ATMEL AT89C51SND1C

1. Features
• MPEG I/II-Layer 3 Hardwired Decoder
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– Stand-alone MP3 Decoder
– 48, 44.1, 32, 24, 22.05, 16 kHz Sampling Frequency
– Separated Digital Volume Control on Left and Right Channels (Software Control
using 31 Steps)
– Bass, Medium, and Treble Control (31 Steps)
– Bass Boost Sound Effect
– Ancillary Data Extraction
– CRC Error and MPEG Frame Synchronization Indicators
Programmable Audio Output for Interfacing with Common Audio DAC
– PCM Format Compatible
– I2S Format Compatible
8-bit MCU C51 Core Based (FMAX = 20 MHz)
2304 Bytes of Internal RAM
64K Bytes of Code Memory
– AT89C51SND1C: Flash (100K Erase/Write Cycles)
– AT83SND1C: ROM
4K Bytes of Boot Flash Memory (AT89C51SND1C)
– ISP: Download from USB (standard) or UART (option)
External Code Memory
– AT80C51SND1C: ROMless
USB Rev 1.1 Controller
– Full Speed Data Transmission
Built-in PLL
– MP3 Audio Clocks
– USB Clock
MultiMedia Card® Interface Compatibility
Atmel DataFlash® SPI Interface Compatibility
IDE/ATAPI Interface
2 Channels 10-bit ADC, 8 kHz (8-true bit)
– Battery Voltage Monitoring
– Voice Recording Controlled by Software
Up to 44 Bits of General-purpose I/Os
– 4-bit Interrupt Keyboard Port for a 4 x n Matrix
– SmartMedia® Software Interface
2 Standard 16-bit Timers/Counters
Hardware Watchdog Timer
Standard Full Duplex UART with Baud Rate Generator
Two Wire Master and Slave Modes Controller
SPI Master and Slave Modes Controller
Power Management
– Power-on Reset
– Software Programmable MCU Clock
– Idle Mode, Power-down Mode
Operating Conditions:
– 3V, ±10%, 25 mA Typical Operating at 25°C
– Temperature Range: -40°C to +85°C
Packages
– TQFP80, BGA81, PLCC84 (Development Board)
– Dice
Single-Chip
Flash
Microcontroller
with MP3
Decoder and
Human Interface
AT83SND1C
AT89C51SND1C
AT80C51SND1C
Rev. 4109H–8051–01/05
2. Description
The AT8xC51SND1C are fully integrated stand-alone hardwired MPEG I/II-Layer 3
decoder with a C51 microcontroller core handling data flow and MP3-player control.
The AT89C51SND1C includes 64K Bytes of Flash memory and allows In-System Programming through an embedded 4K Bytes of Boot Flash memory.
The AT83SND1C includes 64K Bytes of ROM memory.
The AT80C51SND1C does not include any code memory.
The AT8xC51SND1C include 2304 Bytes of RAM memory.
The AT8xC51SND1C provides the necessary features for human interface like timers,
keyboard port, serial or parallel interface (USB, TWI, SPI, IDE), ADC input, I2S output,
and all external memory interface (NAND or NOR Flash, SmartMedia, MultiMedia,
DataFlash cards).
3. Typical
Applications
•
MP3-Player
•
PDA, Camera, Mobile Phone MP3
•
Car Audio/Multimedia MP3
•
Home Audio/Multimedia MP3
4. Block Diagram
Figure 1. AT8xC51SND1C Block Diagram
INT0
INT1
3
3
VDD VSS UVDD UVSS AVDD AVSS AREF AIN1:0
Interrupt
Handler Unit
RAM
2304 Bytes
C51 (X2 Core)
Clock and PLL
Unit
Flash
ROM
64 KBytes
Flash Boot
4 KBytes
10-bit A to D
Converter
TXD RXD
T0
T1
SS MISO MOSI SCK
SCL SDA
3
3
3
4
1
3
UART
and
BRG
Timers 0/1
Watchdog
4
4
4
SPI/DataFlash
Controller
1
TWI
Controller
8-Bit Internal Bus
MP3 Decoder
Unit
I2S/PCM
Audio Interface
USB
Controller
MMC
Interface
Keyboard
Interface
I/O
Ports
IDE
Interface
1
FILT
X1
X2
RST
ISP
ALE
DOUT DCLK DSEL SCLK
D+
D-
MCLK MDAT MCMD
KIN3:0
P0-P5
1 Alternate function of Port 1
3 Alternate function of Port 3
4 Alternate function of Port 4
2
AT8xC51SND1C
4109H–8051–01/05
AT8xC51SND1C
5. Pin Description
5.1 Pinouts
80
79
78
77
76
75
74
73
72
71
70
69
68
67
66
65
64
63
62
61
P5.1
P5.0
P0.0/AD0
P0.1/AD1
P0.2/AD2
P0.3/AD3
P0.4/AD4
P0.5/AD5
VSS
VDD
P0.6/AD6
P0.7/AD7
P4.3/SS
P4.2/SCK
P4.1/MOSI
P4.0/MISO
P2.0/A8
P2.1/A9
P4.7
P4.6
Figure 1. AT8xC51SND1C 80-pin QFP Package
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
AT89C51SND1C-RO (FLASH)
AT83SND1C-RO (ROM)
AT80C51SND1C-RO (ROMLESS)
60
59
58
57
56
55
54
53
52
51
50
49
48
47
46
45
44
43
42
41
P4.5
P4.4
P2.2/A10
P2.3/A11
P2.4/A12
P2.5/A13
P2.6/A14
P2.7/A15
VSS
VDD
MCLK
MDAT
MCMD
RST
SCLK
DSEL
DCLK
DOUT
VSS
VDD
D+
DVDD
VSS
P3.0/RXD
P3.1/TXD
P3.2/INT0
P3.3/INT1
P3.4/T0
P3.5/T1
P3.6/WR
P3.7/RD
AVDD
AVSS
AREFP
AREFN
AIN0
AIN1
P5.2
P5.3
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
ALE
ISP1/PSEN2/NC
P1.0/KIN0
P1.1/KIN1
P1.2/KIN2
P1.3/KIN3
P1.4
P1.5
P1.6/SCL
P1.7/SDA
VDD
PVDD
FILT
PVSS
VSS
X2
X1
TST
UVDD
UVSS
Notes:
1. ISP pin is only available in AT89C51SND1C product.
Do not connect this pin on AT83SND1C product.
2. PSEN pin is only available in AT80C51SND1C product.
3
4109H–8051–01/05
Figure 2. AT8xC51SND1C 81-pin BGA Package
9
8
7
6
5
4
P4.6
P2.0/
A8
P4.0/
MISO
P4.4
P4.7
P2.5/
A13
P4.2/
SCK
VDD
P0.2/
AD2
P0.3/
AD3
P5.0
ALE
A
P4.1/
MOSI
P4.3/
SS
P0.1/
AD1
P0.4/
AD4
P0.0/
AD0
ISP1/
PSEN2
NC
P1.1
B
P2.2/
A10
P2.1/
A9
P0.6
VSS
P5.1
P1.0/
KIN0
P1.3/
KIN3
P1.2/
KIN2
C
P2.4/
A12
P2.6/
A14
P4.5
P0.7/
AD7
P0.5/
AD5
P1.6/
SCL
P1.7/
SDA
P1.5
P1.4
D
VDD
P2.3/
A11
VSS
P2.7/
A15
FILT
PVDD
X1
VDD
E
RST
MCMD
MCLK
MDAT
AVDD
P3.4/
T0
UVSS
PVSS
X2
F
DSEL
SCLK
DOUT
P5.3
P3.7/
RD
P3.5/
T1
VDD
TST
VSS
G
DCLK
VSS
AIN1
AVSS
AIN0
P3.3/
INT1
P3.1/
TXD
D-
UVDD
H
VDD
P5.2
AREFP
AREFN
P3.6/
WR
P3.2/
INT0
P3.0/
RXD
VSS
D+
J
Notes:
4
3
2
1
1. ISP pin is only available in AT89C51SND1C product.
Do not connect this pin on AT83SND1C and AT80C51SND1C product.
2. PSEN pin is only available in AT80C51SND1C product.
AT8xC51SND1C
4109H–8051–01/05
AT8xC51SND1C
11
10
9
8
7
6
5
4
3
2
1
84
83
82
81
80
79
78
77
76
75
NC
P5.1
P5.0
P0.0/AD0
P0.1/AD1
P0.2/AD2
P0.3/AD3
P0.4/AD4
P0.5/AD5
VSS
VDD
P0.6/AD6
P0.7/AD7
P4.3/SS
P4.2/SCK
P4.1/MOSI
P4.0/MISO
P2.0/A8
P2.1/A9
P4.7
P4.6
Figure 3. AT8xC51SND1C 84-pin PLCC Package
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
AT89C51SND1C-SR (FLASH)
74
73
72
71
70
69
68
67
66
65
64
63
62
61
60
59
58
57
56
55
54
NC
P4.5
P4.4
P2.2/A10
P2.3/A11
P2.4/A12
P2.5/A13
P2.6/A14
P2.7/A15
VSS
VDD
MCLK
MDAT
MCMD
RST
SCLK
DSEL
DCLK
DOUT
VSS
VDD
D+
DVDD
VSS
P3.0/RXD
P3.1/TXD
P3.2/INT0
P3.3/INT1
P3.4/T0
P3.5/T1
P3.6/WR
P3.7/RD
AVDD
AVSS
AREFP
AREFN
AIN0
AIN1
P5.2
P5.3
NC
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
ALE
ISP
P1.0/KIN0
P1.1/KIN1
P1.2/KIN2
P1.3/KIN3
P1.4
P1.5
P1.6/SCL
P1.7/SDA
VDD
PAVDD
FILT
PAVSS
VSS
X2
NC
X1
TST
UVDD
UVSS
5
4109H–8051–01/05
5.2 Signals
All the AT8xC51SND1C signals are detailed by functionality in Table 3 to Table 16.
Table 3. Ports Signal Description
Signal
Name
Type
Alternate
Function
Description
P0.7:0
I/O
Port 0
P0 is an 8-bit open-drain bidirectional I/O port. Port 0 pins that have 1s
written to them float and can be used as high impedance inputs. To
avoid any parasitic current consumption, floating P0 inputs must be
polarized to VDD or VSS.
P1.7:0
I/O
Port 1
P1 is an 8-bit bidirectional I/O port with internal pull-ups.
KIN3:0
SCL
SDA
P2.7:0
I/O
Port 2
P2 is an 8-bit bidirectional I/O port with internal pull-ups.
A15:8
AD7:0
RXD
TXD
INT0
INT1
T0
T1
WR
RD
I/O
Port 3
P3 is an 8-bit bidirectional I/O port with internal pull-ups.
P4.7:0
I/O
Port 4
P4 is an 8-bit bidirectional I/O port with internal pull-ups.
MISO
MOSI
SCK
SS
P5.3:0
I/O
Port 5
P5 is a 4-bit bidirectional I/O port with internal pull-ups.
-
P3.7:0
Table 4. Clock Signal Description
Signal
Name
6
Type
Alternate
Function
Description
X1
I
Input to the on-chip inverting oscillator amplifier
To use the internal oscillator, a crystal/resonator circuit is connected to
this pin. If an external oscillator is used, its output is connected to this
pin. X1 is the clock source for internal timing.
X2
O
Output of the on-chip inverting oscillator amplifier
To use the internal oscillator, a crystal/resonator circuit is connected to
this pin. If an external oscillator is used, leave X2 unconnected.
-
FILT
I
PLL Low Pass Filter input
FILT receives the RC network of the PLL low pass filter.
-
-
AT8xC51SND1C
4109H–8051–01/05
AT8xC51SND1C
Table 5. Timer 0 and Timer 1 Signal Description
Signal
Name
Type
Description
Alternate
Function
Timer 0 Gate Input
INT0 serves as external run control for timer 0, when selected by
GATE0 bit in TCON register.
INT0
I
External Interrupt 0
INT0 input sets IE0 in the TCON register. If bit IT0 in this register is set,
bit IE0 is set by a falling edge on INT0. If bit IT0 is cleared, bit IE0 is set
by a low level on INT0.
P3.2
Timer 1 Gate Input
INT1 serves as external run control for timer 1, when selected by
GATE1 bit in TCON register.
INT1
I
T0
I
Timer 0 External Clock Input
When timer 0 operates as a counter, a falling edge on the T0 pin
increments the count.
P3.4
T1
I
Timer 1 External Clock Input
When timer 1 operates as a counter, a falling edge on the T1 pin
increments the count.
P3.5
External Interrupt 1
INT1 input sets IE1 in the TCON register. If bit IT1 in this register is set,
bit IE1 is set by a falling edge on INT1. If bit IT1 is cleared, bit IE1 is set
by a low level on INT1.
P3.3
Table 6. Audio Interface Signal Description
Signal
Name
Type
DCLK
O
DAC Data Bit Clock
-
DOUT
O
DAC Audio Data
-
DSEL
O
DAC Channel Select Signal
DSEL is the sample rate clock output.
-
SCLK
O
DAC System Clock
SCLK is the oversampling clock synchronized to the digital audio data
(DOUT) and the channel selection signal (DSEL).
-
Description
Alternate
Function
Table 7. USB Controller Signal Description
Signal
Name
Type
D+
I/O
USB Positive Data Upstream Port
This pin requires an external 1.5 KΩ pull-up to VDD for full speed
operation.
-
D-
I/O
USB Negative Data Upstream Port
-
Description
Alternate
Function
7
4109H–8051–01/05
Table 8. MutiMediaCard Interface Signal Description
Signal
Name
Type
Alternate
Function
MCLK
O
MMC Clock output
Data or command clock transfer.
-
MCMD
I/O
MMC Command line
Bidirectional command channel used for card initialization and data
transfer commands. To avoid any parasitic current consumption,
unused MCMD input must be polarized to VDD or VSS.
-
MDAT
I/O
MMC Data line
Bidirectional data channel. To avoid any parasitic current consumption,
unused MDAT input must be polarized to VDD or VSS.
-
Description
Table 9. UART Signal Description
Signal
Name
Type
Alternate
Function
RXD
I/O
Receive Serial Data
RXD sends and receives data in serial I/O mode 0 and receives data in
serial I/O modes 1, 2 and 3.
P3.0
TXD
O
Transmit Serial Data
TXD outputs the shift clock in serial I/O mode 0 and transmits data in
serial I/O modes 1, 2 and 3.
P3.1
Description
Table 10. SPI Controller Signal Description
Signal
Name
Type
Alternate
Function
MISO
I/O
SPI Master Input Slave Output Data Line
When in master mode, MISO receives data from the slave peripheral.
When in slave mode, MISO outputs data to the master controller.
P4.0
MOSI
I/O
SPI Master Output Slave Input Data Line
When in master mode, MOSI outputs data to the slave peripheral.
When in slave mode, MOSI receives data from the master controller.
P4.1
SCK
I/O
SPI Clock Line
When in master mode, SCK outputs clock to the slave peripheral. When
in slave mode, SCK receives clock from the master controller.
P4.2
SS
I
SPI Slave Select Line
When in controlled slave mode, SS enables the slave mode.
P4.3
Description
Table 11. TWI Controller Signal Description
8
Signal
Name
Type
Alternate
Function
SCL
I/O
TWI Serial Clock
When TWI controller is in master mode, SCL outputs the serial clock to
the slave peripherals. When TWI controller is in slave mode, SCL
receives clock from the master controller.
