)
A
S
DADR
R
A
DATA
N
P
Two bytes internal address
TWD
S
DADR
W
A
IADR(15:8)
A
IADR(7:0)
A
S
W
A
IADR(7:0)
A
S
R
A
DADR
R
A
DATA
N
P
One byte internal address
TWD
260
S
DADR
DADR
DATA
N
P
AT91SAM7A3 Preliminary
6042A–ATARM–23-Dec-04
AT91SAM7A3 Preliminary
Figure 33. Master Read with One Byte Internal Address and Multiple Data Bytes
TWD
S
DADR
W
A
IADR(7:0)
S
A
DADR
R
A
DATA
A
DATA
N
P
TXCOMP
Write START Bit
Write STOP Bit
RXRDY
Read RHR
Read RHR
•
S = Start
•
P = Stop
•
W = Write/Read
•
A = Acknowledge
•
DADR= Device Address
•
IADR = Internal Address
Figure 34 below shows a byte write to an Atmel AT24LC512 EEPROM. This demonstrates the
use of internal addresses to access the device.
Figure 34. 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
261
6042A–ATARM–23-Dec-04
Read/Write
Flowcharts
The following flowcharts shown in Figure 35 on page 262 and in Figure 36 on page 263 give
examples for read and write operations in Master 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 35. TWI Write in Master Mode
START
Set TWI clock:
TWI_CWGR = clock
Set the control register:
- Master enable
TWI_CR = MSEN
Set the Master Mode register:
- Device slave address
- Internal address size
- Transfer direction bit
Write ==> bit MREAD = 0
Internal address size = 0?
Set theinternal address
TWI_IADR = address
Yes
Load transmit register
TWI_THR = Data to send
Start the transfer
TWI_CR = START
Read status register
TWI_THR = data to send
TXRDY = 0?
Yes
Data to send?
Yes
Stop the transfer
TWI_CR = STOP
Read status register
TXCOMP = 0?
Yes
END
262
AT91SAM7A3 Preliminary
6042A–ATARM–23-Dec-04
AT91SAM7A3 Preliminary
Figure 36. TWI Read in Master Mode
START
Set TWI clock:
TWI_CWGR = clock
Set the control register:
- Master enable
- Slave disable
TWI_CR = MSEN
Set the Master Mode register:
- Device slave address
- Internal address size
- Transfer direction bit
Read ==> bit MREAD = 0
Internal address size = 0?
Set the internal address
TWI_IADR = address
Yes
Start the transfer
TWI_CR = START
Read status register
RXRDY = 0?
Yes
Data to read?
Yes
Stop the transfer
TWI_CR = STOP
Read status register
TXCOMP = 0?
Yes
END
263
6042A–ATARM–23-Dec-04
Two-wire Interface (TWI) User Interface
Table 34. Two-wire Interface (TWI) Register Mapping
Offset
Register
Name
Access
Reset Value
0x0000
Control Register
TWI_CR
Write-only
N/A
0x0004
Master Mode Register
TWI_MMR
Read/Write
0x0000
0x0008
Reserved
–
–
–
0x000C
Internal Address Register
TWI_IADR
Read/Write
0x0000
0x0010
Clock Waveform Generator Register
TWI_CWGR
Read/Write
0x0000
0x0020
Status Register
TWI_SR
Read-only
0x0008
0x0024
Interrupt Enable Register
TWI_IER
Write-only
N/A
0x0028
Interrupt Disable Register
TWI_IDR
Write-only
N/A
0x002C
Interrupt Mask Register
TWI_IMR
Read-only
0x0000
0x0030
Receive Holding Register
TWI_RHR
Read-only
0x0000
0x0034
Transmit Holding Register
TWI_THR
Read/Write
0x0000
–
–
–
0x0038-0x00FC
264
Reserved
AT91SAM7A3 Preliminary
6042A–ATARM–23-Dec-04
AT91SAM7A3 Preliminary
TWI Control Register
Register Name:
TWI_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
SWRST
6
–
5
–
4
–
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 with the mode register as soon as the user writes a character in the holding register.
• STOP: Send a STOP Condition
0 = No effect.
1 = STOP Condition is sent just after completing the current byte transmission in master read or write mode.
In single data byte master read or write, the START and STOP must both be set.
In multiple data bytes master read or write, the STOP must be set before ACK/NACK bit transmission.
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 Transfer Enabled
0 = No effect.
1 = If MSDIS = 0, the master data transfer is enabled.
• MSDIS: TWI Master Transfer Disabled
0 = No effect.
1 = The master data transfer is disabled, all pending data is transmitted. The shifter and holding characters (if they contain
data) are transmitted in case of write operation. In read operation, the character being transferred must be completely
received before disabling.
• SWRST: Software Reset
0 = No effect.
1 = Equivalent to a system reset.
265
6042A–ATARM–23-Dec-04
TWI Master Mode Register
Register Name:
TWI_MMR
Address Type:
Read/Write
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 in Master Mode to access slave devices in read or write mode.
266
AT91SAM7A3 Preliminary
6042A–ATARM–23-Dec-04
AT91SAM7A3 Preliminary
TWI Internal Address Register
Register Name:
TWI_IADR
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
IADR
15
14
13
12
IADR
7
6
5
4
IADR
• IADR: Internal Address
0, 1, 2 or 3 bytes depending on IADRSZ.
TWI Clock Waveform Generator Register
Register Name:
TWI_CWGR
Access Type:
Read/Write
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
• CLDIV: Clock Low Divider
The SCL low period is defined as follows:
T low = ( ( CLDIV × 2
CKDIV
) + 3 ) × T MCK
• CHDIV: Clock High Divider
The SCL high period is defined as follows:
T high = ( ( CHDIV × 2
CKDIV
) + 3 ) × T MCK
• CKDIV: Clock Divider
The CKDIV is used to increase both SCL high and low periods.
267
6042A–ATARM–23-Dec-04
TWI Status Register
Register Name:
TWI_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
NACK
7
UNRE
6
OVRE
5
–
4
–
3
–
2
TXRDY
1
RXRDY
0
TXCOMP
• TXCOMP: Transmission Completed
0 = In master, during the length of the current frame. In slave, from START received to STOP received.
1 = When both holding and shift registers are empty and STOP condition has been sent (in Master) or received (in Slave),
or when MSEN is set (enable TWI).
• RXRDY: Receive Holding Register Ready
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.
• TXRDY: Transmit Holding Register Ready
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 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).
• OVRE: Overrun Error
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.
• UNRE: Underrun Error
0 = No underrun error
1 = No valid data in TWI_THR (TXRDY set) while trying to load the data shifter. This action automatically generated a
STOP bit in Master Mode. Reset by read in TWI_SR when TXCOMP is set.
• NACK: Not Acknowledged
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. Reset after read.
268
AT91SAM7A3 Preliminary
6042A–ATARM–23-Dec-04
AT91SAM7A3 Preliminary
TWI Interrupt Enable Register
Register Name:
TWI_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
NACK
7
UNRE
6
OVRE
5
–
4
–
3
–
2
TXRDY
1
RXRDY
0
TXCOMP
• TXCOMP: Transmission Completed
• RXRDY: Receive Holding Register Ready
• TXRDY: Transmit Holding Register Ready
• OVRE: Overrun Error
• UNRE: Underrun Error
• NACK: Not Acknowledge
0 = No effect.
1 = Enables the corresponding interrupt.
269
6042A–ATARM–23-Dec-04
TWI Interrupt Disable Register
Register Name:
TWI_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
NACK
7
UNRE
6
OVRE
5
–
4
–
3
–
2
TXRDY
1
RXRDY
0
TXCOMP
• TXCOMP: Transmission Completed
• RXRDY: Receive Holding Register Ready
• TXRDY: Transmit Holding Register Ready
• OVRE: Overrun Error
• UNRE: Underrun Error
• NACK: Not Acknowledge
0 = No effect.
1 = Disables the corresponding interrupt.
270
AT91SAM7A3 Preliminary
6042A–ATARM–23-Dec-04
AT91SAM7A3 Preliminary
TWI Interrupt Mask Register
Register Name:
TWI_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
NACK
7
UNRE
6
OVRE
5
–
4
–
3
–
2
TXRDY
1
RXRDY
0
TXCOMP
• TXCOMP: Transmission Completed
• RXRDY: Receive Holding Register Ready
• TXRDY: Transmit Holding Register Ready
• OVRE: Overrun Error
• UNRE: Underrun Error
• NACK: Not Acknowledge
0 = The corresponding interrupt is disabled.
1 = The corresponding interrupt is enabled.
271
6042A–ATARM–23-Dec-04
TWI Receive Holding Register
Register Name:
TWI_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
RXDATA
• RXDATA: Master or Slave Receive Holding Data
TWI Transmit Holding Register
Register Name:
TWI_THR
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
TXDATA
• TXDATA: Master or Slave Transmit Holding Data
272
AT91SAM7A3 Preliminary
6042A–ATARM–23-Dec-04
AT91SAM7A3 Preliminary
Universal Synchronous/Asynchronous Receiver/Transmitter (USART)
Description
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 timeout 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 and infrared transceivers. 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 Data Controller, which enables data
transfers to the transmitter and from the receiver. The PDC provides chained buffer management without any intervention of the processor.
273
6042A–ATARM–23-Dec-04
Block Diagram
Figure 37. USART Block Diagram
Peripheral Data
Controller
Channel
Channel
PIO
Controller
USART
RXD
Receiver
RTS
AIC
TXD
USART
Interrupt
Transmitter
CTS
PMC
MCK
DIV
Baud Rate
Generator
SCK
MCK/DIV
User Interface
SLCK
APB
274
AT91SAM7A3 Preliminary
6042A–ATARM–23-Dec-04
AT91SAM7A3 Preliminary
Application Block Diagram
Figure 38. Application Block Diagram
IrLAP
PPP
Serial
Driver
Field Bus
Driver
EMV
Driver
IrDA
Driver
USART
RS232
Drivers
RS485
Drivers
Serial
Port
Differential
Bus
Smart
Card
Slot
IrDA
Transceivers
I/O Lines Description
Table 35. I/O Line Description
Name
Description
Type
Active Level
SCK
Serial Clock
I/O
TXD
Transmit Serial Data
I/O
RXD
Receive Serial Data
Input
CTS
Clear to Send
Input
Low
RTS
Request to Send
Output
Low
275
6042A–ATARM–23-Dec-04
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.
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.
Interrupt
276
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.
AT91SAM7A3 Preliminary
6042A–ATARM–23-Dec-04
AT91SAM7A3 Preliminary
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 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 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
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.
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.
277
6042A–ATARM–23-Dec-04
Figure 39. Baud Rate Generator
USCLKS
MCK
MCK/DIV
SCK
Reserved
CD
CD
SCK
0
1
16-bit Counter
2
FIDI
>1
3
1
0
0
0
SYNC
OVER
Sampling
Divider
0
Baud Rate
Clock
1
1
SYNC
Sampling
Clock
USCLKS = 3
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.
SelectedClock
Baudrate = -------------------------------------------( 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.
Baud Rate Calculation
Example
Table 36 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 36. Baud Rate Example (OVER = 0)
278
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%
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%
Calculation Result
CD
Actual Baud Rate
Error
Bit/s
AT91SAM7A3 Preliminary
6042A–ATARM–23-Dec-04
AT91SAM7A3 Preliminary
Table 36. Baud Rate Example (OVER = 0) (Continued)
Source Clock
Expected Baud
Rate
Calculation Result
CD
Actual Baud Rate
Error
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%
60 000 000
38 400
97.66
98
38 265.31
0.35%
70 000 000
38 400
113.93
114
38 377.19
0.06%
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 ⎠
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.
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
279
6042A–ATARM–23-Dec-04
•
Di is the bit-rate adjustment factor
•
Fi is the clock frequency division factor
•
f is the ISO7816 clock frequency (Hz)
Di is a binary value encoded on a 4-bit field, named DI, as represented in Table 37.
Table 37. Binary and Decimal Values for D
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 38.
Table 38. Binary and Decimal Values for F
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 39 shows the resulting Fi/Di Ratio, which is the ratio between the ISO7816 clock and the
baud rate clock.
Table 39. 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 40 shows the relation between the Elementary Time Unit, corresponding to a bit time,
and the ISO 7816 clock.
280
AT91SAM7A3 Preliminary
6042A–ATARM–23-Dec-04
AT91SAM7A3 Preliminary
Figure 40. Elementary Time Unit (ETU)
FI_DI_RATIO
ISO7816 Clock Cycles
ISO7816 Clock
on SCK
ISO7816 I/O Line
on TXD
1 ETU
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 reset commands have the same effect as a hardware reset on the corresponding logic. 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.
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 MODE9 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.
281
6042A–ATARM–23-Dec-04
Figure 41. Character Transmit
Example: 8-bit, Parity Enabled One Stop
Baud Rate
Clock
TXD
D0
Start
Bit
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 raises.
Both TXRDY and TXEMPTY bits are low since the transmitter is disabled. Writing a character
in US_THR while TXRDY is active has no effect and the written character is lost.
Figure 42. 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
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. 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
282
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AT91SAM7A3 Preliminary
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 43 and Figure 44 illustrate start detection and character reception when USART operates in asynchronous mode.
Figure 43. 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 44. 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
D1
D2
D3
D4
D5
D6
D7
Parity
Bit
Stop
Bit
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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 45 illustrates a character reception in synchronous mode.
Figure 45. 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
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 46. 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
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AT91SAM7A3 Preliminary
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, which is discussed in a
separate paragraph. 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 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 odd 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 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 40 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. I
Table 40. 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 47 illustrates the parity bit status setting and clearing.
Figure 47. 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
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6042A–ATARM–23-Dec-04
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.
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 48, 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.
Figure 48. 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
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AT91SAM7A3 Preliminary
Table 41 indicates the maximum length of a timeguard period that the transmitter can handle
in relation to the function of the Baud Rate.
Table 41. 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.
287
6042A–ATARM–23-Dec-04
The user can either:
•
Obtain an interrupt when a time-out is detected after having received at least one
character. This is performed by writing the Control Register (US_CR) with the STTTO
(Start Time-out) bit at 1.
•
Obtain a periodic 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 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 49 shows the block diagram of the Receiver Time-out feature.
Figure 49. Receiver Time-out Block Diagram
TO
Baud Rate
Clock
1
D
Q
Clock
16-bit Time-out
Counter
16-bit
Value
=
STTTO
Character
Received
Clear
Load
TIMEOUT
0
RETTO
Table 42 gives the maximum time-out period for some standard baud rates.t
Table 42. Maximum Time-out Period
288
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
56000
18
1 170
57600
17
1 138
200000
5
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AT91SAM7A3 Preliminary
6042A–ATARM–23-Dec-04
AT91SAM7A3 Preliminary
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 50. 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
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.
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.
289
6042A–ATARM–23-Dec-04
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 51 illustrates the effect of both the Start Break (STTBRK) and Stop Break (STP BRK)
commands on the TXD line.
Figure 51. Break Transmission
Baud Rate
Clock
TXD
Start
D0
Bit
D1
D2
D3
D4
D5
D6
D7
Parity Stop
Bit Bit
STTBRK = 1
Break Transmùission
End of Break
STPBRK = 1
Write
US_CR
TXRDY
TXEMPTY
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.
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 52.
Figure 52. 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.
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AT91SAM7A3 Preliminary
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 53 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 53. Receiver Behavior when Operating with Hardware Handshaking
RXD
RXEN = 1
RXDIS = 1
Write
US_CR
RTS
RXBUFF
Figure 54 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 54. Transmitter Behavior when Operating with Hardware Handshaking
CTS
TXD
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.
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 277).
The USART connects to a smart card as shown in Figure 55. 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
291
6042A–ATARM–23-Dec-04
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 55. Connection of a Smart Card to the USART
USART
CLK
SCK
I/O
TXD
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.
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).
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 56.
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 57. 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 56. T = 0 Protocol without Parity Error
Baud Rate
Clock
RXD
Start
Bit
292
D0
D1
D2
D3
D4
D5
D6
D7
Parity Guard Guard Next
Bit Time 1 Time 2 Start
Bit
AT91SAM7A3 Preliminary
6042A–ATARM–23-Dec-04
AT91SAM7A3 Preliminary
Figure 57. T = 0 Protocol with Parity Error
Baud Rate
Clock
Error
I/O
Start
Bit
D0
D1
D2
D3
D4
D5
D6
D7
Parity Guard
Bit Time 1
Guard Start
Time 2 Bit
D0
D1
Repetition
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.
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.
Transmit Character
Repetition
When the USART is transmitting a character and gets a NACK, it can automatically repeat the
chara cte r b efore moving on to the n ext o ne. Rep etition is enab led by writin g th e
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.
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.
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.
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).
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 58. The modulator and demodulator are compliant
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6042A–ATARM–23-Dec-04
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 58. Connection to IrDA Transceivers
USART
IrDA
Transceivers
Receiver
Demodulator
Transmitter
Modulator
RXD
RX
TX
TXD
The receiver and the transmitter must be enabled or disabled according to the direction of the
transmission to be managed.
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 43.
Table 43. 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 59 shows an example of character transmission.
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AT91SAM7A3 Preliminary
Figure 59. IrDA Modulation
Start
Bit
Transmitter
Output
0
Start
Bit
Data Bits
1
0
1
0
1
0
1
0
1
TXD
3
16 Bit Period
Bit Period
IrDA Baud Rate
Table 44 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 44. 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
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
295
6042A–ATARM–23-Dec-04
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 60 illustrates the operations of the IrDA demodulator.
Figure 60. IrDA Demodulator Operations
MCK
RXD
Counter
Value
Receiver
Input
6
5
4
3
2
6
6
5
4
3
2
1
0
Pulse
Accepted
Pulse
Rejected
Driven Low During 16 Baud Rate Clock Cycles
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.
296
AT91SAM7A3 Preliminary
6042A–ATARM–23-Dec-04
AT91SAM7A3 Preliminary
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 61.
Figure 61. 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 62 gives an example of the RTS waveform during a character transmission
when the timeguard is enabled.
Figure 62. 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
297
6042A–ATARM–23-Dec-04
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.
Normal Mode
Normal mode connects the RXD pin on the receiver input and the transmitter output on the
TXD pin.
Figure 63. Normal Mode Configuration
RXD
Receiver
TXD
Transmitter
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 64. 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 64. Automatic Echo Mode Configuration
RXD
Receiver
TXD
Transmitter
Local Loopback Mode
Local loopback mode connects the output of the transmitter directly to the input of the receiver,
as shown in Figure 65. 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 65. Local Loopback Mode Configuration
RXD
Receiver
Transmitter
298
1
TXD
AT91SAM7A3 Preliminary
6042A–ATARM–23-Dec-04
AT91SAM7A3 Preliminary
Remote Loopback Mode
Remote loopback mode directly connects the RXD pin to the TXD pin, as shown in Figure 66.
The transmitter and the receiver are disabled and have no effect. This mode allows bit-by-bit
retransmission.
Figure 66. Remote Loopback Mode Configuration
Receiver
1
RXD
TXD
Transmitter
299
6042A–ATARM–23-Dec-04
USART User Interface
Table 45. USART Memory Map
Offset
Register
Name
Access
Reset State
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
0
0x0014
Channel Status Register
US_CSR
Read-only
–
0x0018
Receiver Holding Register
US_RHR
Read-only
0
0x001C
Transmitter Holding Register
US_THR
Write-only
–
0x0020
Baud Rate Generator Register
US_BRGR
Read/Write
0
0x0024
Receiver Time-out Register
US_RTOR
Read/Write
0
0x0028
Transmitter Timeguard Register
US_TTGR
Read/Write
0
–
–
–
0x2C - 0x3C
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
0
–
–
–
0x100 - 0x128
300
Reserved
Reserved for PDC Registers
AT91SAM7A3 Preliminary
6042A–ATARM–23-Dec-04
AT91SAM7A3 Preliminary
USART Control Register
Name:
US_CR
Access Type:
Write-only
31
–
30
–
29
–
28
–
27
–
26
–
25
–
24
–
23
–
22
–
21
–
20
–
19
RTSDIS
18
RTSEN
17
–
16
–
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.
• RSTSTA: Reset Status Bits
0: No effect.
1: Resets the status bits PARE, FRAME, OVRE and RXBRK in the 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.
301
6042A–ATARM–23-Dec-04
• STTTO: Start Time-out
0: No effect
1: Starts waiting for a character before clocking the time-out counter.
• 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
• RTSEN: Request to Send Enable
0: No effect.
1: Drives the pin RTS to 0.
• RTSDIS: Request to Send Disable
0: No effect.
1: Drives the pin RTS to 1.
302
AT91SAM7A3 Preliminary
6042A–ATARM–23-Dec-04
AT91SAM7A3 Preliminary
USART Mode Register
Name:
US_MR
Access Type:
Read/Write
31
–
30
–
29
–
28
FILTER
27
–
26
25
MAX_ITERATION
24
23
–
22
–
21
DSNACK
20
INACK
19
OVER
18
CLKO
17
MODE9
16
MSBF
14
13
12
11
10
PAR
9
8
SYNC
4
3
2
1
0
15
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
Reserved
0
1
0
0
IS07816 Protocol: T = 0
0
1
0
1
Reserved
0
1
1
0
IS07816 Protocol: T = 1
0
1
1
1
Reserved
1
0
0
0
IrDA
1
1
x
x
Reserved
• USCLKS: Clock Selection
USCLKS
Selected Clock
0
0
MCK
0
1
MCK / DIV
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
303
6042A–ATARM–23-Dec-04
• 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.
• CKLO: 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.
1: 8x Oversampling.
304
AT91SAM7A3 Preliminary
6042A–ATARM–23-Dec-04
AT91SAM7A3 Preliminary
• 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.
• 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).
305
6042A–ATARM–23-Dec-04
USART Interrupt Enable Register
Name:
US_IER
Access Type:
Write-only
31
–
30
–
29
–
28
–
27
–
26
–
25
–
24
–
23
–
22
–
21
–
20
–
19
CTSIC
18
–
17
–
16
–
15
–
14
–
13
NACK
12
RXBUFF
11
TXBUFE
10
ITERATION
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
• ITERATION: Iteration Interrupt Enable
• TXBUFE: Buffer Empty Interrupt Enable
• RXBUFF: Buffer Full Interrupt Enable
• NACK: Non Acknowledge Interrupt Enable
• CTSIC: Clear to Send Input Change Interrupt Enable
0: No effect.
1: Enables the corresponding interrupt.
306
AT91SAM7A3 Preliminary
6042A–ATARM–23-Dec-04
AT91SAM7A3 Preliminary
USART Interrupt Disable Register
Name:
US_IDR
Access Type:
Write-only
31
–
30
–
29
–
28
–
27
–
26
–
25
–
24
–
23
–
22
–
21
–
20
–
19
CTSIC
18
–
17
–
16
–
15
–
14
–
13
NACK
12
RXBUFF
11
TXBUFE
10
ITERATION
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
• ITERATION: Iteration Interrupt Disable
• TXBUFE: Buffer Empty Interrupt Disable
• RXBUFF: Buffer Full Interrupt Disable
• NACK: Non Acknowledge Interrupt Disable
• CTSIC: Clear to Send Input Change Interrupt Disable
0: No effect.
1: Disables the corresponding interrupt.
307
6042A–ATARM–23-Dec-04
USART Interrupt Mask Register
Name:
US_IMR
Access Type:
Read-only
31
–
30
–
29
–
28
–
27
–
26
–
25
–
24
–
23
–
22
–
21
–
20
–
19
CTSIC
18
–
17
–
16
–
15
–
14
–
13
NACK
12
RXBUFF
11
TXBUFE
10
ITERATION
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
• ITERATION: Iteration Interrupt Mask
• TXBUFE: Buffer Empty Interrupt Mask
• RXBUFF: Buffer Full Interrupt Mask
• NACK: Non Acknowledge Interrupt Mask
• CTSIC: Clear to Send Input Change Interrupt Mask
0: The corresponding interrupt is disabled.
1: The corresponding interrupt is enabled.
308
AT91SAM7A3 Preliminary
6042A–ATARM–23-Dec-04
AT91SAM7A3 Preliminary
USART Channel Status Register
Name:
US_CSR
Access Type:
Read-only
31
–
30
–
29
–
28
–
27
–
26
–
25
–
24
–
23
CTS
22
–
21
–
20
–
19
CTSIC
18
–
17
–
16
–
15
–
14
–
13
NACK
12
RXBUFF
11
TXBUFE
10
ITERATION
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 since the last RSTSTA.
1: At least one overrun error has occurred since the last RSTSTA.
• 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 or the Time-out Register is 0.
1: There has been a time-out since the last Start Time-out command.
309
6042A–ATARM–23-Dec-04
• TXEMPTY: Transmitter Empty
0: There are characters in either US_THR or the Transmit Shift Register, or the transmitter is disabled.
1: There is at least one character in either US_THR or the Transmit Shift Register.
• ITERATION: Max number of Repetitions Reached
0: Maximum number of repetitions has not been reached since the last RSIT.
1: Maximum number of repetitions has been reached since the last RSIT.
• 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.
• 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.
1: At least one input change has been detected on the CTS pin since the last read of US_CSR.
• CTS: Image of CTS Input
0: CTS is at 0.
1: CTS is at 1.
310
AT91SAM7A3 Preliminary
6042A–ATARM–23-Dec-04
AT91SAM7A3 Preliminary
USART Receive Holding Register
Name:
US_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
RXCHR
7
6
5
4
3
2
1
0
RXCHR
• RXCHR: Received Character
Last character received if RXRDY is set.
USART Transmit Holding Register
Name:
US_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
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.
311
6042A–ATARM–23-Dec-04
USART Baud Rate Generator Register
Name:
US_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 Divider
USART_MODE ≠ ISO7816
SYNC = 0
CD
OVER = 0
0
1 to 65535
312
SYNC = 1
USART_MODE =
ISO7816
OVER = 1
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
AT91SAM7A3 Preliminary
6042A–ATARM–23-Dec-04
AT91SAM7A3 Preliminary
USART Receiver Time-out Register
Name:
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.
313
6042A–ATARM–23-Dec-04
USART Transmitter Timeguard Register
Name:
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.
314
AT91SAM7A3 Preliminary
6042A–ATARM–23-Dec-04
AT91SAM7A3 Preliminary
USART FI DI RATIO Register
Name:
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.
315
6042A–ATARM–23-Dec-04
USART Number of Errors Register
Name:
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.
USART IrDA FILTER Register
Name:
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.
316
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AT91SAM7A3 Preliminary
Synchronous Serial Controller (SSC)
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. Transfers contain up to
16 data of up to 32 bits. They 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:
Block Diagram
•
CODECs in master or slave mode
•
DAC through dedicated serial interface, particularly I2S
•
Magnetic card reader
Figure 67. Block Diagram
ASB
APB Bridge
PDC
APB
TF
TK
PMC
TD
MCK
SSC Interface
PIO
RF
RK
Interrupt Control
RD
SSC Interrupt
317
6042A–ATARM–23-Dec-04
Application
Block Diagram
Figure 68. Application Block Diagram
OS or RTOS Driver
Power
Management
Interrupt
Management
Test
Management
SSC
Serial AUDIO
318
Codec
Time Slot
Management
Frame
Management
Line Interface
AT91SAM7A3 Preliminary
6042A–ATARM–23-Dec-04
AT91SAM7A3 Preliminary
Pin Name List
Table 46. I/O Lines Description
Pin Name
Pin Description
Type
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
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.
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.
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.
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. Each level of the clock
must be stable for at least two master clock periods.
319
6042A–ATARM–23-Dec-04
Figure 69. 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
Transmit Holding
Register
APB
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
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.
320
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AT91SAM7A3 Preliminary
Clock Divider
Figure 70. 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 or greater to 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 if the
DIV value is even or odd.
Figure 71. 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 47. Bit Rate
Transmitter Clock
Management
Maximum
Minimum
MCK / 2
MCK / 8190
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.
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.
321
6042A–ATARM–23-Dec-04
Figure 72. Transmitter Clock Management
SSC_TCMR.CKS
SSC_TCMR.CKO
TK
Receiver Clock
TK
Divider Clock
0
Transmitter Clock
1
SSC_TCMR.CKI
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) might lead to
unpredictable results.
Figure 73. Receiver Clock Management
SSC_RCMR.CKO
SSC_RCMR.CKS
RK
Transmitter Clock
RK
Divider Clock
0
Receiver Clock
1
SSC_RCMR.CKI
322
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AT91SAM7A3 Preliminary
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 324.
The frame synchronization is configured setting the Transmit Frame Mode Register
(SSC_TFMR). See “Frame Sync” on page 326.
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.
Figure 74. Transmitter Block Diagram
SSC_CR.TXEN
SSC_SR.TXEN
SSC_CR.TXDIS
SSC_TFMR.DATDEF
1
RF
Transmitter Clock
TF
Start
Selector
TD
0
SSC_TFMR.MSBF
Transmit Shift Register
SSC_TFMR.FSDEN
SSC_TCMR.STTDLY
SSC_TFMR.DATLEN
SSC_TCMR.STTDLY
SSC_TFMR.FSDEN
SSC_TFMR.DATNB
0
SSC_THR
1
SSC_TSHR
SSC_TFMR.FSLEN
323
6042A–ATARM–23-Dec-04
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 324.
The frame synchronization is configured setting the Receive Frame Mode Register
(SSC_RFMR). See “Frame Sync” on page 326.
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 in function of 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 the RHR register, the status flag OVERUN is set in
SSC_SR and the receiver shift register is transferred in the RHR register.
Figure 75. Receiver Block Diagram
SSC_CR.RXEN
SSC_SR.RXEN
SSC_CR.RXDIS
RF
Receiver Clock
SSC_RFMR.MSBF
TF
Start
Selector
SSC_RFMR.DATNB
Receive Shift Register
SSC_RSHR
SSC_RHR
SSC_RFMR.FSLEN
SSC_RFMR.DATLEN
RD
SSC_RCMR.STTDLY
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 TK/RK
•
On detection of a low level/high level on TK/RK
•
On detection of a level change or an edge on TK/RK
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).
Detection on TF/RF input/output is done through the field FSOS of the Transmit/Receive
Frame Mode Register (TFMR/RFMR).
324
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AT91SAM7A3 Preliminary
Generating a Frame Sync signal is not possible without generating it on its related output.
Figure 76. 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 77. 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
325
6042A–ATARM–23-Dec-04
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 16-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.
Frame Sync Data
Frame Sync Data transmits or receives a specific tag during the Frame Synchro 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.
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.
Frame Sync Edge
Detection
Th e Fra me Sync Edge de tectio n is pro gra mme d b y the FSED GE 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).
Data Format
The data framing format of both the transmitter and the receiver are largely 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.
326
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AT91SAM7A3 Preliminary
Table 48. 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 Word transmitter 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
1 most significant bit in 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 78. 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
Default
From SSC_TSHR FromDATDEF
Default
Data
From SSC_THR
Ignored
To SSC_RSHR
STTDLY
From SSC_THR
Default
From SSC_THR
Data
Data
To SSC_RHR
To SSC_RHR
DATLEN
DATLEN
Sync Data
FromDATDEF
Data
Data
From DATDEF
Sync Data
Data
From SSC_THR
Default
From DATDEF
Ignored
Sync Data
DATNB
Note:
1. Example of Input on falling edge of TF/RF.
327
6042A–ATARM–23-Dec-04
Figure 79. Transmit Frame Format in Continuous Mode
Start
Data
TD
Default
Data
From SSC_THR
From SSC_THR
DATLEN
DATLEN
Start: 1. TXEMPTY set to 1
2. Write into the SSC_THR
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 80. Receive Frame Format in Continuous Mode
Start = Enable Receiver
RD
Note:
Data
Data
To SSC_RHR
To SSC_RHR
DATLEN
DATLEN
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.
Interrupt
Most bits in SSC_SR have a corresponding bit in interrupt management registers.
The SSC Controller 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), which respectively enable and disable 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.