P1.6
SDA
I/O
TWI Serial Data
SDA is the bidirectional Two Wire data line.
P1.7
Description
AT8xC51SND1C
4109H–8051–01/05
AT8xC51SND1C
Table 12. A/D Converter Signal Description
Signal
Name
Type
AIN1:0
I
A/D Converter Analog Inputs
-
AREFP
I
Analog Positive Voltage Reference Input
-
AREFN
I
Analog Negative Voltage Reference Input
This pin is internally connected to AVSS.
-
Description
Alternate
Function
Table 13. Keypad Interface Signal Description
Signal
Name
Type
KIN3:0
I
Description
Alternate
Function
Keypad Input Lines
Holding one of these pins high or low for 24 oscillator periods triggers a
keypad interrupt.
P1.3:0
Table 14. External Access Signal Description
Signal
Name
Type
A15:8
I/O
Address Lines
Upper address lines for the external bus.
Multiplexed higher address and data lines for the IDE interface.
P2.7:0
AD7:0
I/O
Address/Data Lines
Multiplexed lower address and data lines for the external memory or the
IDE interface.
P0.7:0
ALE
O
Address Latch Enable Output
ALE signals the start of an external bus cycle and indicates that valid
address information is available on lines A7:0. An external latch is used
to demultiplex the address from address/data bus.
-
PSEN
I/O
Program Store Enable Output (AT80C51SND1C Only)
This signal is active low during external code fetch or external code
read (MOVC instruction).
-
ISP
I/O
ISP Enable Input (AT89C51SND1C Only)
This signal must be held to GND through a pull-down resistor at the
falling reset to force execution of the internal bootloader.
-
RD
O
Read Signal
Read signal asserted during external data memory read operation.
P3.7
WR
O
Write Signal
Write signal asserted during external data memory write operation.
P3.6
EA(1)(2)
I
External Access Enable (Dice Only)
EA must be externally held low to enable the device to fetch code from
external program memory locations 0000h to FFFFh.
Notes:
Description
Alternate
Function
-
1. For ROM/Flash Dice product versions: pad EA must be connected to VCC.
2. For ROMless Dice product versions: pad EA must be connected to VSS.
9
4109H–8051–01/05
Table 15. System Signal Description
Signal
Name
Type
Alternate
Function
Description
RST
I
Reset Input
Holding this pin high for 64 oscillator periods while the oscillator is
running resets the device. The Port pins are driven to their reset
conditions when a voltage lower than VIL is applied, whether or not the
oscillator is running.
This pin has an internal pull-down resistor which allows the device to be
reset by connecting a capacitor between this pin and VDD.
Asserting RST when the chip is in Idle mode or Power-Down mode
returns the chip to normal operation.
TST
I
Test Input
Test mode entry signal. This pin must be set to VDD.
-
-
Table 16. Power Signal Description
10
Signal
Name
Type
Description
Alternate
Function
VDD
PWR
Digital Supply Voltage
Connect these pins to +3V supply voltage.
-
VSS
GND
Circuit Ground
Connect these pins to ground.
-
AVDD
PWR
Analog Supply Voltage
Connect this pin to +3V supply voltage.
-
AVSS
GND
Analog Ground
Connect this pin to ground.
-
PVDD
PWR
PLL Supply voltage
Connect this pin to +3V supply voltage.
-
PVSS
GND
PLL Circuit Ground
Connect this pin to ground.
-
UVDD
PWR
USB Supply Voltage
Connect this pin to +3V supply voltage.
-
UVSS
GND
USB Ground
Connect this pin to ground.
-
AT8xC51SND1C
4109H–8051–01/05
AT8xC51SND1C
5.17 Internal Pin
Structure
Table 18. Detailed Internal Pin Structure
Circuit(1)
Type
Pins
Input
TST
Input/Output
RST
Input/Output
P1(2)
P2(3)
P3
P4
P53:0
RTST
VDD
VDD
P
RRST
Watchdog Output
VSS
2 osc
periods
Latch Output
VDD
VDD
VDD
P1
P2
P3
N
VSS
VDD
P
Input/Output
P0
MCMD
MDAT
ISP
N
PSEN
VSS
ALE
SCLK
DCLK
VDD
P
Output
N
DOUT
DSEL
MCLK
VSS
D+
Input/Output
D+
D-
D-
Notes:
1. For information on resistors value, input/output levels, and drive capability, refer to
the Section “DC Characteristics”, page 184.
2. When the Two Wire controller is enabled, P1, P2, and P3 transistors are disabled
allowing pseudo open-drain structure.
3. In Port 2, P1 transistor is continuously driven when outputting a high level bit address
(A15:8).
11
4109H–8051–01/05
6. Clock Controller
The AT8xC51SND1C clock controller is based on an on-chip oscillator feeding an onchip Phase Lock Loop (PLL). All internal clocks to the peripherals and CPU core are
generated by this controller.
6.1 Oscillator
The AT8xC51SND1C X1 and X2 pins are the input and the output of a single-stage onchip inverter (see Figure 4) that can be configured with off-chip components such as a
Pierce oscillator (see Figure 5). Value of capacitors and crystal characteristics are
detailed in the Section “DC Characteristics”, page 163.
The oscillator outputs three different clocks: a clock for the PLL, a clock for the CPU
core, and a clock for the peripherals as shown in Figure 4. These clocks are either
enabled or disabled, depending on the power reduction mode as detailed in the section
“Power Management” on page 48. The peripheral clock is used to generate the Timer 0,
Timer 1, MMC, ADC, SPI, and Port sampling clocks.
Figure 4. Oscillator Block Diagram and Symbol
÷2
X1
0
Peripheral
Clock
1
CPU Core
Clock
X2
X2
CKCON.0
IDL
PCON.0
PD
Oscillator
Clock
PCON.1
PER
CLOCK
Peripheral Clock Symbol
CPU
CLOCK
OSC
CLOCK
CPU Core Clock Symbol
Oscillator Clock Symbol
Figure 5. Crystal Connection
X1
C1
Q
C2
VSS
6.2 X2 Feature
Unlike standard C51 products that require 12 oscillator clock periods per machine cycle,
the AT8xC51SND1C need only 6 oscillator clock periods per machine cycle. This feature called the “X2 feature” can be enabled using the X2 bit(1) in CKCON (see Table 5)
and allows the AT8xC51SND1C to operate in 6 or 12 oscillator clock periods per
machine cycle. As shown in Figure 4, both CPU and peripheral clocks are affected by
this feature. Figure 6 shows the X2 mode switching waveforms. After reset the standard
mode is activated. In standard mode the CPU and peripheral clock frequency is the
oscillator frequency divided by 2 while in X2 mode, it is the oscillator frequency.
Note:
12
X2
1. The X2 bit reset value depends on the X2B bit in the Hardware Security Byte (see
Table 12 on page 24). Using the AT89C51SND1C (Flash Version) the system can
boot either in standard or X2 mode depending on the X2B value. Using AT83SND1C
(ROM Version) the system always boots in standard mode. X2B bit can be changed
to X2 mode later by software.
AT8xC51SND1C
4109H–8051–01/05
AT8xC51SND1C
Figure 6. Mode Switching Waveforms
X1
X1 ÷ 2
X2 Bit
Clock
STD Mode
Note:
STD Mode
X2 Mode(1)
1. In order to prevent any incorrect operation while operating in X2 mode, user must be
aware that all peripherals using clock frequency as time reference (timers, etc.) will
have their time reference divided by 2. For example, a free running timer generating
an interrupt every 20 ms will then generate an interrupt every 10 ms.
6.3 PLL
6.3.1 PLL Description
The AT8xC51SND1C PLL is used to generate internal high frequency clock (the PLL
Clock) synchronized with an external low-frequency (the Oscillator Clock). The PLL
clock provides the MP3 decoder, the audio interface, and the USB interface clocks.
Figure 7 shows the internal structure of the PLL.
The PFLD block is the Phase Frequency Comparator and Lock Detector. This block
makes the comparison between the reference clock coming from the N divider and the
reverse clock coming from the R divider and generates some pulses on the Up or Down
signal depending on the edge position of the reverse clock. The PLLEN bit in PLLCON
register is used to enable the clock generation. When the PLL is locked, the bit PLOCK
in PLLCON register (see Table 6) is set.
The CHP block is the Charge Pump that generates the voltage reference for the VCO by
injecting or extracting charges from the external filter connected on PFILT pin (see
Fi gure 8) . Value of the filter components ar e detailed in the Section “ DC
Characteristics”.
The VCO block is the Voltage Controlled Oscillator controlled by the voltage Vref produced by the charge pump. It generates a square wave signal: the PLL clock.
Figure 7. PLL Block Diagram and Symbol
PFILT
PLLCON.1
PLLEN
N divider
OSC
CLOCK
N6:0
Up
PFLD
CHP
Vref
VCO
Down
PLOCK
PLLCON.0
PLL
Clock
R divider
R9:0
OSCclk × ( R + 1 )
PLLclk = ----------------------------------------------N+1
PLL
CLOCK
PLL Clock Symbol
13
4109H–8051–01/05
Figure 8. PLL Filter Connection
FILT
R
C2
C1
VSS
6.3.2 PLL Programming
VSS
The PLL is programmed using the flow shown in Figure 9. As soon as clock generation
is enabled, the user must wait until the lock indicator is set to ensure the clock output is
stable. The PLL clock frequency will depend on MP3 decoder clock and audio interface
clock frequencies.
Figure 9. PLL Programming Flow
PLL
Programming
Configure Dividers
N6:0 = xxxxxxb
R9:0 = xxxxxxxxxxb
Enable PLL
PLLRES = 0
PLLEN = 1
PLL Locked?
PLOCK = 1?
14
AT8xC51SND1C
4109H–8051–01/05
AT8xC51SND1C
6.4 Registers
Table 5. CKCON Register
CKCON (S:8Fh) – Clock Control Register
7
6
5
4
3
2
1
0
TWIX2
WDX2
-
SIX2
-
T1X2
T0X2
X2
Bit
Number
Bit
Mnemonic Description
TWIX2
Two-Wire Clock Control Bit
Set to select the oscillator clock divided by 2 as TWI clock input (X2
independent).
Clear to select the peripheral clock as TWI clock input (X2 dependent).
6
WDX2
Watchdog Clock Control Bit
Set to select the oscillator clock divided by 2 as watchdog clock input (X2
independent).
Clear to select the peripheral clock as watchdog clock input (X2 dependent).
5
-
7
4
SIX2
3
-
2
1
0
Reserved
The values read from this bit is indeterminate. Do not set this bit.
Enhanced UART Clock (Mode 0 and 2) Control Bit
Set to select the oscillator clock divided by 2 as UART clock input (X2
independent).
Clear to select the peripheral clock as UART clock input (X2 dependent)..
Reserved
The values read from this bit is indeterminate. Do not set this bit.
T1X2
Timer 1 Clock Control Bit
Set to select the oscillator clock divided by 2 as timer 1 clock input (X2
independent).
Clear to select the peripheral clock as timer 1 clock input (X2 dependent).
T0X2
Timer 0 Clock Control Bit
Set to select the oscillator clock divided by 2 as timer 0 clock input (X2
independent).
Clear to select the peripheral clock as timer 0 clock input (X2 dependent).
X2
System Clock Control Bit
Clear to select 12 clock periods per machine cycle (STD mode, FCPU = FPER =
FOSC/2).
Set to select 6 clock periods per machine cycle (X2 mode, FCPU = FPER = FOSC).
Reset Value = 0000 000Xb (AT89C51SND1C) or 0000 0000b (AT83SND1C)
Table 6. PLLCON Register
PLLCON (S:E9h) – PLL Control Register
7
6
5
4
3
2
1
0
R1
R0
-
-
PLLRES
-
PLLEN
PLOCK
Bit
Number
Bit
Mnemonic Description
7-6
R1:0
5-4
-
3
PLLRES
PLL Least Significant Bits R Divider
2 LSB of the 10-bit R divider.
Reserved
The values read from these bits are always 0. Do not set these bits.
PLL Reset Bit
Set this bit to reset the PLL.
Clear this bit to free the PLL and allow enabling.
15
4109H–8051–01/05
Bit
Number
Bit
Mnemonic Description
Reserved
The value read from this bit is always 0. Do not set this bit.
2
-
1
PLLEN
PLL Enable Bit
Set to enable the PLL.
Clear to disable the PLL.
0
PLOCK
PLL Lock Indicator
Set by hardware when PLL is locked.
Clear by hardware when PLL is unlocked.
Reset Value = 0000 1000b
Table 7. PLLNDIV Register
PLLNDIV (S:EEh) – PLL N Divider Register
7
6
5
4
3
2
1
0
-
N6
N5
N4
N3
N2
N1
N0
Bit
Number
Bit
Mnemonic Description
7
-
6-0
N6:0
Reserved
The value read from this bit is always 0. Do not set this bit.
PLL N Divider
7 - bit N divider.
Reset Value = 0000 0000b
Table 8. PLLRDIV Register
PLLRDIV (S:EFh) – PLL R Divider Register
7
6
5
4
3
2
1
0
R9
R8
R7
R6
R5
R4
R3
R2
Bit
Number
7-0
Bit
Mnemonic Description
R9:2
PLL Most Significant Bits R Divider
8 MSB of the 10-bit R divider.
Reset Value = 0000 0000b
16
AT8xC51SND1C
4109H–8051–01/05
AT8xC51SND1C
7. Program/Code
Memory
The AT8xC51SND1C execute up to 64K Bytes of program/code memory. Figure 10
shows the split of internal and external program/code memory spaces depending on the
product.
The AT83SND1C product provides the internal program/code memory in ROM memory
while the AT89C51SND1C product provides it in Flash memory. These 2 products do
not allow external code memory execution. External code memory execution is
achieved using the AT80C51SND1C product which does not provide any internal program/code memory.
The Flash memory increases EPROM and ROM functionality by in-circuit electrical erasure and programming. The high voltage needed for programming or erasing Flash cells
is generated on-chip using the standard V DD voltage, made possible by the internal
charge pump. Thus, the AT89C51SND1C can be programmed using only one voltage
and allows In-application software programming. Hardware programming mode is also
available using common programming tools. See the application note ‘Programming
T89C51x and AT89C51x with Device Programmers’.
The AT89C51SND1C implements an additional 4K Bytes of on-chip boot Flash memory
provided in Flash memory. This boot memory is delivered programmed with a standard
boot loader software allowing In-System Programming (ISP). It also contains some
Application Programming Interface routines named API routines allowing In Application
Programming (IAP) by using user’s own boot loader.
Figure 10. Program/Code Memory Organization
FFFFh
FFFFh
64K Bytes
External Code
0000h
FFFFh
F000h
F000h
64K Bytes
Code ROM
0000h
AT80C51SND1C
FFFFh
4K Bytes
Boot Flash
64K Bytes
Code Flash
0000h
AT83SND1C
AT89C51SND1C
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4109H–8051–01/05
7.1 ROMLESS Memory
Architecture
As shown in Figure 11 the AT80C51SND1C external memory is composed of one
space detailed in the following paragraph.
Figure 11. AT80C51SND1C Memory Architecture
FFFFh
64K Bytes
User
External Memory
0000h
7.1.1 User Space
This space is composed of a 64K Bytes code (Flash, EEPROM, EPROM…) memory. It
contains the user’s application code.
7.1.2 Memory Interface
The external memory interface comprises the external bus (port 0 and port 2) as well as
the bus control signals (PSEN, and ALE).