328
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AT91SAM7A3 Preliminary
Figure 81. 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
329
6042A–ATARM–23-Dec-04
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 82. Audio Application Block Diagram
Clock SCK
TK
Word Select WS
I2S
RECEIVER
TF
Data SD
SSC
TD
RD
Clock SCK
RF
Word Select WS
RK
MSB
Data SD
LSB
MSB
Right Channel
Left Channel
Figure 83. 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
330
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AT91SAM7A3 Preliminary
Figure 84. 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
331
6042A–ATARM–23-Dec-04
Synchronous Serial Controller (SSC) User Interface
Table 49. Synchronous Serial Controller (SSC) Register Mapping
Offset
Register Name
Access
Reset
SSC_CR
Write
–
SSC_CMR
Read/Write
0x0
0x0
Control Register
0x4
Clock Mode Register
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
Reserved
–
–
–
0x3C
Reserved
–
–
–
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
Reserved
–
–
–
Reserved for Peripheral Data Controller (PDC)
–
–
–
0x50-0xFC
0x100 - 0x124
332
Register
AT91SAM7A3 Preliminary
6042A–ATARM–23-Dec-04
AT91SAM7A3 Preliminary
SSC Control Register
Name:
SSC_CR
Access Type:
Write-only
31
–
23
–
15
SWRST
7
–
30
–
22
–
14
–
6
–
29
–
21
–
13
–
5
–
28
–
20
–
12
–
4
–
27
–
19
–
11
–
3
–
26
–
18
–
10
–
2
–
25
–
17
–
9
TXDIS
1
RXDIS
24
–
16
–
8
TXEN
0
RXEN
• RXEN: Receive Enable
0: No effect.
1: Enables Data Receive if RXDIS is not set(1).
• RXDIS: Receive Disable
0: No effect.
1: Disables Data Receive (1).
• TXEN: Transmit Enable
0: No effect.
1: Enables Data Transmit if TXDIS is not set(1).
• TXDIS: Transmit Disable
0: No effect.
1: Disables Data Transmit(1) .
• SWRST: Software Reset
0: No effect.
1: Performs a software reset. Has priority on any other bit in SSC_CR.
Note:
1. Only the data management is affected
333
6042A–ATARM–23-Dec-04
SSC Clock Mode Register
Name:
SSC_CMR
Access Type:
Read/Write
31
–
23
–
15
–
7
30
–
22
–
14
–
6
29
–
21
–
13
–
5
28
–
20
–
12
–
4
27
–
19
–
11
26
–
18
–
10
25
–
17
–
9
24
–
16
–
8
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.
334
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AT91SAM7A3 Preliminary
SSC Receive Clock Mode Register
Name:
SSC_RCMR
Access Type:
Read/Write
31
30
29
28
27
26
25
24
19
18
17
16
11
10
9
8
PERIOD
23
22
21
20
STTDLY
15
–
7
–
14
–
6
–
13
–
5
CKI
12
–
4
START
3
CKO
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
0x2-0x7
RK pin
Input-only
Output
Reserved
• CKI: Receive Clock Inversion
0: The data and the Frame Sync signal are sampled on Receive Clock falling edge.
1: The data and the Frame Sync signal are shifted out on Receive Clock rising edge.
CKI does not affect the RK output clock signal.
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6042A–ATARM–23-Dec-04
• 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 input
0x3
Detection of a high level on RF input
0x4
Detection of a falling edge on RF input
0x5
Detection of a rising edge on RF input
0x6
Detection of any level change on RF input
0x7
Detection of any edge on RF input
0x8-0xF
Reserved
• 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.
Please 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.
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AT91SAM7A3 Preliminary
SSC Receive Frame Mode Register
Name:
SSC_RFMR
Access Type:
Read/Write
31
–
23
–
15
–
7
MSBF
30
–
22
14
–
6
–
29
–
21
FSOS
13
–
5
LOOP
28
–
20
27
–
19
26
–
18
12
–
4
11
10
25
–
17
24
FSEDGE
16
9
8
1
0
FSLEN
DATNB
3
2
DATLEN
• DATLEN: Data Length
0x0 is not supported. The value of DATLEN can be set between 0x1 and 0x1F.
The bit stream contains DATLEN + 1 data bits. Moreover, it defines the transfer size performed by the PDC assigned to the
Receiver.
If DATLEN is less than or equal to 7, data transfers are in bytes. If DATLEN is between 8 and 15 (included), half-words are
transferred. 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. If 0, only 1 data word is transferred. Up
to 16 data words can be transferred.
• FSLEN: Receive Frame Sync Length
This field defines the length of the Receive Frame Sync Signal and the number of bits sampled and stored in the Receive
Sync Data Register. Only when FSOS is set on negative or positive pulse.
• 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
Reserved
Input-only
Undefined
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6042A–ATARM–23-Dec-04
• FSEDGE: Frame Sync Edge Detection
Determines which edge on Frame Sync sets RXSYN in the SSC Status Register.
FSEDGE
338
Frame Sync Edge Detection
0x0
Positive Edge Detection
0x1
Negative Edge Detection
AT91SAM7A3 Preliminary
6042A–ATARM–23-Dec-04
AT91SAM7A3 Preliminary
SSC Transmit Clock Mode Register
Name:
SSC_TCMR
Access Type:
Read/Write
31
30
29
28
27
26
25
24
19
18
17
16
11
10
9
8
PERIOD
23
22
21
20
STTDLY
15
–
7
–
14
–
6
–
13
–
5
CKI
12
–
4
START
3
CKO
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
0x2-0x7
TK pin
Input-only
Output
Reserved
• CKI: Transmit Clock Inversion
0: The data and the Frame Sync signal are shifted out on Transmit Clock falling edge.
1: The data and the Frame Sync signal are shifted out on Transmit Clock rising edge.
CKI affects only the Transmit Clock and not the output clock signal.
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6042A–ATARM–23-Dec-04
• 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.
Please 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.
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AT91SAM7A3 Preliminary
SSC Transmit Frame Mode Register
Name:
SSC_TFMR
Access Type:
Read/Write
31
–
23
FSDEN
15
–
7
MSBF
30
–
22
14
–
6
–
29
–
21
FSOS
13
–
5
DATDEF
28
–
20
27
–
19
26
–
18
12
–
4
11
10
25
–
17
24
FSEDGE
16
9
8
1
0
FSLEN
DATNB
3
2
DATLEN
• DATLEN: Data Length
0x0 is not supported. The value of DATLEN can be set between 0x1 and 0x1F.
The bit stream contains DATLEN + 1 data bits. Moreover, it defines the transfer size performed by the PDC assigned to the
Receiver.
If DATLEN is less than or equal to 7, data transfers are in bytes. If DATLEN is between 8 and 15 (included), half-words are
transferred. 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. If 0, only 1 data word is transferred
and up to 16 data words can be transferred.
• 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. If 0, the Transmit Frame Sync signal is generated during one Transmit Clock period and up to
16 clock period pulse length is possible.
• 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
341
6042A–ATARM–23-Dec-04
• 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.
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AT91SAM7A3 Preliminary
• FSEDGE: Frame Sync Edge Detection
Determines which edge on frame sync sets TXSYN (Status Register).
FSEDGE
Frame Sync Edge Detection
0x0
Positive Edge Detection
0x1
Negative Edge Detection
343
6042A–ATARM–23-Dec-04
SSC Receive Holding Register
Name:
SSC_RHR
Access Type:
Read-only
31
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.
SSC Transmit Holding Register
Name:
SSC_THR
Access Type:
Write only
31
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.
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AT91SAM7A3 Preliminary
SSC Receive Synchronization Holding Register
Name:
SSC_RSHR
Access Type:
Read/Write
31
–
23
–
15
30
–
22
–
14
29
–
21
–
13
28
–
20
–
12
27
–
19
–
11
26
–
18
–
10
25
–
17
–
9
24
–
16
–
8
3
2
1
0
RSDAT
7
6
5
4
RSDAT
• RSDAT: Receive Synchronization Data
Right aligned regardless of the number of data bits defined by FSLEN in SSC_RFMR.
SSC Transmit Synchronization Holding Register
Name:
SSC_TSHR
Access Type:
Read/Write
31
–
23
–
15
30
–
22
–
14
29
–
21
–
13
28
–
20
–
12
27
–
19
–
11
26
–
18
–
10
25
–
17
–
9
24
–
16
–
8
3
2
1
0
TSDAT
7
6
5
4
TSDAT
• TSDAT: Transmit Synchronization Data
Right aligned regardless of the number of data bits defined by FSLEN in SSC_TFMR.
345
6042A–ATARM–23-Dec-04
SSC Status Register
Register Name:
SSC_SR
Access Type:
Read-only
31
–
23
–
15
–
7
RXBUFF
30
–
22
–
14
–
6
ENDRX
29
–
21
–
13
–
5
OVRUN
28
–
20
–
12
–
4
RXRDY
27
–
19
–
11
RXSYN
3
TXBUFE
26
–
18
–
10
TXSYN
2
ENDTX
25
–
17
RXEN
9
–
1
TXEMPTY
24
–
16
TXEN
8
–
0
TXRDY
• TXRDY: Transmit Ready
0: Data has been loaded in SSC_THR and is waiting to be loaded in the Transmit Shift Register.
1: SSC_THR is empty.
• TXEMPTY: Transmit Empty
0: Data remains in SSC_THR or is currently transmitted from Transmit Shift Register.
1: Last data written in SSC_THR has been loaded in Transmit Shift Register and transmitted by it.
• 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.
• 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.
• 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.
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AT91SAM7A3 Preliminary
• RXSYN: Receive Sync
0: A Rx Sync has not occurred since the last read of the Status Register.
1: A Rx Sync has occurred since the last read of the Status Register.
347
6042A–ATARM–23-Dec-04
• TXEN: Transmit Enable
0: Transmit data is disabled.
1: Transmit data is enabled.
• RXEN: Receive Enable
0: Receive data is disabled.
1: Receive data is enabled.
348
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AT91SAM7A3 Preliminary
SSC Interrupt Enable Register
Register Name:
SSC_IER
Access Type:
Write-only
31
–
23
–
15
–
7
RXBUFF
30
–
22
–
14
–
6
ENDRX
29
–
21
–
13
–
5
OVRUN
28
–
20
–
12
–
4
RXRDY
27
–
19
–
11
RXSYN
3
TXBUFE
26
–
18
–
10
TXSYN
2
ENDTX
25
–
17
–
9
–
1
TXEMPTY
24
–
16
–
8
–
0
TXRDY
• TXRDY: Transmit Ready
• TXEMPTY: Transmit Empty
• ENDTX: End of Transmission
• TXBUFE: Transmit Buffer Empty
• RXRDY: Receive Ready
• OVRUN: Receive Overrun
• ENDRX: End of Reception
• RXBUFF: Receive Buffer Full
• TXSYN: Tx Sync
• RXSYN: Rx Sync
0: No effect.
1: Enables the corresponding interrupt.
349
6042A–ATARM–23-Dec-04
SSC Interrupt Disable Register
Register Name:
SSC_IDR
Access Type:
Write-only
31
–
23
–
15
–
7
RXBUFF
30
–
22
–
14
–
6
ENDRX
29
–
21
–
13
–
5
OVRUN
28
–
20
–
12
–
4
RXRDY
27
–
19
–
11
RXSYN
3
TXBUFE
26
–
18
–
10
TXSYN
2
ENDTX
25
–
17
–
9
–
1
TXEMPTY
24
–
16
–
8
–
0
TXRDY
• TXRDY: Transmit Ready
• TXEMPTY: Transmit Empty
• ENDTX: End of Transmission
• TXBUFE: Transmit Buffer Empty
• RXRDY: Receive Ready
• OVRUN: Receive Overrun
• ENDRX: End of Reception
• RXBUFF: Receive Buffer Full
• TXSYN: Tx Sync
• RXSYN: Rx Sync
0: No effect.
1: Disables the corresponding interrupt.
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AT91SAM7A3 Preliminary
SSC Interrupt Mask Register
Register Name:
SSC_IMR
Access Type:
Read-only
31
–
23
–
15
–
7
RXBUFF
30
–
22
–
14
–
6
ENDRX
29
–
21
–
13
–
5
OVRUN
28
–
20
–
12
–
4
RXRDY
27
–
19
–
11
RXSYN
3
TXBUFE
26
–
18
–
10
TXSYN
2
ENDTX
25
–
17
–
9
–
1
TXEMPTY
24
–
16
–
8
–
0
TXRDY
• TXRDY: Transmit Ready
• TXEMPTY: Transmit Empty
• ENDTX: End of Transmission
• TXBUFE: Transmit Buffer Empty
• RXRDY: Receive Ready
• OVRUN: Receive Overrun
• ENDRX: End of Reception
• RXBUFF: Receive Buffer Full
• TXSYN: Tx Sync
• RXSYN: Rx Sync
0: The corresponding interrupt is disabled.
1: The corresponding interrupt is enabled.
351
6042A–ATARM–23-Dec-04
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AT91SAM7A3 Preliminary
Timer/Counter (TC)
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.
Block Diagram
Figure 85. Timer/Counter Block Diagram
Parallel I/O
Controller
TIMER_CLOCK1
TCLK0
TIMER_CLOCK2
TIOA1
TIOA2
TIMER_CLOCK3
TIMER_CLOCK4
XC0
XC1
TCLK1
Timer/Counter
Channel 0
TIOA
TIOA0
TIOB0
TIOA0
TIOB
XC2
TCLK2
TIMER_CLOCK5
TC0XC0S
TIOB0
SYNC
TCLK0
TCLK1
TCLK2
INT0
TCLK0
XC0
TCLK1
TIOA0
XC1
Timer/Counter
Channel 1
TIOA
TIOA1
TIOB1
TIOA1
TIOB
TIOA2
TCLK2
XC2
TC1XC1S
TCLK0
XC0
TCLK1
XC1
TCLK2
XC2
TIOB1
SYNC
Timer/Counter
Channel 2
INT1
TIOA
TIOA2
TIOB2
TIOA2
TIOB
TIOA0
TIOA1
TC2XC2S
TIOB2
SYNC
INT2
Timer Counter
Advanced
Interrupt
Controller
353
6042A–ATARM–23-Dec-04
Table 50. Signal Name Description
Block/Channel
Signal Name
XC0, XC1, XC2
Channel Signal
Description
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
Interrupt Signal Output
Synchronization Input Signal
Pin Name List
Table 51. 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.
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.
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.
Functional
Description
TC Description
The three channels of the Timer/Counter are independent and identical in operation. The registers for channel programming are listed in Table 53 on page 366.
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.
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AT91SAM7A3 Preliminary
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.
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 configurable I/O signals TIOA0,
TIOA1 or TIOA2 for chaining by programming the TC_BMR (Block Mode). See Figure 86.
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).
Note:
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
Figure 86. Clock Selection
TCCLKS
TIMER_CLOCK1
TIMER_CLOCK2
CLKI
TIMER_CLOCK3
TIMER_CLOCK4
TIMER_CLOCK5
Selected
Clock
XC0
XC1
XC2
BURST
1
Clock Control
The clock of each counter can be controlled in two different ways: it can be enabled/disabled
and started/stopped. See Figure 87.
•
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.
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6042A–ATARM–23-Dec-04
•
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 87. Clock Control
Selected
Clock
Trigger
CLKSTA
Q
Q
S
CLKEN
CLKDIS
S
R
R
Counter
Clock
TC Operating Modes
Stop
Event
Disable
Event
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.
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:
•
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.
356
AT91SAM7A3 Preliminary
6042A–ATARM–23-Dec-04
AT91SAM7A3 Preliminary
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.
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 88 shows the configuration of the TC channel when programmed in Capture Mode.
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.
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.
357
6042A–ATARM–23-Dec-04
358
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 88. Capture Mode
LOVRS
CPCS
LDRBS
LDRAS
ETRGS
TC1_IMR
AT91SAM7A3 Preliminary
6042A–ATARM–23-Dec-04
AT91SAM7A3 Preliminary
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 oneshot 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 89 shows the configuration of the TC channel when programmed in Waveform Operating Mode.
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.
359
6042A–ATARM–23-Dec-04
360
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 89. Waveform Mode
CPCS
CPBS
COVFS
TC1_SR
ETRGS
TC1_IMR
AT91SAM7A3 Preliminary
6042A–ATARM–23-Dec-04
AT91SAM7A3 Preliminary
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 90.
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 91.
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 90. WAVSEL= 00 without trigger
Counter Value
Counter cleared by compare match with 0xFFFF
0xFFFF
RC
RB
RA
Time
Waveform Examples
TIOB
TIOA
Figure 91. WAVSEL= 00 with trigger
Counter Value
Counter cleared by compare match with 0xFFFF
0xFFFF
RC
Counter cleared by trigger
RB
RA
Waveform Examples
Time
TIOB
TIOA
361
6042A–ATARM–23-Dec-04
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 92.
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 93.
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 92. WAVSEL = 10 Without Trigger
Counter Value
0xFFFF
Counter cleared by compare match with RC
RC
RB
RA
Waveform Examples
Time
TIOB
TIOA
Figure 93. 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
362
AT91SAM7A3 Preliminary
6042A–ATARM–23-Dec-04
AT91SAM7A3 Preliminary
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 94.
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 95.
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).
Figure 94. WAVSEL = 01 Without Trigger
Counter Value
Counter decremented by compare match with 0xFFFF
0xFFFF
RC
RB
RA
Time
Waveform Examples
TIOB
TIOA
Figure 95. WAVSEL = 01 With Trigger
Counter Value
Counter decremented by compare match with 0xFFFF
0xFFFF
Counter decremented
by trigger
RC
RB
Counter incremented
by trigger
RA
Waveform Examples
Time
TIOB
TIOA
363
6042A–ATARM–23-Dec-04
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
96.
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 97.
RC Compare can stop the counter clock (CPCSTOP = 1) and/or disable the counter clock
(CPCDIS = 1).
Figure 96. WAVSEL = 11 Without Trigger
Counter Value
0xFFFF
Counter decremented by compare match with RC
RC
RB
RA
Time
Waveform Examples
TIOB
TIOA
Figure 97. 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
364
AT91SAM7A3 Preliminary
6042A–ATARM–23-Dec-04
AT91SAM7A3 Preliminary
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 parameter 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 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.
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.
365
6042A–ATARM–23-Dec-04
Timer/Counter (TC) User Interface
Global Register Mapping
Table 52. Timer/Counter (TC) Global Register Mapping
Offset
Channel/Register
Name
Access
Reset Value
0x00
TC Channel 0
See Table 53
0x40
TC Channel 1
See Table 53
0x80
TC Channel 2
See Table 53
0xC0
TC Block Control Register
TC_BCR
Write-only
–
0xC4
TC Block Mode Register
TC_BMR
Read/Write
0
TC_BCR (Block Control Register) and TC_BMR (Block Mode Register) control the whole TC
block. TC channels are controlled by the registers listed in Table 53 . The offset of each of the
channel registers in Table 53 is in relation to the offset of the corresponding channel as mentioned in Table 53.
Channel Memory Mapping
Table 53. Timer/Counter (TC) Channel Memory Mapping
Offset
Register
Access
Reset Value
0x00
Channel Control Register
TC_CCR
Write-only
–
0x04
Channel Mode Register
TC_CMR
Read/Write
0
0x08
Reserved
–
–
–
0x0C
Reserved
–
–
–
0x10
Counter Value
TC_CV
Read-only
0x14
Register A
TC_RA
0
Read/Write
(1)
0
Read/Write
(1)
0
0x18
Register B
TC_RB
0x1C
Register C
TC_RC
Read/Write
0
0x20
Status Register
TC_SR
Read-only
0
0x24
Interrupt Enable Register
TC_IER
Write-only
–
0x28
Interrupt Disable Register
TC_IDR
Write-only
–
0x2C
Interrupt Mask Register
TC_IMR
Read-only
0
–
–
–
0x30-0xFC
Note:
366
Name
Reserved
1. Read only if WAVE = 0
AT91SAM7A3 Preliminary
6042A–ATARM–23-Dec-04
AT91SAM7A3 Preliminary
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.
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
TCXC1S
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
367
6042A–ATARM–23-Dec-04
• TC2XC2S: External Clock Signal 2 Selection
TC2XC2S
Signal Connected to XC2
0
0
TCLK2
0
1
none
1
0
TIOA0
1
1
TIOA1
TC Channel Control Register
Register Name: TC_CCR
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.
368
AT91SAM7A3 Preliminary
6042A–ATARM–23-Dec-04
AT91SAM7A3 Preliminary
TC Channel Mode Register: Capture Mode
Register Name: TC_CMR
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 = 0
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.
• 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.
369
6042A–ATARM–23-Dec-04
• 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
370
Edge
0
0
none
0
1
rising edge of TIOA
1
0
falling edge of TIOA
1
1
each edge of TIOA
AT91SAM7A3 Preliminary
6042A–ATARM–23-Dec-04
AT91SAM7A3 Preliminary
TC Channel Mode Register: Waveform Mode
Register Name: TC_CMR
Access Type:
Read/Write
31
30
29
28
BSWTRG
27
BEEVT
23
22
21
20
ASWTRG
19
AEEVT
15
14
13
WAVE = 1
7
6
CPCDIS
CPCSTOP
24
BCPB
18
11
ENETRG
5
25
17
16
ACPC
12
WAVSEL
26
BCPC
10
9
EEVT
4
BURST
ACPA
3
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.
• 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.
371
6042A–ATARM–23-Dec-04
• 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
Note:
Signal selected as external event
TIOB Direction
0
0
TIOB
input(1)
0
1
XC0
output
1
0
XC1
output
1
1
XC2
output
1. If TIOB is chosen as the external event signal, it is configured as an input and no longer generates waveforms.
• 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 = 1
0 = Waveform Mode is disabled (Capture Mode is enabled).
1 = Waveform Mode is enabled.
• 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
372
Effect
0
0
none
0
1
set
1
0
clear
1
1
toggle
AT91SAM7A3 Preliminary
6042A–ATARM–23-Dec-04
AT91SAM7A3 Preliminary
• 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
• 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
Effect
0
0
none
0
1
set
1
0
clear
1
1
toggle
373
6042A–ATARM–23-Dec-04
TC Counter Value Register
Register Name: TC_CV
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.
TC Register A
Register Name: TC_RA
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.
374
AT91SAM7A3 Preliminary
6042A–ATARM–23-Dec-04
AT91SAM7A3 Preliminary
TC Register B
Register Name: TC_RB
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.
TC Register C
Register Name: TC_RC
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.
375
6042A–ATARM–23-Dec-04
TC Status Register
Register Name: TC_SR
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.
• CLKSTA: Clock Enabling Status
0 = Clock is disabled.
1 = Clock is enabled.
376
AT91SAM7A3 Preliminary
6042A–ATARM–23-Dec-04
AT91SAM7A3 Preliminary
• 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.
377
6042A–ATARM–23-Dec-04
TC Interrupt Enable Register
Register Name: TC_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
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.
378
AT91SAM7A3 Preliminary
6042A–ATARM–23-Dec-04
AT91SAM7A3 Preliminary
TC Interrupt Disable Register
Register Name: TC_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
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.
379
6042A–ATARM–23-Dec-04
TC Interrupt Mask Register
Register Name: TC_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
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.
380
AT91SAM7A3 Preliminary
6042A–ATARM–23-Dec-04
AT91SAM7A3 Preliminary
Pulse Width Modulation Controller (PWM)
Overview
The PWM macrocell controls several channels independently. Each channel controls one
square output waveform. Characteristics of the output waveform such as period, duty-cycle
and polarity are configurable through the user interface. Each channel selects and uses one of
the clocks provided by the clock generator. The clock generator provides several clocks resulting from the division of the PWM macrocell master clock.
All PWM macrocell accesses are made through APB mapped registers.
Channels can be synchronized, to generate non overlapped waveforms. All channels integrate
a double buffering system in order to prevent an unexpected output waveform while modifying
the period or the duty-cycle.
Block Diagram
Figure 98. Pulse Width Modulation Controller Block Diagram
PWM
Controller
PWMx
Channel
Period
PWMx
Update
Duty Cycle
Clock
Selector
Comparator
PWMx
Counter
PIO
PWM0
Channel
Period
PWM0
Update
Duty Cycle
Clock
Selector
PMC
MCK
Clock Generator
Comparator
PWM0
Counter
APB Interface
Interrupt Generator
AIC
APB
381
6042A–ATARM–23-Dec-04
I/O Lines
Description
Each channel outputs one waveform on one external I/O line.
Table 54. I/O Line Description
Name
Description
Type
PWMx
PWM Waveform Output for channel x
Output
Product
Dependencies
I/O Lines
The pins used for interfacing the PWM may be multiplexed with PIO lines. The programmer
must first program the PIO controller to assign the desired PWM pins to their peripheral function. If I/O lines of the PWM are not used by the application, they can be used for other
purposes by the PIO controller.
All of the PWM outputs may or may not not be enabled. If an application requires only four
channels then just four PIO lines will be assigned to PWM output.
Power
Management
The PWM is not continuously clocked. The programmer must first enable the PWM clock in
the Power Management Controller (PMC) before using the PWM. However, if the application
does not require PWM operations, the PWM clock can be stopped when not needed and be
restarted later. In this case, the PWM will resume its operations where it left off.
Configuring the PWM does not require the PWM clock to be enabled.
Interrupt Sources
382
The PWM interrupt line is connected on one of the internal sources of the Advanced Interrupt
Controller. Using the PWM interrupt requires the AIC to be programmed first. Note that it is not
recommended to use the PWM interrupt line in edge sensitive mode.
AT91SAM7A3 Preliminary
6042A–ATARM–23-Dec-04
AT91SAM7A3 Preliminary
Functional
Description
PWM Clock
Generator
The PWM macrocell is primarily composed of a clock generator module and 8 channels.
–
Clocked by the system clock, MCK, the clock generator module provides 13 clocks.
–
Each channel can independently choose one of the clock generator outputs.
–
Each channel generates an output waveform with attributes that can be defined
independently for each channel through the user interface registers.
Figure 99. Functional View of the Clock Generator Block Diagram
MCK
modulo n counter
MCK
MCK/2
MCK/4
MCK/8
MCK/16
MCK/32
MCK/64
MCK/128
MCK/256
MCK/512
MCK/1024
Divider A
PREA
clkA
DIVA
PWM_MR
Divider B
PREB
clkB
DIVB
PWM_MR
Caution: Before using the PWM macrocell, the programmer must first enable the PWM clock
in the Power Management Controller (PMC).
The PWM macrocell master clock, MCK, is divided in the clock generator module to provide
different clocks available for all channels. Each channel can independently select one of the
divided clocks.
The clock generator is divided in three blocks:
–
a modulo n counter which provides 11 clocks: FMCK, FMCK/2, FMCK/4, F MCK/8,
FMCK/16, FMCK/32, FMCK/64, FMCK/128, FMCK/256, FMCK/512, FMCK/1024
–
two linear dividers (1, 1/2, 1/3, ... 1/255) that provide two separate clocks: clkA and
clkB
Each linear divider can independently divide one of the clocks of the modulo n counter. The
selection of the clock to be divided is made according to the PREA (PREB) field of the PWM
383
6042A–ATARM–23-Dec-04
Mode register (PWM_MR). The resulting clock clkA (clkB) is the clock selected divided by
DIVA (DIVB) field value in the PWM Mode register (PWM_MR).
After a reset of the PWM controller, DIVA (DIVB) and PREA (PREB) in the PWM Mode register are set to 0. This implies that after reset clkA (clkB) are turned off.
At reset, all clocks provided by the modulo n counter are turned off except clock “clk”. This situation is also true when the PWM master clock is turned off through the Power Management
Controller.
PWM Channel
Block Diagram
Figure 100. Functional View of the Channel Block Diagram
inputs
from clock
generator
Channel
Clock
Selector
Internal
Counter
Comparator
PWMx
output waveform
inputs from
APB bus
Each of the 8 channels is composed of three blocks:
Waveform Properties
384
•
A clock selector which selects one of the clocks provided by the clock generator described
in Section “PWM Clock Generator” on page 383.
•
An internal counter clocked by the output of the clock selector. This internal counter is
incremented or decremented according to the channel configuration and comparators
events. The size of the internal counter is 20 bits.
•
A comparator used to generate events according to the internal counter value. It also
computes the PWMx output waveform according to the configuration.
The different properties of output waveforms are:
•
the internal clock selection . The internal channel counter is clocked by one of the clocks
provided by the clock generator described in the previous section. This channel parameter
is defined in the CPRE field of the PWM_CMRx register. This field is reset at 0.
•
the waveform period. This channel parameter is defined in the CPRD field of the
PWM_CPRDx register.
If the waveform is left aligned then: period = 1/fchannel_x_clock * CPRD
If the waveform is center aligned then: period = 2/fchannel_x_clock * CPRD
•
the waveform duty cycle. This channel parameter is defined in the CDTY field of the
PWM_CDTYx register.
If the waveform is left aligned then:
duty cycle = (period - 1/fchannel_x_clock * CDTY) / period
If the waveform is center aligned, then:
duty cycle = ((period / 2) - 1/fchannel_x_clock * CDTY)) / (period / 2)
•
the waveform polarity. At the beginning of the period, the signal can be at high or low
level. This property is defined in the CPOL field of the PWM_CMRx register. By default the
signal starts by a low level.
AT91SAM7A3 Preliminary
6042A–ATARM–23-Dec-04
AT91SAM7A3 Preliminary
•
the waveform alignment. The output waveform can be left or center aligned. Center
aligned waveforms can be used to generate non overlapped waveforms. This property is
defined in the CALG field of the PWM_CMRx register. The default mode is left aligned.
Figure 101. Non Overlapped Center Aligned Waveforms
No overlap
PWM0
PWM1
Period
Note:
1. See Figure 102 on page 386 for a detailed description of center aligned waveforms.
When center aligned, the internal channel counter increases up to CPRD and decreases down
to 0. This ends the period.
When left aligned, the internal channel counter increases up to CPRD and is reset. This ends
the period.
Thus, for the same CPRD value, the period for a center aligned channel is twice the period for
a left aligned channel.
Waveforms are fixed at 0 when:
•
CDTY = CPRD and CPOL = 0
•
CDTY = 0 and CPOL = 1
Waveforms are fixed at 1 (once the channel is enabled) when:
•
CDTY = 0 and CPOL = 0
•
CDTY = CPRD and CPOL = 1
The waveform polarity must be set before enabling the channel. This immediately affects the
channel output level. Changes on channel polarity are not taken into account while the channel is enabled.
385
6042A–ATARM–23-Dec-04
Figure 102. Waveform Properties
PWM_MCKx
CHIDx(PWM_SR)
CHIDx(PWM_ENA)
CHIDx(PWM_DIS)
Center Aligned
CALG(PWM_CMRx) = 1
PWM_CCNTx
CPRD(PWM_CPRDx)
CDTY(PWM_CDTYx)
Period
Output Waveform PWMx
CPOL(PWM_CMRx) = 0
Output Waveform PWMx
CPOL(PWM_CMRx) = 1
CHIDx(PWM_ISR)
Left Aligned
CALG(PWM_CMRx) = 0
PWM_CCNTx
CPRD(PWM_CPRDx)
CDTY(PWM_CDTYx)
Period
Output Waveform PWMx
CPOL(PWM_CMRx) = 0
Output Waveform PWMx
CPOL(PWM_CMRx) = 1
CHIDx(PWM_ISR)
386
AT91SAM7A3 Preliminary
6042A–ATARM–23-Dec-04
AT91SAM7A3 Preliminary
PWM Controller
Operations
Initialization
Before enabling the output channel, this channel must have been configured by the software
application:
•
Configuration of the clock generator if DIVA and DIVB are required
•
Selection of the clock for each channel (CPRE field in the PWM_CMRx register)
•
Configuration of the waveform alignment for each channel (CALG field in the PWM_CMRx
register)
•
Configuration of the period for each channel (CPRD in the PWM_CPRDx register)
•
Configuration of the duty cycle for each channel (CDTY in the PWM_CDTYx register)
•
Configuration of the output waveform polarity for each channel (CPOL in the PWM_CMRx
register)
•
Enable Interrupts (Writing CHIDx in the PWM_IER register)
•
Enable the PWM channel (Writing CHIDx in the PWM_ENA register)
It is possible to synchronize different channels by enabling them at the same time by means of
writing simultaneously several CHIDx bits in the PWM_ENA register.
•
Signal Modulation
In such a situation, all channels may have the same clock selector configuration and the
same period specified.
It is possible to modulate the output waveform duty cycle or period.
To prevent an unexpected output waveform when modifying the waveform parameters while
the channel is still enabled, PWM_CPRDx and PWM_CDTYx registers are double buffered.
Th e user can write a new pe riod value or du ty cycle value in the upda te re gister
(PWM_CUPDx). This register holds the new value until the end of the current cycle and
updates the value for the next cycle. According to the CPD field in the PWM_CMRx register,
PWM_CUPDx either updates the PWM_CPRDx or PWM_CDTYx.
The software can be synchronized to the waveform period by enabling the interrupt for the
considered channel. The Interrupt Service Routine associated with the PWM channel must:
•
clear the interrupt by reading the PWM_ISR register
•
set the new value for the duty-cycle or the period in the PWM_CUPDx register
387
6042A–ATARM–23-Dec-04
Pulse Width Modulation Controller (PWM) User Interface
Table 55. Pulse Width Modulation Controller Registers
Access
Peripheral
Reset Value
PWM_MR
Read/Write
0
PWM Enable Register
PWM_ENA
Write-only
-
0x08
PWM Disable Register
PWM_DIS
Write-only
-
0x0C
PWM Status Register
PWM_SR
Read-only
0
0x10
PWM Interrupt Enable Register
PWM_IER
Write-only
-
0x14
PWM Interrupt Disable Register
PWM_IDR
Write-only
-
0x18
PWM Interrupt Mask Register
PWM_IMR
Read-only
0
0x1C
PWM Interrupt Status Register
PWM_ISR
Read-only
0
0x4C - 0xFC
Reserved
–
–
–
0x100 - 0x1FC
Reserved
–
–
–
0x200
Channel 0 Mode Register
PWM_CMR0
Read/Write
0x0
0x204
Channel 0 Duty Cycle Register
PWM_CDTY0
Read/Write
0x0
0x208
Channel 0 Period Register
PWM_CPRD0
Read/Write
0x0
0x20C
Channel 0 Counter Register
PWM_CCNT0
Read-only
0x0
0x210
Channel 0 Update Register
PWM_CUPD0
Write-only
-
...
Reserved
0x220
Channel 1 Mode Register
PWM_CMR1
Read/Write
0x0
0x224
Channel 1 Duty Cycle Register
PWM_CDTY1
Read/Write
0x0
0x228
Channel 1 Period Register
PWM_CPRD1
Read/Write
0x0
0x22C
Channel 1 Counter Register
PWM_CCNT1
Read-only
0x0
0x230
Channel 1 Update Register
PWM_CUPD1
Write-only
-
...
...
...
...
...
Offset
Register
Name
0x00
PWM Mode Register
0x04
388
AT91SAM7A3 Preliminary
6042A–ATARM–23-Dec-04
AT91SAM7A3 Preliminary
PWM Mode Register
Register Name: PWM_MR
Access Type:
Read/Write
31
–
30
–
29
–
28
–
23
22
21
20
27
26
25
24
17
16
9
8
1
0
PREB
19
18
10
DIVB
15
–
14
–
13
–
12
–
11
7
6
5
4
3
PREA
2
DIVA
• DIVA, DIVB: CLKA, CLKB Divide Factor
DIVA, DIVB
CLKA, CLKB
0
CLKA, CLKB clock is turned off
1
CLKA, CLKB clock is clock selected by PREA, PREB
2-255
CLKA, CLKB clock is clock selected by PREA, PREB divided by DIVA, DIVB factor.
• PREA, PREB
PREA, PREB
Divider Input Clock
0
0
0
0
MCK
0
0
0
1
MCK/2
0
0
1
0
MCK/4
0
0
1
1
MCK/8
0
1
0
0
MCK/16
0
1
0
1
MCK/32
0
1
1
0
MCK/64
0
1
1
1
MCK/128
1
0
0
0
MCK/256
1
0
0
1
MCK/512
1
0
1
0
MCK/1024
Other
Reserved
389
6042A–ATARM–23-Dec-04
PWM Enable Register
Register Name: PWM_ENA
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
CHID7
6
CHID6
5
CHID5
4
CHID4
3
CHID3
2
CHID2
1
CHID1
0
CHID0
• CHIDx: Channel ID
0 = No effect.
1 = Enable PWM output for channel x.
PWM Disable Register
Register Name: PWM_DIS
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
CHID7
6
CHID6
5
CHID5
4
CHID4
3
CHID3
2
CHID2
1
CHID1
0
CHID0
• CHIDx: Channel ID
0 = No effect.
1 = Disable PWM output for channel x.
390
AT91SAM7A3 Preliminary
6042A–ATARM–23-Dec-04
AT91SAM7A3 Preliminary
PWM Status Register
Register Name: PWM_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
CHID7
6
CHID6
5
CHID5
4
CHID4
3
CHID3
2
CHID2
1
CHID1
0
CHID0
• CHIDx: Channel ID
0 = PWM output for channel x is disabled.
1 = PWM output for channel x is enabled.
391
6042A–ATARM–23-Dec-04
PWM Interrupt Enable Register
Register Name: PWM_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
CHID7
6
CHID6
5
CHID5
4
CHID4
3
CHID3
2
CHID2
1
CHID1
0
CHID0
• CHIDx: Channel ID.
0 = No effect.
1 = Enable interrupt for PWM channel x.
PWM Interrupt Disable Register
Register Name: PWM_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
CHID7
6
CHID6
5
CHID5
4
CHID4
3
CHID3
2
CHID2
1
CHID1
0
CHID0
• CHIDx: Channel ID.
0 = No effect.
1 = Disable interrupt for PWM channel x.
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PWM Interrupt Mask Register
Register Name: PWM_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
CHID7
6
CHID6
5
CHID5
4
CHID4
3
CHID3
2
CHID2
1
CHID1
0
CHID0
• CHIDx: Channel ID.
0 = Interrupt for PWM channel x is disabled.
1 = Interrupt for PWM channel x is enabled.
PWM Interrupt Status Register
Register Name: PWM_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
CHID7
6
CHID6
5
CHID5
4
CHID4
3
CHID3
2
CHID2
1
CHID1
0
CHID0
• CHIDx: Channel ID
0 = No new channel period has been achieved since the last read of the PWM_ISR register.
1 = At least one new channel period has been achieved since the last read of the PWM_ISR register.
Note: Reading PWM_ISR automatically clears CHIDx flags.
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PWM Channel Mode Register
Register Name: PWM_CMRx
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
CPD
9
CPOL
8
CALG
7
–
6
–
5
–
4
–
3
2
1
0
CPRE
• CPRE: Channel Pre-scaler
CPRE
Channel Pre-scaler
0
0
0
0
MCK
0
0
0
1
MCK/2
0
0
1
0
MCK/4
0
0
1
1
MCK/8
0
1
0
0
MCK/16
0
1
0
1
MCK/32
0
1
1
0
MCK/64
0
1
1
1
MCK/128
1
0
0
0
MCK/256
1
0
0
1
MCK/512
1
0
1
0
MCK/1024
1
0
1
1
CLKA
1
1
0
0
CLKB
Other
Reserved
• CALG: Channel Alignment
0 = The period is left aligned.
1 = The period is center aligned.
• CPOL: Channel Polarity
0 = The output waveform starts at a low level.
1 = The output waveform starts at a high level.
• CPD: Channel Update Period
0 = Writing to the PWM_CUPDx will modify the duty cycle at the next period start event.
1 = Writing to the PWM_CUPDx will modify the period at the next period start event.
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PWM Channel Duty Cycle Register
Register Name: PWM_CDTYx
Access Type:
Read/Write
31
30
29
28
27
26
25
24
19
18
17
16
11
10
9
8
3
2
1
0
CDTY
23
22
21
20
CDTY
15
14
13
12
CDTY
7
6
5
4
CDTY
Only the first 20 bits (internal channel counter size) are significant.
• CDTY: Channel Duty Cycle
Defines the waveform duty cycle. This value must be defined between 0 and CPRD (PWM_CPRx).
PWM Channel Period Register
Register Name: PWM_CPRDx
Access Type:
Read/Write
31
30
29
28
27
26
25
24
19
18
17
16
11
10
9
8
3
2
1
0
CPRD
23
22
21
20
CPRD
15
14
13
12
CPRD
7
6
5
4
CPRD
Only the first 20 bits (internal channel counter size) are significant.
• CPRD: Channel Period
If the waveform is left aligned (CALG set to 0 in the PWM_CMRx register), the waveform period is CPRD * TMCK / CPRE.
If the waveform is center aligned (CALG set to 1 in the PWM_CMRx register), the waveform period is 2 * CPRD * TMCK /
CPRE.
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PWM Channel Counter Register
Register Name: PWM_CCNTx
Access Type:
Read-only
31
30
29
28
27
26
25
24
19
18
17
16
11
10
9
8
3
2
1
0
CNT
23
22
21
20
CNT
15
14
13
12
CNT
7
6
5
4
CNT
• CNT: Channel Counter Register
Internal counter value. This register is reset when:
•
the channel is enabled (writing CHIDx in the PWM_ENA register).
•
the counter reaches CPRD value defined in the PWM_CPRDx register if the waveform is left aligned.
PWM Channel Update Register
Register Name: PWM_CUPDx
Access Type:
Write-only
31
30
29
28
27
26
25
24
19
18
17
16
11
10
9
8
3
2
1
0
CUPD
23
22
21
20
CUPD
15
14
13
12
CUPD
7
6
5
4
CUPD
This register acts as a double buffer for the period or the duty cycle. This prevents an unexpected waveform when modifying the waveform period or duty-cycle.
Only the first 20 bits (internal channel counter size) are significant.
CPD (PWM_CMRx Register)
0
The duty-cycle (CDTC in the PWM_CDRx register) is updated with the CUPD value at the
beginning of the next period.
1
The period (CPRD in the PWM_CPRx register) is updated with the CUPD value at the beginning
of the next period.
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USB Device Port (UDP)
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 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 56. USB Endpoint Description
Endpoint
Number
Mnemonic
Dual-bank
Max. Endpoint Size
Endpoint Type
0
EP0
No
8
Control/Bulk/Interrupt
1
EP1
Yes
64
Bulk/Iso/Interrupt
3
EP2
Yes
64
Bulk/Iso/Interrupt
3
EP3
No
64
Control/Bulk/Interrupt
4
EP4
Yes
512
Bulk/Iso/Interrupt
5
EP5
Yes
512
Bulk/Iso/Interrupt
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.
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6042A–ATARM–23-Dec-04
Block Diagram
Figure 103. Block Diagram
Atmel Bridge
MCK
USB Device
APB
to
MCU
Bus
txoen
U
s
e
r
UDPCK
I
n
t
e
r
f
a
c
e
udp_int
W
r
a
p
p
e
r
Dual
Port
RAM
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
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 MCK domain and a
48 MHz clock 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.
Product
Dependencies
For further details on the USB Device hardware implementation, see “USB Device Port” on
page 27.
The USB physical transceiver is integrated into the product. The bidirectional differential signals DP and DM are available from the product boundary.
Two I/O lines may be used by the application:
400
•
One 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 board pull-up on
DP must be disabled in order to prevent feeding current to the host.
•
One to control the board pull-up on DP. Thus, when the device is ready to communicate
with the host, it activates its DP pull-up through this control line.
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AT91SAM7A3 Preliminary
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.
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.
To reserve an I/O line to control the board pull-up, the programmer must first program the PIO
controller to assign this I/O in output PIO mode.
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).
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.
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6042A–ATARM–23-Dec-04
Typical Connection
Figure 104. Board Schematic to Interface USB Device Peripheral
PAm
USB_CNX
22 kΩ
15 kΩ
3V3
1.5 kΩ
47 kΩ
PAn
USB_DP_PUP
System
Reset
33 pF
27Ω
2
DM
1
100 nF
DP
27Ω
15 pF
3
Type B
4
Connector
15 pF
USB_CNX is an input signal used to check if the host is connected
USB_DP_PUP is an output signal used to enable pull-up on DP.
Figure 104 shows automatic activation of pull-up after reset.
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AT91SAM7A3 Preliminary
Functional Description
USB V2.0 Fullspeed 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 an USB device through a set of
communication flows.
Figure 105. Example of USB V2.0 Full-speed Communication Control
USB Host V2.0
Software Client 1
Software Client 2
Data Flow: Control Transfer
Data Flow: Isochronous In Transfer
Data Flow: Isochronous Out Transfer
Data Flow: Control Transfer
EP1
USB Device 2.0
Block 1
EP2
EP0
Data Flow: Bulk In Transfer
EP4
Data Flow: Bulk Out Transfer
USB V2.0 Full-speed
Transfer Types
EP0
USB Device 2.0
Block 2
EP5
A communication flow is carried over one of four transfer types defined by the USB device.
Table 57. USB Communication Flow
Transfer
Direction
Bandwidth
Endpoint Size
Error Detection
Retrying
Bi-directional
Not guaranteed
8, 16, 32, 64
Yes
Automatic
Isochronous
Uni-directional
Guaranteed
1 - 1023
Yes
No
Interrupt
Uni-directional
Not guaranteed
≤64
Yes
Yes
Bulk
Uni-directional
Not guaranteed
8, 16, 32, 64
Yes
Yes
Control
USB Bus Transactions
Each transfer results in one or more transactions over the USB bus. There are five kinds of
transactions flowing across the bus in packets:
1. Setup Transaction
2. Data IN Transaction
3. Data OUT Transaction
4. Status IN Transaction
5. Status OUT Transaction
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USB Transfer Event
Definitions
As indicated below, transfers are sequential events carried out on the USB bus.
Table 58. USB Transfer Events
•
Setup transaction > Data IN transactions > Status
OUT transaction
•
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
Control Transfers(1) (3)
Interrupt IN Transfer
(device toward host)
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.
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 USB_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 USB_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.
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AT91SAM7A3 Preliminary
Figure 106. Setup Transaction Followed by a Data OUT Transaction
Setup Received
USB
Bus Packets
Setup
PID
Setup Handled by Firmware
Data Setup
RXSETUP Flag
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
(USB_CSRx)
FIFO (DPR)
Content
Data Out Received
XX
Data Setup
XX
Data OUT
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.
Using Endpoints
Without Ping-pong
Attributes
To perform a Data IN transaction using a non ping-pong endpoint:
1. The microcontroller checks if it is possible to write in the FIFO by polling TXPKTRDY in
the endpoint’s USB_CSRx register (TXPKTRDY must be cleared).
2. The microcontroller writes data to be sent in the endpoint’s FIFO, writing zero or more
byte values in the endpoint’s USB_FDRx register,
3. The microcontroller notifies the USB peripheral it has finished by setting the TXPKTRDY in the endpoint’s USB_CSRx register.
4. The microcontroller is notified that the endpoint’s FIFO has been released by the USB
device when TXCOMP in the endpoint’s USB_CSRx register has been set. Then an
interrupt for the corresponding endpoint is pending while TXCOMP is 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.
Note:
Refer to Chapter 8 of the Universal Serial Bus Specification, Rev 2.0, for more information on
the Data IN protocol layer.
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6042A–ATARM–23-Dec-04
Figure 107. Data IN Transfer for Non Ping-pong Endpoint
Prevous Data IN TX
USB Bus Packets
Data IN
PID
Data IN 1
Microcontroller Load Data in FIFO
NAK
PID
Data IN
PID
ACK
PID
Data is Sent on USB Bus
Data IN
PID
ACK
PID
Data IN 2
TXPKTRDY Flag
(USB_CSRx)
Set by the Firmware
Data Payload Written in FIFO
Cleared by USB Device
Interrupt Pending
TXCOMP Flag
(USB_CSRx)
FIFO (DPR)
Content
Cleared by Firmware
Data IN 1
Using Endpoints With
Ping-pong Attribute
Interrupt Pending
Start to Write Data
Payload in FIFO
Load In Progress
Load In
Progress
Data IN 2
The use of an endpoint with ping-pong attributes is necessary during isochronous transfer. To
be able to guarantee a constant 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 108. Bank Swapping Data IN Transfer for Ping-pong Endpoints
1st Data Payload
USB Bus
USB Device
Microcontroller
Write
Bank 0
Endpoint 1
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:
1. The microcontroller checks if it is possible to write in the FIFO by polling TXPKTRDY to
be cleared in the endpoint’s USB_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 USB_FDRx register.
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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 USB_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 USB_FDRx register.
5. The microcontroller is notified that the first Bank has been released by the USB device
when TXCOMP in the endpoint’s USB_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 rising TXPKTRDY in the endpoint’s USB_CSRx register.
7. At this step, Bank 0 is available and the microcontroller can prepare a third data payload to be sent.
Figure 109. Data IN Transfer for Ping-pong Endpoint
Microcontroller
Load Data IN Bank 0
USB Bus
Packets
Data IN
PID
TXPKTRDY Flag
(USB_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
TXCOMP Flag
(USB_CSRx)
FIFO (DPR) Written by
Microcontroller
Bank 0
FIFO (DPR)
Bank 1
Data IN
ACK
PID
Set by Firmware,
Data Payload Written in FIFO Bank 1
Interrupt Pending
Set by USB
Device
Set by USB Device
Interrupt Cleared by Firmware
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 is too long, some Data IN packets may be NACKed,
reducing the bandwidth.
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.
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
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6042A–ATARM–23-Dec-04
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 USB_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 USB_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 USB_FDRx register.
6. The microcontroller notifies the USB device that it has finished the transfer by clearing
RX_DATA_BK0 in the endpoint’s USB_CSRx register.
7. A new Data OUT packet can be accepted by the USB device.
Figure 110. 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
(USB_CSRx)
Data OUT2 Data OUT2 NAK
PID
PID
Host Resends the Next Data Payload
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.
Using Endpoints With
Ping-pong Attributes
408
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 payload 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.
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AT91SAM7A3 Preliminary
Figure 111. Bank Swapping in Data OUT Transfers for Ping-pong Endpoints
USB Bus
USB Device
Microcontroller
Write
Write and Read at the Same Time
Read
1st Data Payload
Bank 1
Endpoint 1
2nd Data Payload
Bank 0
Endpoint 1
3rd Data Payload
1st Data Payload
Bank 0
Endpoint 1
2nd Data Payload
Bank 1
Endpoint 1
Data IN Packet
Bank 0
Endpoint 1
Data IN Packet
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 USB_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 USB_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
USB_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 USB_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 USB_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
USB_FDRx register.
11. The microcontroller notifies the USB device it has finished the transfer by clearing
RX_DATA_BK1 in the endpoint’s USB_CSRx register.
12. A fourth Data OUT packet can be accepted by the USB device and copied in the FIFO
Bank 0.
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6042A–ATARM–23-Dec-04
Figure 112. 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
(USB_CSRx)
Data OUT 1
Data OUT
PID
Data OUT 2
Set by USB Device,
Data Payload Written
in FIFO Endpoint Bank 0
Data OUT1
Write by USB Device
ACK
PID
Set by USB Device,
Data Payload Written
in FIFO Endpoint Bank 1
Data OUT 3
A
P
Cleared by Firmware
Interrupt Pending
Data OUT 1
Data OUT 3
Read By Microcontroller
FIFO (DPR)
Bank 1
Write In Progress
Data OUT 2
Write by USB Device
Note:
Data OUT
PID
Cleared by Firmware
Interrupt Pending
RX_DATA_BK1 Flag
(USB_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.
Status Transaction
410
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.
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AT91SAM7A3 Preliminary
Figure 113. Control Read and Write Sequences
Setup Stage
Control Read
Setup TX
Data OUT TX
Setup Stage
Control Write
No Data
Control
Notes:
Status Stage
Data Stage
Data OUT TX
Data Stage
Setup TX
Data IN TX
Setup Stage
Status Stage
Setup TX
Status IN TX
Status IN TX
Status Stage
Data IN TX
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).
Status IN Transfer
Once a control request has been processed, the device returns a status to the host. This is a
zero length Data IN transaction.
1. The microcontroller waits for TXPKTRDY in the USB_CSRx endpoint’s register to be
cleared. (At this step, TXPKTRDY must be cleared because the previous transaction
was a setup transaction or a Data OUT transaction.)
2. Without writing anything to the USB_FDRx endpoint’s register, the microcontroller sets
TXPKTRDY. The USB device generates a Data IN packet using DATA1 PID.
3. This packet is acknowledged by the host and TXPKTRDY is set in the USB_CSRx endpoint’s register.
Figure 114. Data Out Followed by Status IN Transfer.
Host Sends the Last
Data Payload to the Device
USB Bus
Packets
Data OUT
PID
Data OUT
Device Sends a Status IN
to the Host
NAK
PID
Data IN
PID
ACK
PID
Interrupt Pending
RX_DATA_BKO
(USB_CSRx)
Cleared by Firmware
Set by USB Device
Cleared by USB Device
TXPKTRDY
(USB_CSRx)
Set by Firmware
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6042A–ATARM–23-Dec-04
Status OUT Transfer
Once a control request has been processed and the requested data returned, the host
acknowledges by sending a zero length packet. This is a zero length Data OUT transaction.
1. The USB device receives a zero length packet. It sets RX_DATA_BK0 flag in the
USB_CSRx register and acknowledges the zero length packet.
2. The microcontroller is notified that the USB device has received a zero length packet
sent by the host polling RX_DATA_BK0 in the USB_CSRx register. An interrupt is
pending while RX_DATA_BK0 is set. The number of bytes received in the endpoint’s
USB_BCR register is equal to zero.
3. The microcontroller must clear RX_DATA_BK0.
Figure 115. Data IN Followed by Status OUT Transfer
Device Sends the Last
Data Payload to Host
USB Bus
Packets
Data IN
PID
Data IN
Device Sends a
Status OUT to Host
ACK
PID
Data OUT
PID
ACK
PID
Interrupt Pending
Set by USB Device
RX_DATA_BKO
(USB_CSRx)
Cleared by Firmware
TXCOMP
(USB_CSRx)
Set by USB Device
Stall Handshake
Cleared by Firmware
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 USB_CSRx endpoint’s register.
2. The host receives the stall packet.
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.
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AT91SAM7A3 Preliminary
Figure 116. 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 117. 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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Controlling Device States
A USB device has several possible states. Refer to Chapter 9 of the Universal Serial Bus
Specification, Rev 2.0.
Figure 118. 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 UDP 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.
414
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AT91SAM7A3 Preliminary
From Powered State to
Default State
After its connection to a USB host, the USB device waits for an end-of-bus reset. The USB
host stops driving a reset state once it has detected the device’s pull-up on DP. The unmasked
flag ENDBURST is set in the register UDP_ISR and an interrupt is triggered. The UDP software enables 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.
From Default State to
Address State
After a set address standard device request, the USB host peripheral enters the address state.
Before this, it achieves 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 m ove to address s tate, t he driv er sof tware set s the FA DDEN f lag in t he
UDP_GLB_STATE, sets its new address, and sets the FEN bit in the UDP_FADDR register.
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.
Enabling Suspend
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. 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 may be switched off. However, the transceiver and the USB
peripheral must not be switched off, otherwise the resume is not detected.
Receiving a Host
Resume
In suspend mode, the USB transceiver and the USB peripheral must be powered to detect the
RESUME. However, the USB device peripheral may not be clocked as the WAKEUP signal is
asynchronous.
Once the resume is detected on the bus, the signal WAKEUP 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. The
WAKEUP bit must be cleared as soon as possible by setting WAKEUP in the UDP_ICR
register.
Sending an External
Resume
The External Resume is negotiated with the host and enabled by setting the ESR bit in the
USB_GLB_STATE. An asynchronous event on the ext_resume_pin of the peripheral generates a WAKEUP interrupt. On early versions of the USP peripheral, the K-state on the USB
line is generated immediately. This means that the USB device must be able to answer to the
ho st very q uickly . On r ece nt ver sio ns, the softwa re se ts the R MWU PE bit in th e
UDP_GLB_STATE register once it is ready to communicate with the host. The K-state on the
bus is then generated.
The WAKEUP bit must be cleared as soon as possible by setting WAKEUP in the UDP_ICR
register.
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USB Device Port (UDP) User Interface
Table 59. USB Device Port (UDP) Register Mapping
Offset
Register
Name
Access
Reset State
0x000
Frame Number Register
USB_FRM_NUM
Read
0x0000_0000
0x004
Global State Register
USB_GLB_STAT
Read/write
0x0000_0010
0x008
Function Address Register
USB_FADDR
Read/write
0x0000_0100
0x00C
Reserved
–
–
–
0x010
Interrupt Enable Register
USB_IER
Write
0x014
Interrupt Disable Register
USB_IDR
Write
0x018
Interrupt Mask Register
USB_IMR
Read
0x0000_1200
0x01C
Interrupt Status Register
USB_ISR
Read
0x0000_0000
0x020
Interrupt Clear Register
USB_ICR
Write
0x024
Reserved
–
–
0x028
Reset Endpoint Register
USB_RST_EP
Read/write
0x02C
Reserved
–
–
–
0x030
Endpoint 0 Control and Status Register
USB _CSR0
Read/write
0x0000_0000
.
.
.
.
.
.
See Note 1
Endpoint 4 Control and Status Register
USB _CSR4
Read/write
0x0000_0000
0x050
Endpoint 0 FIFO Data Register
USB_FDR0
Read/write
0x0000_0000
.
.
.
.
.
.
See Note 2
Endpoint 4 FIFO Data Register
USB_FDR4
Read/write
0x0000_0000
0x070
Reserved
–
–
–
0x074
Transceiver Control Register
USB_TXVC
Read/write
0x0000_0100
0x078 - 0x0FC
Reserved
–
–
–
Notes:
416
–
1. The addresses of the USB_CSRx registers are calculated as: 0x030 + 4(Endpoint Number - 1).
2. The addresses of the USB_FDRx registers are calculated as: 0x050 + 4(Endpoint Number - 1).
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AT91SAM7A3 Preliminary
USB Frame Number Register
Register Name:
USB_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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6042A–ATARM–23-Dec-04
USB Global State Register
Register Name:
USB_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
RMWUPE
3
RSMINPR
2
ESR
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 USB_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.
• ESR: Enable Send Resume
0 = Disables the Remote Wake Up sequence.
1 = Remote Wake Up can be processed and the pin send_resume is enabled.
• RSMINPR: A Resume Has Been Sent to the Host
Read:
0 = No effect.
1 = A Resume has been received from the host during Remote Wake Up feature.
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• RMWUPE: Remote Wake Up Enable
0 = Must be cleared after receiving any HOST packet or SOF interrupt.
1 = Enables the K-state on the USB cable if ESR is enabled.
USB Function Address Register
Register Name:
USB_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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6042A–ATARM–23-Dec-04
USB Interrupt Enable Register
Register Name:
USB_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 USB Suspend Interrupt
0 = No effect.
1 = Enables USB Suspend Interrupt.
• RXRSM: Enable USB Resume Interrupt
0 = No effect.
1 = Enables USB 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 USB bus Wakeup Interrupt
0 = No effect.
1 = Enables USB bus Interrupt.
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USB Interrupt Disable Register
Register Name:
USB_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 USB Suspend Interrupt
0 = No effect.
1 = Disables USB Suspend Interrupt.
• RXRSM: Disable USB Resume Interrupt
0 = No effect.
1 = Disables USB 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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USB Interrupt Mask Register
Register Name:
USB_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
–
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 USB Suspend Interrupt
0 = USB Suspend Interrupt is disabled.
1 = USB Suspend Interrupt is enabled.
• RXRSM: Mask USB Resume Interrupt.
0 = USB Resume Interrupt is disabled.
1 = USB Resume Interrupt is enabled.
• EXTRSM: Mask External Resume Interrupt
0 = External Resume Interrupt is disabled.
1 = 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.
• WAKEUP: USB Bus WAKEUP Interrupt
0 = USB Bus Wakeup Interrupt is disabled.
1 = USB Bus Wakeup Interrupt is enabled.
Note:
422
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 USB_IMR is
enabled.
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USB Interrupt Status Register
Register Name:
USB_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
0 = No Endpoint0 Interrupt pending.
1 = Endpoint0 Interrupt has been raised.
Several signals can generate this interrupt. The reason can be found by reading USB_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 USB_CSR0 bit.
• EP1INT: Endpoint 1 Interrupt Status
0 = No Endpoint1 Interrupt pending.
1 = Endpoint1 Interrupt has been raised.
Several signals can generate this interrupt. The reason can be found by reading USB_CSR1:
RXSETUP set to 1
RX_DATA_BK0 set to 1
RX_DATA_BK1 set to 1
TXCOMP set to 1
STALLSENT set to 1
EP1INT is a sticky bit. Interrupt remains valid until EP1INT is cleared by writing in the corresponding USB_CSR1 bit.
• EP2INT: Endpoint 2 Interrupt Status
0 = No Endpoint2 Interrupt pending.
1 = Endpoint2 Interrupt has been raised.
Several signals can generate this interrupt. The reason can be found by reading USB_CSR2:
RXSETUP set to 1
RX_DATA_BK0 set to 1
RX_DATA_BK1 set to 1
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AT91SAM7A3 Preliminary
TXCOMP set to 1
STALLSENT set to 1
EP2INT is a sticky bit. Interrupt remains valid until EP2INT is cleared by writing in the corresponding USB_CSR2 bit.
• EP3INT: Endpoint 3 Interrupt Status
0 = No Endpoint3 Interrupt pending.
1 = Endpoint3 Interrupt has been raised.
Several signals can generate this interrupt. The reason can be found by reading USB_CSR3:
RXSETUP set to 1
RX_DATA_BK0 set to 1
RX_DATA_BK1 set to 1
TXCOMP set to 1
STALLSENT set to 1
EP3INT is a sticky bit. Interrupt remains valid until EP3INT is cleared by writing in the corresponding USB_CSR3 bit.
• EP4INT: Endpoint 4 Interrupt Status
0 = No Endpoint4 Interrupt pending.
1 = Endpoint4 Interrupt has been raised.
Several signals can generate this interrupt. The reason can be found by reading USB_CSR4:
RXSETUP set to 1
RX_DATA_BK0 set to 1
RX_DATA_BK1 set to 1
TXCOMP set to 1
STALLSENT set to 1
EP4INT is a sticky bit. Interrupt remains valid until EP4INT is cleared by writing in the corresponding USB_CSR4 bit.
• EP5INT: Endpoint 5 Interrupt Status
0 = No Endpoint5 Interrupt pending.
1 = Endpoint5 Interrupt has been raised.
Several signals can generate this interrupt. The reason can be found by reading USB_CSR5:
RXSETUP set to 1
RX_DATA_BK0 set to 1
RX_DATA_BK1 set to 1
TXCOMP set to 1
STALLSENT set to 1
EP5INT is a sticky bit. Interrupt remains valid until EP5INT is cleared by writing in the corresponding USB_CSR5 bit.
• RXSUSP: USB Suspend Interrupt Status
0 = No USB Suspend Interrupt pending.
1 = USB 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: USB Resume Interrupt Status
0 = No USB Resume Interrupt pending.
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1 =USB Resume Interrupt has been raised.
The USB device sets this bit when a USB resume signal is detected at its port.
• EXTRSM: External Resume Interrupt Status
0 = No External Resume Interrupt pending.
1 = External Resume Interrupt has been raised.
This interrupt is raised when, in suspend mode, an asynchronous rising edge on the send_resume is detected.
If RMWUPE = 1, a resume state is sent in the USB bus.
• 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 USB reset sequence. The USB device must prepare to receive requests on the endpoint 0. The host starts the enumeration, then performs the configuration.
• WAKEUP: USB Resume Interrupt Status
0 = No Wakeup Interrupt pending.
1 = A Wakeup Interrupt (USB Host Sent a RESUME or RESET) occurred since the last clear.
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USB Interrupt Clear Register
Register Name:
USB_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
ENDBURST
11
SOFINT
10
EXTRSM
9
8
RXRSM
RXSUSP
7
–
6
–
5
–
4
–
3
–
2
–
1
–
0
–
• RXSUSP: Clear USB Suspend Interrupt
0 = No effect.
1 = Clears USB Suspend Interrupt.
• RXRSM: Clear USB Resume Interrupt
0 = No effect.
1 = Clears USB Resume Interrupt.
• EXTRSM: Clear External Resume Interrupt
0 = No effect.
1 = Clears External Resume Interrupt.
• SOFINT: Clear Start Of Frame Interrupt
0 = No effect.
1 = Clears Start Of Frame Interrupt.
• ENDBURST: Clear End of Bus Reset Interrupt
0 = No effect.
1 = Clears Start Of Frame Interrupt.
• WAKEUP: Clear Wakeup Interrupt
0 = No effect.
1 = Clears Wakeup Interrupt.
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USB Reset Endpoint Register
Register Name:
USB_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
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 USB_CSRx flags.