Figure 12 shows the structure of the external address bus. P0 carries address A7:0
while P2 carries address A15:8. Data D7:0 is multiplexed with A7:0 on P0. Table 12
describes the external memory interface signals.
Figure 12. External Code Memory Interface Structure
Flash
EPROM
AT80C51SND1C
A15:8
P2
A15:8
ALE
P0
AD7:0
Latch
A7:0
A7:0
D7:0
PSEN
OE
Table 2. External Code Memory Interface Signals
18
Signal
Name
Type
Alternate
Function
A15:8
O
Address Lines
Upper address lines for the external bus.
P2.7:0
AD7:0
I/O
Address/Data Lines
Multiplexed lower address lines and data for the external memory.
P0.7:0
ALE
O
Address Latch Enable
ALE signals indicates that valid address information are available on lines
AD7:0.
-
PSEN
O
Program Store Enable Output (AT80C51SND1C Only)
This signal is active low during external code fetch or external code read
(MOVC instruction).
-
Description
AT8xC51SND1C
4109H–8051–01/05
AT8xC51SND1C
7.2.1 External Bus Cycles
This section describes the bus cycles the AT80C51SND1C executes to fetch code (see
Figure 13) in the external program/code memory.
External memory cycle takes 6 CPU clock periods. This is equivalent to 12 oscillator
clock periods in standard mode or 6 oscillator clock periods in X2 mode. For further
information on X2 mode see section “Clock “.
For simplicity, the accompanying figure depicts the bus cycle waveforms in idealized
form and does not provide precise timing information.
For bus cycling parameters refer to the ‘AC-DC parameters’ section.
Figure 13. External Code Fetch Waveforms
CPU Clock
ALE
PSEN
P0 D7:0
PCL
P2 PCH
7.3 ROM Memory
Architecture
D7:0
PCL
PCH
D7:0
PCH
As shown in Figure 14 the AT83SND1C ROM memory is composed of one space
detailed in the following paragraph.
Figure 14. AT83SND1C Memory Architecture
FFFFh
64K Bytes
User
ROM Memory
0000h
7.3.1 User Space
This space is composed of a 64K Bytes ROM memory programmed during the manufacturing process. It contains the user’s application code.
7.4 Flash Memory
Architecture
As shown in Figure 15 the AT89C51SND1C Flash memory is composed of four spaces
detailed in the following paragraphs.
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4109H–8051–01/05
Figure 15. AT89C51SND1C Memory Architecture
Hardware Security
Extra Row
FFFFh
FFFFh
F000h
4K Bytes
Flash Memory
Boot
64K Bytes
User
Flash Memory
0000h
7.4.1 User Space
This space is composed of a 64K Bytes Flash memory organized in 512 pages of 128
Bytes. It contains the user’s application code.
This space can be read or written by both software and hardware modes.
7.4.2 Boot Space
This space is composed of a 4K Bytes Flash memory. It contains the boot loader for InSystem Programming and the routines for In Application Programming.
This space can only be read or written by hardware mode using a parallel programming
tool.
7.4.3 Hardware Security Space This space is composed of one Byte: the Hardware Security Byte (HSB see Table 12)
divided in 2 separate nibbles. The MSN contains the X2 mode configuration bit and the
Boot Loader Jump Bit as detailed in Section “Boot Memory Execution”, page 21 and can
be written by software while the LSN contains the lock system level to protect the memory content against piracy as detailed in Section “Hardware Security System”, page 21
and can only be written by hardware.
7.4.4 Extra Row Space
20
This space is composed of 2 Bytes:
•
The Software Boot Vector (SBV, see Table 13).
This Byte is used by the software boot loader to build the boot address.
•
The Software Security Byte (SSB, see Table 14).
This Byte is used to lock the execution of some boot loader commands.
AT8xC51SND1C
4109H–8051–01/05
AT8xC51SND1C
7.5 Hardware Security
System
The AT89C51SND1C implements three lock bits LB2:0 in the LSN of HSB (see
Table 12) providing three levels of security for user’s program as described in Table 12
while the AT83SND1C is always set in read disabled mode.
Level 0 is the level of an erased part and does not enable any security feature.
Level 1 locks the hardware programming of both user and boot memories.
Level 2 locks also hardware verifying of both user and boot memories
Level 3 locks also the external execution.
Table 6. Lock Bit Features(1)
Level LB2(2)
LB1
LB0
Internal
Execution
External
Execution
Hardware
Verifying
Hardware
Software
Programming Programming
0
U
U
U
Enable
Enable
Enable
Enable
Enable
1
U
U
P
Enable
Enable
Enable
Disable
Enable
2
U
P
X
Enable
Enable
Disable
Disable
Enable
(3)
P
X
X
Enable
Disable
Disable
Disable
Enable
3
Notes:
1. U means unprogrammed, P means programmed and X means don’t care (programmed or unprogrammed).
2. LB2 is not implemented in the AT8xC51SND1C products.
3. AT89C51SND1C products are delivered with third level programmed to ensure that
the code programmed by software using ISP or user’s boot loader is secured from
any hardware piracy.
7.7 Boot Memory
Execution
As internal C51 code space is limited to 64K Bytes, some mechanisms are implemented
to allow boot memory to be mapped in the code space for execution at addresses from
F000h to FFFFh. The boot memory is enabled by setting the ENBOOT bit in AUXR1
(see Figure 10). The three ways to set this bit are detailed in the following sections.
7.7.1 Software Boot Mapping
The software way to set ENBOOT consists in writing to AUXR1 from the user’s software. This enables boot loader or API routines execution.
7.7.2 Hardware Condition
Boot Mapping
The hardware condition is based on the ISP pin. When driving this pin to low level, the
chip reset sets ENBOOT and forces the reset vector to F000h instead of 0000h in order
to execute the boot loader software.
As shown in Figure 16 the hardware condition always allows in-system recovery when
user’s memory has been corrupted.
7.7.3 Programmed Condition
Boot Mapping
The programmed condition is based on the Boot Loader Jump Bit (BLJB) in HSB. As
shown in Figure 16 when this bit is programmed (by hardware or software programming
mode), the chip reset set ENBOOT and forces the reset vector to F000h instead of
0000h, in order to execute the boot loader software.
21
4109H–8051–01/05
Figure 16. Hardware Boot Process Algorithm
RESET
Hard Cond?
Software
Process
Hardware
Process
ISP = L?
Prog Cond?
BLJB = P?
Standard Init
ENBOOT = 0
PC = 0000h
FCON = F0h
Prog Cond Init
ENBOOT = 1
PC = F000h
FCON = F0h
User’s
Application
Atmel’s
Boot Loader
Hard Cond Init
ENBOOT = 1
PC = F000h
FCON = 00h
The software process (boot loader) is detailed in the “Boot Loader Datasheet”
Document.
7.8 Preventing Flash
Corruption
22
See Section “Reset Recommendation to Prevent Flash Corruption”, page 49.
AT8xC51SND1C
4109H–8051–01/05
AT8xC51SND1C
7.9 Registers
Table 10. AUXR1 Register
AUXR1 (S:A2h) – Auxiliary Register 1
7
6
5
4
3
2
1
0
-
-
ENBOOT
-
GF3
0
-
DPS
Bit
Number
7-6
Bit
Mnemonic Description
Reserved
The value read from these bits are indeterminate. Do not set these bits.
-
1
Enable Boot Flash
Set this bit to map the boot Flash in the code space between at addresses F000h
to FFFFh.
Clear this bit to disable boot Flash.
5
ENBOOT
4
-
3
GF3
2
0
Always Zero
This bit is stuck to logic 0 to allow INC AUXR1 instruction without affecting GF3
flag.
1
-
Reserved for Data Pointer Extension.
0
DPS
Reserved
The value read from this bit is indeterminate. Do not set this bit.
General Flag
This bit is a general-purpose user flag.
Data Pointer Select Bit
Set to select second data pointer: DPTR1.
Clear to select first data pointer: DPTR0.
Reset Value = XXXX 00X0b
Note:
1. ENBOOT bit is only available in AT89C51SND1C product.
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4109H–8051–01/05
7.11 Hardware Bytes
Table 12. HSB Byte – Hardware Security Byte
7
6
5
4
3
2
1
0
X2B
BLJB
-
-
-
LB2
LB1
LB0
Bit
Number
Bit
Mnemonic Description
X2B(1)
7
(2)
6
BLJB
5-4
-
3
-
2-0
LB2:0
X2 Bit
Program this bit to start in X2 mode.
Unprogram (erase) this bit to start in standard mode.
Boot Loader Jump Bit
Program this bit to execute the boot loader at address F000h on next reset.
Unprogram (erase) this bit to execute user’s application at address 0000h on
next reset.
Reserved
The value read from these bits is always unprogrammed. Do not program these
bits.
Reserved
The value read from this bit is always unprogrammed. Do not program this bit.
Hardware Lock Bits
Refer to for bits description.
Reset Value = XXUU UXXX, UUUU UUUU after an hardware full chip erase.
Note:
1. X2B initializes the X2 bit in CKCON during the reset phase.
2. In order to ensure boot loader activation at first power-up, AT89C51SND1C products
are delivered with BLJB programmed.
3. Bits 0 to 3 (LSN) can only be programmed by hardware mode.
Table 13. SBV Byte – Software Boot Vector
7
6
5
4
3
2
1
0
ADD15
ADD14
ADD13
ADD12
ADD11
ADD10
ADD9
ADD8
Bit
Number
7-0
Bit
Mnemonic Description
ADD15:8
MSB of the user’s boot loader 16-bit address location
Refer to the boot loader datasheet for usage information (boot loader dependent)
Reset Value = XXXX XXXX, UUUU UUUU after an hardware full chip erase.
Table 14. SSB Byte – Software Security Byte
7
6
5
4
3
2
1
0
SSB7
SSB6
SSB5
SSB4
SSB3
SSB2
SSB1
SSB0
Bit
Number
7-0
Bit
Mnemonic Description
SSB7:0
Software Security Byte Data
Refer to the boot loader datasheet for usage information (boot loader dependent)
Reset Value = XXXX XXXX, UUUU UUUU after an hardware full chip erase.
24
AT8xC51SND1C
4109H–8051–01/05
AT8xC51SND1C
8. Data Memory
The AT8xC51SND1C provides data memory access in 2 different spaces:
1. The internal space mapped in three separate segments:
–
The lower 128 Bytes RAM segment
–
The upper 128 Bytes RAM segment
–
The expanded 2048 Bytes RAM segment
2. The external space.
A fourth internal segment is available but dedicated to Special Function Registers,
SFRs, (addresses 80h to FFh) accessible by direct addressing mode. For information
on this segment, refer to the Section “Special Function Registers”, page 32.
Figure 17 shows the internal and external data memory spaces organization.
Figure 17. Internal and External Data Memory Organization
FFFFh
64K Bytes
External XRAM
7FFh
FFh
2K Bytes
Internal ERAM
EXTRAM = 0
00h
FFh
Upper
128 Bytes
Internal RAM
Indirect Addressing
80h
7Fh
00h
Special
Function
Registers
Direct Addressing
80h
Lower
128 Bytes
Internal RAM
Direct or Indirect
Addressing
0800h
EXTRAM = 1
0000h
8.1 Internal Space
8.1.1 Lower 128 Bytes RAM
The lower 128 Bytes of RAM (see Figure 18) are accessible from address 00h to 7Fh
using direct or indirect addressing modes. The lowest 32 Bytes are grouped into 4
banks of 8 registers (R0 to R7). 2 bits RS0 and RS1 in PSW register (see Table 8)
select which bank is in use according to Table 2. This allows more efficient use of code
space, since register instructions are shorter than instructions that use direct addressing, and can be used for context switching in interrupt service routines.
Table 2. Register Bank Selection
RS1
RS0
Description
0
0
Register bank 0 from 00h to 07h
0
1
Register bank 1 from 08h to 0Fh
1
0
Register bank 2 from 10h to 17h
1
1
Register bank 3 from 18h to 1Fh
The next 16 Bytes above the register banks form a block of bit-addressable memory
space. The C51 instruction set includes a wide selection of single-bit instructions, and
the 128 bits in this area can be directly addressed by these instructions. The bit
addresses in this area are 00h to 7Fh.
25
4109H–8051–01/05
Figure 18. Lower 128 Bytes Internal RAM Organization
7Fh
30h
2Fh
20h
18h
10h
08h
00h
Bit-Addressable Space
(Bit Addresses 0-7Fh)
1Fh
17h
0Fh
4 Banks of
8 Registers
R0-R7
07h
8.2.1 Upper 128 Bytes RAM
The upper 128 Bytes of RAM are accessible from address 80h to FFh using only indirect
addressing mode.
8.2.2 Expanded RAM
The on-chip 2K Bytes of expanded RAM (ERAM) are accessible from address 0000h to
07FFh using indirect addressing mode through MOVX instructions. In this address
range, EXTRAM bit in AUXR register (see Table 9) is used to select the ERAM (default)
or the XRAM. As shown in Figure 17 when EXTRAM = 0, the ERAM is selected and
when EXTRAM = 1, the XRAM is selected (see Section “External Space”).
The ERAM memory can be resized using XRS1:0 bits in AUXR register to dynamically
increase external access to the XRAM space. Table 3 details the selected ERAM size
and address range.
Table 3. ERAM Size Selection
XRS1
XRS0
0
Note:
26
ERAM Size
Address
0
256 Bytes
0 to 00FFh
0
1
512 Bytes
0 to 01FFh
1
0
1K Byte
0 to 03FFh
1
1
2K Bytes
0 to 07FFh
Lower 128 Bytes RAM, Upper 128 Bytes RAM, and expanded RAM are made of volatile
memory cells. This means that the RAM content is indeterminate after power-up and
must then be initialized properly.
AT8xC51SND1C
4109H–8051–01/05
AT8xC51SND1C
8.4 External Space
8.4.1 Memory Interface
The external memory interface comprises the external bus (port 0 and port 2) as well as
the bus control signals (RD, WR, and ALE).
Figure 19 shows the structure of the external address bus. P0 carries address A7:0
while P2 carries address A15:8. Data D7:0 is multiplexed with A7:0 on P0. Table 5
describes the external memory interface signals.
Figure 19. External Data Memory Interface Structure
RAM
PERIPHERAL
AT8xC51SND1C
A15:8
P2
A15:8
ALE
P0
AD7:0
Latch
A7:0
A7:0
D7:0
RD
WR
OE
WR
Table 5. External Data Memory Interface Signals
8.5.1 Page Access Mode
Signal
Name
Type
A15:8
O
Address Lines
Upper address lines for the external bus.
P2.7:0
AD7:0
I/O
Address/Data Lines
Multiplexed lower address lines and data for the external memory.
P0.7:0
ALE
O
Address Latch Enable
ALE signals indicates that valid address information are available on lines
AD7:0.
RD
O
Read
Read signal output to external data memory.
P3.7
WR
O
Write
Write signal output to external memory.
P3.6
Description
Alternate
Function
-
The AT8xC51SND1C implement a feature called Page Access that disables the output
of DPH on P2 when executing MOVX @DPTR instruction. Page Access is enable by
setting the DPHDIS bit in AUXR register.
Page Access is useful when application uses both ERAM and 256 Bytes of XRAM. In
this case, software modifies intensively EXTRAM bit to select access to ERAM or XRAM
and must save it if used in interrupt service routine. Page Access allows external access
above 00FFh address without generating DPH on P2. Thus ERAM is accessed using
MOVX @Ri or MOVX @DPTR with DPTR < 0100h, < 0200h, < 0400h or < 0800h
depending on the XRS1:0 bits value. Then XRAM is accessed using MOVX @DPTR
with DPTR ≥ 0800h regardless of XRS1:0 bits value while keeping P2 for general I/O
usage.