0 = No reset.
1 = Forces the corresponding endpoint FIF0 pointers to 0, therefore RXBYTECNT field is read at 0 in USB_CSRx register.
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USB Endpoint Control and Status Register
Register Name:
USB_CSRx [x = 0..4]
Access Type:
Read/Write
31
–
30
–
29
–
28
–
23
22
21
20
27
–
26
25
RXBYTECNT
24
19
18
17
16
RXBYTECNT
15
EPEDS
14
–
13
–
12
–
11
DTGLE
10
9
EPTYPE
8
7
DIR
6
RX_DATA_
BK1
5
FORCE
STALL
4
TXPKTRDY
3
STALLSENT
ISOERROR
2
RXSETUP
1
RX_DATA_
BK0
0
TXCOMP
• 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.
• 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 = No effect.
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 USB_FDRx register. Once a transfer is done, the device firmware must release Bank 0 to the USB peripheral
device by clearing RX_DATA_BK0.
• RXSETUP: Sends STALL to the Host (Control Endpoints)
This flag generates an interrupt while it is set to one.
Read:
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6042A–ATARM–23-Dec-04
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
USB_FDRx register to the microcontroller memory. Once a transfer has been done, RXSETUP must be cleared by the
device firmware.
Ensuing Data OUT transactions 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.
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 = Data values can be written in the FIFO.
1 = Data values can not be written in the FIFO.
Write:
0 = No effect.
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1 = A new data payload is 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 USB_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.
• FORCESTALL: Force Stall (used by Control, Bulk and Isochronous Endpoints)
Write-only
0 = No effect.
1 = Sends 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 indicates that the microcontroller cannot complete the
request.
Bulk and interrupt endpoints: 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 = No effect.
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 USB_FDRx register. Once a transfer is done, the device firmware must release Bank 1 to the USB device by clearing RX_DATA_BK1.
• 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 USB_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
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Read/Write
010
Bulk OUT
110
Bulk IN
011
Interrupt OUT
111
Interrupt IN
• 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.
• 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 USB_FDRx register.
USB FIFO Data Register
Register Name:
USB_FDRx [x = 0..4]
Access Type:
Read/Write
432
31
–
30
–
29
–
28
–
27
–
26
–
25
–
24
–
23
–
22
–
21
–
20
–
19
–
18
–
17
–
16
–
15
–
14
–
13
–
12
–
11
–
10
–
9
8
–
–
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AT91SAM7A3 Preliminary
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 USB_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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6042A–ATARM–23-Dec-04
USB Transceiver Control Register
Register Name:
USB_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
–
TXVDIS
7
–
6
–
5
–
4
–
3
–
2
–
1
0
–
–
• 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.
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MultiMedia Card Interface (MCI)
Description
The MultiMedia Card Interface (MCI) supports the MultiMediaCard (MMC) Specification V2.2
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 Data Controller 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
one slot. Each slot may be used to interface with a MultiMediaCard bus (up to 30 Cards) or
with an 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 MultiMediaCard 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.
Block Diagram
Figure 119. Block Diagram
APB Bridge
PDC
APB
MCCK
MCCDA
MCI Interface
PMC
MCK
MCDA0
PIO
MCDA1
MCDA2
Interrupt Control
MCDA3
MCI Interrupt
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6042A–ATARM–23-Dec-04
Application
Block Diagram
Figure 120. Application Block Diagram
Application Layer
ex: File System, Audio, Security, etc.
Physical Layer
MCI Interface
1 2 3 4 5 6 78
1234567
9
SDCard
MMC
Pin Name List
Table 1. I/O Lines Description
Pin Name
Pin Description
Type(1)
Comments
MCCDA
Command/response
I/O/PP/OD
CMD of an MMC or SD Card
MCCK
Clock
I/O
CLK of an MMC or SD Card
MCDA0 - MCDA3
Data 0..3 of Slot A
I/O/PP
DAT0 of an MMC
DAT[0..3] of an SD Card
Note:
1. I: Input, O: Output, PP: Push/Pull, OD: Open Drain.
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.
Power
Management
The MCI may be clocked through the Power Management Controller (PMC), so the programmer must first to configure the PMC to enable the MCI clock.
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.
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Bus Topology
Figure 121. 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 2. Bus Topology
MCI Pin Name
(Slot x)
Pin
Number
Name
Type(1)
Description
1
RSV
NC
Not connected
2
CMD
I/O/PP/OD
Command/response
MCCDx
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
MCDx0
Note:
1. I: Input, O: Output, PP: Push/Pull, OD: Open Drain.
Figure 122. MMC Bus Connections (One Slot)
MCI
MCCDA
MCDA0
MCCK
1234567
1234567
1234567
MMC1
MMC2
MMC3
Figure 123. SD Memory Card Bus Topology
1 2 3 4 5 6 78
9
SD CARD
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6042A–ATARM–23-Dec-04
The SD Memory Card bus includes the signals listed in Table 3.
Table 3. SD Memory Card Bus Signals
Pin Number
Name
Type(1)
Description
MCI Pin Name
(Slot x)
1
CD/DAT[3]
I/O/PP
Card detect/ Data line Bit 3
MCDx3
2
CMD
PP
Command/response
MCCDx
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
MCDx0
8
DAT[1]
I/O/PP
Data line Bit 1
MCDx1
9
DAT[2]
I/O/PP
Data line Bit 2
MCDx2
Note:
1. I: input, O: output, PP: Push Pull, OD: Open Drain
MCDA0 - MCDA3
MCCK
SD CARD
9
MCCDA
1 2 3 4 5 6 78
Figure 124. SD Card Bus Connections with One Slot
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.
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 Version 2.2. See also Table 4 on page 439.
MultiMediaCard bus data transfers are composed of these tokens.
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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 MCCK.
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.
The MCI provides a set of registers to perform the entire range of MultiMedia Card operations.
Command Response
Operation
After reset, the MCI is disabled and becomes valid after setting the MCIEN bit in the MCI_CR
Control Register. The bit PWSEN allows saving power by dividing the MCI clock by 2PWSDIV
(MCI_MR)
when the bus is inactive.
The command and the response of the card are clocked out with the rising edge of the MCCK.
All the timings for MultiMedia Card are defined in the MultiMediaCard System Specification
Version 2.2.
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:
NID Cycles
Host Command
CMD
S
T
Content
CRC
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 4 and Table 5.
Table 4. 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.
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Table 5. 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)
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 5).
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 125. 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:
1. If the command is SEND_OP_COND, the CRC error flag is always present (refer to R3 response in the MultiMediaCard
specification).
Data Transfer
Operation
The MultiMedia Card allows several read/write operations (single block, multiple blocks,
stream, etc.).
These operations can be done using the features of the Peripheral Data 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 must be defined in the mode register.
Read Operation
The following flowchart shows how to read a single block with or without use of PDC facilities.
In this example (see Figure 126), 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. These two methods can be applied for all MultiMedia Card read functions.
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6042A–ATARM–23-Dec-04
Figure 126. Read Functional Flow Diagram
Send command SEL_DESEL_CARD
to select the card
Send command SET_BLOCKLEN
No
Yes
Read with PDC
Reset the PDCMODE bit
MCI_MR &= ~PDCMODE
Set the block length (in bytes)
MCI_MR |= (BlockLenght <<16)
Set the PDCMODE bit
MCI_MR |= PDCMODE
Set the block length (in bytes)
MCI_MR |= (BlockLength << 16)
Send command
READ_SINGLE_BLOCK(1)
Configure the PDC channel
MCI_RPR = Data Buffer Address
MCI_RCR = BlockLength/4
MCI_PTCR = RXTEN
Number of words to read = BlockLength/4
Send command
READ_SINGLE_BLOCK(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:
442
1. This command is supposed to have been correctly sent (see Figure 125).
AT91SAM7A3 Preliminary
6042A–ATARM–23-Dec-04
AT91SAM7A3 Preliminary
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 127).
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).
This flowchart can be adapted to perform all the MultiMedia Card write functions.
443
6042A–ATARM–23-Dec-04
Figure 127. Write Functional Flow Diagram
Send command SEL_DESEL_CARD
to select the card
Send command SET_BLOCKLEN
Yes
No
Write using PDC
Reset the PDCMODE bit
MCI_MR &= ~PDCMODE
Set the block length
MCI_MR |= (BlockLenght <<16)
Set the PDCMODE bit
MCI_MR |= PDCMODE
Set the block length
MCI_MR |= (BlockLength << 16)
Send command
WRITE_SINGLE_BLOCK(1)
Configure the PDC channel
MCI_TPR = Data Buffer Address to write
MCI_TCR = BlockLength/4
Number of words to write = BlockLength/4
Send command
WRITE_SINGLE_BLOCK(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
ENDTX = 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
Note:
444
1. This command is supposed to have been correctly sent (see Figure 125).
AT91SAM7A3 Preliminary
6042A–ATARM–23-Dec-04
AT91SAM7A3 Preliminary
SD Card
Operations
The MultiMedia Card Interface allows processing of SD Memory Card (Secure Digital Memory
Card) commands. The SD Memory Card includes a copyright protection mechanism that complies with the security requirements of the SDMI standard (Secure Digital Music Initiative), is
faster and applicable to higher memory capacity.
The physical form factor, pin assignment and data transfer protocol are forward-com-patible
with the MultiMedia Card with some additions.
The SD Memory 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 Memory Card and the MultiMedia Card is the
initialization process.
The SD Card Register (MCI_SDCR) allows selection of the Card Slot and the data bus width.
The SD Card bus allows dynamic configuration of the number of data lines. After power up, by
default, the SD Memory Card uses only DAT0 for data transfer. After initialization, the host can
change the bus width (number of active data lines).
445
6042A–ATARM–23-Dec-04
MultiMedia Card Interface (MCI) User Interface
Table 2. MultiMedia Card Interface (MCI) Register Mapping
Offset
Read/Write
Reset
Control Register
MCI_CR
Write
–
0x04
Mode Register
MCI_MR
Read/write
0x0
0x08
Data Timeout Register
MCI_DTOR
Read/write
0x0
0x0C
SD Card Register
MCI_SDCR
Read/write
0x0
0x10
Argument Register
MCI_ARGR
Read/write
0x0
0x14
Command Register
MCI_CMDR
Write
–
–
–
–
0x20
Response Register
(1)
MCI_RSPR
Read
0x0
0x24
Response Register(1)
MCI_RSPR
Read
0x0
0x28
Response Register(1)
MCI_RSPR
Read
0x0
0x2C
Response Register
(1)
MCI_RSPR
Read
0x0
0x30
Receive Data Register
MCI_RDR
Read
0x0
0x34
Transmit Data Register
MCI_TDR
Write
–
–
–
–
0x38 - 0x3C
Reserved
Reserved
0x40
Status Register
MCI_SR
Read
0xC0E5
0x44
Interrupt Enable Register
MCI_IER
Write
–
0x48
Interrupt Disable Register
MCI_IDR
Write
–
0x4C
Interrupt Mask Register
MCI_IMR
Read
0x0
Reserved
–
–
–
Reserved for the PDC
–
–
–
0x50-0xFC
0x100-0x124
446
Register Name
0x00
0x18 - 0x1C
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.
AT91SAM7A3 Preliminary
6042A–ATARM–23-Dec-04
AT91SAM7A3 Preliminary
MCI Control Register
Name:
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 in the PWSDIV field a value different from 0 (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.
447
6042A–ATARM–23-Dec-04
MCI Mode Register
Name:
MCI_MR
Access Type:
Read/write
31
30
–
–
23
22
29
28
27
26
25
24
18
17
16
0
0
9
8
BLKLEN
21
20
19
BLKLEN
15
14
13
12
11
PDCMODE
PDCPADV
–
–
–
7
6
5
4
3
10
PWSDIV
2
1
0
CLKDIV
• CLKDIV: Clock Divider
Multi-Media Card Interface clock (MCCK) is Master Clock (MCK) divided by (2*(CLKDIV+1)).
• PWSDIV: Power Saving Divider
Multimedia Card Interface clock is divided by 2 (PWSDIV) 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).
• 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).
• 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.
Bits 16 and 17 must be 0.
448
AT91SAM7A3 Preliminary
6042A–ATARM–23-Dec-04
AT91SAM7A3 Preliminary
MCI Data Timeout Register
Name:
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.
449
6042A–ATARM–23-Dec-04
MCI SD Card Register
Name:
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
–
–
–
–
–
–
–
–
3
2
1
0
7
6
5
4
SDCBUS
–
–
–
29
28
SDCSEL
• SDCSEL: SD Card Selector
0 = SDCARD Slot A selected.
• SDCBUS: SD Card Bus Width
0 = 1-bit data bus
1 = 4-bit data bus
MCI Argument Register
Name:
MCI_ARGR
Access Type:
Read/write
31
30
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
450
AT91SAM7A3 Preliminary
6042A–ATARM–23-Dec-04
AT91SAM7A3 Preliminary
MCI Command Register
Name:
MCI_CMDR
Access Type:
Write-only
31
30
29
28
27
26
25
24
–
–
–
–
–
–
–
–
23
22
21
20
18
17
–
–
–
15
14
13
12
11
–
–
–
MAXLAT
OPDCMD
6
5
4
3
7
19
TRTYP
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
451
6042A–ATARM–23-Dec-04
• 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
452
Transfer Type
0
0
Block
0
1
Multiple Block
1
0
Stream
1
1
Reserved
AT91SAM7A3 Preliminary
6042A–ATARM–23-Dec-04
AT91SAM7A3 Preliminary
MCI SD Response Register
Name:
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:
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.
453
6042A–ATARM–23-Dec-04
MCI SD Receive Data Register
Name:
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
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
MCI SD Transmit Data Register
Name:
MCI_TDR
Access Type:
Write-only
31
30
29
28
DATA
23
22
21
20
DATA
15
14
13
12
DATA
7
6
5
4
DATA
• DATA: Data to Write
454
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6042A–ATARM–23-Dec-04
AT91SAM7A3 Preliminary
MCI Status Register
Name:
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
–
–
–
–
–
–
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
0 = A data block transfer is not yet finished.
1 = A data block transfer has ended. Set at the end of the last block in PDCMODE (when RXBUFF or TXBUFE is set), otherwise at the end of the first block. Cleared when reading the MCI_SR.
• 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: Data Not Busy
0 = The card is not ready for new data transfer.
1 = The card is ready for new data transfer (Data line DAT0 high corresponding to a free data receive buffer in the card).
• 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.
• RXBUFF: RX Buffer Full
0 = MCI_RCR or MCI_RNCR has a value other than 0.
455
6042A–ATARM–23-Dec-04
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.
456
AT91SAM7A3 Preliminary
6042A–ATARM–23-Dec-04
AT91SAM7A3 Preliminary
• 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.
• 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. Cleared when sending a new data transfer command.
• DTOE: Data Time-out Error
0 = No error.
1 = The data time-out set by DTOCYC and DTOMUL in MCI_DTOR has been exceeded. Cleared when writing in the
MCI_CMDR.
• 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.
457
6042A–ATARM–23-Dec-04
MCI Interrupt Enable Register
Name:
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
–
–
–
–
–
–
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
• 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.
458
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6042A–ATARM–23-Dec-04
AT91SAM7A3 Preliminary
MCI Interrupt Disable Register
Name:
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
–
–
–
–
–
–
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
• 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.
459
6042A–ATARM–23-Dec-04
MCI Interrupt Mask Register
Name:
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
–
–
–
–
–
–
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
• 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.
460
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6042A–ATARM–23-Dec-04
AT91SAM7A3 Preliminary
Analog-to-digital Converter (ADC)
Overview
The ADC is based on a Successive Approximation Register (SAR) 10-bit Analog-to-Digital
Converter (ADC). It also integrates an 8-to-1 analog multiplexer, making possible the analogto-digital conversions of up to eight 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.
Block Diagram
Figure 128. Analog-to-Digital Converter Block Diagram
Timer
Counter
Channels
ADC
Trigger
Selection
ADTRG
Control
Logic
ADC Interrupt
AIC
VDDANA
ADVREF
ASB
AD0
AD1
PDC
PIO
User
Interface
AD2
AD3
AD4
AD5
Peripheral Bridge
Successive
Approximation
Register
Analog-to-Digital
Converter
APB
AD6
AD7
GND
461
6042A–ATARM–23-Dec-04
Signal Description
Table 60. ADC Pin Description
Pin Name
Description
VDDANA
Analog power supply
ADVREF
Reference voltage
AD0 - AD7
Analog input channels
ADTRG
External trigger
Product
Dependencies
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.
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.
Analog Inputs
The pins AD0 to AD7 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 pullup enabled and the ADC input is connected to the GND.
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.
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.
Conversion
Performances
For performance and electrical characteristics of the ADC, see the DC Characteristics section.
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AT91SAM7A3 Preliminary
Functional
Description
Analog-to-digital
Conversion
The ADC uses the ADC Clock to perform conversions. Converting a single analog value to a
10-bit digital data requires Sample and Hold Clock cycles as defined in the field SHTIM of the
“ADC Mode Register” on page 469 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.
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.
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.
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.
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6042A–ATARM–23-Dec-04
Figure 129. 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)
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.
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AT91SAM7A3 Preliminary
Figure 130. 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.
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 Channe l Disab le
(ADC_CHDR) Registers enable the analog channels to be enabled or disabled independently.
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6042A–ATARM–23-Dec-04
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.
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:
ADC Timings
The reference voltage pins always remain connected in normal mode as in sleep mode.
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 DC
Characteristics in the product datasheet.
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Analog-to-digital Converter (ADC) User Interface
Table 61. Analog-to-digital Converter (ADC) Register Mapping
Offset
Register
Name
Access
Reset State
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
0x38
Channel Data Register 2
ADC_CDR2
Read-only
0x00000000
0x3C
Channel Data Register 3
ADC_CDR3
Read-only
0x00000000
0x40
Channel Data Register 4
ADC_CDR4
Read-only
0x00000000
0x44
Channel Data Register 5
ADC_CDR5
Read-only
0x00000000
0x48
Channel Data Register 6
ADC_CDR6
Read-only
0x00000000
0x4C
Channel Data Register 7
ADC_CDR7
Read-only
0x00000000
–
–
–
0x50 - 0xFC
Reserved
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6042A–ATARM–23-Dec-04
ADC Control Register
Register Name:ADC_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
–
–
–
–
–
–
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.
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AT91SAM7A3 Preliminary
ADC Mode Register
Register Name:ADC_MR
Access Type: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
TIOA Ouput of the Timer Counter Channel 3
1
0
0
TIOA Ouput of the Timer Counter Channel 4
1
0
1
TIOA Ouput of the Timer Counter Channel 5
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
Selected Mode
0
Normal Mode
1
Sleep Mode
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6042A–ATARM–23-Dec-04
• 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
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AT91SAM7A3 Preliminary
ADC Channel Enable Register
Register Name:ADC_CHER
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
CH7
CH6
CH5
CH4
CH3
CH2
CH1
CH0
• CHx: Channel x Enable
0 = No effect.
1 = Enables the corresponding channel.
ADC Channel Disable Register
Register Name:ADC_CHDR
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
CH7
CH6
CH5
CH4
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.
471
6042A–ATARM–23-Dec-04
ADC Channel Status Register
Register Name:ADC_CHSR
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
CH7
CH6
CH5
CH4
CH3
CH2
CH1
CH0
• CHx: Channel x Status
0 = Corresponding channel is disabled.
1 = Corresponding channel is enabled.
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AT91SAM7A3 Preliminary
ADC Status Register
Register Name:ADC_SR
Access Type: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
OVRE7
OVRE6
OVRE5
OVRE4
OVRE3
OVRE2
OVRE1
OVRE0
7
6
5
4
3
2
1
0
EOC7
EOC6
EOC5
EOC4
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 Overrun Error occurred since the last read of ADC_SR.
1 = At least one 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.
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6042A–ATARM–23-Dec-04
ADC Last Converted Data Register
Register Name:ADC_LCDR
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
–
–
–
–
–
–
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.
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AT91SAM7A3 Preliminary
ADC Interrupt Enable Register
Register Name:ADC_IER
Access Type: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
OVRE7
OVRE6
OVRE5
OVRE4
OVRE3
OVRE2
OVRE1
OVRE0
7
6
5
4
3
2
1
0
EOC7
EOC6
EOC5
EOC4
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.
ADC Interrupt Disable Register
Register Name:ADC_IDR
Access Type: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
OVRE7
OVRE6
OVRE5
OVRE4
OVRE3
OVRE2
OVRE1
OVRE0
7
6
5
4
3
2
1
0
EOC7
EOC6
EOC5
EOC4
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.
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6042A–ATARM–23-Dec-04
ADC Interrupt Mask Register
Register Name:ADC_IMR
Access Type: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
OVRE7
OVRE6
OVRE5
OVRE4
OVRE3
OVRE2
OVRE1
OVRE0
7
6
5
4
3
2
1
0
EOC7
EOC6
EOC5
EOC4
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.
ADC Channel Data Register
Register Name:ADC_CDRx
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
–
–
–
–
–
–
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.
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AT91SAM7A3 Preliminary
Controller Area Network (CAN)
Overview
The CAN controller provides all the features required to implement the serial communication
protocol CAN defined by Robert Bosch GmbH, the CAN specification as referred to by
ISO/11898A (2.0 Part A and 2.0 Part B) for high speeds and ISO/11519-2 for low speeds. The
CAN Controller is able to handle all types of frames (Data, Remote, Error and Overload) and
achieves a bitrate of 1 Mbit/sec.
CAN controller accesses are made through configuration registers. sixteen independent message objects (mailboxes) are implemented.
Any mailbox can be programmed as a reception buffer block (even non-consecutive buffers).
For the reception of defined messages, one or several message objects can be masked without participating in the buffer feature. An interrupt is generated when the buffer is full.
According to the mailbox configuration, the first message received can be locked in the CAN
controller registers until the application acknowledges it, or this message can be discarded by
new received messages.
Any mailbox can be programmed for transmission. Several transmission mailboxes can be
enabled in the same time. A priority can be defined for each mailbox independently.
An internal 16-bit timer is used to stamp each received and sent message. This timer starts
counting as soon as the CAN controller is enabled. This counter can be reset by the application or automatically after a reception in the last mailbox in Time Triggered Mode.
The CAN controller offers optimized features to support the Time Triggered Communication
(TTC) protocol.
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6042A–ATARM–23-Dec-04
Block Diagram
Figure 131. CAN Block Diagram
Controller Area Network
CANRX
CAN Protocol Controller
PIO
CANTX
Error Counter
Mailbox
Priority
Encoder
Control
&
Status
MB0
MB1
MCK
PMC
MBx
(x = number of mailboxes - 1)
CAN Interrupt
User Interface
Internal Bus
Application
Block Diagram
Figure 132. Application Block Diagram
Layers
Implementation
CAN-based Profiles
Software
CAN-based Application Layer
Software
CAN Data Link Layer
CAN Controller
CAN Physical Layer
Transceiver
I/O Lines
Description
Table 62. I/O Lines Description
Name
Description
Type
CANRX
CAN Receive Serial Data
Input
CANTX
CAN Transmit Serial Data
Output
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Product Dependencies
I/O Lines
The pins used for interfacing the CAN may be multiplexed with the PIO lines. The programmer
must first program the PIO controller to assign the desired CAN pins to their peripheral function. If I/O lines of the CAN are not used by the application, they can be used for other
purposes by the PIO Controller.
Power
Management
The programmer must first enable the CAN clock in the Power Management Controller (PMC)
before using the CAN.
A Low-power Mode is defined for the CAN controller: If the application does not require CAN
operations, the CAN clock can be stopped when not needed and be restarted later. Before
stopping the clock, the CAN Controller must be in Low-power Mode to complete the current
transfer. After restarting the clock, the application must disable the Low-power Mode of the
CAN controller.
Interrupt
The CAN interrupt line is connected on one of the internal sources of the Advanced Interrupt
Controller. Using the CAN interrupt requires the AIC to be programmed first. Note that it is not
recommended to use the CAN interrupt line in Edge-sensitive Mode.
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6042A–ATARM–23-Dec-04
CAN Controller Features
CAN Protocol
Overview
The Controller Area Network (CAN) is a multi-master serial communication protocol that efficiently supports real-time control with a very high level of security with bit rates up to 1 Mbit/s.
The CAN protocol supports four different frame types:
•
Data frames: They carry data from a transmitter node to the receiver nodes. The overall
maximum data frame length is 108 bits for a standard frame and 128 bits for an extended
frame.
•
Remote frames: A destination node can request data from the source by sending a remote
frame with an identifier that matches the identifier of the required data frame. The
appropriate data source node then sends a data frame as a response to this node request.
•
Error frames: An error frame is generated by any node that detects a bus error.
•
Overload frames: They provide an extra delay between the preceeding and the successive
data frames or remote frames.
The Atmel CAN controller provides the CPU with full functionality of the CAN protocol V2.0
Part A and V2.0 Part B. It minimizes the CPU load in communication overhead. The Data Link
Layer and part of the physical layer are automatically handled by the CAN controller itself.
The CPU reads or writes data or messages via the CAN controller mailboxes. An identifier is
assigned to each mailbox. The CAN controller encapsulates or decodes data messages to
build or to decode bus data frames. Remote frames, error frames and overload frames are
automatically handled by the CAN controller under supervision of the software application.
Mailbox
Organization
The CAN module has sixteen buffers, also called channels or mailboxes. An identifier that corresponds to the CAN identifier is defined for each active mailbox. Message identifiers can
match the standard frame identifier or the extended frame identifier. This identifier is defined
for the first time during the CAN initialization, but can be dynamically reconfigured later so that
the mailbox can handle a new message family. Several mailboxes can be configured with the
same ID.
Each mailbox can be configured in receive or in transmit mode independently. The mailbox
object type is defined in the MOT field of the CAN_MMRx register.
Message Acceptance
Procedure
480
If the MIDE field in the CAN_MIDx register is set, the mailbox can handle the extended format
identifier; otherwise, the mailbox handles the standard format identifier. Once a new message
is received, its ID is masked with the CAN_MAMx value and compared with the CAN_MIDx
value. If accepted, the message ID is copied to the CAN_MIDx register.
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Figure 133. Message Acceptance Procedure
CAN_MAMx
CAN_MIDx
&
Message Received
&
==
No
Message Refused
Yes
Message Accepted
CAN_MFIDx
If a mailbox is dedicated to receiving several messages (a family of messages) with different
IDs, the acceptance mask defined in the CAN_MAMx register must mask the variable part of
the ID family. Once a message is received, the application must decode the masked bits in the
CAN_MIDx. To speed up the decoding, masked bits are grouped in the family ID register
(CAN_MFIDx).
For example, if the following message IDs are handled by the same mailbox:
ID0 000011101000100100010010000100 0 11 00b
ID1 000011101000100100010010000100 0 11 01b
ID2 000011101000100100010010000100 0 11 10b
ID3 000011101000100100010010000100 0 11 11b
ID4 000011101000100100010010000100 1 11 00b
ID5 000011101000100100010010000100 1 11 01b
ID6 000011101000100100010010000100 1 11 10b
ID7 000011101000100100010010000100 1 11 11b
The CAN_MIDx and CAN_MAMx of Mailbox x must be initialized to the corresponding values:
CAN_MIDx = 000011101000100100010010000100 x 11 xxb
CAN_MAMx = 111111111111111111111111111111 0 11 00b
If Mailbox x receives a message with ID6, then CAN_MIDx and CAN_MFIDx are set:
CAN_MIDx = 000011101000100100010010000100 1 11 10b
CAN_MFIDx = 00000000000000000000000000000000110b
If the application associates a handler for each message ID, it may define an array of pointers
to functions:
void (*pHandler[8])(void);
When a message is received, the corresponding handler can be invoked using CAN_MFIDx
register and there is no need to check masked bits:
unsigned int MFID0_register;
MFID0_register = Get_CAN_MFID0_Register();
// Get_CAN_MFID0_Register() returns the value of the CAN_MFID0 register
pHandler[MFID0_register]();
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Receive Mailbox
When the CAN module receives a message, it looks for the first available mailbox with the lowest number and compares the received message ID with the mailbox ID. If such a mailbox is
found, then the message is stored in its data registers. Depending on the configuration, the
mailbox is disabled as long as the message has not been acknowledged by the application
(Receive only), or, if new messages with the same ID are received, then they overwrite the
previous ones (Receive with overwrite).
It is also possible to configure a mailbox in Consumer Mode. In this mode, after each transfer
request, a remote frame is automatically sent. The first answer received is stored in the corresponding mailbox data registers.
Several mailboxes can be chained to receive a buffer. They must be configured with the same
ID in Receive Mode, except for the last one, which can be configured in Receive with Overwrite Mode. The last mailbox can be used to detect a buffer overflow.
Mailbox Object Type
Receive
Receive with overwrite
Consumer
Transmit Mailbox
Description
The first message received is stored in mailbox data registers. Data remain available until the
next transfer request.
The last message received is stored in mailbox data register. The next message always
overwrites the previous one. The application has to check whether a new message has not
overwritten the current one while reading the data registers.
A remote frame is sent by the mailbox. The answer received is stored in mailbox data register.
This extends Receive mailbox features. Data remain available until the next transfer request.
When transmitting a message, the message length and data are written to the transmit mailbox with the correct identifier. For each transmit mailbox, a priority is assigned. The controller
automatically sends the message with the highest priority first (set with the field PRIOR in
CAN_MMRx register).
It is also possible to configure a mailbox in Producer Mode. In this mode, when a remote frame
is received, the mailbox data are sent automatically. By enabling this mode, a producer can be
done using only one mailbox instead of two: one to detect the remote frame and one to send
the answer.
Mailbox Object Type
482
Description
Transmit
The message stored in the mailbox data registers will try to win the bus arbitration immediately
or later according to or not the Time Management Unit configuration (see Section ).
The application is notified that the message has been sent or aborted.
Producer
The message prepared in the mailbox data registers will be sent after receiving the next remote
frame. This extends transmit mailbox features.
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Time Management
Unit
The CAN Controller integrates a free-runnning 16-bit internal timer. The counter is driven by
the bit clock of the CAN bus line. It is enabled when the CAN controller is enabled (CANEN set
in the CAN_MR register). It is automatically cleared in the following cases:
•
after a reset
•
when Low-power Mode is enabled (rising edge of the WAKEUP signal)
•
after a reset of the CAN controller (CANEN bit in the CAN_MR register)
•
in Time-triggered Mode, when a message is accepted by the last mailbox (rising edge of
the MRDY signal in the CAN_MSRlast_mailbox_number register).
The application can also reset the internal timer by setting TIMRST in the CAN_TCR register.
The current value of the internal timer is always accessible by reading the CAN_TIM register.
When the timer rolls-over from FFFFh to 0000h, TOVF (Timer Overflow) signal in the CAN_SR
register is set. TOVF bit in the CAN_SR register is cleared by reading the CAN_SR register.
Depending on the corresponding interrupt mask in the CAN_IMR register, an interrupt is generated while TOVF is set.
In a CAN network, some CAN devices may have a larger counter. In this case, the application
can also decide to freeze the internal counter when the timer reaches FFFFh and to wait for a
restart condition from another device. This feature is enabled by setting TIMFRZ in the
CAN_MR register. The CAN_TIM register is frozen to the FFFFh value. A clear condition
described above restarts the timer. A timer overflow (TOVF) interrupt is triggered.
To monitor the CAN bus activity, the CAN_TIM register is copied to the CAN _TIMESTP register after each start of frame or end of frame and a TSTP interrupt is triggered. If TEOF bit in
the CAN_MR register is set, the value is captured at each End Of Frame, else it is captured at
each Start Of Frame. Depending on the corresponding mask in the CAN_IMR register, an
interrupt is generated while TSTP is set in the CAN_SR. TSTP bit is cleared by reading the
CAN_SR register.
The time management unit can operate in one of the two following modes:
•
Timestamping mode: The value of the internal timer is captured at each Start Of Frame or
each End Of Frame
•
Time Triggered mode: A mailbox transfer operation is triggered when the internal timer
reaches the mailbox trigger.
Timestamping Mode is enabled by clearing TTM field in the CAN_MR register. Time Triggered
Mode is enabled by setting TTM field in the CAN_MR register.
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CAN 2.0 Standard
Features
CAN Bit Timing
Configuration
All controllers on a CAN bus must have the same bit rate and bit length. At different clock frequencies of the individual controllers, the bit rate has to be adjusted by the time segments.
The CAN protocol specification partitions the nominal bit time into four different segments:
Figure 134. Partition of the CAN Bit Time
NOMINAL BIT TIME
SYNC_SEG
PROP_SEG
PHASE_SEG1
PHASE_SEG2
Sample Point
TIME QUANTUM:
The TIME QUANTUM is a fixed unit of time derived from the MCK period. The total number of
TIME QUANTA in a bit time is programmable from 8 to 25.
SYNC SEG:
This part of the bit time is used to synchronize the various nodes on the bus. An edge is
expected to lie within this segment.
PROP SEG:
This part of the bit time is used to compensate for the physical delay times within the network.
It is twice the sum of the signal’s propagation time on the bus line, the input comparator delay,
and the output driver delay.
This parameter is defined in the PROPAG field of the CAN_BR register.
PHASE SEG1, PHASE SEG2:
The Phase-Buffer-Segments are used to compensate for edge phase errors. These segments
can be lengthened or shortened by resynchronization.
These parameters are defined in the PHASE1 and PHASE2 fields of the CAN_BR register.
SAMPLE POINT:
The SAMPLE POINT is the point in time at which the bus level is read and interpreted as the
value of that respective bit. Its location is at the end of PHASE_SEG1.
If the SMP field in the CAN_BR register is set, then the incoming bit stream is sampled three
times with a period of half a CAN clock period, centered on sample point.
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In the CAN controller, the length of a bit on the CAN bus is determined by the parameters
(BRP, PROPAG, PHASE1 and PHASE2).
t BIT = t CSC + t PRS + t PHS1 + t PHS2
The time quantum is calculated as follows:
CSC
= 2 × ( BRP + 1 ) ⁄ MCK
t PRS = t CSC × ( PROPAG + 1 )
t PHS1 = t CSC × ( PHASE1 + 1 )
t PHS2 = t CSC × ( PHASE2 + 1 )
To compensate for phase shifts between clock oscillators of different controllers on the bus,
the CAN controller must resynchronize on any relevant signal edge of the current transmission. The synchronization jump width (SJW) defines the maximum of clock cycles by which a
bit period may be shortened or lengthened by re-synchronization.
t SJW = t CSC × ( SYNC + 1 )
Figure 135. CAN Bit Timing
MCK
CAN Clock
tCSC
tPRS
tPHS1
tPHS2
tSJW
tSJW
NOMINAL BIT TIME
SYNC_SEG
PROP_SEG
PHASE_SEG1
PHASE_SEG2
Sample Point
Transmission Point
Example of bit timing determination for CAN baudrate of 500 Kbit/s:
MCK = 48MHz
CAN baudrate= 500kbit/s => bittime = 2us
Tcsc = 2us => BRP = (Tcsc x MCK) -1 = 95
The time quanta must be comprised between 8 and 25. If we fix the time
quanta to 12 and if we choose a sample point at 66.6%, then:
Tphs2 = (33.3% x 12) x Tcsc = 4 x Tcsc => PHASE2 = 3
Then, we choose Tphs2 = Tphs1 = Tsjw:
Tphs1 = 4 x Tcsc => PHASE1 = 3
Tsjw = 1x Tcsc => SYNC = 0
And so: Tprs = 2 x Tcsc => PROPAG = 1
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Finally: CAN_BR = 0x005F0133
CAN Bus
Synchronization
Two types of synchronization are distinguished: “hard synchronization” at the start of a frame
and “resynchronization” inside a frame. After a hard synchronization, the bit time is restarted
with the end of the SYNC segment, regardless of the phase error. Resynchronization causes a
reduction or increase in the bit time so that the position of the sample point is shifted with
respect to the detected edge.
The effect of resynchronization is the same as that of hard synchronization when the magnitude of the phase error of the edge causing the resynchronization is less than or equal to the
programmed value of the resynchronization jump width (tSJW).
When the magnitude of the phase error is larger than the resynchronization jump width and
•
and the phase error is positive, then PHASE_SEG1 is lengthened by an amount equal to
the resynchronization jump width.
•
the phase error is negative, then PHASE_SEG2 is shortened by an amount equal to the
resynchronization jump width.
Autobaud Mode
The autobaud feature is enabled by setting the ABM field in the CAN_MR register. In this
mode, the CAN controller is only listening to the line without acknowledging the received messages. It can not send any message. The errors flags are updated. The bit timing can be
adjusted until no error occurs (good configuration found). In this mode, the error counters are
frozen. To go back to the standard mode, the ABM bit must be cleared in the CAN_MR
register.
Error Detection
There are five different error types that are not mutually exclusive. Each error concerns only
specific fields of the CAN data frame (refer to the Bosch CAN specification for their
correspondence):
Fault Confinement
486
•
CRC error (CERR bit in the CAN_SR register): With the CRC, the transmitter calculates a
checksum for the CRC bit sequence from the Start of Frame bit until the end of the Data
Field. This CRC sequence is transmitted in the CRC field of the Data or Remote Frame.
•
Bit-stuffing error (SERR bit in the CAN_SR register): If a node detects a sixth consecutive
equal bit level during the bit-stuffing area of a frame, it generates an Error Frame starting
with the next bit-time.
•
Bit error (BERR bit in CAN_SR register): A bit error occurs if a transmitter sends a
dominant bit but detects a recessive bit on the bus line, or if it sends a recessive bit but
detects a dominant bit on the bus line. An error frame is generated and starts with the next
bit time.
•
Form Error (FERR bit in the CAN_SR register): If a transmitter detects a dominant bit in
one of the fix-formatted segments CRC Delimiter, ACK Delimiter or End of Frame, a form
error has occurred and an error frame is generated.
•
Acknowledgment error (AERR bit in the CAN_SR register): The transmitter checks the
Acknowledge Slot, which is transmitted by the transmitting node as a recessive bit,
contains a dominant bit. If this is the case, at least one other node has received the frame
correctly. If not, an Acknowledge Error has occured and the transmitter will start in the next
bit-time an Error Frame transmission.
To distinguish between temporary and permanent failures, every CAN controller has two error
counters: REC (Receive Error Counter) and TEC (Transmit Error Counter). The counters are
incremented upon detected errors and respectively are decremented upon correct transmissions or receptions. Depending on the counter values, the state of the node changes: the
initial state of the CAN controller is Error Active, meaning that the controller can send Error
Active flags. The controller changes to the Error Passive state if there is an accumulation of
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errors. If the CAN controller fails or if there is an extreme accumulation of errors, there is a
state transition to Bus Off.
Figure 136. Line Error Mode
Init
TEC > 127
or
REC > 127
ERROR
PASSIVE
ERROR
ACTIVE
TEC < 127
and
REC < 127
128 occurences of 11 consecutive recessive bits
or
CAN controller reset
BUS OFF
TEC > 255
An error active unit takes part in bus communication and sends an active error frame when the
CAN controller detects an error.
An error passive unit cannot send an active error frame. It takes part in bus communication,
but when an error is detected, a passive error frame is sent. Also, after a transmission, an
error passive unit waits before initiating further transmission.
A bus off unit is not allowed to have any influence on the bus.
For fault confinment, two errors counters (TEC and REC) are implemented. These counters
are accessible via the CAN_ECR register. The state of the CAN controller is automatically
updated according to these counter values. If the CAN controller is in Error Active state, then
the ERRA bit is set in the CAN_SR register. The corresponding interrupt is pending while the
interrupt is not masked in the CAN_IMR register. If the CAN controller is in Error Passive
Mode, then the ERRP bit is set in the CAN_SR register and an interrupt remains pending while
the ERRP bit is set in the CAN_IMR register. If the CAN is in Bus-off Mode, then the BOFF bit
is set in the CAN_SR register. As for ERRP and ERRA, an interrupt is pending while the BOFF
bit is set in the CAN_IMR register.
When one of the error counters values exceeds 96, an increased error rate is indicated to the
controller through the WARN bit in CAN_SR register, but the node remains error active. The
corresponding interrupt is pending while the interrupt is set in the CAN_IMR register.
Refer to the Bosch CAN specification v2.0 for details on fault confinment.
Overload
The overload frame is provided to request a delay of the next data or remote frame by the
receiver node (“Request overload frame”) or to signal certain error conditions (“Reactive overload frame”) related to the intermission field respectively.
Reactive overload frames are transmitted after detection of the following error conditions:
•
Detection of a dominant bit during the first two bits of the intermission field
•
Detection of a dominant bit in the last bit of EOF by a receiver, or detection of a dominant
bit by a receiver or a transmitter at the last bit of an error or overload frame delimiter
The CAN controller can generate a request overload frame automatically after each message
sent to one of the CAN controller mailboxes. This feature is enabled by setting the OVL bit in
the CAN_MR register.
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Reactive overload frames are automatically handled by the CAN controller even if the OVL bit
in the CAN_MR register is not set. An overload flag is generated in the same way as an error
flag, but error counters do not increment.
Low-power mode
In Low-power Mode, the CAN controller cannot send or receive messages. All mailboxes are
inactive.
In Low-power Mode, the SLEEP signal in the CAN_SR register is set; otherwise, the WAKEUP
signal in the CAN_SR register is set. These two fields are exclusive except after a CAN controller reset (WAKEUP and SLEEP are stuck at 0 after a reset). After power-up reset, the Lowpower Mode is disabled and the WAKEUP bit is set in the CAN_SR register only after detection of 11 consecutive recessive bits on the bus.
Enabling Low-power
Mode
A software application can enable Low-power Mode by setting the LPM bit in the CAN_MR
global register. The CAN controller enters Low-power Mode once all pending transmit messages are sent.
When the CAN controller enters Low-power Mode, the SLEEP signal in the CAN_SR register
is set. Depending on the corresponding mask in the CAN_IMR register, an interrupt is generated while SLEEP is set.
The SLEEP signal in the CAN_SR register is automatically cleared once WAKEUP is set. The
WAKEUP signal is automatically cleared once SLEEP is set.
Reception is disabled while the SLEEP signal is set to one in the CAN_SR register. It is important to note that those messages with higher priority than the last message transmitted can be
received between the LPM command and entry in Low-power Mode.
Once in Low-power Mode, the CAN controller clock can be switched off by programming the
chip’s Power Management Controller (PMC). The CAN controller drains only the static current.
Error counters are disabled while the SLEEP signal is set to one.
Thus, to enter Low-power Mode, the software application must:
–
Set LPM field in the CAN_MR register
–
Wait for SLEEP signal rising
Now the CAN Controller clock can be disabled. This is done by programming the Power Management Controller (PMC).
Figure 137. Enabling Low-power Mode
Arbitration lost
Mailbox 1
CAN BUS
Mailbox 3
LPEN= 1
LPM
(CAN_MR)
SLEEP
(CAN_SR)
WAKEUP
(CAN_SR)
MRDY
(CAN_MSR1)
MRDY
(CAN_MSR3)
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Disabling Low-power
Mode
The CAN controller can be awake after detecting a CAN bus activity. Bus activity detection is
done by an external module that may be embedded in the chip. When it is notified of a CAN
bus activity, the software application disables Low-power Mode by programming the CAN
controller.
To disable Low-power Mode, the software application must:
–
Enable the CAN Controller clock. This is done by programming the Power
Management Controller (PMC).
–
Clear LPM field in the CAN_MR register
The CAN controller synchronizes itself with the bus activity by checking for eleven consecutive
“recessive” bits. Once synchronized, the WAKEUP signal in the CAN_SR register is set.
Depending on the corresponding mask in the CAN_IMR register, an interrupt is generated
while WAKEUP is set. The SLEEP signal in the CAN_SR register is automatically cleared
once WAKEUP is set. WAKEUP signal is automatically cleared once SLEEP is set.
If no message is being sent on the bus, then the CAN controller is able to send a message
eleven bit times after disabling Low-power Mode.
If there is bus activity when Low-power mode is disabled, the CAN controller is synchronized
with the bus activity in the next interframe. The previous message is lost (see Figure 138).
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Figure 138. Disabling Low-power Mode
Bus Activity Detected
CAN BUS
LPM
(CAN_MR)
Message lost
Message x
Interframe synchronization
SLEEP
(CAN_SR)
WAKEUP
(CAN_SR)
MRDY
(CAN_MSRx)
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Functional Description
CAN Controller
Initialization
After power-up reset, the CAN controller is disabled. The CAN controller clock must be activated by the Power Management Controller (PMC) and the CAN controller interrupt line must
be enabled by the interrupt controller (AIC).
The CAN controller must be initialized with the CAN network parameters. The CAN_BR register defines the sampling point in the bit time period. CAN_BR must be set before the CAN
controller is enabled by setting the CANEN field in the CAN_MR register.
The CAN controller is enabled by setting the CANEN flag in the CAN_MR register. At this
stage, the internal CAN controller state machine is reset, error counters are reset to 0, error
flags are reset to 0.
Once the CAN controller is enabled, bus synchronization is done automatically by scanning
eleven recessive bits. The WAKEUP bit in the CAN_SR register is automatically set to 1 when
the CAN controller is synchronized (WAKEUP and SLEEP are stuck at 0 after a reset).
The CAN controller can start listening to the network in Autobaud Mode. In this case, the error
counters are locked and a mailbox is configured in Receive Mode. By scanning error flags, the
CAN_BR register values synchronized with the network. Once no error has been detected, the
application disables the Autobaud Mode, clearing the ABM field in the CAN_MR register.
Figure 139. Possible Initialization Procedure
Enable CAN Controller Clock
(PMC)
Enable CAN Controller Interrupt Line
(AIC)
Configure a Mailbox in Reception Mode
Change CAN_BR value
(ABM == 1 and CANEN == 1)
Errors ?
Yes
(CAN_SR or CAN_MSRx)
No
ABM = 0 and CANEN = 0
CANEN = 1 (ABM == 0)
End of Initialization
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CAN Controller
Interrupt Handling
There are two different types of interrupts. One type of interrupt is a message-object related
interrupt, the other is a system interrupt that handles errors or system-related interrupt
sources.
All interrupt sources can be masked by writing the corresponding field in the CAN_IDR register. They can be unmasked by writing to the CAN_IER register. After a power-up reset, all
interrupt sources are disabled (masked). The current mask status can be checked by reading
the CAN_IMR register.
The CAN_SR register gives all interrupt source states.
The following events may initiate one of the two interrupts:
•
•
Message object interrupt
–
Data registers in the mailbox object are available to the application. In Receive
Mode, a new message was received. In Transmit Mode, a message was
transmitted successfully.
–
A sent transmission was aborted.
System interrupts
–
Bus-off interrupt: The CAN module enters the bus-off state.
–
Error-passive interrupt: The CAN module enters Error Passive Mode.
–
Error-active Mode: The CAN module is neither in Error Passive Mode nor in Busoff mode.
–
Warn Limit interrupt: The CAN module is in Error-active Mode, but at least one of
its error counter value exceeds 96.
–
Wake-up interrupt: This interrupt is generated after a wake-up and a bus
synchronization.
–
Sleep interrupt: This interrupt is generated after a Low-power Mode enable once all
pending messages in transmission have been sent.
–
Internal timer counter overflow interrupt: This interrupt is generated when the
internal timer rolls over.
–
Timestamp interrupt: This interrupt is generated after the reception or the
transmission of a start of frame or an end of frame. The value of the internal
counter is copied in the CAN_TIMESTP register.
All interrupts are cleared by clearing the interrupt source except for the internal timer counter
overflow interrupt and the timestamp interrupt. These interrupts are cleared by reading the
CAN_SR register.
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CAN Controller
Message Handling
Receive Handling
Two modes are available to configure a mailbox to receive messages. In Receive Mode, the
first message received is stored in the mailbox data register. In Receive with Overwrite
Mode, the last message received is stored in the mailbox.
Simple Receive Mailbox
A mailbox is in Receive Mode once the MOT field in the CAN_MMRx register has been configured. Message ID and Message Acceptance Mask must be set before the Receive Mode is
enabled.
After Receive Mode is enabled, the MRDY flag in the CAN_MSR register is automatically
cleared until the first message is received. When the first message has been accepted by the
mailbox, the MRDY flag is set. An interrupt is pending for the mailbox while the MRDY flag is
set. This interrupt can be masked depending on the mailbox flag in the CAN_IMR global
register.
Message data are stored in the mailbox data register until the software application notifies that
data processing has ended. This is done by asking for a new transfer command, setting the
MTCR flag in the CAN_MCRx register. This automatically clears the MRDY signal.
The MMI flag in the CAN_MSRx register notifies the software that a message has been lost by
the mailbox. This flag is set when messages are received while MRDY is set in the
CAN_MSRx register. This flag is cleared by reading the CAN_MSRs register. A receive mailbox prevents from overwriting the first message by new ones while MRDY flag is set in the
CAN_MSRx register. See Figure 140.
Figure 140. Receive Mailbox
Message ID = CAN_MIDx
CAN BUS
Message 1
Message 2 lost
Message 3
MRDY
(CAN_MSRx)
MMI
(CAN_MSRx)
(CAN_MDLx
CAN_MDHx)
Message 1
Message 3
MTCR
(CAN_MCRx)
Reading CAN_MSRx
Reading CAN_MDHx & CAN_MDLx
Writing CAN_MCRx
Note:
In the case of ARM architecture, CAN_MSRx, CAN_MDLx, CAN_MDHx can be read using an optimized ldm assembler
instruction.
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Receive with Overwrite
Mailbox
A mailbox is in Receive with Overwrite Mode once the MOT field in the CAN_MMRx register
has been configured. Message ID and Message Acceptance masks must be set before
Receive Mode is enabled.
After Receive Mode is enabled, the MRDY flag in the CAN_MSR register is automatically
cleared until the first message is received. When the first message has been accepted by the
mailbox, the MRDY flag is set. An interrupt is pending for the mailbox while the MRDY flag is
set. This interrupt is masked depending on the mailbox flag in the CAN_IMR global register.
If a new message is received while the MRDY flag is set, this new message is stored in the
mailbox data register, overwriting the previous message. The MMI flag in the CAN_MSRx register notifies the software that a message has been dropped by the mailbox. This flag is
cleared when reading the CAN_MSRx register.
The CAN controller may store a new message in the CAN data registers while the application
reads them. To check that CAN_MDHx and CAN_MDLx do not belong to different messages,
the application must check the MMI field in the CAN_MSRx register before and after reading
CAN_MDHx and CAN_MDLx. If the MMI flag is set again after the data registers have been
read, the software application has to re-read CAN_MDHx and CAN_MDLx (see Figure 141).
Figure 141. Receive with Overwrite Mailbox
Message ID = CAN_MIDx
CAN BUS
Message 1
Message 2
Message 3
Message 4
MRDY
(CAN_MSRx)
MMI
(CAN_MSRx)
(CAN_MDLx
CAN_MDHx)
Message 1
Message 2
Message 3
Message 4
MTCR
(CAN_MCRx)
Reading CAN_MSRx
Reading CAN_MDHx & CAN_MDLx
Writing CAN_MCRx
Chaining Mailboxes
Several mailboxes may be used to receive a buffer split into several messages with the same
ID. In this case, the mailbox with the lowest number is serviced first. The field PRIOR in the
CAN_MMRx register has no effect. If Mailbox 0 and Mailbox 5 accept messages with the
same ID, the first message is received by Mailbox 0 and the second message is received by
Mailbox 5. Mailbox 0 must be configured in Receive Mode (i.e., the first message received is
considered) and Mailbox 5 must be configured in Receive with Overwrite Mode. Mailbox 0
cannot be configured in Receive with Overwrite Mode; otherwise, all messages are accepted
by this mailbox and Mailbox 5 is never serviced.
If several mailboxes are chained to receive a buffer split into several messages, all mailboxes
except the last one (with the highest number) must be configured in Receive Mode. The first
message received is handled by the first mailbox, the second one is refused by the first mailbox and accepted by the second mailbox, the last message is accepted by the last mailbox
and refused by previous ones (see Figure 142).
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Figure 142. Chaining Three Mailboxes to Receive a Buffer Split into Three Messages
Buffer split in 3 messages
CAN BUS
Message s1
Message s2
Message s3
MRDY
(CAN_MSRx)
MMI
(CAN_MSRx)
MRDY
(CAN_MSRy)
MMI
(CAN_MSRy)
MRDY
(CAN_MSRz)
MMI
(CAN_MSRz)
Reading CAN_MSRx, CAN_MSRy and CAN_MSRz
Reading CAN_MDH & CAN_MDL for mailboxes x, y and z
Writing MBx MBy MBz in CAN_TCR
If the number of mailboxes is not sufficient (the MMI flag of the last mailbox raises), the user
must read each data received on the last mailbox in order to retrieve all the messages of the
buffer split (see Figure 143).
Figure 143. Chaining Three Mailboxes to Receive a Buffer Split into Four Messages
Buffer split in 4 messages
CAN BUS
Message s1
Message s2
Message s3
Message s4
MRDY
(CAN_MSRx)
MMI
(CAN_MSRx)
MRDY
(CAN_MSRy)
MMI
(CAN_MSRy)
MRDY
(CAN_MSRz)
MMI
(CAN_MSRz)
Reading CAN_MSRx, CAN_MSRy and CAN_MSRz
Reading CAN_MDH & CAN_MDL for mailboxes x, y and z
Writing MBx MBy MBz in CAN_TCR
495
6042A–ATARM–23-Dec-04
Transmission
Handling
A mailbox is in Transmit Mode once the MOT field in the CAN_MMRx register has been configured. Message ID and Message Acceptance mask must be set before Receive Mode is
enabled.
After Transmit Mode is enabled, the MRDY flag in the CAN_MSR register is automatically set
until the first command is sent. When the MRDY flag is set, the software application can prepare a message to be sent by writing to the CAN_MDx registers. The message is sent once
the software asks for a transfer command setting the MTCR bit and the message data length
in the CAN_MCRx register.
The MRDY flag remains at zero as long as the message has not been sent or aborted. It is
important to note that no access to the mailbox data register is allowed while the MRDY flag is
cleared. An interrupt is pending for the mailbox while the MRDY flag is set. This interrupt can
be masked depending on the mailbox flag in the CAN_IMR global register.
It is also possible to send a remote frame setting the MRTR bit instead of setting the MDLC
field. The answer to the remote frame is handled by another reception mailbox. In this case,
the device acts as a consumer but with the help of two mailboxes. It is possible to handle the
remote frame emission and the answer reception using only one mailbox configured in Consumer Mode. Refer to the section “Remote Frame Handling” on page 497.
Several messages can try to win the bus arbitration in the same time. The message with the
highest priority is sent first. Several transfer request commands can be generated in the same
time by setting MBx bits in the CAN_MTCR register. The priority is set in the PRIOR field of
the CAN_MMRx register. Priority 0 is the highest priority, priority 15 is the lowest priority. Thus
it is possible to use a part of the message ID to set the PRIOR field. If two mailboxes have the
same priority, the message of the mailbox with the lowest number is sent first. Thus if mailbox
0 and mailbox 5 have the same priority and have a message to send at the same time, then
the message of the mailbox 0 is sent first.
Setting the MACR bit in the CAN_MCRx register aborts the transmission. Transmission for
several mailboxes can be aborted by writing MBx fields in the CAN_MACR register. If the
message is being sent when the abort command is set, then the application is notified by the
MRDY bit set and not the MABT in the CAN_MSRx register. Otherwise, if the message has
not been sent, then the MRDY and the MABT are set in the CAN_MSR register.
When the bus arbitration is lost by a mailbox message, the CAN controller tries to win the next
bus arbitration with the same message if this one still has the highest priority. Messages to be
sent are re-tried automatically until they win the bus arbitration. This feature can be disabled
by setting the bit DRPT in the CAN_MR register. In this case if the message was not sent the
first time it was transmitted to the CAN transceiver, it is automatically aborted. The MABT flag
is set in the CAN_MSRx register until the next transfer command.
Figure 144 shows three MBx message attempts being made (MRDY of MBx set to 0).
The first MBx message is sent, the second is aborted and the last one is trying to be aborted
but too late bacause it has already been transmitted to the CAN transceiver.
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Figure 144. Transmitting Messages
CAN BUS
MBx message
MBx message
MRDY
(CAN_MSRx)
MABT
(CAN_MSRx)
MTCR
(CAN_MCRx)
MACR
(CAN_MCRx)
Abort MBx message
Try to Abort MBx message
Reading CAN_MSRx
Writing CAN_MDHx &
CANMDLx
Remote Frame
Handling
Producer/consumer model is an efficient means of handling broadcasted messages. The push
model allows a producer to broadcast messages; the pull model allows a customer to ask for
messages.
Figure 145. Producer / Consumer Model
Producer
Request
PUSH MODEL
CAN Data Frame
Consumer
Indication(s)
PULL MODEL
Producer
Indications
Response
Consumer
CAN Remote Frame
Request(s)
CAN Data Frame
Confirmation(s)
In Pull Mode, a consumer transmits a remote frame to the producer. When the producer
receives a remote frame, it sends the answer accepted by one or many consumers. Using
transmit and receive mailboxes, a consumer must dedicate two mailboxes, one in Transmit
Mode to send remote frames, and at least one in Receive Mode to capture the producer’s
answer. The same structure is applicable to a producer: one reception mailbox is required to
get the remote frame and one transmit mailbox to answer.
497
6042A–ATARM–23-Dec-04
Mailboxes can be configured in Producer or Consumer Mode. A lonely mailbox can handle the
remote frame and the answer. With sixteen mailboxes, the CAN controller can handle sixteen
independent producers/consumers.
Producer Configuration
A mailbox is in Producer Mode once the MOT field in the CAN_MMRx register has been configured. Message ID and Message Acceptance masks must be set before Receive Mode is
enabled.
After Producer Mode is enabled, the MRDY flag in the CAN_MSR register is automatically set
until the first transfer command. The software application prepares data to be sent by writing
to the CAN_MDHx and the CAN_MDLx register then by setting the MTCR register in the
CAN_MCRx register. Data is sent after the reception of a remote frame as soon as it wins the
bus arbitration.
The MRDY flag remains at zero as long as the message has not been sent or aborted. No
access to the mailbox data register can be done while MRDY flag is cleared. An interrupt is
pending for the mailbox while the MRDY flag is set. This interrupt can be masked according to
the mailbox flag in the CAN_IMR global register.
If a remote frame is received while no data are ready to be sent (signal MRDY set in the
CAN_MSRx register), then the MMI signal is set in the CAN_MSRx register. This bit is cleared
by reading the CAN_MSRx register.
The MRTR field in the CAN_MSRx register has no meaning. This field is used only when using
Receive and Receive with Overwrite modes.
After a remote frame has been received, the mailbox functions like a transmit mailbox. The
message with the highest priority is sent first. The transmitted message is aborted by setting
the MACR field in the MAC_MCR register. Please refer to the section “Transmission Handling”
on page 496.
Figure 146. Producer Handling
Remote Frame
CAN BUS
Message 1
Remote Frame
Remote Frame
Message 2
MRDY
(CAN_MSRx)
MMI
(CAN_MSRx)
Reading CAN_MSRx
MTCR
(CAN_MCRx)
(CAN_MDLx
CAN_MDHx)
Message 1
Consumer Configuration
Message 2
A mailbox is in Consumer Mode once the MOT field in the CAN_MMRx register has been configured. Message ID and Message Acceptance masks must be set before Receive Mode is
enabled.
After Consumer Mode is enabled, the MRDY flag in the CAN_MSR register is automatically
cleared until the first transfer request command. The software application sends a remote
frame by setting the MTCR bit in the CAN_MCRx register or the MBx bit in the global
CAN_TCR register. The application is notified of the answer by the MRDY flag set in the
CAN_MSRx register. The application can read the data contents in the CAN_MDHx and
CAN_MDLx registers. An interrupt is pending for the mailbox while the MRDY flag is set. This
interrupt can be masked according to the mailbox flag in the CAN_IMR global register.
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The MRTR field in the CAN_MCRx register has no effect. This field is used only when using
Transmit Mode.
After a remote frame has been sent, the consumer mailbox functions as a reception mailbox.
The first message received is stored in the mailbox data registers. If other messages intended
for this mailbox have been sent while the MRDY flag is set in the CAN_MSRx register, they
will be lost. The application is notified by reading the MMI field in the CAN_MSRx register. The
read operation automatically clears the MMI flag.
If several messages are answered by the Producer, the CAN controller may have one mailbox
in consumer configuration, zero or several mailboxes in Receive Mode and one mailbox in
Receive with Overwrite Mode. In this case, the consumer mailbox must have a lower number
than the Receive with Overwrite mailbox (e.g., MBX0 and MBX3). The transfer command can
be triggered for all mailboxes at the same time by setting several MBx fields in the CAN_TCR
register.
Figure 147. Consumer Handling
CAN BUS
Remote Frame
Message x
Remote Frame
Message y
MRDY
(CAN_MSRx)
MMI
(CAN_MSRx)
MTCR
(CAN_MCRx)
(CAN_MDLx
CAN_MDHx)
Message x
Message y
499
6042A–ATARM–23-Dec-04
CAN Controller
Timing Modes
Using the free running 16-bit internal timer, the CAN controller can be set in one of the two following timing modes:
•
Timestamping Mode: The value of the internal timer is captured at each Start Of Frame or
each End Of Frame.
•
Time Triggered Mode: The mailbox transfer operation is triggered when the internal timer
reaches the mailbox trigger.
Timestamping Mode is enabled by clearing the TTM bit in the CAN_MR register. Time Triggered Mode is enabled by setting the TTM bit in the CAN_MR register.
Timestamping Mode
Each mailbox has its own timestamp value. Each time a message is sent or received by a
mailbox, the 16-bit value MTIMESTAMP of the CAN_TIMESTP register is transfered to the
LSB bits of the CAN_MSRx register. The value read in the CAN_MSRx register correponds to
the internal timer value at the Start Of Frame or the End Of Frame of the message handled by
the mailbox.
Figure 148. Mailbox Timestamp
Start of Frame
CAN BUS
End of Frame
Message 1
Message 2
CAN_TIM
TEOF
(CAN_MR)
TIMESTAMP
(CAN_TSTP)
Timestamp 1
MTIMESTAMP
(CAN_MSRx)
Timestamp 1
Timestamp 2
MTIMESTAMP
(CAN_MSRy)
Time Triggered Mode
Timestamp 2
In Time Triggered Mode, basic cycles can be split into several time windows. A basic cycle
starts with a reference message. Each time a window is defined from the reference message,
a transmit operation should occur within a pre-defined time window. A mailbox must not win
the arbitration in a previous time window, and it must not be retried if the arbitration is lost in
the time window.
Figure 149. Time Triggered Operations
Time Cycle
Reference
Message
Reference
Message
Time Windows for Messages
Global Time
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Time Trigger Mode is enabled by setting the TTM field in the CAN_MR register. In Time Triggered Mode, as in Timestamp Mode, the CAN_TIMESTP field captures the values of the
internal counter, but the MTIMESTAMP fields in the CAN_MSRx registers are not active and
are read at 0.
Synchronization by a
Reference Message
In Time Triggered Mode, the internal timer counter is automatically reset when a new message is received in the last mailbox. This reset occurs after the reception of the End Of Frame
on the rising edge of the MRDY signal in the CAN_MSRx register. This allows synchronization
of the internal timer counter with the reception of a reference message and the start a new
time window.
Transmitting within a
Time Window
A time mark is defined for each mailbox. It is defined in the 16-bit MTIMEMARK field of the
CAN_MMRx register. At each internal timer clock cycle, the value of the CAN_TIM is compared with e ach ma ilbox time mark. Whe n the internal timer counter reaches the
MTIMEMARK value, an internal timer event for the mailbox is generated for the mailbox.
In Time Triggered Mode, transmit operations are delayed until the internal timer event for the
mailbox. The application prepares a message to be sent by setting the MTCR in the
CAN_MCRx register. The message is not sent until the CAN_TIM value is less than the
MTIMEMARK value defined in the CAN_MMRx register.
If the transmit operation is failed, i.e., the message loses the bus arbitration and the next transmit attempt is delayed until the next internal time trigger event. This prevents overlapping the
next time window, but the message is still pending and is retried in the next time window when
CAN_TIM value equals the MTIMEMARK value. It is also possible to prevent a retry by setting
the DRPT field in the CAN_MR register.