27
4109H–8051–01/05
8.5.2 External Bus Cycles
This section describes the bus cycles the AT8xC51SND1C executes to read (see
Figure 20), and write data (see Figure 21) in the external data memory.
External memory cycle takes 6 CPU clock periods. This is equivalent to 12 oscillator
clock period in standard mode or 6 oscillator clock periods in X2 mode. For further information on X2 mode, refer to the Section “X2 Feature”, page 12.
Slow peripherals can be accessed by stretching the read and write cycles. This is done
using the M0 bit in AUXR register. Setting this bit changes the width of the RD and WR
signals from 3 to 15 CPU clock periods.
For simplicity, Figure 20 and Figure 21 depict the bus cycle waveforms in idealized form
and do not provide precise timing information. For bus cycle timing parameters refer to
the Section “AC Characteristics”.
Figure 20. External Data Read Waveforms
CPU Clock
ALE
RD(1)
P0
P2
Notes:
DPL or Ri
D7:0
DPH or P2(2),(3)
P2
1. RD signal may be stretched using M0 bit in AUXR register.
2. When executing MOVX @Ri instruction, P2 outputs SFR content.
3. When executing MOVX @DPTR instruction, if DPHDIS is set (Page Access Mode),
P2 outputs SFR content instead of DPH.
Figure 21. External Data Write Waveforms
CPU Clock
ALE
WR(1)
P0
P2
Notes:
28
DPL or Ri
P2
D7:0
DPH or P2(2),(3)
1. WR signal may be stretched using M0 bit in AUXR register.
2. When executing MOVX @Ri instruction, P2 outputs SFR content.
3. When executing MOVX @DPTR instruction, if DPHDIS is set (Page Access Mode),
P2 outputs SFR content instead of DPH.
AT8xC51SND1C
4109H–8051–01/05
AT8xC51SND1C
8.6 Dual Data Pointer
8.6.1 Description
The AT8xC51SND1C implement a second data pointer for speeding up code execution
and reducing code size in case of intensive usage of external memory accesses.
DPTR0 and DPTR1 are seen by the CPU as DPTR and are accessed using the SFR
addresses 83h and 84h that are the DPH and DPL addresses. The DPS bit in AUXR1
register (see Table 10) is used to select whether DPTR is the data pointer 0 or the data
pointer 1 (see Figure 22).
Figure 22. Dual Data Pointer Implementation
DPL0
0
DPL1
1
DPL
DPTR0
DPS
DPTR1
DPH0
0
DPH1
1
AUXR1.0
DPTR
DPH
8.6.2 Application
Software can take advantage of the additional data pointers to both increase speed and
reduce code size, for example, block operations (copy, compare, search …) are well
served by using one data pointer as a “source” pointer and the other one as a “destination” pointer.
Below is an example of block move implementation using the 2 pointers and coded in
assembler. The latest C compiler also takes advantage of this feature by providing
enhanced algorithm libraries.
The INC instruction is a short (2 Bytes) and fast (6 CPU clocks) way to manipulate the
DPS bit in the AUXR1 register. However, note that the INC instruction does not directly
force the DPS bit to a particular state, but simply toggles it. In simple routines, such as
the block move example, only the fact that DPS is toggled in the proper sequence matters, not its actual value. In other words, the block move routine works the same whether
DPS is '0' or '1' on entry.
;
;
;
;
ASCII block move using dual data pointers
Modifies DPTR0, DPTR1, A and PSW
Ends when encountering NULL character
Note: DPS exits opposite of entry state unless an extra INC AUXR1 is added
AUXR1
move:
EQU
mov
inc
mov
mv_loop: inc
movx
inc
inc
movx
inc
jnz
end_move:
0A2h
DPTR,#SOURCE
AUXR1
DPTR,#DEST
AUXR1
A,@DPTR
DPTR
AUXR1
@DPTR,A
DPTR
mv_loop
;
;
;
;
;
;
;
;
;
;
address of SOURCE
switch data pointers
address of DEST
switch data pointers
get a Byte from SOURCE
increment SOURCE address
switch data pointers
write the Byte to DEST
increment DEST address
check for NULL terminator
29
4109H–8051–01/05
8.7 Registers
Table 8. PSW Register
PSW (S:8Eh) – Program Status Word Register
7
6
5
4
3
2
1
0
CY
AC
F0
RS1
RS0
OV
F1
P
Bit
Number
Bit
Mnemonic Description
7
CY
Carry Flag
Carry out from bit 1 of ALU operands.
6
AC
Auxiliary Carry Flag
Carry out from bit 1 of addition operands.
5
F0
User Definable Flag 0
4-3
RS1:0
2
OV
Overflow Flag
Overflow set by arithmetic operations.
1
F1
User Definable Flag 1
0
P
Parity Bit
Set when ACC contains an odd number of 1’s.
Cleared when ACC contains an even number of 1’s.
Register Bank Select Bits
Refer to Table 2 for bits description.
Reset Value = 0000 0000b
30
AT8xC51SND1C
4109H–8051–01/05
AT8xC51SND1C
Table 9. AUXR Register
AUXR (S:8Eh) – Auxiliary Control Register
7
6
5
4
3
2
1
0
-
EXT16
M0
DPHDIS
XRS1
XRS0
EXTRAM
AO
Bit
Number
Bit
Mnemonic Description
Reserved
The value read from this bit is indeterminate. Do not set this bit.
7
-
6
EXT16
5
M0
External Memory Access Stretch Bit
Set to stretch RD or WR signals duration to 15 CPU clock periods.
Clear not to stretch RD or WR signals and set duration to 3 CPU clock periods.
4
DPHDIS
DPH Disable Bit
Set to disable DPH output on P2 when executing MOVX @DPTR instruction.
Clear to enable DPH output on P2 when executing MOVX @DPTR instruction.
3-2
XRS1:0
Expanded RAM Size Bits
Refer to Table 3 for ERAM size description.
1
EXTRAM
0
AO
External 16-bit Access Enable Bit
Set to enable 16-bit access mode during MOVX instructions.
Clear to disable 16-bit access mode and enable standard 8-bit access mode
during MOVX instructions.
External RAM Enable Bit
Set to select the external XRAM when executing MOVX @Ri or MOVX @DPTR
instructions.
Clear to select the internal expanded RAM when executing MOVX @Ri or MOVX
@DPTR instructions.
ALE Output Enable Bit
Set to output the ALE signal only during MOVX instructions.
Clear to output the ALE signal at a constant rate of FCPU/3.
Reset Value = X000 1101b
31
4109H–8051–01/05
9. Special Function
Registers
The Special Function Registers (SFRs) of the AT8xC51SND1C derivatives fall into the
categories detailed in Table 1 to Table 17. The relative addresses of these SFRs are
provided together with their reset values in Table 18. In this table, the bit-addressable
registers are identified by Note 1.
Table 1. C51 Core SFRs
Mnemonic
Add
Name
ACC
E0h
Accumulator
B
F0h
B Register
PSW
D0h
Program Status Word
SP
81h
Stack Pointer
DPL
82h
Data Pointer Low Byte
DPH
83h
Data Pointer High Byte
7
6
5
4
3
2
1
0
CY
AC
F0
RS1
RS0
OV
F1
P
7
6
5
4
3
2
1
0
SMOD1
SMOD0
-
-
GF1
GF0
PD
IDL
Table 2. System Management SFRs
Mnemonic
Add
Name
PCON
87h
Power Control
AUXR
8Eh
Auxiliary Register 0
-
EXT16
M0
DPHDIS
XRS1
XRS0
EXTRAM
AO
AUXR1
A2h
Auxiliary Register 1
-
-
ENBOOT(1)
-
GF3
0
-
DPS
NVERS
FBh
Version Number
NV7
NV6
NV5
NV4
NV3
NV2
NV1
NV0
Note:
1. ENBOOT bit is only available in AT89C51SND1C product.
Table 3. PLL and System Clock SFRs
Mnemonic
Add
Name
7
6
5
4
3
2
1
0
CKCON
8Fh
Clock Control
-
-
-
-
-
-
-
X2
PLLCON
E9h
PLL Control
R1
R0
-
-
PLLRES
-
PLLEN
PLOCK
PLLNDIV
EEh
PLL N Divider
-
N6
N5
N4
N3
N2
N1
N0
PLLRDIV
EFh
PLL R Divider
R9
R8
R7
R6
R5
R4
R3
R2
7
6
5
4
3
2
1
0
Table 4. Interrupt SFRs
Mnemonic
Add
Name
IEN0
A8h
Interrupt Enable Control 0
EA
EAUD
EMP3
ES
ET1
EX1
ET0
EX0
IEN1
B1h
Interrupt Enable Control 1
-
EUSB
-
EKB
EADC
ESPI
EI2C
EMMC
IPH0
B7h
Interrupt Priority Control High 0
-
IPHAUD
IPHMP3
IPHS
IPHT1
IPHX1
IPHT0
IPHX0
IPL0
B8h
Interrupt Priority Control Low 0
-
IPLAUD
IPLMP3
IPLS
IPLT1
IPLX1
IPLT0
IPLX0
IPH1
B3h
Interrupt Priority Control High 1
-
IPHUSB
-
IPHKB
IPHADC
IPHSPI
IPHI2C
IPHMMC
IPL1
B2h
Interrupt Priority Control Low 1
-
IPLUSB
-
IPLKB
IPLADC
IPLSPI
IPLI2C
IPLMMC
32
AT8xC51SND1C
4109H–8051–01/05
AT8xC51SND1C
Table 5. Port SFRs
Mnemonic
Add
Name
P0
80h
8-bit Port 0
P1
90h
8-bit Port 1
P2
A0h
8-bit Port 2
P3
B0h
8-bit Port 3
P4
C0h
8-bit Port 4
P5
D8h
4-bit Port 5
7
6
5
4
3
2
1
0
-
-
-
-
7
6
5
4
3
2
1
0
FPL3
FPL2
FPL1
FPL0
FPS
FMOD1
FMOD0
FBUSY
Table 6. Flash Memory SFR
Mnemonic
Add
Name
FCON(1)
D1h
Flash Control
Note:
1. FCON register is only available in AT89C51SND1C product.
Table 7. Timer SFRs
Mnemonic
Add
Name
7
6
5
4
3
2
1
0
TCON
88h
Timer/Counter 0 and 1 Control
TF1
TR1
TF0
TR0
IE1
IT1
IE0
IT0
TMOD
89h
Timer/Counter 0 and 1 Modes
GATE1
C/T1#
M11
M01
GATE0
C/T0#
M10
M00
TL0
8Ah
Timer/Counter 0 Low Byte
TH0
8Ch
Timer/Counter 0 High Byte
TL1
8Bh
Timer/Counter 1 Low Byte
TH1
8Dh
Timer/Counter 1 High Byte
WDTRST
A6h
Watchdog Timer Reset
WDTPRG
A7h
Watchdog Timer Program
-
-
-
-
-
WTO2
WTO1
WTO0
33
4109H–8051–01/05
Table 8. MP3 Decoder SFRs
Mnemonic
Add
Name
7
6
5
4
3
2
1
0
MP3CON
AAh
MP3 Control
MPEN
MPBBST
CRCEN
MSKANC
MSKREQ
MSKLAY
MSKSYN
MSKCRC
MP3STA
C8h
MP3 Status
MPANC
MPREQ
ERRLAY
ERRSYN
ERRCRC
MPFS1
MPFS0
MPVER
MP3STA1
AFh
MP3 Status 1
-
-
-
MPFREQ
MPBREQ
-
-
-
MP3DAT
ACh
MP3 Data
MPD7
MPD6
MPD5
MPD4
MPD3
MPD2
MPD1
MPD0
MP3ANC
ADh
MP3 Ancillary Data
AND7
AND6
AND5
AND4
AND3
AND2
AND1
AND0
MP3VOL
9Eh
MP3 Audio Volume Control Left
-
-
-
VOL4
VOL3
VOL2
VOL1
VOL0
MP3VOR
9Fh
MP3 Audio Volume Control
Right
-
-
-
VOR4
VOR3
VOR2
VOR1
VOR0
MP3BAS
B4h
MP3 Audio Bass Control
-
-
-
BAS4
BAS3
BAS2
BAS1
BAS0
MP3MED
B5h
MP3 Audio Medium Control
-
-
-
MED4
MED3
MED2
MED1
MED0
MP3TRE
B6h
MP3 Audio Treble Control
-
-
-
TRE4
TRE3
TRE2
TRE1
TRE0
MP3CLK
EBh
MP3 Clock Divider
-
-
-
MPCD4
MPCD3
MPCD2
MPCD1
MPCD0
7
6
5
4
3
2
1
0
Table 9. Audio Interface SFRs
Mnemonic
Add
Name
AUDCON0
9Ah
Audio Control 0
JUST4
JUST3
JUST2
JUST1
JUST0
POL
DSIZ
HLR
AUDCON1
9Bh
Audio Control 1
SRC
DRQEN
MSREQ
MUDRN
-
DUP1
DUP0
AUDEN
AUDSTA
9Ch
Audio Status
SREQ
UDRN
AUBUSY
-
-
-
-
-
AUDDAT
9Dh
Audio Data
AUD7
AUD6
AUD5
AUD4
AUD3
AUD2
AUD1
AUD0
AUDCLK
ECh
Audio Clock Divider
-
-
-
AUCD4
AUCD3
AUCD2
AUCD1
AUCD0
34
AT8xC51SND1C
4109H–8051–01/05
AT8xC51SND1C
Table 10. USB Controller SFRs
Mnemonic
Add
Name
USBCON
BCh
USB Global Control
USBADDR
C6h
USB Address
USBINT
BDh
USBIEN
7
USBE
6
5
SUSPCLK SDRMWUP
4
3
2
1
0
-
UPRSM
RMWUPE
CONFG
FADDEN
FEN
UADD6
UADD5
UADD4
UADD3
UADD2
UADD1
UADD0
USB Global Interrupt
-
-
WUPCPU
EORINT
SOFINT
-
-
SPINT
BEh
USB Global Interrupt Enable
-
-
ESOFINT
-
-
ESPINT
UEPNUM
C7h
USB Endpoint Number
-
-
-
-
-
-
EPNUM1
EPNUM0
UEPCONX
D4h
USB Endpoint X Control
EPEN
NAKIEN
NAKOUT
NAKIN
DTGL
EPDIR
UEPSTAX
CEh
USB Endpoint X Status
DIR
RXOUTB1 STALLRQ
TXRDY
STLCRC
UEPRST
D5h
USB Endpoint Reset
-
-
-
-
-
EP2RST
EP1RST
EP0RST
UEPINT
F8h
USB Endpoint Interrupt
-
-
-
-
-
EP2INT
EP1INT
EP0INT
UEPIEN
C2h
USB Endpoint Interrupt Enable
-
-
-
-
-
EP2INTE
EP1INTE
EP0INTE
UEPDATX
CFh
USB Endpoint X FIFO Data
FDAT7
FDAT6
FDAT5
FDAT4
FDAT3
FDAT2
FDAT1
FDAT0
UBYCTX
E2h
USB Endpoint X Byte Counter
-
BYCT6
BYCT5
BYCT4
BYCT3
BYCT2
BYCT1
BYCT0
UFNUML
BAh
USB Frame Number Low
FNUM7
FNUM6
FNUM5
FNUM4
FNUM3
FNUM2
FNUM1
FNUM0
UFNUMH
BBh
USB Frame Number High
-
-
CRCOK
CRCERR
-
FNUM10
FNUM9
FNUM8
USBCLK
EAh
USB Clock Divider
-
-
-
-
-
-
USBCD1
USBCD0
7
6
5
4
3
2
1
0
EWUPCPU EEORINT
EPTYPE1 EPTYPE0
RXSETUP RXOUTB0
TXCMP