Freezing the Internal
Timer Counter
The internal counter can be frozen by setting TIMFRZ in the CAN_MR register. This prevents
an unexpected roll-over when the counter reaches FFFFh. When this occurs, it automatically
freezes until a new reset is issued, either due to a message received in the last mailbox or any
other reset counter operations. The TOVF bit in the CAN_SR register is set when the counter
is frozen. The TOVF bit in the CAN_SR register is cleared by reading the CAN_SR register.
Depending on the corresponding interrupt mask in the CAN_IMR register, an interrupt is generated when TOVF is set.
501
6042A–ATARM–23-Dec-04
Figure 150. Time Triggered Operations
Message x
Arbitration Lost
End of Frame
CAN BUS
Reference
Message
Message y
Arbitration Win
Message y
Internal Counter Reset
CAN_TIM
Cleared by software
MRDY
(CAN_MSRlast_mailbox_number)
Timer Event x
MTIMEMARKx == CAN_TIM
MRDY
(CAN_MSRx)
MTIMEMARKy == CAN_TIM
Timer Event y
MRDY
(CAN_MSRy)
Time Window
Basic Cycle
Message x
Arbitration Win
End of Frame
CAN BUS
Reference
Message
Message x
Internal Counter Reset
CAN_TIM
Cleared by software
MRDY
(CAN_MSRlast_mailbox_number)
Timer Event x
MTIMEMARKx == CAN_TIM
MRDY
(CAN_MSRx)
Time Window
Basic Cycle
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AT91SAM7A3 Preliminary
Controller Area Network (CAN) Controller User Interface
Table 63. Controller Area Network (CAN) Register Mapping
Offset
Register
Name
Access
Reset State
0x0000
Mode Register
CAN_MR
Read-Write
0x0
0x0004
Interrupt Enable Register
CAN_IER
Write-only
-
0x0008
Interrupt Disable Register
CAN_IDR
Write-only
-
0x000C
Interrupt Mask Register
CAN_IMR
Read-only
0x0
0x0010
Status Register
CAN_SR
Read-only
0x0
0x0014
Baudrate Register
CAN_BR
Read/Write
0x0
0x0018
Timer Register
CAN_TIM
Read-only
0x0
0x001C
Timestamp Register
CAN_TIMESTP
Read-only
0x0
0x0020
Error Counter Register
CAN_ECR
Read-only
0x0
0x0024
Transfer Command Register
CAN_TCR
Write-only
-
0x0028
Abort Command Register
CAN_ACR
Write-only
-
–
–
–
0x0100 - 0x01FC
Reserved
0x0200
Mailbox 0 Mode Register
CAN_MMR0
Read/Write
0x0
0x0204
Mailbox 0 Acceptance Mask Register
CAN_MAM0
Read/Write
0x0
0x0208
Mailbox 0 ID Register
CAN_MID0
Read/Write
0x0
0x020C
Mailbox 0 Family ID Register
CAN_MFID0
Read-only
0x0
0x0210
Mailbox 0 Status Register
CAN_MSR0
Read-only
0x0
0x0214
Mailbox 0 Data Low Register
CAN_MDL0
Read/Write
0x0
0x0218
Mailbox 0 Data High Register
CAN_MDH0
Read/Write
0x0
0x021C
Mailbox 0 Control Register
CAN_MCR0
Write-only
-
0x0220
Mailbox 1 Mode Register
CAN_MMR1
Read/Write
0x0
0x0224
Mailbox 1 Acceptance Mask Register
CAN_MAM1
Read/Write
0x0
0x0228
Mailbox 1 ID register
CAN_MID1
Read/Write
0x0
0x022C
Mailbox 1 Family ID Register
CAN_MFID1
Read-only
0x0
0x0230
Mailbox 1 Status Register
CAN_MSR1
Read-only
0x0
0x0234
Mailbox 1 Data Low Register
CAN_MDL1
Read/Write
0x0
0x0238
Mailbox 1 Data High Register
CAN_MDH1
Read/Write
0x0
0x023C
Mailbox 1 Control Register
CAN_MCR1
Write-only
-
...
...
-
...
...
503
6042A–ATARM–23-Dec-04
CAN Mode Register
Name:
CAN_MR
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
DRPT
6
TIMFRZ
5
TTM
4
TEOF
3
OVL
2
ABM
1
LPM
0
CANEN
• CANEN: CAN Controller Enable
0 = The CAN Controller is disabled.
1 = The CAN Controller is enabled.
• LPM: Disable/Enable Low Power Mode
w Power Mode.
1 = Enable Low Power M
CAN controller enters Low Power Mode once all pending messages have been transmitted.
• ABM: Disable/Enable Autobaud/Listen mode
0 = Disable Autobaud/listen mode.
1 = Enable Autobaud/listen mode.
• OVL: Disable/Enable Overload Frame
0 = No overload frame is generated.
1 = An overload frame is generated after each successful reception for mailboxes configured in Receive with/without overwrite Mode, Producer and Consumer.
• TEOF: Timestamp messages at each end of Frame
0 = The value of CAN_TIM is captured in the CAN_TIMESTP register at each Start Of Frame.
1 = The value of CAN_TIM is captured in the CAN_TIMESTP register at each End Of Frame.
• TTM: Disable/Enable Time Triggered Mode
0 = Time Triggered Mode is disabled.
1 = Time Triggered Mode is enabled.
• TIMFRZ: Enable Timer Freeze
0 = The internal timer continues to be incremented after it reached 0xFFFF.
1 = The internal timer stops incrementing after reaching 0xFFFF. It is restarted after a timer reset. See “Freezing the Internal Timer Counter” on page 501.
• DRPT: Disable Repeat
0 = When a transmit mailbox loses the bus arbitration, the transfer request remains pending.
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6042A–ATARM–23-Dec-04
AT91SAM7A3 Preliminary
1 = When a transmit mailbox lose the bus arbitration, the transfer request is automatically aborted. It automatically raises
the MABT and MRDT flags in the corresponding CAN_MSRx.
505
6042A–ATARM–23-Dec-04
CAN Interrupt Enable Register
Name:
CAN_IER
Access Type:
Write-only
31
–
30
–
29
–
28
BERR
27
FERR
26
AERR
25
SERR
24
CERR
23
TSTP
22
TOVF
21
WAKEUP
20
SLEEP
19
BOFF
18
ERRP
17
WARN
16
ERRA
15
MB15
14
MB14
13
MB13
12
MB12
11
MB11
10
MB10
9
MB9
8
MB8
7
MB7
6
MB6
5
MB5
4
MB4
3
MB3
2
MB2
1
MB1
0
MB0
• MBx: Mailbox x Interrupt Enable
0 = No effect.
1 = Enable Mailbox x interrupt.
• ERRA: Error Active mode Interrupt Enable
0 = No effect.
1 = Enable ERRA interrupt.
• WARN: Warning Limit Interrupt Enable
0 = No effect.
1 = Enable WARN interrupt.
• ERRP: Error Passive mode Interrupt Enable
0 = No effect.
1 = Enable ERRP interrupt.
• BOFF: Bus-off mode Interrupt Enable
0 = No effect.
1 = Enable BOFF interrupt.
• SLEEP: Sleep Interrupt Enable
0 = No effect.
1 = Enable SLEEP interrupt.
• WAKEUP: Wakeup Interrupt Enable
0 = No effect.
1 = Enable SLEEP interrupt.
• TOVF: Timer Overflow Interrupt Enable
0 = No effect.
1 = Enable TOVF interrupt.
• TSTP: TimeStamp Interrupt Enable
0 = No effect.
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1 = Enable TSTP interrupt.
• CERR: CRC Error Interrupt Enable
0 = No effect.
1 = Enable CRC Error interrupt.
• SERR: Stuffing Error Interrupt Enable
0 = No effect.
1 = Enable Stuffing Error interrupt.
• AERR: Acknowledgment Error Interrupt Enable
0 = No effect.
1 = Enable Acknowledgment Error interrupt.
• FERR: Form Error Interrupt Enable
0 = No effect.
1 = Enable Form Error interrupt.
• BERR: Bit Error Interrupt Enable
0 = No effect.
1 = Enable Bit Error interrupt.
507
6042A–ATARM–23-Dec-04
CAN Interrupt Disable Register
Name:
CAN_IDR
Access Type:
Write-only
31
–
30
–
29
–
28
BERR
27
FERR
26
AERR
25
SERR
24
CERR
23
TSTP
22
TOVF
21
WAKEUP
20
SLEEP
19
BOFF
18
ERRP
17
WARN
16
ERRA
15
MB15
14
MB14
13
MB13
12
MB12
11
MB11
10
MB10
9
MB9
8
MB8
7
MB7
6
MB6
5
MB5
4
MB4
3
MB3
2
MB2
1
MB1
0
MB0
• MBx: Mailbox x Interrupt Disable
0 = No effect.
1 = Disable Mailbox x interrupt.
• ERRA: Error Active Mode Interrupt Disable
0 = No effect.
1 = Disable ERRA interrupt.
• WARN: Warning Limit Interrupt Disable
0 = No effect.
1 = Disable WARN interrupt.
• ERRP: Error Passive mode Interrupt Disable
0 = No effect.
1 = Disable ERRP interrupt.
• BOFF: Bus-off mode Interrupt Disable
0 = No effect.
1 = Disable BOFF interrupt.
• SLEEP: Sleep Interrupt Disable
0 = No effect.
1 = Disable SLEEP interrupt.
• WAKEUP: Wakeup Interrupt Disable
0 = No effect.
1 = Disable WAKEUP interrupt.
• TOVF: Timer Overflow Interrupt
0 = No effect.
1 = Disable TOVF interrupt.
• TSTP: TimeStamp Interrupt Disable
0 = No effect.
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1 = Disable TSTP interrupt.
• CERR: CRC Error Interrupt Disable
0 = No effect.
1 = Disable CRC Error interrupt.
• SERR: Stuffing Error Interrupt Disable
0 = No effect.
1 = Disable Stuffing Error interrupt.
• AERR: Acknowledgment Error Interrupt Disable
0 = No effect.
1 = Disable Acknowledgment Error interrupt.
• FERR: Form Error Interrupt Disable
0 = No effect.
1 = Disable Form Error interrupt.
• BERR: Bit Error Interrupt Disable
0 = No effect.
1 = Disable Bit Error interrupt.
509
6042A–ATARM–23-Dec-04
CAN Interrupt Mask Register
Name:
CAN_IMR
Access Type:
Read-only
31
–
30
–
29
–
28
BERR
27
FERR
26
AERR
25
SERR
24
CERR
23
TSTP
22
TOVF
21
WAKEUP
20
SLEEP
19
BOFF
18
ERRP
17
WARN
16
ERRA
15
MB15
14
MB14
13
MB13
12
MB12
11
MB11
10
MB10
9
MB9
8
MB8
7
MB7
6
MB6
5
MB5
4
MB4
3
MB3
2
MB2
1
MB1
0
MB0
• MBx: Mailbox x Interrupt Mask
0 = Mailbox x interrupt is disabled.
1 = Mailbox x interrupt is enabled.
• ERRA: Error Active mode Interrupt Mask
0 = ERRA interrupt is disabled..
1 = ERRA interrupt is enabled.
• WARN: Warning Limit Interrupt Mask
0 = Warning Limit interrupt is disabled.
1 = Warning Limit interrupt is enabled.
• ERRP: Error Passive Mode Interrupt Mask
0 = ERRP interrupt is disabled.
1 = ERRP interrupt is enabled.
• BOFF: Bus-off Mode Interrupt Mask
0 = BOFF interrupt is disabled.
1 = BOFF interrupt is enabled.
• SLEEP: Sleep Interrupt Mask
0 = SLEEP interrupt is disabled.
1 = SLEEP interrupt is enabled.
• WAKEUP: Wakeup Interrupt Mask
0 = WAKEUP interrupt is disabled.
1 = WAKEUP interrupt is enabled.
• TOVF: Timer Overflow Interrupt Mask
0 = TOVF interrupt is disabled.
1 = TOVF interrupt is enabled.
• TSTP: Timestamp Interrupt Mask
0 = TSTP interrupt is disabled.
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1 = TSTP interrupt is enabled.
• CERR: CRC Error Interrupt Mask
0 = CRC Error interrupt is disabled.
1 = CRC Error interrupt is enabled.
• SERR: Stuffing Error Interrupt Mask
0 = Bit Stuffing Error interrupt is disabled.
1 = Bit Stuffing Error interrupt is enabled.
• AERR: Acknowledgment Error Interrupt Mask
0 = Acknowledgment Error interrupt is disabled.
1 = Acknowledgment Error interrupt is enabled.
• FERR: Form Error Interrupt Mask
0 = Form Error interrupt is disabled.
1 = Form Error interrupt is enabled.
• BERR: Bit Error Interrupt Mask
0 = Bit Error interrupt is disabled.
1 = Bit Error interrupt is enabled.
511
6042A–ATARM–23-Dec-04
CAN Status Register
Name:
CAN_SR
Access Type:
Read-only
31
OVLSY
30
TBSY
29
RBSY
28
BERR
27
FERR
26
AERR
25
SERR
24
CERR
23
TSTP
22
TOVF
21
WAKEUP
20
SLEEP
19
BOFF
18
ERRP
17
WARN
16
ERRA
15
MB15
14
MB14
13
MB13
12
MB12
11
MB11
10
MB10
9
MB9
8
MB8
7
MB7
6
MB6
5
MB5
4
MB4
3
MB3
2
MB2
1
MB1
0
MB0
• MBx: Mailbox x Event
0 = No event occured on Mailbox x.
1 = An event occured on Mailbox x.
An event corresponds to MRDY, MABT fields in the CAN_MSRx register.
• ERRA: Error Active mode
0 = CAN controller is not in error active mode
1 = CAN controller is in error active mode
This flag is set depending on TEC and REC counter values. It is set when node is neither in error passive mode nor in bus
off mode.
This flag is automatically reset when above condition is not satisfied.
• WARN: Warning Limit
0 = CAN controller Warning Limit is not reached.
1 = CAN controller Warning Limit is reached.
This flag is set depending on TEC and REC counters values. It is set when at least one of the counters values exceeds 96.
This flag is automatically reset when above condition is not satisfied.
• ERRP: Error Passive mode
0 = CAN controller is not in error passive mode
1 = CAN controller is in error passive mode
This flag is set depending on TEC and REC counters values.
A node is error passive when TEC counter is greater or equal to 128 (decimal) or when the REC counter is greater or equal
to 128 (decimal) and less than 256.
This flag is automatically reset when above condition is not satisfied.
• BOFF: Bus Off mode
0 = CAN controller is not in bus-off mode
1 = CAN controller is in bus-off mode
This flag is set depending on TEC counter value. A node is bus off when TEC counter is greater or equal to 256 (decimal).
512
AT91SAM7A3 Preliminary
6042A–ATARM–23-Dec-04
AT91SAM7A3 Preliminary
This flag is automatically reset when above condition is not satisfied.
• SLEEP: CAN controller in Low power Mode.
0 = CAN controller is not in low power mode.
1 = CAN controller is in low power mode.
This flag is automatically reset when Low power mode is disabled
• WAKEUP: CAN controller is not in Low power Mode.
0 = CAN controller is in low power mode.
1 = CAN controller is not in low power mode.
When a WAKEUP event occurs, the CAN controller is synchronized with the bus activity. Messages can be transmitted or
received. The CAN controller clock must be available when a WAKEUP event occurs. This flag is automatically reset when
the CAN Controller enters Low Power mode.
• TOVF: Timer Overflow
0 = The timer has not rolled-over FFFFh to 0000h.
1 = The timer rolls-over FFFFh to 0000h.
This flag is automatically cleared reading CAN_SR register.
• TSTP Timestamp
0 = No bus activity has been detected.
1 = A start of frame or an end of frame has been detected (according to the TEOF field in the CAN_MR register).
This flag is automatically cleared by reading the CAN_SR register.
• CERR: Mailbox CRC Error
0 = No CRC error occurred during a previous transfer.
1 = A CRC error occurred during a previous transfer.
A CRC error has been detected during last reception.
This flag is automatically cleared reading CAN_SR register.
• SERR: Mailbox Stuffing Error
0 = No stuffing error occurred during a previous transfer.
1 = A stuffing error occurred during a previous transfer.
A form error results from the detection of more than five consecutive bit with the same polarity.
This flag is automatically cleared by reading CAN_SR register.
• AERR: Acknowledgment Error
0 = No acknowledgment error occured during a previous transfer.
1 = An acknowledgment error occured during a previous transfer.
An acknowledgment error is detected when no detection of the dominant bit in the acknowledge slot occurs.
This flag is automatically cleared reading CAN_SR register.
• FERR: Form Error
513
6042A–ATARM–23-Dec-04
0 = No form error occurred during a previous transfer
1 = A form error occurred during a previous transfer
A form error results from violations on one or more of the fixed form of the following bit fields:
–
CRC delimiter
–
ACK delimiter
–
End of frame
–
Error delimiter
–
Overload delimiter
This flag is automatically cleared by reading CAN_SR register.
• BERR: Bit Error
0 = No bit error occurred during a previous transfer.
1 = A bit error occurred during a previous transfer.
A bit error is set when the bit value monitored on the line is different from the bit value sent.
This flag is automatically cleared by reading CAN_SR register.
• RBSY: Receiver busy
0 = CAN receiver is not receiving a frame.
1 = CAN receiver is receiving a frame.
Receiver busy. This status bit is set by hardware while CAN receiver is acquiring or monitoring a frame (remote, data, overload or error frame). It is automatically reset when CAN is not receiving.
• TBSY: Transmitter busy
0 = CAN transmitter is not transmitting a frame.
1 = CAN transmitter is transmitting a frame.
Transmitter busy. This status bit is set by hardware while CAN transmitter is generating a frame (remote, data, overload or
error frame). It is automatically reset when CAN is not transmitting.
• OVLSY: Overload busy
0 = CAN transmitter is not transmitting an overload frame.
1 = CAN transmitter is transmitting a overload frame.
It is automatically reset when the bus is not transmitting an overload frame.
514
AT91SAM7A3 Preliminary
6042A–ATARM–23-Dec-04
AT91SAM7A3 Preliminary
CAN Baudrate Register
Name:
CAN_BR
Access Type:
Read/Write
31
–
30
–
29
–
28
–
27
–
26
–
25
–
24
SMP
23
–
22
21
20
19
BRP
18
17
16
15
–
14
–
13
12
11
–
10
9
PROPAG
8
7
–
6
5
PHASE1
4
3
–
2
1
PHASE2
0
SYNC
Any modification on one of the fields of the CANBR register must be done while CAN module is disabled.
• PHASE2: Phase 2 segment
This phase is used to compensate the edge phase error.
t PHS2 = t CSC × ( PHASE2 + 1 )
• PHASE1: Phase 1 segment
This phase is used to compensate for edge phase error.
t PHS1 = t CSC × ( PHASE1 + 1 )
• PROPAG: Programming time segment
This part of the bit time is used to compensate for the physical delay times within the network.
t PRS = t CSC × ( PROPAG + 1 )
• SYNC: Re-synchronization jump width
To compensate for phase shifts between clock oscillators of different controlers on bus. The controller must re-synchronize
on any relevant signal edge of the current transmission. The synchronization jump width defines the maximum of clock
cycles a bit period may be shortened or lenghtened by re-synchronization.
t SJW = t CSC × ( SYNC + 1 )
• BRP: Baudrate Prescaler.
This field allows user to program the period of the CAN system clock to determine the individual bit timing.
Tcsc = (BRP + 1) / MCK
• SMP: Sampling Mode
0 = The incoming bit stream is sampled once at sample point.
1 = The incoming bit stream is sampled three times with a period of a MCK clock period, centered on sample point.
SMP Sampling Mode is automatically disabled if BRP = 0.
515
6042A–ATARM–23-Dec-04
CAN Timer Register
Name:
CAN_TIM
Access Type:
Read-only
31
–
30
–
29
–
28
–
27
–
26
–
25
–
24
–
23
–
22
–
21
–
20
–
19
–
18
–
17
–
16
–
15
TIMER15
14
TIMER14
13
TIMER13
12
TIMER12
11
TIMER11
10
TIMER10
9
TIMER9
8
TIMER8
7
TIMER7
6
TIMER6
5
TIMER5
4
TIMER4
3
TIMER3
2
TIMER2
1
TIMER1
0
TIMER0
• TIMERx: Timer
This field represents the internal CAN controller 16-bit timer value.
516
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CAN Timestamp Register
Name:
CAN_TIMESTP
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
MTIMESTAMP
15
MTIMESTAMP
14
MTIMESTAMP
13
MTIMESTAMP
12
MTIMESTAMP
11
MTIMESTAMP
10
MTIMESTAMP
9
MTIMESTAMP
8
7
6
5
4
3
2
1
0
MTIMESTAMP
7
MTIMESTAMP
6
MTIMESTAMP
5
MTIMESTAMP
4
MTIMESTAMP
3
MTIMESTAMP
2
MTIMESTAMP
1
MTIMESTAMP
0
• MTIMESTAMPx: Timestamp
This field represents the internal CAN controller 16-bit timer value.
If the TEOF bit is cleared in the CAN_MR register, the internal Timer Counter value is captured in the MTIMESTAMP field
at each start of frame. Else the value is captured at each end of frame. When the value is captured, the TSTP flag is set in
the CAN_SR register. If the TSTP mask in the CAN_IMR register is set, an interrupt is generated while TSTP flag is set in
the CAN_SR register. This flag is cleared by reading the CAN_SR register.
517
6042A–ATARM–23-Dec-04
CAN Error Counter Register
Name:
CAN_ECR
Access Type:
Read-only
31
–
30
–
29
–
28
–
23
22
21
20
27
–
26
–
25
–
24
–
19
18
17
16
TEC
15
–
14
–
13
–
12
–
11
–
10
–
9
–
8
–
7
6
5
4
3
2
1
0
REC
• REC: Receive Error Counter
When a receiver detects an error, REC will be increased by one, except when the detected error is a BIT ERROR while
sending an ACTIVE ERROR FLAG or an OVERLOAD FLAG.
When a receiver detects a dominant bit as the first bit after sending an ERROR FLAG, REC is increased by 8.
When a receiver detects a BIT ERROR while sending an ACTIVE ERROR FLAG, REC is increased by 8.
Any node tolerates up to 7 consecutive dominant bits after sending an ACTIVE ERROR FLAG, PASSIVE ERROR FLAG or
OVERLOAD FLAG. After detecting the 14th consecutive dominant bit (in case of an ACTIVE ERROR FLAG or an OVERLOAD FLAG) or after detecting the 8th consecutive dominant bit following a PASSIVE ERROR FLAG, and after each
sequence of additional eight consecutive dominant bits, each receiver increases its REC by 8.
After succesful reception of a message, REC is decreased by 1 if it was between 1 and 127. If REC was 0, it stays 0, and if
it was greater than 127, then it is set to a value between 119 and 127.
• TEC: Transmit Error Counter
When a tansmitter sends an ERROR FLAG, TEC is increased by 8 except when
–
the transmitter is error passive and detects an ACKNOWLEDGMENT ERROR because of not detecting a
dominant ACK and does not detect a dominant bit while sending its PASSIVE ERROR FLAG.
–
the transmitter sends an ERROR FLAG because a STUFF ERROR occurred during arbitration and should have
been receissive and has been sent as recessive but monitored as dominant.
When a transmitter detects a BIT ERROR while sending an ACTIVE ERROR FLAG or an OVERLOAD FLAG, the TEC will
be increased by 8.
Any node tolerates up to 7 consecutive dominant bits after sending an ACTIVE ERROR FLAG, PASSIVE ERROR FLAG or
OVERLOAD FLAG. After detecting the 14th consecutive dominant bit (in case of an ACTIVE ERROR FLAG or an OVERLOAD FLAG) or after detecting the 8th consecutive dominant bit following a PASSIVE ERROR FLAG, and after each
sequence of additional eight consecutive dominant bits every transmitter increases its TEC by 8.
After a succesfull transmission the TEC is decreased by 1 unless it was already 0.
518
AT91SAM7A3 Preliminary
6042A–ATARM–23-Dec-04
AT91SAM7A3 Preliminary
CAN Transfer Command Register
Name:
CAN_TCR
Access Type:
Write-only
31
TIMRST
30
–
29
–
28
–
27
–
26
–
25
–
24
–
23
–
22
–
21
–
20
–
19
–
18
–
17
–
16
–
15
MB15
14
MB14
13
MB13
12
MB12
11
MB11
10
MB10
9
MB9
8
MB8
7
MB7
6
MB6
5
MB5
4
MB4
3
MB3
2
MB2
1
MB1
0
MB0
This register initializes several transfer requests at the same time.
• MBx: Transfer Request for Mailbox x
Mailbox Object Type
Description
Receive
It receives the next message.
Receive with overwrite
This triggers a new reception.
Transmit
Sends data prepared in the mailbox as soon as possible.
Consumer
Sends a remote frame.
Producer
Sends data prepared in the mailbox after receiving a remote frame from a
consumer.
This flag clears the MRDY and MABT flags in the correponding CAN_MSRx register.
When several mailboxes are requested to be transmitted simultaneously, they are transmitted in turn, starting with the mailbox with the highest priority. If several mailboxes have the same priority, then the mailbox with the lowest number is sent
first (i.e., MB0 will be transfered before MB1).
• TIMRST: Timer Reset
Resets the internal timer counter. If the internal timer counter is frozen, this command automatically re-enables it. This
command is useful in Time Triggered mode.
519
6042A–ATARM–23-Dec-04
CAN Abort Command Register
Name:
CAN_ACR
Access Type:
Write-only
31
–
30
–
29
–
28
–
27
–
26
–
25
–
24
–
23
–
22
–
21
–
20
–
19
–
18
–
17
–
16
–
15
MB15
14
MB14
13
MB13
12
MB12
11
MB11
10
MB10
9
MB9
8
MB8
7
MB7
6
MB6
5
MB5
4
MB4
3
MB3
2
MB2
1
MB1
0
MB0
This register initializes several abort requests at the same time.
• MBx: Abort Request for Mailbox x
Mailbox Object Type
Description
Receive
No action
Receive with overwrite
No action
Transmit
Cancels transfer request if the message has not been transmitted to the
CAN transceiver.
Consumer
Cancels the current transfer before the remote frame has been sent.
Producer
Cancels the current transfer. The next remote frame is not serviced.
It is possible to set MACR field (in the CAN_MCRx register) for each mailbox.
520
AT91SAM7A3 Preliminary
6042A–ATARM–23-Dec-04
AT91SAM7A3 Preliminary
CAN Message Mode Register
Name:
CAN_MMRx
Access Type:
Read/Write
31
–
30
–
29
–
28
–
27
–
26
23
–
22
–
21
–
20
–
19
18
15
MTIMEMARK
15
14
MTIMEMARK
14
13
MTIMEMARK
13
12
MTIMEMARK
12
11
MTIMEMARK
11
25
24
MOT
17
16
9
8
MTIMEMARK9
MTIMEMARK8
PRIOR
10
MTIMEMARK
10
7
6
5
4
3
2
1
0
MTIMEMARK7
MTIMEMARK6
MTIMEMARK5
MTIMEMARK4
MTIMEMARK3
MTIMEMARK2
MTIMEMARK1
MTIMEMARK0
• MTIMEMARK: Mailbox Timemark
This field is active in Time Triggered Mode. Transmit operations are allowed when the internal timer counter reaches the
Mailbox Timemark. See “Transmitting within a Time Window” on page 501.
In Timestamp Mode, MTIMEMARK is set to 0.
• PRIOR: Mailbox Priority
When several mailboxes try to transmit a message at the same time, the mailbox with the highest priority is serviced first. If
several mailboxes have the same priority, the mailbox with the lowest number is serviced first (i.e., MBx0 is serviced before
MBx 15 if they have the same priority).
• MOT: Mailbox Object Type
This field allows the user to define the type of the mailbox. All mailboxes are independently configurable. Five different
types are possible for each mailbox:
MOT
Mailbox Object Type
0
0
0
Mailbox is disabled. This prevents receiving or transmitting any messages
with this mailbox.
0
0
1
Reception Mailbox. Mailbox is configured for reception. If a message is
received while the mailbox data register is full, it is discarded.
0
1
0
Reception mailbox with overwrite. Mailbox is configured for reception. If a
message is received while the mailbox is full, it overwrites the previous
message.
0
1
1
Transmit mailbox. Mailbox is configured for transmission.
1
0
0
Consumer Mailbox. Mailbox is configured in reception but behaves as a
Transmit Mailbox, i.e., it sends a remote frame and waits for an answer.
1
0
1
Producer Mailbox. Mailbox is configured in transmission but also behaves
like a reception mailbox, i.e., it waits to receive a Remote Frame before
sending its contents.
1
1
X
Reserved
521
6042A–ATARM–23-Dec-04
CAN Message Acceptance Mask Register
Name:
CAN_MAMx
Access Type:
Read/Write
31
–
30
–
29
MIDE
23
22
21
28
27
26
MIDvA
25
20
19
18
17
MIDvA
15
14
13
24
16
MIDvB
12
11
10
9
8
3
2
1
0
MIDvB
7
6
5
4
MIDvB
To prevent concurrent access with the internal CAN core, the application must disable the mailbox before writing to
CAN_MAMx registers.
• MIDvB: Complementary bits for identifier in extended frame mode
Acceptance mask for corresponding field of the message IDvB register of the mailbox.
• MIDvA: Identifier for standard frame mode
Acceptance mask for corresponding field of the message IDvA register of the mailbox.
• MIDE: Identifier Version
0= Compares IDvA from the received frame with the CAN_MIDx register masked with CAN_MAMx register.
1= Compares IDvA and IDvB from the received frame with the CAN_MIDx register masked with CAN_MAMx register.
522
AT91SAM7A3 Preliminary
6042A–ATARM–23-Dec-04
AT91SAM7A3 Preliminary
CAN Message ID Register
Name:
CAN_MIDx
Access Type:
Read/Write
31
–
30
–
29
MIDE
23
22
21
28
27
26
MIDvA
25
20
19
18
17
MIDvA
15
14
13
24
16
MIDvB
12
11
10
9
8
3
2
1
0
MIDvB
7
6
5
4
MIDvB
To prevent concurrent access with the internal CAN core, the application must disable the mailbox before writing to
CAN_MIDx registers.
• MIDvB: Complementary bits for identifier in extended frame mode
If MIDE is cleared, MIDvB value is 0.
• MIDE: Identifier Version
This bit allows the user to define the version of messages processed by the mailbox. If set, mailbox is dealing with version
2.0 Part B messages; otherwise, mailbox is dealing with version 2.0 Part A messages.
• MIDvA: Identifier for standard frame mode
523
6042A–ATARM–23-Dec-04
CAN Message Family ID Register
Name:
CAN_MFIDx
Access Type:
Read-only
31
–
30
–
29
–
28
23
22
21
20
27
26
MFID
25
24
19
18
17
16
11
10
9
8
3
2
1
0
MFID
15
14
13
12
MFID
7
6
5
4
MFID
• MFID: Family ID
This field contains the concatenation of CAN_MIDx register bits masked by the CAN_MAMx register. This field is useful to
speed up message ID decoding. The message acceptance procedure is described below.
As an example:
CAN_MIDx = 0x305A4321
CAN_MAMx = 0x3FF0F0FF
CAN_MFIDx = 0x000000A3
524
AT91SAM7A3 Preliminary
6042A–ATARM–23-Dec-04
AT91SAM7A3 Preliminary
CAN Message Status Register
Name:
CAN_MSRx
Access Type:
Read only
31
–
30
–
29
–
28
–
27
–
26
–
23
MRDY
22
MABT
21
–
20
MRTR
19
18
25
–
24
MMI
17
16
MDLC
15
14
13
12
11
10
9
8
MTIMESTAMP
15
MTIMESTAMP
14
MTIMESTAMP
13
MTIMESTAMP
12
MTIMESTAMP
11
MTIMESTAMP
10
MTIMESTAMP
9
MTIMESTAMP
8
7
6
5
4
3
2
1
0
MTIMESTAMP
7
MTIMESTAMP
6
MTIMESTAMP
5
MTIMESTAMP
4
MTIMESTAMP
3
MTIMESTAMP
2
MTIMESTAMP
1
MTIMESTAMP
0
These register fields are updated each time a message transfer is received or aborted.
MMI is cleared reading the CAN_MSRx register.
MRDY, MABT are cleared by writing MTCR or MACR in the CAN_MCRx register.