Table 11. MMC Controller SFRs
Mnemonic
Add
Name
MMCON0
E4h
MMC Control 0
DRPTR
DTPTR
CRPTR
CTPTR
MBLOCK
DFMT
RFMT
CRCDIS
MMCON1
E5h
MMC Control 1
BLEN3
BLEN2
BLEN1
BLEN0
DATDIR
DATEN
RESPEN
CMDEN
MMCON2
E6h
MMC Control 2
MMCEN
DCR
CCR
-
-
DATD1
DATD0
FLOWC
MMSTA
DEh
MMC Control and Status
-
-
CBUSY
CRC16S
DATFS
CRC7S
RESPFS
CFLCK
MMINT
E7h
MMC Interrupt
MCBI
EORI
EOCI
EOFI
F2FI
F1FI
F2EI
F1EI
MMMSK
DFh
MMC Interrupt Mask
MCBM
EORM
EOCM
EOFM
F2FM
F1FM
F2EM
F1EM
MMCMD
DDh
MMC Command
MC7
MC6
MC5
MC4
MC3
MC2
MC1
MC0
MMDAT
DCh
MMC Data
MD7
MD6
MD5
MD4
MD3
MD2
MD1
MD0
MMCLK
EDh
MMC Clock Divider
MMCD7
MMCD6
MMCD5
MMCD4
MMCD3
MMCD2
MMCD1
MMCD0
7
6
5
4
3
2
1
0
D15
D14
D13
D12
D11
D10
D9
D8
Table 12. IDE Interface SFR
Mnemonic
Add
Name
DAT16H
F9h
High Order Data Byte
35
4109H–8051–01/05
Table 13. Serial I/O Port SFRs
Mnemonic
Add
Name
SCON
98h
Serial Control
SBUF
99h
Serial Data Buffer
SADEN
B9h
Slave Address Mask
SADDR
A9h
Slave Address
BDRCON
92h
Baud Rate Control
BRL
91h
Baud Rate Reload
7
6
5
4
3
2
1
0
FE/SM0
SM1
SM2
REN
TB8
RB8
TI
RI
BRR
TBCK
RBCK
SPD
SRC
Table 14. SPI Controller SFRs
Mnemonic
Add
Name
7
6
5
4
3
2
1
0
SPCON
C3h
SPI Control
SPR2
SPEN
SSDIS
MSTR
CPOL
CPHA
SPR1
SPR0
SPSTA
C4h
SPI Status
SPIF
WCOL
-
MODF
-
-
-
-
SPDAT
C5h
SPI Data
SPD7
SPD6
SPD5
SPD4
SPD3
SPD2
SPD1
SPD0
7
6
5
4
3
2
1
0
Table 15. Two Wire Controller SFRs
Mnemonic
Add
Name
SSCON
93h
Synchronous Serial Control
SSCR2
SSPE
SSSTA
SSSTO
SSI
SSAA
SSCR1
SSCR0
SSSTA
94h
Synchronous Serial Status
SSC4
SSC3
SSC2
SSC1
SSC0
0
0
0
SSDAT
95h
Synchronous Serial Data
SSD7
SSD6
SSD5
SSD4
SSD3
SSD2
SSD1
SSD0
SSADR
96h
Synchronous Serial Address
SSA7
SSA6
SSA5
SSA4
SSA3
SSA2
SSA1
SSGC
7
6
5
4
3
2
1
0
Table 16. Keyboard Interface SFRs
Mnemonic
Add
Name
KBCON
A3h
Keyboard Control
KINL3
KINL2
KINL1
KINL0
KINM3
KINM2
KINM1
KINM0
KBSTA
A4h
Keyboard Status
KPDE
-
-
-
KINF3
KINF2
KINF1
KINF0
Table 17. A/D Controller SFRs
Mnemonic
Add
Name
7
6
5
4
3
2
1
0
ADCON
F3h
ADC Control
-
ADIDL
ADEN
ADEOC
ADSST
-
-
ADCS
ADCLK
F2h
ADC Clock Divider
-
-
-
ADCD4
ADCD3
ADCD2
ADCD1
ADCD0
ADDL
F4h
ADC Data Low Byte
-
-
-
-
-
-
ADAT1
ADAT0
ADDH
F5h
ADC Data High Byte
ADAT9
ADAT8
ADAT7
ADAT6
ADAT5
ADAT4
ADAT3
ADAT2
36
AT8xC51SND1C
4109H–8051–01/05
AT8xC51SND1C
Table 18. SFR Addresses and Reset Values
0/8
1/9
F8h
UEPINT
0000 0000
DAT16H
XXXX XXXX
F0h
B(1)
0000 0000
PLLCON
0000 1000
E8h
ACC(1)
E0h
P5(1)
XXXX 1111
D0h
PSW(1)
0000 0000
C8h
MP3STA(1)
0000 0001
C0h
P4(1)
1111 1111
B8h
IPL0(1)
X000 0000
B0h
3/B
4/C
5/D
6/E
FFh
ADCLK
0000 0000
ADCON
0000 0000
ADDL
0000 0000
ADDH
0000 0000
USBCLK
0000 0000
MP3CLK
0000 0000
AUDCLK
0000 0000
MMCLK
0000 0000
PLLNDIV
0000 0000
PLLRDIV
0000 0000
EFh
MMCON0
0000 0000
MMCON1
0000 0000
MMCON2
0000 0000
MMINT
0000 0011
E7h
MMDAT
1111 1111
MMCMD
1111 1111
MMSTA
0000 0000
MMMSK
1111 1111
DFh
UEPCONX
1000 0000
UEPRST
0000 0000
FCON(3)
1111 0000(4)
F7h
D7h
UEPSTAX
0000 0000
UEPDATX
XXXX XXXX
CFh
UEPNUM
0000 0000
C7h
UEPIEN
0000 0000
SPCON
0001 0100
SPSTA
0000 0000
SPDAT
XXXX XXXX
USBADDR
0000 0000
SADEN
0000 0000
UFNUML
0000 0000
UFNUMH
0000 0000
USBCON
0000 0000
USBINT
0000 0000
USBIEN
0001 0000
P3(1)
1111 1111
IEN1
0000 0000
IPL1
0000 0000
IPH1
0000 0000
MP3BAS
0000 0000
MP3MED
0000 0000
MP3TRE
0000 0000
A8h
IEN0(1)
0000 0000
SADDR
0000 0000
MP3CON
0011 1111
MP3DAT
0000 0000
MP3ANC
0000 0000
A0h
P2(1)
1111 1111
98h
SCON
0000 0000
90h
88h
80h
7/F
NVERS
XXXX XXXX(2)
UBYCTLX
0000 0000
0000 0000
D8h
2/A
IPH0
X000 0000
B7h
MP3STA1
0100 0001
AFh
WDTRST
XXX XXXX
WDTPRG
XXXX X000
A7h
MP3VOR
0000 0000
9Fh
AUXR1
XXXX 00X0
KBCON
0000 1111
KBSTA
0000 0000
SBUF
XXXX XXXX
AUDCON0
0000 1000
AUDCON1
1011 0010
AUDSTA
1100 0000
AUDDAT
1111 1111
MP3VOL
0000 0000
P1(1)
1111 1111
BRL
0000 0000
BDRCON
XXX0 0000
SSCON
0000 0000
SSSTA
1111 1000
SSDAT
1111 1111
SSADR
1111 1110
TCON(1)
0000 0000
TMOD
0000 0000
TL0
0000 0000
TL1
0000 0000
TH0
0000 0000
TH1
0000 0000
AUXR
X000 1101
P0(1)
1111 1111
SP
0000 0111
DPL
0000 0000
DPH
0000 0000
0/8
1/9
2/A
3/B
4/C
5/D
BFh
6/E
97h
CKCON
0000 000X(5)
8Fh
PCON
00XX 0000
87h
7/F
Reserved
Notes:
1. SFR registers with least significant nibble address equal to 0 or 8 are bit-addressable.
2. NVERS reset value depends on the silicon version: 1000 0100 for AT89C51SND1C product and 0000 0001 for AT83SND1C
product.
3. FCON register is only available in AT89C51SND1C product.
4. FCON reset value is 00h in case of reset with hardware condition.
5. CKCON reset value depends on the X2B bit (programmed or unprogrammed) in the Hardware Byte.
37
4109H–8051–01/05
10. Interrupt System
The AT8xC51SND1C, like other control-oriented computer architectures, employ a program interrupt method. This operation branches to a subroutine and performs some
service in response to the interrupt. When the subroutine completes, execution resumes
at the point where the interrupt occurred. Interrupts may occur as a result of internal
AT8xC51SND1C activity (e.g., timer overflow) or at the initiation of electrical signals
external to the microcontroller (e.g., keyboard). In all cases, interrupt operation is programmed by the system designer, who determines priority of interrupt service relative to
normal code execution and other interrupt service routines. All of the interrupt sources
are enabled or disabled by the system designer and may be manipulated dynamically.
A typical interrupt event chain occurs as follows:
•
An internal or external device initiates an interrupt-request signal. The
AT8xC51SND1C, latches this event into a flag buffer.
•
The priority of the flag is compared to the priority of other interrupts by the interrupt
handler. A high priority causes the handler to set an interrupt flag.
•
This signals the instruction execution unit to execute a context switch. This context
switch breaks the current flow of instruction sequences. The execution unit
completes the current instruction prior to a save of the program counter (PC) and
reloads the PC with the start address of a software service routine.
•
The software service routine executes assigned tasks and as a final activity
performs a RETI (return from interrupt) instruction. This instruction signals
completion of the interrupt, resets the interrupt-in-progress priority and reloads the
program counter. Program operation then continues from the original point of
interruption.
Table 1. Interrupt System Signals
Signal
Name
Type
INT0
I
External Interrupt 0
See section "External Interrupts", page 41.
P3.2
INT1
I
External Interrupt 1
See section “External Interrupts”, page 41.
P3.3
KIN3:0
I
Keyboard Interrupt Inputs
See section “Keyboard Interface”, page 182.
Description
Alternate
Function
P1.3:0
Six interrupt registers are used to control the interrupt system. 2 8-bit registers are used
to enable separately the interrupt sources: IEN0 and IEN1 registers (see Table 7 and
Table 8).
Four 8-bit registers are used to establish the priority level of the different sources: IPH0,
IPL0, IPH1 and IPL1 registers (see Table 9 to Table 12).
10.2 Interrupt System
Priorities
38
Each of the interrupt sources on the AT8xC51SND1C can be individually programmed
to one of four priority levels. This is accomplished by one bit in the Interrupt Priority High
registers (IPH0 and IPH1) and one bit in the Interrupt Priority Low registers (IPL0 and
IPL1). This provides each interrupt source four possible priority levels according to
Table 3.
AT8xC51SND1C
4109H–8051–01/05
AT8xC51SND1C
Table 3. Priority Levels
IPHxx
IPLxx
Priority Level
0
0
0 Lowest
0
1
1
1
0
2
1
1
3 Highest
A low-priority interrupt is always interrupted by a higher priority interrupt but not by
another interrupt of lower or equal priority. Higher priority interrupts are serviced before
lower priority interrupts. The response to simultaneous occurrence of equal priority interrupts is determined by an internal hardware polling sequence detailed in Table 4. Thus,
within each priority level there is a second priority structure determined by the polling
sequence. The interrupt control system is shown in Figure 23.
Table 4. Priority within Same Level
Interrupt Request Flag
Cleared by Hardware
(H) or by Software (S)
Interrupt Name
Priority Number
Interrupt Address
Vectors
INT0
0 (Highest Priority)
C:0003h
H if edge, S if level
Timer 0
1
C:000Bh
H
INT1
2
C:0013h
H if edge, S if level
Timer 1
3
C:001Bh
H
Serial Port
4
C:0023h
S
MP3 Decoder
5
C:002Bh
S
Audio Interface
6
C:0033h
S
MMC Interface
7
C:003Bh
S
Two Wire Controller
8
C:0043h
S
SPI Controller
9
C:004Bh
S
A to D Converter
10
C:0053h
S
Keyboard
11
C:005Bh
S
Reserved
12
C:0063h
-
USB
13
C:006Bh
S
14 (Lowest Priority)
C:0073h
-
Reserved
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4109H–8051–01/05
Figure 23. Interrupt Control System
INT0
00
01
10
11
External
Interrupt 0
Highest
Priority
Interrupts
EX0
00
01
10
11
IEN0.0
Timer 0
ET0
INT1
External
Interrupt 1
00
01
10
11
IEN0.1
EX1
00
01
10
11
IEN0.2
Timer 1
ET1
TXD
RXD
Serial
Port
00
01
10
11
IEN0.3
ES
MP3
Decoder
00
01
10
11
IEN0.4
EMP3
Audio
Interface
00
01
10
11
IEN0.5
EAUD
MCLK
MDAT
MCMD
MMC
Controller
00
01
10
11
IEN0.6
EMMC
SCL
SDA
TWI
Controller
00
01
10
11
IEN1.0
EI2C
SCK
SI
SO
SPI
Controller
00
01
10
11
IEN1.1
ESPI
AIN1:0
A to D
Converter
00
01
10
11
IEN1.2
EADC
00
01
10
11
IEN1.3
KIN3:0
Keyboard
EKB
D+
D-
USB
Controller
00
01
10
11
IEN1.4
EUSB
EA
IEN1.6
IEN0.7
Interrupt Enable
40
IPH/L
Priority Enable
Lowest Priority Interrupts
AT8xC51SND1C
4109H–8051–01/05
AT8xC51SND1C
10.5 External Interrupts
10.5.1 INT1:0 Inputs
External interrupts INT0 and INT1 (INTn, n = 0 or 1) pins may each be programmed to
be level-triggered or edge-triggered, dependent upon bits IT0 and IT1 (ITn, n = 0 or 1) in
TCON register as shown in Figure 24. If ITn = 0, INTn is triggered by a low level at the
pin. If ITn = 1, INTn is negative-edge triggered. External interrupts are enabled with bits
EX0 and EX1 (EXn, n = 0 or 1) in IEN0. Events on INTn set the interrupt request flag IEn
in TCON register. If the interrupt is edge-triggered, the request flag is cleared by hardware when vectoring to the interrupt service routine. If the interrupt is level-triggered, the
interrupt service routine must clear the request flag and the interrupt must be deasserted before the end of the interrupt service routine.
INT0 and INT1 inputs provide both the capability to exit from Power-down mode on low
level signals as detailed in section “Exiting Power-down Mode”, page 50.
Figure 24. INT1:0 Input Circuitry
INT0/1
INT0/1
Interrupt
Request
0
IE0/1
1
TCON.1/3
EX0/1
IEN0.0/2
IT0/1
TCON.0/2
10.5.2 KIN3:0 Inputs
External interrupts KIN0 to KIN3 provide the capability to connect a matrix keyboard. For
detailed information on these inputs, refer to section “Keyboard Interface”, page 182.