Warning: MRTR and MDLC state depends partly on the mailbox object type.
• MTIMESTAMP: Timer value
This field is updated only when time-triggered operations are disabled (TTM cleared in CAN_MR register). If the TEOF field
in the CAN_MR register is cleared, TIMESTAMP is the internal timer value at the start of frame of the last message
received or sent by the mailbox. If the TEOF field in the CAN_MR register is set, TIMESTAMP is the internal timer value at
the end of frame of the last message received or sent by the mailbox.
In Time Triggered Mode, MTIMESTAMP is set to 0.
• MDLC: Mailbox Data Length Code
Mailbox Object Type
Description
Receive
Length of the first mailbox message received
Receive with overwrite
Length of the last mailbox message received
Transmit
No action
Consumer
Length of the mailbox message received
Producer
No action
• MRTR: Mailbox Remote Transmission Request
Mailbox Object Type
Description
Receive
The first frame received has the RTR bit set.
Receive with overwrite
The last frame received has the RTR bit set.
Transmit
Reserved
Consumer
Reserved
Producer
Reserved
525
6042A–ATARM–23-Dec-04
• MABT: Mailbox Message Abort
An interrupt is triggered when MABT is set.
0 = Previous transfer is not aborted.
1 = Previous transfer has been aborted.
This flag is cleared writing to CAN_MCRx register
Mailbox Object Type
Description
Receive
Reserved
Receive with overwrite
Reserved
Transmit
Previous transfer has been aborted since the last abort command (MACR
set in the CAN_MCRx register).
Consumer
The remote frame transfer request has been aborted.
Producer
The response to the remote frame transfer has been aborted since the last
abort command (MACR set in the CAN_MCRx register).
• MRDY: Mailbox Ready
An interrupt is triggered when MRDY is set.
0 = Mailbox data registers can not be read/written by the software application. CAN_MDx are locked by the CAN_MDx.
1 = Mailbox data registers can be read/written by the software application.
This flag is cleared by writing to CAN_MCRx register.
Mailbox Object Type
Receive
Receive with overwrite
Transmit
Description
At least one message has been received since the last mailbox transfer
order. Data from the first frame received can be read in the CAN_MDxx
registers.
After setting the MOT field in the CAN_MMR, MRDY is reset to 0.
At least one frame has been received since the last mailbox transfer order.
Data from the last frame received can be read in the CAN_MDxx registers.
After setting the MOT field in the CAN_MMR, MRDY is reset to 0.
Mailbox data have been transmitted.
After setting the MOT field in the CAN_MMR, MRDY is reset to 1.
Consumer
At least one message has been received since the last mailbox transfer
order. Data from the first message received can be read in the CAN_MDxx
registers.
After setting the MOT field in the CAN_MMR, MRDY is reset to 0.
Producer
A remote frame has been received, mailbox data have been transmitted.
After setting the MOT field in the CAN_MMR, MRDY is reset to 1.
• MMI: Mailbox Message Ignored
0 = No message has been ignored during the previous transfer
1 = At least one message has been ignored during the previous transfer
526
AT91SAM7A3 Preliminary
6042A–ATARM–23-Dec-04
AT91SAM7A3 Preliminary
Cleared by reading the CAN_MSRx register.
Mailbox Object Type
Description
Receive
Set when at least two messages intended for the mailbox have been sent.
The first one is available in the mailbox data register. Others have been
ignored. A mailbox with a lower priority may have accepted the message.
Receive with overwrite
Set when at least two messages intended for the mailbox have been sent.
The last one is available in the mailbox data register. Previous ones have
been lost.
Transmit
Reserved
Consumer
A remote frame has been sent by the mailbox but several messages have
been received. The first one is available in the mailbox data register. Others
have been ignored. Another mailbox with a lower priority may have
accepted the message.
Producer
A remote frame has been received, but no data are available to be sent.
527
6042A–ATARM–23-Dec-04
CAN Message Data Low Register
Name:
CAN_MDLx
Access Type:
Read/Write
31
30
29
28
27
26
25
24
19
18
17
16
11
10
9
8
3
2
1
0
MDL
23
22
21
20
MDL
15
14
13
12
MDL
7
6
5
4
MDL
• MDL: Message Data Low Value
When MRDY field is set in the CAN_MSRx register, the lower 32 bits of a received message can be read or written by the
software application. Otherwise, the MDH value is locked by the CAN controller to send/receive a new message.
In Receive with overwrite, the CAN controller may modify MDL value while the software application reads MDH and MDL
registers. To check that MDH and MDL do not belong to different messages, the application has to check the MMI field in
the CAN_MSRx register. In this mode, the software application must re-read CAN_MDH and CAN_MDL, while the MMI bit
in the CAN_MSRx register is set.
528
AT91SAM7A3 Preliminary
6042A–ATARM–23-Dec-04
AT91SAM7A3 Preliminary
CAN Message Data High Register
Name:
CAN_MDHx
Access Type:
Read/Write
31
30
29
28
27
26
25
24
19
18
17
16
11
10
9
8
3
2
1
0
MDH
23
22
21
20
MDH
15
14
13
12
MDH
7
6
5
4
MDH
• MDH: Message Data High Value
When MRDY field is set in the CAN_MSRx register, the upper 32 bits of a received message are read or written by the software application. Otherwise, the MDH value is locked by the CAN controller to send/receive a new message.
In Receive with overwrite, the CAN controller may modify MDH value while the software application reads MDH and MDL
registers. To check that MDH and MDL do not belong to different messages, the application has to check the MMI field in
the CAN_MSRx register. In this mode, the software application must re-read CAN_MDH and CAN_MDL, while the MMI bit
in the CAN_MSRx register is set.
529
6042A–ATARM–23-Dec-04
CAN Message Control Register
Name:
CAN_MCRx
Access Type:
Write-only
31
–
30
–
29
–
28
–
27
–
26
–
23
MTCR
22
MACR
21
–
20
MRTR
19
18
15
–
14
13
–
12
11
–
7
–
6
5
–
4
3
–
–
–
–
–
25
24
–
–
17
16
10
9
–
–
8
–
2
–
1
0
–
–
MDLC
• MDLC: Mailbox Data Length Code
Mailbox Object Type
Description
Receive
No action.
Receive with overwrite
No action.
Transmit
Length of the mailbox message.
Consumer
No action.
Producer
Length of the mailbox message to be sent after the remote frame reception.
• MRTR: Mailbox Remote Transmission Request
Mailbox Object Type
Description
Receive
No action
Receive with overwrite
No action
Transmit
Set the RTR bit in the sent frame
Consumer
No action, the RTR bit in the sent frame is set automatically
Producer
No action
Consumer situations can be handled automatically by setting the mailbox object type in Consumer. This requires only one
mailbox.
It can also be handled using two mailboxes, one in reception, the other in transmission. The MRTR and the MTCR bits must
be set in the same time.
530
AT91SAM7A3 Preliminary
6042A–ATARM–23-Dec-04
AT91SAM7A3 Preliminary
• MACR: Abort Request for Mailbox x
Mailbox Object Type
Description
Receive
No action
Receive with overwrite
No action
Transmit
Cancels transfer request if the message has not been transmitted to the
CAN transceiver.
Consumer
Cancels the current transfer before the remote frame has been sent.
Producer
Cancels the current transfer. The next remote frame will not be serviced.
It is possible to set MACR field for several mailboxes in the same time, setting several bits to the CAN_ACR register.
• MTCR: Mailbox Transfer Command
Mailbox Object Type
Receive
Receive with overwrite
Transmit
Description
Allows the reception of the next message.
Triggers a new reception.
Sends data prepared in the mailbox as soon as possible.
Consumer
Sends a remote transmission frame.
Producer
Sends data prepared in the mailbox after receiving a remote frame from a
consumer.
This flag clears the MRDY and MABT flags in the CAN_MSRx register.
When several mailboxes are requested to be transmitted simultaneously, they are transmitted in turn. The mailbox with the
highest priority is serviced first. If several mailboxes have the same priority, the mailbox with the lowest number is serviced
first (i.e., MBx0 will be serviced before MBx 15 if they have the same priority).
It is possible to set MTCR for several mailboxes at the same time by writing to the CAN_TCR register.
531
6042A–ATARM–23-Dec-04
532
AT91SAM7A3 Preliminary
6042A–ATARM–23-Dec-04
AT91SAM7A3 Preliminary
AT91SAM7A3 Electrical Characteristics
Absolute Maximum Ratings
Table 64. Absolute Maximum Ratings*
Operating Temperature (Industrial)..... -40° C to +85° C
Storage Temperature ......................... -60°C to +150°C
Voltage on Input Pins
with Respect to Ground .........................-0.3V to +5.5V
Maximum Operating Voltage
(VDDCORE and VDDPLL) ................................. 1.95V
*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
(VDDIO, VDDIN, VDDBU and VDDANA) ............. 3.6V
Total DC Output Current on all I/O lines .......... 200 mA
533
6042A–ATARM–23-Dec-04
DC Characteristics
The following characteristics are applicable to the operating temperature range: TA = -40°C to 85°C, unless otherwise specified and are certified for a junction temperature up to TJ = 100°C and for VDDIO between 3.0 and 3.6V.
Table 65. DC Characteristics
Symbol
Parameter
VVDDCORE
DC Supply Core
VVDDPLL
Max
Units
1.65
1.95
V
DC Supply PLL
1.65
1.95
V
VVDDIO
DC Supply I/Os and Flash
3.0
3.6
V
VVDDBU
DC Supply Backup I/O
Lines
3.0
3.6
V
VVDDANA
DC Supply Analog
3.0
3.6
V
VIL
Input Low-level Voltage
-0.3
0.8
V
VIH
Input High-level Voltage
2.0
5.5
V
VOL
Output Low-level Voltage
IO = 2 mA
0.4
V
VOH
Output High-level Voltage
IO = 2 mA
ILEAK
Input Leakage Current
Pullup resistors disabled (Typ: TA =
25°C, Max: TA = 85°C)
IPULLUP
Input Pull-up Current
C IN
Input Capacitance
ISC
IO
534
Static Current
Output Current
Conditions
Min
Typ
VDDIO - 0.4
143
V
20
200
nA
321
600
µA
14.1
pF
100-pin LQFP Package
On V VDDCORE = 1.8V,
MCK = 0 Hz, excluding
POR
TA = 25°C
All inputs driven TMS,
TDI, TCK, NRST = 1
TA = 85°C
350
2300
On V VDDBU = 3.6V,
Logic cells consumption,
excluding POR and
RCOSC cells
TA = 25°C
47
60
All inputs driven FWKUP,
WKUP0, WKUP1 = 0
TA = 85°C
PA0-PA31 PB0-PB29
30
200
µA
nA
576
784
2
mA
AT91SAM7A3 Preliminary
6042A–ATARM–23-Dec-04
AT91SAM7A3 Preliminary
Table 66. 1.8V Voltage Regulator Characteristics
Symbol
Parameter
VDDIN
Conditions
Min
Typ
Max
Units
Supply Voltage
2.7
3.3
3.6
V
VDDOUT
Output Voltage
1.65
1.8
1.95
V
70
120
µA
IVDDIN
Current Consumption
During startup, no load
100
mA
TSTART
Startup Time
Cload = 2.2 µF, after VDDIN > 3.0V
150
µS
PSRR
DC to 100 kHz
After startup, no load
IO
Maximum DC Output Current
35
dB
VDDIN = 3.3V
130
mA
VDDIN = 2.7V
100
mA
535
6042A–ATARM–23-Dec-04
Power Consumption
Power
Consumption
versus Modes
•
Typical power consumption of PLLs, Slow Clock and Main Oscillator.
•
Power consumption of power supply in three different modes: Active, Ultra Low-power and
Backup.
•
Power consumption by peripheral: calculated as the difference in current measurement
after having enabled then disabled the corresponding clock.
The values in Table 67 and Table 68 on page 537 are estimated values of the power consumption with operating conditions as follows:
•
VDDIN= VDDIO= V DDBU= VDDANA = 3.3V
•
VDDCORE = VDDPLL = 1.8V
•
TA = 25° C
•
MCK = 60 MHz
•
USB Pads deactivated
•
There is no consumption on the I/Os of the device
Figure 151. Measures Schematics
VDDBU
AMP1
VDDANA
VDDIO
VDDIN
3.3V
Voltage
Regulator
AMP2
VDDOUT
AMP3
1.8V
VDDCORE
VDDPLL
These figures represent the power consumption estimated on the power supplies.
536
AT91SAM7A3 Preliminary
6042A–ATARM–23-Dec-04
AT91SAM7A3 Preliminary
Table 67. Power Consumption for different Modes(1)
Mode
Conditions
Active
Flash is read.
ARM Core clock is 60 MHz.
Analog-to-Digital Converter activated.
All peripheral clocks activated.
Ultra low
power
Backup
Consumption
Unit
onto AMP2
onto AMP3
79
76
mA
Flash is in standby mode.
ARM Core clock is 500 Hz.
Analog-to-Digital Converter de-activated.
All peripheral clocks de-activated.
onto AMP2
onto AMP3
113
35
µA
6.5
µA
Device only VDDBU powered
onto AMP1
Table 68. Power Consumption by Peripheral in Active Mode
Peripheral
Consumption
PIO Controller
0.5
USART
1.1
ADC
0.7
UDP
1.2
PWM
0.4
CAN
1.3
TWI
0.2
SPI
1.0
MCI
1.5
SSC
1.3
Timer Counter Channels
0.2
Unit
mA
537
6042A–ATARM–23-Dec-04
Power Consumption versus Master Clock Frequency in Active Mode
Figure 152 produces estimated values with operating conditions as follows:
•
VDDIN= VDDIO= V DDBU= VDDANA = 3.3V
•
VDDCORE = VDDPLL = 1.8V
•
TA = 25° C
•
MCK in the MHz range
•
Flash is read
•
Two analog-to-digital converters are activated
•
USB pads deactivated
•
All peripheral clocks activated
•
PLL activated
•
There is no consumption on the I/Os of the device
Figure 152 presents the power consumption estimated on the power supply.
Figure 152. Power Consumption versus MCK Frequency in the MHz Range
Current Consumption at 3.3V
40,378
21,248
11,683
10000
6,901
4,509
3,314
Consumption (µa)
100000
78,638
1000
0.9375
1.875
3.75
7.5
15
30
60
Frequency (MHz)
538
AT91SAM7A3 Preliminary
6042A–ATARM–23-Dec-04
AT91SAM7A3 Preliminary
Power Consumption versus Master Clock Frequency in Ultra Low-power Mode
Figure 153 produces estimated values with operating conditions as follows:
•
VDDIN= VDDIO= V DDBU= VDDANA = 3.3V
•
VDDCORE = VDDPLL = 1.8V
•
TA = 25° C
•
Flash is inactive
•
MCK in the kHz range
•
USB pads deactivated
•
All peripheral clocks deactivated
•
PLL deactivated
•
There is no consumption on the I/Os of the device
Figure 153 presents the power consumption estimated on the power supply.
Figure 153. Power Consumption versus MCK Frequency in Ultra Low-power Mode
Current Consumption at 3.3V
Consumption (µa)
1000
113
112.5
0.5
1
116
114
2
144.3
128.1
120.1
100
4
8
16
32
Frequency (kHz)
539
6042A–ATARM–23-Dec-04
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.
RC Oscillator Characteristics
Table 69. RC Oscillator Characteristics
Symbol
Parameter
Conditions
Min
Typ
Max
Unit
1/(t CPRC)
RC Oscillator Frequency
VDDBU = 3V
22
32
42
KHz
45
50
55
%
Duty Cycle
tST
Startup Time
VDDBU = 3V
75
µs
IOSC
Current Consumption
After Startup Time
2.5
µA
Main Oscillators Characteristics
Table 70. Main Oscillator Characteristics
Symbol
Parameter
1/(t CPMAIN)
Crystal Oscillator Frequency
CL1, CL2
Internal Load Capacitance
(CL1 = CL2 )
CL
Equivalent Load Capacitance
Conditions
Duty Cycle
tST
IOSC
Startup Time
Current Consumption
540
Typ
Max
Unit
3
16
20
MHz
40
25
pF
12.5
pF
50
VDDPLL = 1.2 to 2V
CS = 3 pF(1) 1/(tCPMAIN) = 3 MHz
CS = 7 pF(1) 1/(tCPMAIN) = 16 MHz
CS = 7 pF(1) 1/(tCPMAIN) = 20 MHz
Active mode @20 MHz
Standby mode @2V
Notes:
Min
60
14.5
1.4
1
350
%
ms
550
µA
1
µA
1. CS is the shunt capacitance
AT91SAM7A3 Preliminary
6042A–ATARM–23-Dec-04
AT91SAM7A3 Preliminary
XIN Clock Characteristics
Table 71. XIN Clock Electrical Characteristics
Symbol
Parameter
1/(t CPXIN)
XIN Clock Frequency
tCPXIN
XIN Clock Period
tCHXIN
XIN Clock High Half-period
0.4 x tCPXIN
0.6 x tCPXIN
tCLXIN
XIN Clock Low Half-period
0.4 x tCPXIN
0.6 x tCPXIN
CIN
XIN Input Capacitance
(1)
25
pF
RIN
XIN Pulldown Resistor
(1)
500
kΩ
Notes:
Conditions
Min
Max
Units
50.0
MHz
20.0
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” on page 171.)
PLL Characteristics
Table 72. Phase Lock Loop Characteristics
Symbol
Parameter
Conditions
FOUT
Output Frequency
Field OUT of CKGR_PLL is 00
Field OUT of CKGR_PLL is 10
FIN
Input Frequency
IPLL
Current Consumption
Note:
Min
Typ
Max
Unit
80
160
MHz
150
220
MHz
1
32
MHz
Active mode
4
mA
Standby mode
1
µA
Startup time depends on PLL RC filter. A calculation tool is provided by Atmel.
541
6042A–ATARM–23-Dec-04
USB Transceiver Characteristics
Electrical Characteristics
Table 73. Electrical Parameters
Symbol
Parameter
Conditions
Min
Typ
Max
Unit
0.8
V
Input Levels
VIL
Low Level
VIH
High Level
VDI
Differential Input Sensivity
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 kOhm tied
to 3.6V
0.0
0.3
V
VOH
High Level Output
Measured with RL of 14.25 kOhm tied
to GND
2.8
3.6
V
VCRS
Output Signal Crossover
Voltage
Measure conditions described in
Figure 154
1.3
2.0
V
Max
Unit
|(D+) - (D-)|
2.0
V
0.2
V
0.8
-10
2.5
V
9.18
pF
+10
µA
Ω
27
Output Levels
Switching Characteristics
Table 74. In Low Speed
Symbol
Parameter
Conditions
Min
Typ
tFR
Transition Rise Time
CLOAD = 400 pF
75
300
ns
tFE
Transition Fall Time
CLOAD = 400 pF
75
300
ns
tFRFM
Rise/Fall time Matching
CLOAD = 400 pF
80
125
%
Min
Max
Unit
Table 75. In Full Speed
Symbol
Parameter
Conditions
tFR
Transition Rise Time
CLOAD = 50 pF
4
20
ns
tFE
Transition Fall Time
CLOAD = 50 pF
4
20
ns
tFRFM
Rise/Fall time Matching
90
111.11
%
542
Typ
AT91SAM7A3 Preliminary
6042A–ATARM–23-Dec-04
AT91SAM7A3 Preliminary
Figure 154. 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 = 6MHz/750kHz
Buffer
Cload
(b)
543
6042A–ATARM–23-Dec-04
Analog-to-Digital Converter Characteristics
Table 76. Channel Conversion Time and ADC Clock
Parameter
Conditions
Min
Typ
Max
Units
5
MHz
20
µs
ADC Clock Frequency
Startup Time
Return from Idle Mode
Track and Hold Acquisition Time
600
ns
Conversion Time
ADC Clock = 5 MHz
2
µs
Throughput Rate
ADC Clock = 5 MHz
384
kSPS
Table 77. External Voltage Reference Input
Parameter
Conditions
Min
Max
Units
2.6
VVDDANA
V
12
250
µA
ADVREF Input Voltage Range
ADVREF Average Current
On 13 samples with ADC Clock = 5 MHz
Table 78. Analog Inputs
Parameter
Min
Input Voltage Range
Typ
0
Max
Units
VADVREF
Input Leakage Current
1
µA
Input Capacitance
12
14
pF
Typ
Max
Units
Table 79. Transfer Characteristics
Parameter
Conditions
Resolution
Min
10
Bit
±2
LSB
±3
LSB
±1
LSB
±2
LSB
Offset Error
±2
LSB
Gain Error
±2
LSB
Integral Non-linearity
ADC Clock = 5 MHz
Differential Non-linearity
ADC Clock = 5 MHz
544
AT91SAM7A3 Preliminary
6042A–ATARM–23-Dec-04
AT91SAM7A3 Preliminary
Applicable Conditions and Derating Data
These conditions and derating process apply to the following paragraphs: Clock Characteristics, Embedded Flash Characteristics and JTAG/ICE Timings.
Conditions and Timings Computation
The delays are given as typical values under the following conditions:
•
VDDIO = 3.3V
•
VDDCORE = 1.8V
•
Ambient Temperature = 25°C
•
Load Capacitance = 0 pF
•
The output level change detection is (0.5 x VDDIO).
•
The input level is 0.8V for a low-level detection and is 2.0V for a high-level detection.
The minimum and maximum values given in the AC characteristics tables of this datasheet
take into account process variation and design. In order to obtain the timingfor other conditions, the following equation should be used:
t = δT ° × ⎛ ( δVDDCORE × t DATASHEET ) + ⎛ δVDDIO ×
⎝
⎝
where:
•
∑( C SIGNAL × δCSIGNAL)⎞⎠ ⎞⎠
δT° is the derating factor in temperature given in Figure 155 on page 546.
•
δVDDCORE is the derating factor for the Core Power Supply given in Figure 156 on page 546.
•
tDATASHEET is the minimum or maximum timing value given in this datasheet for a load
capacitance of 0 pF.
δVDDIO is the derating factor for the IO Power Supply given in Figure 157 on page 547.
•
•
•
CSIGNAL is the capacitance load on the considered output pin(1).
δCSIGNAL is the load derating factor depending on the capacitance load on the related
output pins given in Min and Max in this datasheet.
The input delays are given as typical values.
Note:
1. The user must take into account the package capacitance load contribution (CIN) described
in “DC Characteristics” on page 534, Table 65 on page 534.
545
6042A–ATARM–23-Dec-04
Temperature Derating Factor
Figure 155. Derating Curve for Different Operating Temperatures
1.2
Derating Factor
1.1
1
0.9
0.8
-40
-20
0
20
40
60
80
Operating Temperature (°C)
VDDCORE Voltage Derating Factor
Figure 156. Derating Curve for Different Core Supply Voltages
1.2
Derating Factor
1.15
1.1
1.05
1
0.95
0.9
1.65
1.7
1.75
1.8
1.85
1.9
1.95
Core Supply Voltage (V)
546
AT91SAM7A3 Preliminary
6042A–ATARM–23-Dec-04
AT91SAM7A3 Preliminary
VDDIO Voltage Derating Factor
Figure 157. Derating Curve for Different IO Supply Voltages
1.1
Derating Factor
1.05
1
0.95
0.9
3
3.1
3.2
3.3
3.4
3.5
3.6
I/O Supply Voltage (V)
Note:
The derating factor in this example is applicable only to timings related to output pins.
547
6042A–ATARM–23-Dec-04
Clocks Characteristics
These parameters are given in the following conditions:
•
VDDCORE = 1.8V
•
Ambient Temperature = 25°C
The temperature derating factor described in “Temperature Derating Factor” on page 546 and VDDCORE voltage derating
factor described in “VDDCORE Voltage Derating Factor” on page 546 are both applicable to these characteristics.
Master Clock Characteristics
Table 80. Master Clock Waveform Parameters
Symbol
Parameter
1/(t CPMCK)
Master Clock Frequency
548
Conditions
Min
Max
Units
81
MHz
AT91SAM7A3 Preliminary
6042A–ATARM–23-Dec-04
AT91SAM7A3 Preliminary
AT91SAM7A3 AC Characteristics
Embedded Flash Characteristics
Table 81. DC Flash Characteristics
Symbol
Parameter
TPU
Power-up delay
ISB
Standby current
ICC
Conditions
Min
Max
Units
30
µs
@ 25°C
onto VDDCORE = 1.8V
onto VDDIO = 3.3V
10
20
µA
Random Read @ 40MHz
onto VDDCORE = 1.8V
onto VDDIO = 3.3V
3.0
0.8
mA
400
5.5
µA
mA
Active current
Write
onto VDDCORE = 1.8V
onto VDDIO = 3.3V
The maximum operating frequency is given in Table 81 but is limited by the Embedded Flash access time when the processor is fetching code out of it. Table 82 gives the device maximum operating frequency depending on the field FWS of the
MC_FMR register. This field defines the number of wait states required to access the Embedded Flash Memory.
Table 82. Embedded Flash Wait States
FWS
Read Operations
Maximum Operating Frequency (MHz)
0
1 cycle
40
1
2 cycles
80
2
3 cycles
1/(tCPMCK)
3
4 cycles
1/(tCPMCK)
Table 83. AC Flash Characteristics
Parameter
Condition
Min
Max
Units
per page including auto-erase
4
ms
per page including auto-erase
2
ms
Program Cycle Time
Full Chip Erase
10
ms
549
6042A–ATARM–23-Dec-04
JTAG/ICE Timings
ICE Interface
Signals
Table 84 shows timings relative to operating condition limits defined in the section “Conditions
and Timings Computation” on page 545.
Table 84. ICE Interface Timing Specification
Symbol
Parameter
Conditions
Min
ICE 0
TCK Low Half-period
51
ns
ICE 1
TCK High Half-period
51
ns
ICE 2
TCK Period
102
ns
ICE 3
TDI, TMS, Setup before TCK High
0
ns
ICE 4
TDI, TMS, Hold after TCK High
5
ns
3
ns
ICE 5
TDO Hold Time
0.034
ns/pF
ICE 6
TCK Low to TDO Valid
CTDO = 0 pF
CTDO derating
CTDO = 0 pF
CTDO derating
Max
Units
12
ns
0.034
ns/pF
Figure 158. ICE Interface Signals
ICE2
TCK
ICE0
ICE1
TMS/TDI
ICE3
ICE4
TDO
ICE5
ICE6
550
AT91SAM7A3 Preliminary
6042A–ATARM–23-Dec-04
AT91SAM7A3 Preliminary
JTAG Interface
Signals
The following table shows timings relative to operating condition limits defined in the section
“Conditions and Timings Computation” on page 545.
Table 85. JTAG Interface Timing specification
Symbol
Parameter
Conditions
JTAG0
TCK Low Half-period
6.5
ns
JTAG1
TCK High Half-period
5.5
ns
JTAG2
TCK Period
12
ns
JTAG3
TDI, TMS Setup before TCK High
0
ns
JTAG4
TDI, TMS Hold after TCK High
4
ns
4
ns
JTAG5
TDO Hold Time
0.034
ns/pF
JTAG6
TCK Low to TDO Valid
JTAG7
Device Inputs Setup Time
0
ns
JTAG8
Device Inputs Hold Time
5
ns
7
ns
JTAG9
Device Outputs Hold Time
0.032
ns/pF
JTAG10
TCK to Device Outputs Valid
CTDO = 0 pF
CTDO derating
Min
CTDO = 0 pF
CTDO derating
COUT = 0 pF
COUT derating
COUT = 0 pF
COUT derating
Max
Units
11
ns
0.034
ns/pF
16
ns
0.032
ns/pF
551
6042A–ATARM–23-Dec-04
Figure 159. JTAG Interface Signals
JTAG2
TCK
JTAG
JTAG1
0
TMS/TDI
JTAG3
JTAG4
JTAG7
JTAG8
TDO
JTAG5
JTAG6
Device
Inputs
Device
Outputs
JTAG9
JTAG10
552
AT91SAM7A3 Preliminary
6042A–ATARM–23-Dec-04
AT91SAM7A3 Preliminary
AT91SAM7A3 Mechanical Characteristics
Thermal Considerations
Thermal Data
In Table 86, the device lifetime is estimated using the MIL-217 standard in the “moderately
controlled” environmental model (this model is described as corresponding to an installation in
a permanent rack with adequate cooling air), depending on the device Junction Temperature.
(For details see the section “Junction Temperature” on page 554.)
Note that the user must be extremely cautious with this MTBF calculation. It should be noted
that the MIL-217 model is pessimistic with respect to observed values due to the way the
data/models are obtained (test under severe conditions). The life test results that have been
measured are always better than the predicted ones.
Table 86. MTBF Versus Junction Temperature
Junction Temperature (TJ) (°C)
Estimated Lifetime (MTBF) (Year)
100
8
125
4
150
2
175
1
Table 87 summarizes the thermal resistance data depending on the package.
Table 87. Thermal Resistance Data
Symbol
Parameter
θJA
Junction-to-ambient thermal resistance
θJC
Junction-to-case thermal resistance
Condition
Package
Typ
Still Air
LQFP100
38.3
LQFP100
8.7
Unit
°C/W
553
6042A–ATARM–23-Dec-04
Junction
Temperature
The average chip-junction temperature, TJ, in °C can be obtained from the following:
1. T J = T A + ( P D × θ JA )
2. T J = T A + ( P D × ( θ HEATSINK + θ JC ) )
where:
•
θ JA = package thermal resistance, Junction-to-ambient (°C/W), provided in Table 87 on
page 553.
•
θ JC = package thermal resistance, Junction-to-case thermal resistance (°C/W), provided in
Table 87 on page 553.
•
θ HEAT SINK = cooling device thermal resistance (°C/W), provided in the device datasheet.
•
PD = device power consumption (W) estimated from data provided in the section “Power
Consumption” on page 536.
•
TA = ambient temperature (°C).
From the first equation, the user can derive the estimated lifetime of the chip and decide if a
cooling device is necessary or not. If a cooling device is to be fitted on the chip, the second
equation should be used to compute the resulting average chip-junction temperature TJ in °C.
554
AT91SAM7A3 Preliminary
6042A–ATARM–23-Dec-04
AT91SAM7A3 Preliminary
Package Drawings
Figure 160. 100-lead LQFP Package Drawing
555
6042A–ATARM–23-Dec-04
Table 88. 100-lead LQFP Package Dimensions
Millimeter
Symbol
Min
Nom
Inch
Max
A
Min
Nom
1.60
A1
0.05
A2
1.35
1.40
0.63
0.15
0.002
1.45
0.053
0.006
0.055
D
16.00 BSC
0.630 BSC
D1
14.00 BSC
0.551 BSC
E
16.00 BSC
0.630 BSC
E1
14.00 BSC
0.551 BSC
R2
0.08
R1
0.08
Θ
0°
Θ1
0°
Θ2
11 °
12°
13°
Θ3
11 °
12°
c
0.09
L
0.45
L1
0.20
0.003
0.20
b
0.17
e
0.057
0.008
0.003
3.5°
7°
0°
3.5°
7°
11°
12°
13°
13°
11°
12°
13°
0.20
0.004
0.75
0.018
0°
0.60
1.00 REF
S
Max
0.008
0.024
0.030
0.039 REF
0.008
0.20
0.27
0.007
0.008
0.50 BSC
0.020 BSC
D2
12.00
0.472
E2
12.00
0.472
0.011
Tolerances of form and position
aaa
0.20
0.008
bbb
0.20
0.008
ccc
0.08
0.003
ddd
0.08
0.003
Table 89. Device and 100-lead LQFP Package Maximum Weight
800
mg
Table 90. 100-lead LQFP Package Characteristics
Moisture Sensitivity Level
556
3
AT91SAM7A3 Preliminary
6042A–ATARM–23-Dec-04
AT91SAM7A3 Preliminary
Soldering
Profile
Table 91 gives the recommended soldering profile from J-STD-20.
Table 91. Soldering Profile
Convection or
IR/Convection
VPR
Average Ramp-up Rate (183° C to Peak)
3° C/sec. max.
10° C/sec.
Preheat Temperature 125° C ±25 ° C
120 sec. max
Temperature Maintained Above 183° C
60 sec. to 150 sec.
Time within 5° C of Actual Peak Temperature
10 sec. to 20 sec.
60 sec.
Peak Temperature Range
220 +5/-0° C or
235 +5/-0° C
215 to 219° C or
235 +5/-0° C
Ramp-down Rate
6° C/sec.