10.5.3 Input Sampling
External interrupt pins (INT1:0 and KIN3:0) are sampled once per peripheral cycle (6
peripheral clock periods) (see Figure 25). A level-triggered interrupt pin held low or high
for more than 6 peripheral clock periods (12 oscillator in standard mode or 6 oscillator
clock periods in X2 mode) guarantees detection. Edge-triggered external interrupts
must hold the request pin low for at least 6 peripheral clock periods.
Figure 25. Minimum Pulse Timings
Level-Triggered Interrupt
> 1 Peripheral Cycle
1 cycle
Edge-Triggered Interrupt
> 1 Peripheral Cycle
1 cycle
1 cycle
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4109H–8051–01/05
10.6 Registers
Table 7. IEN0 Register
IEN0 (S:A8h) – Interrupt Enable Register 0
7
6
5
4
3
2
1
0
EA
EAUD
EMP3
ES
ET1
EX1
ET0
EX0
Bit
Number
7
Bit
Mnemonic Description
EA
Enable All Interrupt Bit
Set to enable all interrupts.
Clear to disable all interrupts.
If EA = 1, each interrupt source is individually enabled or disabled by setting or
clearing its interrupt enable bit.
6
EAUD
Audio Interface Interrupt Enable Bit
Set to enable audio interface interrupt.
Clear to disable audio interface interrupt.
5
EMP3
MP3 Decoder Interrupt Enable Bit
Set to enable MP3 decoder interrupt.
Clear to disable MP3 decoder interrupt.
4
ES
Serial Port Interrupt Enable Bit
Set to enable serial port interrupt.
Clear to disable serial port interrupt.
3
ET1
Timer 1 Overflow Interrupt Enable Bit
Set to enable timer 1 overflow interrupt.
Clear to disable timer 1 overflow interrupt.
2
EX1
External Interrupt 1 Enable bit
Set to enable external interrupt 1.
Clear to disable external interrupt 1.
1
ET0
Timer 0 Overflow Interrupt Enable Bit
Set to enable timer 0 overflow interrupt.
Clear to disable timer 0 overflow interrupt.
0
EX0
External Interrupt 0 Enable Bit
Set to enable external interrupt 0.
Clear to disable external interrupt 0.
Reset Value = 0000 0000b
42
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AT8xC51SND1C
Table 8. IEN1 Register
IEN1 (S:B1h) – Interrupt Enable Register 1
7
6
5
4
3
2
1
0
-
EUSB
-
EKB
EADC
ESPI
EI2C
EMMC
Bit
Number
Bit
Mnemonic Description
Reserved
The value read from this bit is always 0. Do not set this bit.
7
-
6
EUSB
5
-
4
EKB
3
EADC
A to D Converter Interrupt Enable Bit
Set to enable ADC interrupt.
Clear to disable ADC interrupt.
2
ESPI
SPI Controller Interrupt Enable Bit
Set to enable SPI interrupt.
Clear to disable SPI interrupt.
1
EI2C
Two Wire Controller Interrupt Enable Bit
Set to enable Two Wire interrupt.
Clear to disable Two Wire interrupt.
0
EMMC
USB Interface Interrupt Enable Bit
Set this bit to enable USB interrupts.
Clear this bit to disable USB interrupts.
Reserved
The value read from this bit is always 0. Do not set this bit.
Keyboard Interface Interrupt Enable Bit
Set to enable Keyboard interrupt.
Clear to disable Keyboard interrupt.
MMC Interface Interrupt Enable Bit
Set to enable MMC interrupt.
Clear to disable MMC interrupt.
Reset Value = 0000 0000b
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4109H–8051–01/05
Table 9. IPH0 Register
IPH0 (S:B7h) – Interrupt Priority High Register 0
7
6
5
4
3
2
1
0
-
IPHAUD
IPHMP3
IPHS
IPHT1
IPHX1
IPHT0
IPHX0
Bit
Number
Bit
Mnemonic Description
Reserved
The value read from this bit is indeterminate. Do not set this bit.
7
-
6
IPHAUD
Audio Interface Interrupt Priority Level MSB
Refer to Table 3 for priority level description.
5
IPHMP3
MP3 Decoder Interrupt Priority Level MSB
Refer to Table 3 for priority level description.
4
IPHS
Serial Port Interrupt Priority Level MSB
Refer to Table 3 for priority level description.
3
IPHT1
Timer 1 Interrupt Priority Level MSB
Refer to Table 3 for priority level description.
2
IPHX1
External Interrupt 1 Priority Level MSB
Refer to Table 3 for priority level description.
1
IPHT0
Timer 0 Interrupt Priority Level MSB
Refer to Table 3 for priority level description.
0
IPHX0
External Interrupt 0 Priority Level MSB
Refer to Table 3 for priority level description.
Reset Value = X000 0000b
44
AT8xC51SND1C
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AT8xC51SND1C
Table 10. IPH1 Register
IPH1 (S:B3h) – Interrupt Priority High Register 1
7
6
5
4
3
2
1
0
-
IPHUSB
-
IPHKB
IPHADC
IPHSPI
IPHI2C
IPHMMC
Bit
Number
Bit
Mnemonic Description
Reserved
The value read from this bit is always 0. Do not set this bit.
7
-
6
IPHUSB
5
-
4
IPHKB
3
IPHADC
A to D Converter Interrupt Priority Level MSB
Refer to Table 3 for priority level description.
2
IPHSPI
SPI Interrupt Priority Level MSB
Refer to Table 3 for priority level description.
1
IPHI2C
Two Wire Controller Interrupt Priority Level MSB
Refer to Table 3 for priority level description.
0
IPHMMC
USB Interrupt Priority Level MSB
Refer to Table 3 for priority level description.
Reserved
The value read from this bit is always 0. Do not set this bit.
Keyboard Interrupt Priority Level MSB
Refer to Table 3 for priority level description.
MMC Interrupt Priority Level MSB
Refer to Table 3 for priority level description.
Reset Value = 0000 0000b
45
4109H–8051–01/05
Table 11. IPL0 Register
IPL0 (S:B8h) - Interrupt Priority Low Register 0
7
6
5
4
3
2
1
0
-
IPLAUD
IPLMP3
IPLS
IPLT1
IPLX1
IPLT0
IPLX0
Bit
Number
Bit
Mnemonic Description
Reserved
The value read from this bit is indeterminate. Do not set this bit.
7
-
6
IPLAUD
Audio Interface Interrupt Priority Level LSB
Refer to Table 3 for priority level description.
5
IPLMP3
MP3 Decoder Interrupt Priority Level LSB
Refer to Table 3 for priority level description.
4
IPLS
Serial Port Interrupt Priority Level LSB
Refer to Table 3 for priority level description.
3
IPLT1
Timer 1 Interrupt Priority Level LSB
Refer to Table 3 for priority level description.
2
IPLX1
External Interrupt 1 Priority Level LSB
Refer to Table 3 for priority level description.
1
IPLT0
Timer 0 Interrupt Priority Level LSB
Refer to Table 3 for priority level description.
0
IPLX0
External Interrupt 0 Priority Level LSB
Refer to Table 3 for priority level description.
Reset Value = X000 0000b
46
AT8xC51SND1C
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AT8xC51SND1C
Table 12. IPL1 Register
IPL1 (S:B2h) – Interrupt Priority Low Register 1
7
6
5
4
3
2
1
0
-
IPLUSB
-
IPLKB
IPLADC
IPLSPI
IPLI2C
IPLMMC
Bit
Number
Bit
Mnemonic Description
Reserved
The value read from this bit is always 0. Do not set this bit.
7
-
6
IPLUSB
5
-
4
IPLKB
3
IPLADC
A to D Converter Interrupt Priority Level LSB
Refer to Table 3 for priority level description.
2
IPLSPI
SPI Interrupt Priority Level LSB
Refer to Table 3 for priority level description.
1
IPLI2C
Two Wire Controller Interrupt Priority Level LSB
Refer to Table 3 for priority level description.
0
IPLMMC
USB Interrupt Priority Level LSB
Refer to Table 3 for priority level description.
Reserved
The value read from this bit is always 0. Do not set this bit.
Keyboard Interrupt Priority Level LSB
Refer to Table 3 for priority level description.
MMC Interrupt Priority Level LSB
Refer to Table 3 for priority level description.
Reset Value = 0000 0000b
47
4109H–8051–01/05
11. Power
Management
2 power reduction modes are implemented in the AT8xC51SND1C: the Idle mode and
the Power-down mode. These modes are detailed in the following sections. In addition
to these power reduction modes, the clocks of the core and peripherals can be dynamically divided by 2 using the X2 mode detailed in section “X2 Feature”, page 12.
11.1 Reset
In order to start-up (cold reset) or to restart (warm reset) properly the microcontroller, an
high level has to be applied on the RST pin. A bad level leads to a wrong initialization of
the internal registers like SFRs, Program Counter… and to unpredictable behavior of
the microcontroller. A proper device reset initializes the AT8xC51SND1C and vectors
the CPU to address 0000h. RST input has a pull-down resistor allowing power-on reset
by simply connecting an external capacitor to VDD as shown in Figure 26. A warm reset
can be applied either directly on the RST pin or indirectly by an internal reset source
such as the watchdog timer. Resistor value and input characteristics are discussed in
the Section “DC Characteristics” of the AT8xC51SND1C datasheet. The status of the
Port pins during reset is detailed in Table 2.
Figure 26. Reset Circuitry and Power-On Reset
From Internal
Reset Source
VDD
P
VDD
To CPU Core
and Peripherals
+
RRST
RST
RST
VSS
RST input circuitry
Power-on Reset
Table 2. Pin Conditions in Special Operating Modes
Mode
Port 0
Port 1
Port 2
Port 3
Port 4
Port 5
MMC
Audio
Floating
High
High
High
High
High
Floating
1
Idle
Data
Data
Data
Data
Data
Data
Data
Data
Power-down
Data
Data
Data
Data
Data
Data
Data
Data
Reset
Note:
11.2.1 Cold Reset
1. Refer to section “Audio Output Interface”, page 75.
2 conditions are required before enabling a CPU start-up:
•
VDD must reach the specified VDD range
•
The level on X1 input pin must be outside the specification (VIH, VIL)
If one of these 2 conditions are not met, the microcontroller does not start correctly and
can execute an instruction fetch from anywhere in the program space. An active level
applied on the RST pin must be maintained till both of the above conditions are met. A
reset is active when the level V IH1 is reached and when the pulse width covers the
period of time where VDD and the oscillator are not stabilized. 2 parameters have to be
taken into account to determine the reset pulse width:
•
VDD rise time,
•
Oscillator startup time.
To determine the capacitor value to implement, the highest value of these 2 parameters
has to be chosen. Table 3 gives some capacitor values examples for a minimum RRST of
50 KΩ and different oscillator startup and VDD rise times.
48
AT8xC51SND1C
4109H–8051–01/05
AT8xC51SND1C
Table 3. Minimum Reset Capacitor Value for a 50 kΩ Pull-down Resistor(1)
VDD Rise Time
Oscillator
Start-Up Time
1 ms
10 ms
100 ms
5 ms
820 nF
1.2 µF
12 µF
20 ms
2.7 µF
3.9 µF
12 µF
Note:
1. These values assume VDD starts from 0V to the nominal value. If the time between 2
on/off sequences is too fast, the power-supply de-coupling capacitors may not be
fully discharged, leading to a bad reset sequence.
11.3.1 Warm Reset
To achieve a valid reset, the reset signal must be maintained for at least 2 machine
cycles (24 oscillator clock periods) while the oscillator is running. The number of clock
periods is mode independent (X2 or X1).
11.3.2 Watchdog Reset
As detailed in section “Watchdog Timer”, page 61, the WDT generates a 96-clock period
pulse on the RST pin. In order to properly propagate this pulse to the rest of the application in case of external capacitor or power-supply supervisor circuit, a 1 kΩ resistor must
be added as shown in Figure 27.
Figure 27. Reset Circuitry for WDT Reset-out Usage
VDD
VDD
+
RST
RST
VSS
P
1K
To CPU Core
and Peripherals
RRST
VDD
From WDT
Reset Source
VSS
To Other
On-board
Circuitry
11.4 Reset
An example of bad initialization situation may occur in an instance where the bit
ENBOOT in AUXR1 register is initialized from the hardware bit BLJB upon reset. Since
Recommendation to
Prevent Flash Corruption this bit allows mapping of the bootloader in the code area, a reset failure can be critical.
If one wants the ENBOOT cleared in order to unmap the boot from the code area (yet
due to a bad reset) the bit ENBOOT in SFRs may be set. If the value of Program
Counter is accidently in the range of the boot memory addresses then a Flash access
(write or erase) may corrupt the Flash on-chip memory.
It is recommended to use an external reset circuitry featuring power supply monitoring to
prevent system malfunction during periods of insufficient power supply voltage (power
supply failure, power supply switched off).
11.5 Idle Mode
Idle mode is a power reduction mode that reduces the power consumption. In this mode,
program execution halts. Idle mode freezes the clock to the CPU at known states while
the peripherals continue to be clocked (refer to section “Oscillator”, page 12). The CPU
status before entering Idle mode is preserved, i.e., the program counter and program
status word register retain their data for the duration of Idle mode. The contents of the
SFRs and RAM are also retained. The status of the Port pins during Idle mode is
detailed in Table 2.
49
4109H–8051–01/05
11.5.1 Entering Idle Mode
To enter Idle mode, the user must set the IDL bit in PCON register (see Table 8). The
AT8xC51SND1C enters Idle mode upon execution of the instruction that sets IDL bit.
The instruction that sets IDL bit is the last instruction executed.
Note:
11.5.2 Exiting Idle Mode
If IDL bit and PD bit are set simultaneously, the AT8xC51SND1C enter Power-down
mode. Then it does not go in Idle mode when exiting Power-down mode.
There are 2 ways to exit Idle mode:
1. Generate an enabled interrupt.
–
Hardware clears IDL bit in PCON register which restores the clock to the
CPU. Execution resumes with the interrupt service routine. Upon completion
of the interrupt service routine, program execution resumes with the
instruction immediately following the instruction that activated Idle mode.
The general-purpose flags (GF1 and GF0 in PCON register) may be used to
indicate whether an interrupt occurred during normal operation or during Idle
mode. When Idle mode is exited by an interrupt, the interrupt service routine
may examine GF1 and GF0.
2. Generate a reset.
–
Note:
11.6 Power-down Mode
A logic high on the RST pin clears IDL bit in PCON register directly and
asynchronously. This restores the clock to the CPU. Program execution
momentarily resumes with the instruction immediately following the
instruction that activated the Idle mode and may continue for a number of
clock cycles before the internal reset algorithm takes control. Reset
initializes the AT8xC51SND1C and vectors the CPU to address C:0000h.
During the time that execution resumes, the internal RAM cannot be accessed; however,
it is possible for the Port pins to be accessed. To avoid unexpected outputs at the Port
pins, the instruction immediately following the instruction that activated Idle mode should
not write to a Port pin or to the external RAM.
The Power-down mode places the AT8xC51SND1C in a very low power state. Powerdown mode stops the oscillator and freezes all clocks at known states (refer to the Section "Oscillator", page 12). The CPU status prior to entering Power-down mode is
preserved, i.e., the program counter, program status word register retain their data for
the duration of Power-down mode. In addition, the SFRs and RAM contents are preserved. The status of the Port pins during Power-down mode is detailed in Table 2.
Note:
VDD may be reduced to as low as VRET during Power-down mode to further reduce power
dissipation. Notice, however, that VDD is not reduced until Power-down mode is invoked.