10° C/sec.
Time 25° C to Peak Temperature
6 min. max
Small packages may be subject to higher temperatures if they are reflowed in boards with
larger components. In this case, small packages may have to withstand temperatures of up to
235° C, not 220° C (IR reflow).
Recommended package reflow conditions depend on package thickness and volume. See
Table 92.
Table 92. Recommended Package Reflow Conditions (1, 2, 3)
Parameter
Temperature
Convection
235 +5/-0° C
VPR
235 +5/-0° C
IR/Convection
235 +5/-0° C
When certain small thin packages are used on boards without larger packages, these small
packages may be classified at 220°C instead of 235°C.
Notes:
1. The packages are qualified by Atmel by using IR reflow conditions, not convection or VPR.
2. By default, the package level 1 is qualified at 220° C (unless 235 ° C is stipulated).
3. The body temperature is the most important parameter but other profile parameters such as
total exposure time to hot temperature or heating rate may also influence component
reliability.
A maximum of three reflow passes is allowed per component.
557
6042A–ATARM–23-Dec-04
AT91SAM7A3 Ordering Information
Table 93. Ordering Information
558
Ordering Code
Package
AT91SAM7A3-AJ
LQFP 100
Temperature
Operating Range
Industrial
(-40 ° C to 85° C)
AT91SAM7A3 Preliminary
6042A–ATARM–23-Dec-04
AT91SAM7A3 Preliminary
Document Details
Title
AT91SAM7A3
Literature Number
6042
Revision History
Version A
23-Dec-2004
i
6042A–ATARM–23-Dec-04
Table of Contents
ii
Features............................................................................................................... 1
Description .......................................................................................................... 2
Block Diagram..................................................................................................... 3
Signal Description ............................................................................................. 4
Package and Pinout............................................................................................ 7
100-lead LQFP Mechanical Overview.............................................................. 7
Pinout ............................................................................................................... 7
Power Considerations........................................................................................ 8
Power Supplies ................................................................................................ 8
Voltage Regulator ............................................................................................ 8
Typical Powering Schematics .......................................................................... 9
I/O Lines Considerations ................................................................................. 10
JTAG Port Pins .............................................................................................. 10
Test Pin .......................................................................................................... 10
Reset Pin........................................................................................................ 10
PIO Controller A and B Lines ......................................................................... 10
Shutdown Logic Pins...................................................................................... 10
I/O Line Drive Levels...................................................................................... 10
Processor and Architecture............................................................................. 11
ARM7TDMI Processor ................................................................................... 11
Debug and Test Features .............................................................................. 11
Memory Controller.......................................................................................... 11
Peripheral Data Controller.............................................................................. 12
Memory .............................................................................................................. 13
Embedded Memories ..................................................................................... 13
Memory Mapping ........................................................................................... 13
Embedded Flash ............................................................................................ 14
System Controller............................................................................................. 15
System Controller Mapping ............................................................................ 16
Reset Controller ............................................................................................. 17
Clock Generator ............................................................................................. 17
Power Management Controller ...................................................................... 18
Advanced Interrupt Controller ........................................................................ 18
Debug Unit ..................................................................................................... 19
Period Interval Timer...................................................................................... 19
Watchdog Timer............................................................................................. 19
Real-time Timer.............................................................................................. 19
Shutdown Controller....................................................................................... 19
PIO Controllers A and B................................................................................. 19
Peripherals ........................................................................................................ 21
Peripheral Mapping ........................................................................................ 21
Peripheral Multiplexing on PIO Lines ............................................................. 22
PIO Controller A Multiplexing ......................................................................... 23
PIO Controller B Multiplexing ......................................................................... 24
Peripheral Identifiers ........................................................................................ 25
Serial Peripheral Interface.............................................................................. 26
AT91SAM7A3 Preliminary
6042A–ATARM–23-Dec-04
AT91SAM7A3 Preliminary
Two-wire Interface..........................................................................................
USART ...........................................................................................................
Serial Synchronous Controller .......................................................................
Timer Counter ................................................................................................
PWM Controller ..............................................................................................
USB Device Port ............................................................................................
Multimedia Card Interface ..............................................................................
CAN Controller ...............................................................................................
Analog-to-Digital Converter............................................................................
26
26
26
27
27
27
28
28
28
ARM7TDMI Processor Overview .................................................................. 31
Overview............................................................................................................
ARM7TDMI Processor ......................................................................................
Instruction Type..............................................................................................
Data Type.......................................................................................................
ARM7TDMI Operating Mode..........................................................................
ARM7TDMI Registers ....................................................................................
ARM Instruction Set Overview .......................................................................
Thumb Instruction Set Overview ....................................................................
31
32
32
32
32
32
34
35
AT91SAM7A3 Debug and Test Features ..................................................... 37
Overview............................................................................................................
Block Diagram...................................................................................................
Application Examples ......................................................................................
Debug Environment .......................................................................................
Test Environment .............................................................................................
Debug and Test Pin Description .....................................................................
Functional Description.....................................................................................
Test Pin ..........................................................................................................
Embedded In-circuit Emulator ........................................................................
Debug Unit .....................................................................................................
IEEE 1149.1 JTAG Boundary Scan ...............................................................
ID Code Register............................................................................................
37
37
38
38
39
39
40
40
40
40
40
47
Reset Controller (RSTC) ............................................................................... 49
Overview............................................................................................................
Block Diagram...................................................................................................
Functional Description.....................................................................................
NRST Manager ..............................................................................................
Reset States...................................................................................................
Reset State Priorities .....................................................................................
Reset Controller Status Register....................................................................
Reset Controller (RSTC) User Interface..........................................................
Reset Controller Control Register ..................................................................
Reset Controller Status Register....................................................................
49
49
50
50
51
56
56
58
59
60
iii
6042A–ATARM–23-Dec-04
Reset Controller Mode Register..................................................................... 61
Real-time Timer (RTT) ................................................................................... 63
Overview............................................................................................................
Block Diagram...................................................................................................
Functional Description.....................................................................................
Real-time Timer (RTT) User Interface .............................................................
Real-time Timer Mode Register .....................................................................
Real-time Timer Alarm Register.....................................................................
Real-time Timer Value Register .....................................................................
Real-time Timer Status Register ....................................................................
63
63
64
66
67
68
69
70
Periodic Interval Timer (PIT)......................................................................... 71
Overview............................................................................................................
Block Diagram...................................................................................................
Functional Description.....................................................................................
Periodic Interval Timer (PIT) User Interface ...................................................
Periodic Interval Timer Mode Register ...........................................................
Periodic Interval Timer Status Register..........................................................
Periodic Interval Timer Value Register...........................................................
Periodic Interval Timer Image Register ..........................................................
71
71
72
74
75
76
77
78
Watchdog Timer (WDT) ................................................................................. 79
Overview............................................................................................................
Block Diagram...................................................................................................
Functional Description.....................................................................................
Watchdog Timer (WDT) User Interface ...........................................................
Watchdog Timer Control Register ..................................................................
Watchdog Timer Mode Register ....................................................................
Watchdog Timer Status Register ...................................................................
79
79
80
82
83
84
85
Shutdown Controller (SHDWC) .................................................................... 87
Description ........................................................................................................
Block Diagram...................................................................................................
I/O Lines Description........................................................................................
Product Dependencies.....................................................................................
Power Management .......................................................................................
Functional Description.....................................................................................
Shutdown Controller (SHDWC) User Interface ..............................................
Shutdown Control Register ............................................................................
Shutdown Mode Register...............................................................................
Shutdown Status Register..............................................................................
87
87
88
88
88
88
89
90
91
92
Memory Controller......................................................................................... 93
iv
AT91SAM7A3 Preliminary
6042A–ATARM–23-Dec-04
AT91SAM7A3 Preliminary
Overview............................................................................................................ 93
Block Diagram................................................................................................... 93
Functional Description..................................................................................... 94
Bus Arbiter ..................................................................................................... 94
Address Decoder ........................................................................................... 94
Remap Command .......................................................................................... 95
Abort Status ................................................................................................... 96
Memory Protection Unit.................................................................................. 96
Embedded Flash Controller ........................................................................... 97
Misalignment Detector ................................................................................... 97
Memory Controller (MC) User Interface .......................................................... 98
MC Remap Control Register .......................................................................... 99
MC Abort Status Register ............................................................................ 100
MC Abort Address Status Register .............................................................. 101
MC Protection Unit Area 0 to 15 Registers .................................................. 102
MC Protection Unit Peripheral...................................................................... 103
MC Protection Unit Enable Register ............................................................ 103
Embedded Flash Controller (EFC) ............................................................. 105
Description ......................................................................................................
Functional Description...................................................................................
Embedded Flash Organization.....................................................................
Read Operations ..........................................................................................
Write Operations ..........................................................................................
Flash Commands .........................................................................................
Embedded Flash Controller (EFC) User Interface .......................................
MC Flash Mode Register .............................................................................
MC Flash Command Register ......................................................................
MC Flash Status Register ............................................................................
105
105
105
106
108
108
112
113
115
117
Peripheral Data Controller (PDC) ............................................................... 119
Overview..........................................................................................................
Block Diagram.................................................................................................
Functional Description...................................................................................
Configuration................................................................................................
Memory Pointers ..........................................................................................
Transfer Counters ........................................................................................
Data Transfers .............................................................................................
Priority of PDC Transfer Requests ...............................................................
Peripheral Data Controller (PDC) User Interface .........................................
PDC Receive Pointer Register.....................................................................
PDC Receive Counter Register ...................................................................
PDC Transmit Pointer Register ....................................................................
PDC Transmit Counter Register ..................................................................
PDC Receive Next Pointer Register ............................................................
119
119
120
120
120
120
121
121
122
123
123
124
124
125
v
6042A–ATARM–23-Dec-04
PDC Receive Next Counter Register ...........................................................
PDC Transmit Next Pointer Register ...........................................................
PDC Transmit Next Counter Register ..........................................................
PDC Transfer Control Register ....................................................................
PDC Transfer Status Register......................................................................
125
126
126
127
128
Advanced Interrupt Controller (AIC) .......................................................... 129
Overview..........................................................................................................
Block Diagram.................................................................................................
Application Block Diagram ............................................................................
AIC Detailed Block Diagram ..........................................................................
I/O Line Description........................................................................................
Product Dependencies...................................................................................
I/O Lines.......................................................................................................
Power Management .....................................................................................
Interrupt Sources..........................................................................................
Functional Description...................................................................................
Interrupt Source Control...............................................................................
Interrupt Latencies .......................................................................................
Normal Interrupt ...........................................................................................
Fast Interrupt................................................................................................
Protect Mode................................................................................................
Spurious Interrupt.........................................................................................
General Interrupt Mask ................................................................................
Advanced Interrupt Controller (AIC) User Interface ....................................
Base Address...............................................................................................
AIC Source Mode Register ..........................................................................
AIC Source Vector Register .........................................................................
AIC Interrupt Vector Register .......................................................................
AIC FIQ Vector Register ......................................................................................
AIC Interrupt Status Register .......................................................................
AIC Interrupt Pending Register ....................................................................
AIC Interrupt Mask Register .........................................................................
AIC Core Interrupt Status Register ..............................................................
AIC Interrupt Enable Command Register.....................................................
AIC Interrupt Disable Command Register ....................................................
AIC Interrupt Clear Command Register .......................................................
AIC Interrupt Set Command Register ..........................................................
AIC End of Interrupt Command Register .....................................................
AIC Spurious Interrupt Vector Register ........................................................
AIC Debug Control Register.........................................................................
AIC Fast Forcing Enable Register................................................................
AIC Fast Forcing Disable Register ...............................................................
AIC Fast Forcing Status Register.................................................................
vi
129
129
129
130
130
130
130
130
130
132
132
134
135
137
140
141
141
142
142
143
144
144
145
146
146
147
147
148
148
149
149
150
150
151
151
152
152
AT91SAM7A3 Preliminary
6042A–ATARM–23-Dec-04
AT91SAM7A3 Preliminary
Clock Generator........................................................................................... 153
Description ...................................................................................................
Slow Clock RC Oscillator .............................................................................
Main Oscillator .............................................................................................
Divider and PLL Block ..................................................................................
153
153
153
155
Power Management Controller (PMC) ....................................................... 157
Description ...................................................................................................
Master Clock Controller................................................................................
Processor Clock Controller ..........................................................................
USB Clock Controller ...................................................................................
Peripheral Clock Controller ..........................................................................
Programmable Clock Output Controller .......................................................
Programming Sequence ..............................................................................
Clock Switching Details ................................................................................
Power Management Controller (PMC) User Interface ................................
157
157
157
158
158
158
159
162
165
Debug Unit (DBGU) ..................................................................................... 179
Overview..........................................................................................................
Block Diagram.................................................................................................
Product Dependencies...................................................................................
I/O Lines.......................................................................................................
Power Management .....................................................................................
Interrupt Source ...........................................................................................
UART Operations............................................................................................
Baud Rate Generator ...................................................................................
Receiver .......................................................................................................
Transmitter ...................................................................................................
Peripheral Data Controller............................................................................
Test Modes ..................................................................................................
Debug Communication Channel Support.....................................................
Chip Identifier ...............................................................................................
ICE Access Prevention ................................................................................
Debug Unit (DBGU) User Interface ...............................................................
Debug Unit Control Register ........................................................................
Debug Unit Mode Register ...........................................................................
Debug Unit Interrupt Enable Register ..........................................................
Debug Unit Interrupt Disable Register .........................................................
Debug Unit Interrupt Mask Register .............................................................
Debug Unit Status Register..........................................................................
Debug Unit Receiver Holding Register ........................................................
Debug Unit Transmit Holding Register.........................................................
Debug Unit Baud Rate Generator Register..................................................
Debug Unit Chip ID Register........................................................................
179
180
181
181
181
181
181
181
182
184
185
185
186
187
187
188
189
190
191
192
193
194
196
197
197
198
vii
6042A–ATARM–23-Dec-04
Debug Unit Chip ID Extension Register ....................................................... 200
Debug Unit Force NTRST Register.............................................................. 201
Parallel Input/Output Controller (PIO) ....................................................... 203
Overview..........................................................................................................
Block Diagram.................................................................................................
Application Block Diagram ............................................................................
Product Dependencies...................................................................................
Pin Multiplexing ............................................................................................
External Interrupt Lines ................................................................................
Power Management .....................................................................................
Interrupt Generation .....................................................................................
Functional Description...................................................................................
Pull-up Resistor Control ...............................................................................
I/O Line or Peripheral Function Selection ....................................................
Peripheral A or B Selection ..........................................................................
Output Control..............................................................................................
Synchronous Data Output............................................................................
Multi Drive Control (Open Drain) ..................................................................
Output Line Timings .....................................................................................
Inputs ...........................................................................................................
Input Glitch Filtering .....................................................................................
Input Change Interrupt .................................................................................
I/O Lines Programming Example ..................................................................
Parallel Input/Output Controller (PIO) User Interface..................................
PIO Controller PIO Enable Register.............................................................
PIO Controller PIO Disable Register............................................................
PIO Controller PIO Status Register..............................................................
PIO Controller Output Enable Register ........................................................
PIO Controller Output Disable Register .......................................................
PIO Controller Output Status Register .........................................................
PIO Controller Input Filter Enable Register ..................................................
PIO Controller Input Filter Disable Register .................................................
PIO Controller Input Filter Status Register...................................................
PIO Controller Set Output Data Register .....................................................
PIO Controller Clear Output Data Register ..................................................
PIO Controller Output Data Status Register ................................................
PIO Controller Pin Data Status Register ......................................................
PIO Controller Interrupt Enable Register .....................................................
PIO Controller Interrupt Disable Register.....................................................
PIO Controller Interrupt Mask Register ........................................................
PIO Controller Interrupt Status Register ......................................................
PIO Multi-driver Enable Register..................................................................
PIO Multi-driver Disable Register.................................................................
PIO Multi-driver Status Register...................................................................
PIO Pull Up Disable Register .......................................................................
viii
203
204
204
205
205
205
205
205
206
206
207
207
207
208
208
208
208
209
209
211
212
214
214
215
215
216
216
217
217
218
218
219
219
220
220
221
221
222
222
223
223
224
AT91SAM7A3 Preliminary
6042A–ATARM–23-Dec-04
AT91SAM7A3 Preliminary
PIO Pull Up Enable Register........................................................................
PIO Pull Up Status Register .........................................................................
PIO Peripheral A Select Register.................................................................
PIO Peripheral B Select Register.................................................................
PIO Peripheral A B Status Register .............................................................
PIO Output Write Enable Register ...............................................................
PIO Output Write Disable Register ..............................................................
PIO Output Write Status Register ................................................................
224
225
225
226
226
227
227
229
Serial Peripheral Interface (SPI) ................................................................. 231
Overview..........................................................................................................
Block Diagram.................................................................................................
Application Block Diagram ............................................................................
Signal Description .........................................................................................
Product Dependencies...................................................................................
I/O Lines.......................................................................................................
Power Management .....................................................................................
Interrupt........................................................................................................
Functional Description...................................................................................
Modes of Operation......................................................................................
Data Transfer ...............................................................................................
Master Mode Operations..............................................................................
SPI Slave Mode ...........................................................................................
Serial Peripheral Interface (SPI) User Interface ..........................................
SPI Control Register ....................................................................................
SPI Mode Register .......................................................................................
SPI Receive Data Register ..........................................................................
SPI Transmit Data Register .........................................................................
SPI Status Register......................................................................................
SPI Interrupt Enable Register ......................................................................
SPI Interrupt Disable Register......................................................................
SPI Interrupt Mask Register .........................................................................
SPI Chip Select Register..............................................................................
231
232
232
233
233
233
233
233
234
234
234
236
241
243
244
245
247
248
249
251
252
253
254
Two-wire Interface (TWI) ............................................................................. 257
Overview..........................................................................................................
Block Diagram.................................................................................................
Application Block Diagram ............................................................................
Product Dependencies...................................................................................
I/O Lines Description....................................................................................
Power Management .....................................................................................
Interrupt........................................................................................................
Functional Description...................................................................................
Transfer Format ...........................................................................................
Modes of Operation......................................................................................
257
257
257
258
258
258
258
259
259
259
ix
6042A–ATARM–23-Dec-04
Transmitting Data .........................................................................................
Read/Write Flowcharts.................................................................................
Two-wire Interface (TWI) User Interface ......................................................
TWI Control Register....................................................................................
TWI Master Mode Register ..........................................................................
TWI Internal Address Register .....................................................................
TWI Clock Waveform Generator Register....................................................
TWI Status Register .....................................................................................
TWI Interrupt Enable Register......................................................................
TWI Interrupt Disable Register.....................................................................
TWI Interrupt Mask Register ........................................................................
TWI Receive Holding Register .....................................................................
TWI Transmit Holding Register ....................................................................
259
262
264
265
266
267
267
268
269
270
271
272
272
Universal Synchronous/Asynchronous Receiver/Transmitter (USART) 273
Description ......................................................................................................
Block Diagram.................................................................................................
Application Block Diagram ............................................................................
I/O Lines Description .....................................................................................
Product Dependencies...................................................................................
I/O Lines.......................................................................................................
Power Management .....................................................................................
Interrupt........................................................................................................
Functional Description...................................................................................
Baud Rate Generator ...................................................................................
Receiver and Transmitter Control ................................................................
Synchronous and Asynchronous Modes......................................................
ISO7816 Mode .............................................................................................
IrDA Mode ....................................................................................................
RS485 Mode ................................................................................................
Test Modes ..................................................................................................
USART User Interface ...................................................................................
USART Control Register ..............................................................................
USART Mode Register.................................................................................
USART Interrupt Enable Register ................................................................
USART Interrupt Disable Register ...............................................................
USART Interrupt Mask Register...................................................................
USART Channel Status Register .................................................................
USART Receive Holding Register ...............................................................
USART Transmit Holding Register ..............................................................
USART Baud Rate Generator Register .......................................................
USART Receiver Time-out Register ............................................................
USART Transmitter Timeguard Register .....................................................
USART FI DI RATIO Register ......................................................................
USART Number of Errors Register ..............................................................
USART IrDA FILTER Register .....................................................................
x
273
274
275
275
276
276
276
276
277
277
281
281
291
293
297
298
300
301
303
306
307
308
309
311
311
312
313
314
315
316
316
AT91SAM7A3 Preliminary
6042A–ATARM–23-Dec-04
AT91SAM7A3 Preliminary
Synchronous Serial Controller (SSC)........................................................ 317
Overview..........................................................................................................
Block Diagram.................................................................................................
Application Block Diagram ............................................................................
Pin Name List ..................................................................................................
Product Dependencies...................................................................................
I/O Lines.......................................................................................................
Power Management .....................................................................................
Interrupt........................................................................................................
Functional Description...................................................................................
Clock Management ......................................................................................
Clock Divider ................................................................................................
Transmitter Operations ................................................................................
Receiver Operations ....................................................................................
Start..............................................................................................................
Frame Sync..................................................................................................
Data Format .................................................................................................
Loop Mode ...................................................................................................
Interrupt........................................................................................................
SSC Application Examples ............................................................................
Synchronous Serial Controller (SSC) User Interface .................................
SSC Control Register...................................................................................
SSC Clock Mode Register ...........................................................................
SSC Receive Clock Mode Register .............................................................
SSC Receive Frame Mode Register ............................................................
SSC Transmit Clock Mode Register ............................................................
SSC Transmit Frame Mode Register ...........................................................
SSC Receive Holding Register ....................................................................
SSC Transmit Holding Register ...................................................................
SSC Receive Synchronization Holding Register..........................................
SSC Transmit Synchronization Holding Register.........................................
SSC Status Register ....................................................................................
SSC Interrupt Enable Register.....................................................................
SSC Interrupt Disable Register ....................................................................
SSC Interrupt Mask Register .......................................................................
317
317
318
319
319
319
319
319
319
320
321
323
324
324
326
326
328
328
330
332
333
334
335
337
339
341
344
344
345
345
346
349
350
351
Timer/Counter (TC)...................................................................................... 353
Overview..........................................................................................................
Block Diagram.................................................................................................
Pin Name List ..................................................................................................
Product Dependencies...................................................................................
I/O Lines.......................................................................................................
Power Management .....................................................................................
Interrupt........................................................................................................
Functional Description...................................................................................
353
353
354
354
354
354
354
354
xi
6042A–ATARM–23-Dec-04
TC Description .............................................................................................
Capture Operating Mode..............................................................................
Waveform Operating Mode ..........................................................................
Timer/Counter (TC) User Interface ................................................................
Global Register Mapping .............................................................................
Channel Memory Mapping ...........................................................................
TC Block Control Register............................................................................
TC Block Mode Register ..............................................................................
TC Channel Control Register .......................................................................
TC Channel Mode Register: Capture Mode .................................................
TC Channel Mode Register: Waveform Mode .............................................
TC Counter Value Register ..........................................................................
TC Register A...............................................................................................
TC Register B...............................................................................................
TC Register C ..............................................................................................
TC Status Register .......................................................................................
TC Interrupt Enable Register .......................................................................
TC Interrupt Disable Register.......................................................................
TC Interrupt Mask Register ..........................................................................
354
357
359
366
366
366
367
367
368
369
371
374
374
375
375
376
378
379
380
Pulse Width Modulation Controller (PWM) ............................................... 381
Overview..........................................................................................................
Block Diagram.................................................................................................
I/O Lines Description......................................................................................
Product Dependencies...................................................................................
I/O Lines.......................................................................................................
Power Management .....................................................................................
Interrupt Sources..........................................................................................
Functional Description...................................................................................
PWM Clock Generator .................................................................................
PWM Channel ..............................................................................................
PWM Controller Operations .........................................................................
Pulse Width Modulation Controller (PWM) User Interface..........................
PWM Mode Register ....................................................................................
PWM Enable Register ..................................................................................
PWM Disable Register .................................................................................
PWM Status Register...................................................................................
PWM Interrupt Enable Register ...................................................................
PWM Interrupt Disable Register...................................................................
PWM Interrupt Mask Register ......................................................................
PWM Interrupt Status Register ....................................................................
PWM Channel Mode Register......................................................................
PWM Channel Duty Cycle Register .............................................................
PWM Channel Period Register ....................................................................
PWM Channel Counter Register ..................................................................
PWM Channel Update Register ...................................................................
xii
381
381
382
382
382
382
382
383
383
384
387
388
389
390
390
391
392
392
393
393
394
395
395
397
397
AT91SAM7A3 Preliminary
6042A–ATARM–23-Dec-04
AT91SAM7A3 Preliminary
USB Device Port (UDP) ............................................................................... 399
Overview..........................................................................................................
Block Diagram.................................................................................................
Product Dependencies...................................................................................
I/O Lines.......................................................................................................
Power Management .....................................................................................
Interrupt........................................................................................................
Typical Connection.........................................................................................
Functional Description...................................................................................
USB V2.0 Full-speed Introduction ................................................................
Handling Transactions with USB V2.0 Device Peripheral............................
Controlling Device States.............................................................................
USB Device Port (UDP) User Interface .........................................................
USB Frame Number Register ......................................................................
USB Global State Register...........................................................................
USB Function Address Register ..................................................................
USB Interrupt Enable Register.....................................................................
USB Interrupt Disable Register ....................................................................
USB Interrupt Mask Register .......................................................................
USB Interrupt Status Register ......................................................................
USB Interrupt Clear Register .......................................................................
USB Reset Endpoint Register ......................................................................
USB Endpoint Control and Status Register .................................................
USB FIFO Data Register..............................................................................
USB Transceiver Control Register ...............................................................
399
400
400
401
401
401
402
403
403
404
414
416
417
418
419
420
421
422
424
427
428
429
432
434
MultiMedia Card Interface (MCI) ................................................................. 435
Description ......................................................................................................
Block Diagram.................................................................................................
Application Block Diagram ............................................................................
Pin Name List .................................................................................................
Product Dependencies...................................................................................
I/O Lines.......................................................................................................
Power Management .....................................................................................
Interrupt........................................................................................................
Bus Topology..................................................................................................
MultiMedia Card Operations ..........................................................................
Command - Response Operation ................................................................
Data Transfer Operation ..............................................................................
Read Operation ............................................................................................
Write Operation ............................................................................................
SD Card Operations........................................................................................
MultiMedia Card Interface (MCI) User Interface ...........................................
MCI Control Register....................................................................................
MCI Mode Register ......................................................................................
435
435
436
436
436
436
436
436
437
438
439
441
441
443
445
446
447
448
xiii
6042A–ATARM–23-Dec-04
MCI Data Timeout Register..........................................................................
MCI SD Card Register .................................................................................
MCI Argument Register................................................................................
MCI Command Register...............................................................................
MCI SD Response Register .........................................................................
MCI SD Receive Data Register....................................................................
MCI SD Transmit Data Register...................................................................
MCI Status Register .....................................................................................
MCI Interrupt Enable Register......................................................................
MCI Interrupt Disable Register.....................................................................
MCI Interrupt Mask Register .......................................................................
449
450
450
451
453
454
454
455
458
459
460
Analog-to-digital Converter (ADC) ............................................................. 461
Overview..........................................................................................................
Block Diagram.................................................................................................
Signal Description ..........................................................................................
Product Dependencies...................................................................................
Power Management .....................................................................................
Interrupt Sources..........................................................................................
Analog Inputs ...............................................................................................
I/O Lines.......................................................................................................
Timer Triggers ..............................................................................................
Conversion Performances .............................................................................
Functional Description...................................................................................
Analog-to-digital Conversion ........................................................................
Conversion Reference .................................................................................
Conversion Resolution .................................................................................
Conversion Results ......................................................................................
Conversion Triggers .....................................................................................
Sleep Mode and Conversion Sequencer .....................................................
ADC Timings ................................................................................................
Analog-to-digital Converter (ADC) User Interface .......................................
ADC Control Register...................................................................................
ADC Mode Register .....................................................................................
ADC Channel Enable Register.....................................................................
ADC Channel Disable Register ....................................................................
ADC Channel Status Register......................................................................
ADC Status Register ....................................................................................
ADC Last Converted Data Register .............................................................
ADC Interrupt Enable Register.....................................................................
ADC Interrupt Disable Register ....................................................................
ADC Interrupt Mask Register .......................................................................
ADC Channel Data Register ........................................................................
461
461
462
462
462
462
462
462
462
462
463
463
463
463
463
465
466
466
467
468
469
471
471
472
473
474
475
475
476
476
Controller Area Network (CAN) .................................................................. 477
xiv
AT91SAM7A3 Preliminary
6042A–ATARM–23-Dec-04
AT91SAM7A3 Preliminary
Overview..........................................................................................................
Block Diagram.................................................................................................
Application Block Diagram ............................................................................
I/O Lines Description .....................................................................................
Product Dependencies...................................................................................
I/O Lines.......................................................................................................
Power Management .....................................................................................
Interrupt........................................................................................................
CAN Controller Features................................................................................
CAN Protocol Overview ...............................................................................
Mailbox Organization ...................................................................................
Time Management Unit................................................................................
CAN 2.0 Standard Features .........................................................................
Low-power mode..........................................................................................
Functional Description...................................................................................
CAN Controller Initialization .........................................................................
CAN Controller Interrupt Handling ...............................................................
CAN Controller Message Handling ..............................................................
CAN Controller Timing Modes .....................................................................
Controller Area Network (CAN) Controller User Interface .........................
CAN Mode Register .....................................................................................
CAN Interrupt Enable Register.....................................................................
CAN Interrupt Disable Register ....................................................................
CAN Interrupt Mask Register .......................................................................
CAN Status Register ....................................................................................
CAN Baudrate Register................................................................................
CAN Timer Register .....................................................................................
CAN Timestamp Register ............................................................................
CAN Error Counter Register ........................................................................
CAN Transfer Command Register ...............................................................
CAN Abort Command Register ....................................................................
CAN Message Mode Register......................................................................
CAN Message Acceptance Mask Register ..................................................
CAN Message ID Register ...........................................................................
CAN Message Family ID Register ...............................................................
CAN Message Status Register ....................................................................
CAN Message Data Low Register ...............................................................
CAN Message Data High Register...............................................................
CAN Message Control Register ...................................................................
477
478
478
478
479
479
479
479
480
480
480
483
484
488
491
491
492
493
500
503
504
506
508
510
512
515
516
517
518
519
520
521
522
523
524
525
528
529
530
AT91SAM7A3 Electrical Characteristics ................................................... 533
Absolute Maximum Ratings...........................................................................
DC Characteristics..........................................................................................
Power Consumption.......................................................................................
Power Consumption versus Modes .............................................................
Power Consumption versus Master Clock Frequency in Active Mode.........
533
534
536
536
538
xv
6042A–ATARM–23-Dec-04
Power Consumption versus Master Clock Frequency in Ultra Low-power Mode
539
Crystal Oscillator Characteristics .................................................................
RC Oscillator Characteristics .......................................................................
Main Oscillators Characteristics...................................................................
XIN Clock Characteristics ............................................................................
PLL Characteristics ......................................................................................
USB Transceiver Characteristics ..................................................................
Electrical Characteristics ..............................................................................
Switching Characteristics .............................................................................
Analog-to-Digital Converter Characteristics................................................
Applicable Conditions and Derating Data ....................................................
Conditions and Timings Computation ..........................................................
Temperature Derating Factor .......................................................................
VDDCORE Voltage Derating Factor ............................................................
VDDIO Voltage Derating Factor...................................................................
Clocks Characteristics ...................................................................................
Master Clock Characteristics .......................................................................
540
540
540
541
541
542
542
542
544
545
545
546
546
547
548
548
AT91SAM7A3 AC Characteristics .............................................................. 549
Embedded Flash Characteristics ..................................................................
JTAG/ICE Timings ..........................................................................................
ICE Interface Signals ...................................................................................
JTAG Interface Signals ................................................................................
549
550
550
551
AT91SAM7A3 Mechanical Characteristics ................................................ 553
Thermal Considerations.................................................................................
Thermal Data ...............................................................................................
Junction Temperature ..................................................................................
Package Drawings ..........................................................................................
Soldering Profile .............................................................................................
553
553
554
555
557
AT91SAM7A3 Ordering Information .......................................................... 558
Document Details ............................................................................................. i
Revision History ................................................................................................ i
xvi
AT91SAM7A3 Preliminary
6042A–ATARM–23-Dec-04
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