11.6.1 Entering Power-down
Mode
To enter Power-down mode, set PD bit in PCON register. The AT8xC51SND1C enters
the Power-down mode upon execution of the instruction that sets PD bit. The instruction
that sets PD bit is the last instruction executed.
11.6.2 Exiting Power-down
Mode
If VDD was reduced during the Power-down mode, do not exit Power-down mode until
VDD is restored to the normal operating level.
There are 2 ways to exit the Power-down mode:
1. Generate an enabled external interrupt.
–
50
The AT8xC51SND1C provides capability to exit from Power-down using
INT0, INT1, and KIN3:0 inputs. In addition, using KIN input provides high or
low level exit capability (see section “Keyboard Interface”, page 182).
Hardware clears PD bit in PCON register which starts the oscillator and
restores the clocks to the CPU and peripherals. Using INTn input, execution
AT8xC51SND1C
4109H–8051–01/05
AT8xC51SND1C
resumes when the input is released (see Figure 28) while using KINx input,
execution resumes after counting 1024 clock ensuring the oscillator is
restarted properly (see Figure 29). This behavior is necessary for decoding
the key while it is still pressed. In both cases, execution resumes with the
interrupt service routine. Upon completion of the interrupt service routine,
program execution resumes with the instruction immediately following the
instruction that activated Power-down mode.
Note:
1. The external interrupt used to exit Power-down mode must be configured as level
sensitive (INT0 and INT1) and must be assigned the highest priority. In addition, the
duration of the interrupt must be long enough to allow the oscillator to stabilize. The
execution will only resume when the interrupt is deasserted.
2. Exit from power-down by external interrupt does not affect the SFRs nor the internal
RAM content.
Figure 28. Power-down Exit Waveform Using INT1:0
INT1:0
OSC
Active phase
Power-down Phase
Oscillator Restart Phase
Active Phase
Figure 29. Power-down Exit Waveform Using KIN3:0
KIN3:01
OSC
Active phase
Note:
Power-down Phase
1024 clock count
Active phase
1. KIN3:0 can be high or low-level triggered.
2. Generate a reset.
–
Notes:
A logic high on the RST pin clears PD bit in PCON register directly and
asynchronously. This starts the oscillator and restores the clock to the CPU
and peripherals. Program execution momentarily resumes with the
instruction immediately following the instruction that activated Power-down
mode and may continue for a number of clock cycles before the internal
reset algorithm takes control. Reset initializes the AT8xC51SND1C and
vectors the CPU to address 0000h.
1. During the time that execution resumes, the internal RAM cannot be accessed; however, it is possible for the Port pins to be accessed. To avoid unexpected outputs at
the Port pins, the instruction immediately following the instruction that activated the
Power-down mode should not write to a Port pin or to the external RAM.
2. Exit from power-down by reset redefines all the SFRs, but does not affect the internal
RAM content.
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4109H–8051–01/05
11.7 Registers
Table 8. PCON Register
PCON (S:87h) – Power Configuration Register
7
6
5
4
3
2
1
0
SMOD1
SMOD0
-
-
GF1
GF0
PD
IDL
Bit
Number
Bit
Mnemonic Description
7
SMOD1
Serial Port Mode Bit 1
Set to select double baud rate in mode 1,2 or 3.
6
SMOD0
Serial Port Mode Bit 0
Set to select FE bit in SCON register.
Clear to select SM0 bit in SCON register.
5-4
-
3
GF1
General-Purpose Flag 1
One use is to indicate whether an interrupt occurred during normal operation or
during Idle mode.
2
GF0
General-Purpose Flag 0
One use is to indicate whether an interrupt occurred during normal operation or
during Idle mode.
PD
Power-Down Mode Bit
Cleared by hardware when an interrupt or reset occurs.
Set to activate the Power-down mode.
If IDL and PD are both set, PD takes precedence.
IDL
Idle Mode Bit
Cleared by hardware when an interrupt or reset occurs.
Set to activate the Idle mode.
If IDL and PD are both set, PD takes precedence.
1
0
Reserved
The value read from these bits is indeterminate. Do not set these bits.
Reset Value = 00XX 0000b
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12. Timers/Counters
The AT8xC51SND1C implement 2 general-purpose, 16-bit Timers/Counters. They are
identified as Timer 0 and Timer 1, and can be independently configured to operate in a
variety of modes as a Timer or as an event Counter. When operating as a Timer, the
Timer/Counter runs for a programmed length of time, then issues an interrupt request.
When operating as a Counter, the Timer/Counter counts negative transitions on an
external pin. After a preset number of counts, the Counter issues an interrupt request.
The various operating modes of each Timer/Counter are described in the following
sections.
12.1 Timer/Counter
Operations
For instance, a basic operation is Timer registers THx and TLx (x = 0, 1) connected in
cascade to form a 16-bit Timer. Setting the run control bit (TRx) in TCON register (see
Table 7) turns the Timer on by allowing the selected input to increment TLx. When TLx
overflows it increments THx; when THx overflows it sets the Timer overflow flag (TFx) in
TCON register. Setting the TRx does not clear the THx and TLx Timer registers. Timer
registers can be accessed to obtain the current count or to enter preset values. They
can be read at any time but TRx bit must be cleared to preset their values, otherwise,
the behavior of the Timer/Counter is unpredictable.
The C/Tx# control bit selects Timer operation or Counter operation by selecting the
divided-down peripheral clock or external pin Tx as the source for the counted signal.
TRx bit must be cleared when changing the mode of operation, otherwise the behavior
of the Timer/Counter is unpredictable.
For Timer operation (C/Tx# = 0), the Timer register counts the divided-down peripheral
clock. The Timer register is incremented once every peripheral cycle (6 peripheral clock
periods). The Timer clock rate is FPER/6, i.e., FOSC/12 in standard mode or FOSC/6 in X2
mode.
For Counter operation (C/Tx# = 1), the Timer register counts the negative transitions on
the Tx external input pin. The external input is sampled every peripheral cycles. When
the sample is high in one cycle and low in the next one, the Counter is incremented.
Since it takes 2 cycles (12 peripheral clock periods) to recognize a negative transition,
the maximum count rate is FPER/12, i.e., FOSC/24 in standard mode or FOSC/12 in X2
mode. There are no restrictions on the duty cycle of the external input signal, but to
ensure that a given level is sampled at least once before it changes, it should be held for
at least one full peripheral cycle.
12.2 Timer Clock
Controller
As shown in Figure 30, the Timer 0 (FT0) and Timer 1 (FT1) clocks are derived from
either the peripheral clock (FPER) or the oscillator clock (FOSC) depending on the T0X2
and T1X2 bits in CKCON register. These clocks are issued from the Clock Controller
block as detailed in Section “Clock Controller”, page 12. When T0X2 or T1X2 bit is set,
the Timer 0 or Timer 1 clock frequency is fixed and equal to the oscillator clock frequency divided by 2. When cleared, the Timer clock frequency is equal to the oscillator
clock frequency divided by 2 in standard mode or to the oscillator clock frequency in X2
mode.
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4109H–8051–01/05
Figure 30. Timer 0 and Timer 1 Clock Controller and Symbols
PER
CLOCK
0
Timer 0 Clock
PER
CLOCK
0
Timer 1 Clock
1
OSC
CLOCK
1
OSC
CLOCK
÷2
T0X2
T1X2
CKCON.1
CKCON.2
TIM0
CLOCK
TIM1
CLOCK
Timer 0 Clock Symbol
12.3 Timer 0
÷2
Timer 1 Clock Symbol
Timer 0 functions as either a Timer or event Counter in four modes of operation.
Figure 31 through Figure 37 show the logical configuration of each mode.
Timer 0 is controlled by the four lower bits of TMOD register (see Table 8) and bits 0, 1,
4 and 5 of TCON register (see Table 7). TMOD register selects the method of Timer gating (GATE0), Timer or Counter operation (C/T0#) and mode of operation (M10 and
M00). TCON register provides Timer 0 control functions: overflow flag (TF0), run control
bit (TR0), interrupt flag (IE0) and interrupt type control bit (IT0).
For normal Timer operation (GATE0 = 0), setting TR0 allows TL0 to be incremented by
the selected input. Setting GATE0 and TR0 allows external pin INT0 to control Timer
operation.
Timer 0 overflow (count rolls over from all 1s to all 0s) sets TF0 flag generating an interrupt request.
It is important to stop Timer/Counter before changing mode.
12.3.1 Mode 0 (13-bit Timer)
Mode 0 configures Timer 0 as a 13-bit Timer which is set up as an 8-bit Timer (TH0 register) with a modulo 32 prescaler implemented with the lower five bits of TL0 register
(see Figure 31). The upper three bits of TL0 register are indeterminate and should be
ignored. Prescaler overflow increments TH0 register. Figure 32 gives the overflow
period calculation formula.
Figure 31. Timer/Counter x (x = 0 or 1) in Mode 0
TIMx
CLOCK
÷6
0
TLx
(5 Bits)
1
THx
(8 Bits)
Overflow
TFx
TCON reg
Timer x
Interrupt
Request
Tx
C/Tx#
TMOD Reg
INTx
GATEx
TMOD Reg
TRx
TCON Reg
Figure 32. Mode 0 Overflow Period Formula
TFxPER=
54
6 ⋅ (16384 – (THx, TLx))
FTIMx
AT8xC51SND1C
4109H–8051–01/05
AT8xC51SND1C
12.3.2 Mode 1 (16-bit Timer)
Mode 1 configures Timer 0 as a 16-bit Timer with TH0 and TL0 registers connected in
cascade (see Figure 33). The selected input increments TL0 register. Figure 34 gives
the overflow period calculation formula when in timer mode.
Figure 33. Timer/Counter x (x = 0 or 1) in Mode 1
TIMx
CLOCK
÷6
0
THx
(8 bits)
1
TLx
(8 bits)
Overflow
TFx
TCON Reg
Tx
Timer x
Interrupt
Request
C/Tx#
TMOD Reg
INTx
GATEx
TRx
TMOD Reg
TCON Reg
Figure 34. Mode 1 Overflow Period Formula
TFxPER=
12.3.3 Mode 2 (8-bit Timer with
Auto-Reload)
6 ⋅ (65536 – (THx, TLx))
FTIMx
Mode 2 configures Timer 0 as an 8-bit Timer (TL0 register) that automatically reloads
from TH0 register (see Table 9). TL0 overflow sets TF0 flag in TCON register and
reloads TL0 with the contents of TH0, which is preset by software. When the interrupt
request is serviced, hardware clears TF0. The reload leaves TH0 unchanged. The next
reload value may be changed at any time by writing it to TH0 register. Figure 36 gives
the autoreload period calculation formula when in timer mode.
Figure 35. Timer/Counter x (x = 0 or 1) in Mode 2
TIMx
CLOCK
÷6
0
TLx
(8 bits)
1
Tx
Overflow
TFx
TCON reg
Timer x
Interrupt
Request
C/Tx#
TMOD reg
INTx
GATEx
TMOD reg
THx
(8 bits)
TRx
TCON reg
Figure 36. Mode 2 Autoreload Period Formula
TFxPER=
12.3.4 Mode 3 (2 8-bit Timers)
6 ⋅ (256 – THx)
FTIMx
Mode 3 configures Timer 0 such that registers TL0 and TH0 operate as separate 8-bit
Timers (see Figure 37). This mode is provided for applications requiring an additional 8bit Timer or Counter. TL0 uses the Timer 0 control bits C/T0# and GATE0 in TMOD register, and TR0 and TF0 in TCON register in the normal manner. TH0 is locked into a
Timer function (counting FTF1/6) and takes over use of the Timer 1 interrupt (TF1) and
run control (TR1) bits. Thus, operation of Timer 1 is restricted when Timer 0 is in mode
55
4109H–8051–01/05
3. Figure 36 gives the autoreload period calculation formulas for both TF0 and TF1
flags.
Figure 37. Timer/Counter 0 in Mode 3: 2 8-bit Counters
TIM0
CLOCK
÷6
0
1
TL0
(8 bits)
Overflow
TH0
(8 bits)
Overflow
TF0
TCON.5
T0
Timer 0
Interrupt
Request
C/T0#
TMOD.2
INT0
GATE0
TR0
TMOD.3
TIM0
CLOCK
TCON.4
÷6
TF1
TCON.7
Timer 1
Interrupt
Request
TR1
TCON.6
Figure 38. Mode 3 Overflow Period Formula
TF0PER =
12.4 Timer 1
56
6 ⋅ (256 – TL0)
FTIM0
TF1PER =
6 ⋅ (256 – TH0)
FTIM0
Timer 1 is identical to Timer 0 except for Mode 3 which is a hold-count mode. The following comments help to understand the differences:
•
Timer 1 functions as either a Timer or event Counter in three modes of operation.
Figure 31 through Figure 35 show the logical configuration for modes 0, 1, and 2.
Timer 1’s mode 3 is a hold-count mode.
•
Timer 1 is controlled by the four high-order bits of TMOD register (see Figure 8) and
bits 2, 3, 6 and 7 of TCON register (see Figure 7). TMOD register selects the
method of Timer gating (GATE1), Timer or Counter operation (C/T1#) and mode of
operation (M11 and M01). TCON register provides Timer 1 control functions:
overflow flag (TF1), run control bit (TR1), interrupt flag (IE1) and interrupt type
control bit (IT1).
•
Timer 1 can serve as the Baud Rate Generator for the Serial Port. Mode 2 is best
suited for this purpose.
•
For normal Timer operation (GATE1 = 0), setting TR1 allows TL1 to be incremented
by the selected input. Setting GATE1 and TR1 allows external pin INT1 to control
Timer operation.
•
Timer 1 overflow (count rolls over from all 1s to all 0s) sets the TF1 flag generating
an interrupt request.
•
When Timer 0 is in mode 3, it uses Timer 1’s overflow flag (TF1) and run control bit
(TR1). For this situation, use Timer 1 only for applications that do not require an
interrupt (such as a Baud Rate Generator for the Serial Port) and switch Timer 1 in
and out of mode 3 to turn it off and on.
•
It is important to stop the Timer/Counter before changing modes.
AT8xC51SND1C
4109H–8051–01/05
AT8xC51SND1C
12.4.1 Mode 0 (13-bit Timer)
Mode 0 configures Timer 1 as a 13-bit Timer, which is set up as an 8-bit Timer (TH1 register) with a modulo-32 prescaler implemented with the lower 5 bits of the TL1 register
(see Figure 31). The upper 3 bits of TL1 register are ignored. Prescaler overflow increments TH1 register.
12.4.2 Mode 1 (16-bit Timer)
Mode 1 configures Timer 1 as a 16-bit Timer with TH1 and TL1 registers connected in
cascade (see Figure 33). The selected input increments TL1 register.
12.4.3 Mode 2 (8-bit Timer with
Auto-Reload)
Mode 2 configures Timer 1 as an 8-bit Timer (TL1 register) with automatic reload from
TH1 register on overflow (see Figure 35). TL1 overflow sets TF1 flag in TCON register
and reloads TL1 with the contents of TH1, which is preset by software. The reload
leaves TH1 unchanged.
12.4.4 Mode 3 (Halt)
Placing Timer 1 in mode 3 causes it to halt and hold its count. This can be used to halt
Timer 1 when TR1 run control bit is not available i.e. when Timer 0 is in mode 3.
12.5 Interrupt
Each Timer handles one interrupt source that is the timer overflow flag TF0 or TF1. This
flag is set every time an overflow occurs. Flags are cleared when vectoring to the Timer
interrupt routine. Interrupts are enabled by setting ETx bit in IEN0 register. This
assumes interrupts are globally enabled by setting EA bit in IEN0 register.
Figure 39. Timer Interrupt System
Timer 0
Interrupt Request
TF0
TCON.5
ET0
IEN0.1
Timer 1
Interrupt Request
TF1
TCON.7
ET1
IEN0.3
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4109H–8051–01/05
12.6 Registers
Table 7. TCON Register
TCON (S:88h) – Timer/Counter Control Register
7
6
5
4
3
2
1
0
TF1
TR1
TF0
TR0
IE1
IT1
IE0
IT0
Bit
Number
Bit
Mnemonic Description
7
TF1
Timer 1 Overflow Flag
Cleared by hardware when processor vectors to interrupt routine.
Set by hardware on Timer/Counter overflow, when Timer 1 register overflows.
6
TR1
Timer 1 Run Control Bit
Clear to turn off Timer/Counter 1.
Set to turn on Timer/Counter 1.
5
TF0
Timer 0 Overflow Flag
Cleared by hardware when processor vectors to interrupt routine.
Set by hardware on Timer/Counter overflow, when Timer 0 register overflows.
4
TR0
Timer 0 Run Control Bit
Clear to turn off Timer/Counter 0.
Set to turn on Timer/Counter 0.
3
IE1
Interrupt 1 Edge Flag
Cleared by hardware when interrupt is processed if edge-triggered (see IT1).
Set by hardware when external interrupt is detected on INT1 pin.
2
IT1
Interrupt 1 Type Control Bit
Clear to select low level active (level triggered) for external interrupt 1 (INT1).
Set to select falling edge active (edge triggered) for external interrupt 1.
1
IE0
Interrupt 0 Edge Flag
Cleared by hardware when interrupt is processed if edge-triggered (see IT0).
Set by hardware when external interrupt is detected on INT0 pin.
0
IT0
Interrupt 0 Type Control Bit
Clear to select low level active (level triggered) for external interrupt 0 (INT0).
Set to select falling edge active (edge triggered) for external interrupt 0.
Reset Value = 0000 0000b
58
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AT8xC51SND1C
Table 8. TMOD Register
TMOD (S:89h) – Timer/Counter Mode Control Register
7
6
5
4
3
2
1
0
GATE1
C/T1#
M11
M01
GATE0
C/T0#
M10
M00
Bit
Bit
Number Mnemonic Description
7
GATE1
Timer 1 Gating Control Bit
Clear to enable Timer 1 whenever TR1 bit is set.
Set to enable Timer 1 only while INT1 pin is high and TR1 bit is set.
6
C/T1#
Timer 1 Counter/Timer Select Bit
Clear for Timer operation: Timer 1 counts the divided-down system clock.
Set for Counter operation: Timer 1 counts negative transitions on external pin T1.
5
M11
4
M01
Timer 1 Mode Select Bits
M11 M01 Operating mode
0
0 Mode 0: 8-bit Timer/Counter (TH1) with 5-bit prescaler (TL1).
0
1 Mode 1: 16-bit Timer/Counter.
1
0 Mode 2: 8-bit auto-reload Timer/Counter (TL1).(1)
1
1
Mode 3: Timer 1 halted. Retains count.
3
GATE0
Timer 0 Gating Control Bit
Clear to enable Timer 0 whenever TR0 bit is set.
Set to enable Timer/Counter 0 only while INT0 pin is high and TR0 bit is set.
2
C/T0#
Timer 0 Counter/Timer Select Bit
Clear for Timer operation: Timer 0 counts the divided-down system clock.
Set for Counter operation: Timer 0 counts negative transitions on external pin T0.
M10
1
Timer 0 Mode Select Bit
M10 M00 Operating mode
0
0 Mode 0: 8-bit Timer/Counter (TH0) with 5-bit prescaler (TL0).
0
1 Mode 1: 16-bit Timer/Counter.
1
0 Mode 2: 8-bit auto-reload Timer/Counter (TL0).(2)
M00
0
1
1 Mode 3: TL0 is an 8-bit Timer/Counter.
TH0 is an 8-bit Timer using Timer 1’s TR0 and TF0 bits.
Notes:
1. Reloaded from TH1 at overflow.
2. Reloaded from TH0 at overflow.
Reset Value = 0000 0000b
Table 9. TH0 Register
TH0 (S:8Ch) – Timer 0 High Byte Register
7
6
5
4
3
2
1
0
-
-
-
-
-
-
-
-
Bit
Number
7:0
Bit
Mnemonic Description
High Byte of Timer 0
Reset Value = 0000 0000b
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4109H–8051–01/05
Table 10. TL0 Register
TL0 (S:8Ah) – Timer 0 Low Byte Register
7
6
5
4
3
2
1
0
-
-
-
-
-
-
-
-
Bit
Number
Bit
Mnemonic Description
7:0
Low Byte of Timer 0
Reset Value = 0000 0000b
Table 11. TH1 Register
TH1 (S:8Dh) – Timer 1 High Byte Register
7
6
5
4
3
2
1
0
-
-
-
-
-
-
-
-
Bit
Number
Bit
Mnemonic Description
7:0
High Byte of Timer 1
Reset Value = 0000 0000b
Table 12. TL1 Register
TL1 (S:8Bh) – Timer 1 Low Byte Register
7
6
5
4
3
2
1
0
-
-
-
-
-
-
-
-
Bit
Number
7:0
Bit
Mnemonic Description
Low Byte of Timer 1
Reset Value = 0000 0000b
60
AT8xC51SND1C
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AT8xC51SND1C
13. Watchdog Timer
The AT8xC51SND1C implement a hardware Watchdog Timer (WDT) that automatically
resets the chip if it is allowed to time out. The WDT provides a means of recovering from
routines that do not complete successfully due to software or hardware malfunctions.
13.1 Description
The WDT consists of a 14-bit prescaler followed by a 7-bit programmable counter. As
shown in Figure 40, the 14-bit prescaler is fed by the WDT clock detailed in
Section “Watchdog Clock Controller”, page 61.
The Watchdog Timer Reset register (WDTRST, see Table 6) provides control access to
the WDT, while the Watchdog Timer Program register (WDTPRG, see Figure 43) provides time-out period programming.
Three operations control the WDT:
•
Chip reset clears and disables the WDT.
•
Programming the time-out value to the WDTPRG register.
•
Writing a specific 2-Byte sequence to the WDTRST register clears and enables the
WDT.
Figure 40. WDT Block Diagram
WDT
CLOCK
14-bit Prescaler
÷6
7-bit Counter
OV
RST
RST
To internal reset
SET
WTO2:0
1Eh-E1h Decoder
System Reset
RST
WDTPRG.2:0
EN
MATCH
OSC
CLOCK
Pulse Generator
RST
WDTRST
13.2 Watchdog Clock
Controller
As shown in Figure 41 the WDT clock (FWDT) is derived from either the peripheral clock
(FPER) or the oscillator clock (FOSC) depending on the WTX2 bit in CKCON register.
These clocks are issued from the Clock Controller block as detailed in Section "Clock
Controller", page 12. When WTX2 bit is set, the WDT clock frequency is fixed and equal
to the oscillator clock frequency divided by 2. When cleared, the WDT clock frequency is
equal to the oscillator clock frequency divided by 2 in standard mode or to the oscillator
clock frequency in X2 mode.
Figure 41. WDT Clock Controller and Symbol
PER
CLOCK
0
WDT Clock
1
OSC
CLOCK
÷2
WDT
CLOCK
WDT Clock Symbol
WTX2
CKCON.6
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4109H–8051–01/05
13.3 Watchdog Operation After reset, the WDT is disabled. The WDT is enabled by writing the sequence 1Eh and
E1h into the WDTRST register. As soon as it is enabled, there is no way except the chip
reset to disable it. If it is not cleared using the previous sequence, the WDT overflows
and forces a chip reset. This overflow generates a high level 96 oscillator periods pulse
on the RST pin to globally reset the application (refer to Section “Power Management”,
page 48).
The WDT time-out period can be adjusted using WTO2:0 bits located in the WDTPRG
register accordingly to the formula shown in Figure 42. In this formula, WTOval represents the decimal value of WTO2:0 bits. Table 4 reports the time-out period depending
on the WDT frequency.
Figure 42. WDT Time-Out Formula
WDTTO=
6 ⋅ ((214 ⋅ 2WTOval) – 1)
FWDT
Table 4. WDT Time-Out Computation
FWDT (ms)
WTO2
WTO1
WTO0
6 MHz(1)
8 MHz(1)
10 MHz(1)
12 MHz(2)
16 MHz(2)
20 MHz(2)
0
0
0
16.38
12.28
9.83
8.19
6.14
4.92
0
0
1
32.77
24.57
19.66
16.38
12.28
9.83
0
1
0
65.54
49.14
39.32
32.77
24.57
19.66
0
1
1
131.07
98.28
78.64
65.54
49.14
39.32
1
0
0
262.14
196.56
157.29
131.07
98.28
78.64
1
0
1
524.29
393.1
314.57
262.14
196.56
157.29
1
1
0
1049
786.24
629.15
524.29
393.12
314.57
1
1
1
2097
1572
1258
1049
786.24
629.15
Notes:
13.4.1 WDT Behavior during
Idle and Power-down Modes
1. These frequencies are achieved in X1 mode or in X2 mode when WTX2 = 1:
FWDT = FOSC ÷ 2.
2. These frequencies are achieved in X2 mode when WTX2 = 0: FWDT = FOSC.
Operation of the WDT during power reduction modes deserves special attention.
The WDT continues to count while the AT8xC51SND1C is in Idle mode. This means
that you must dedicate some internal or external hardware to service the WDT during
Idle mode. One approach is to use a peripheral Timer to generate an interrupt request
when the Timer overflows. The interrupt service routine then clears the WDT, reloads
the peripheral Timer for the next service period and puts the AT8xC51SND1C back into
Idle mode.
The Power-down mode stops all phase clocks. This causes the WDT to stop counting
and to hold its count. The WDT resumes counting from where it left off if the Powerdown mode is terminated by INT0, INT1 or keyboard interrupt. To ensure that the WDT
does not overflow shortly after exiting the Power-down mode, it is recommended to clear
the WDT just before entering Power-down mode.
The WDT is cleared and disabled if the Power-down mode is terminated by a reset.
62
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AT8xC51SND1C
13.5 Registers
Table 6. WDTRST Register
WDTRST (S:A6h Write only) – Watchdog Timer Reset Register
7
6
5
4
3
2
1
0
-
-
-
-
-
-
-
-
Bit
Number
7-0
Bit
Mnemonic Description
-
Watchdog Control Value
Reset Value = XXXX XXXXb
Figure 43. WDTPRG Register
WDTPRG (S:A7h) – Watchdog Timer Program Register
7
6
5
4
3
2
1
0
-
-
-
-
-
WTO2
WTO1
WTO0
Bit
Number
Bit
Mnemonic Description
7-3
-
2-0
WTO2:0
Reserved
The value read from these bits is indeterminate. Do not set these bits.
Watchdog Timer Time-Out Selection Bits
Refer to Table 4 for time-out periods.
Reset Value = XXXX X000b
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4109H–8051–01/05
14. MP3 Decoder
The AT8xC51SND1C implement a MPEG I/II audio layer 3 decoder better known as
MP3 decoder.
In MPEG I (ISO 11172-3) three layers of compression have been standardized supporting three sampling frequencies: 48, 44.1, and 32 kHz. Among these layers, layer 3
allows highest compression rate of about 12:1 while still maintaining CD audio quality.
For example, 3 minutes of CD audio (16-bit PCM, 44.1 kHz) data, which needs about
32M bytes of storage, can be encoded into only 2.7M bytes of MPEG I audio layer 3
data.
In MPEG II (ISO 13818-3), three additional sampling frequencies: 24, 22.05, and 16 kHz
are supported for low bit rates applications.
The AT8xC51SND1C can decode in real-time the MPEG I audio layer 3 encoded data
into a PCM audio data, and also supports MPEG II audio layer 3 additional frequencies.
Additional features are supported by the AT8xC51SND1C MP3 decoder such as volume
control, bass, medium, and treble controls, bass boost effect and ancillary data
extraction.
14.1 Decoder
14.1.1 Description
The C51 core interfaces to the MP3 decoder through nine special function registers:
MP3CON, the MP3 Control register (see Table 12); MP3STA, the MP3 Status register
(see Table 13); MP3DAT, the MP3 Data register (see Table 14); MP3ANC, the Ancillary
Data register (see Table 16); MP3VOL and MP3VOR, the MP3 Volume Left and Right
Control registers (see Table 17 and Table 18); MP3BAS, MP3MED, and MP3TRE, the
MP3 Bass, Medium, and Treble Control registers (see Table 19, Table 20, and
Table 21); and MPCLK, the MP3 Clock Divider register (see Table 22).
Figure 44 shows the MP3 decoder block diagram.
Figure 44. MP3 Decoder Block Diagram
Audio Data
From C51
8
1K Bytes
Frame Buffer
MP3DAT
Header Checker
Huffman Decoder
MPxREQ
ERRxxx MPFS1:0 MPVER
MP3STA1.n
MP3STA.5:3 MP3STA.2:1 MP3STA.0
Dequantizer
Stereo Processor
Side Information
MP3
CLOCK
Ancillary Buffer
MP3ANC
MPEN
MP3CON.7
Anti-Aliasing
MPBBST
MP3CON.6
64
MP3VOL
IMDCT
MP3VOR
MP3BAS
Sub-band
Synthesis
MP3MED
16
Decoded Data
To Audio Interface
MP3TRE
AT8xC51SND1C
4109H–8051–01/05
AT8xC51SND1C
14.1.2 MP3 Data
The MP3 decoder does not start any frame decoding before having a complete frame in
its input buffer(1). In order to manage the load of MP3 data in the frame buffer, a hardware handshake consisting of data request and data acknowledgment is implemented.
Each time the MP3 decoder needs MP3 data, it sets the MPREQ, MPFREQ and
MPBREQ flags respectively in MP3STA and MP3STA1 registers. MPREQ flag can generate an interrupt if enabled as explained in Section “Interrupt”. The CPU must then load
data in the buffer by writing it through MP3DAT register thus acknowledging the previous request. As shown in Figure 45, the MPFREQ flag remains set while data (i.e a
frame) is requested by the decoder. It is cleared when no more data is requested and
set again when new data are requested. MPBREQ flag toggles at every Byte writing.
Note:
1. The first request after enable, consists in 1024 Bytes of data to fill in the input buffer.
Figure 45. Data Timing Diagram
MPREQ Flag
Cleared when Reading MP3STA
MPFREQ Flag
MPBREQ Flag
Write to MP3DAT
14.1.3 MP3 Clock
The MP3 decoder clock is generated by division of the PLL clock. The division factor is
given by MPCD4:0 bits in MP3CLK register. Figure 46 shows the MP3 decoder clock
generator and its calculation formula. The MP3 decoder clock frequency depends only
on the incoming MP3 frames.
Figure 46. MP3 Clock Generator and Symbol
MP3CLK
PLL
CLOCK
MPCD4:0
MP3
CLOCK
MP3 Decoder Clock
MP3 Clock Symbol
PLLclk
MP3clk = ---------------------------MPCD + 1
As soon as the frame header has been decoded and the MPEG version extracted, the
minimum MP3 input frequency must be programmed according to Table 2.
Table 2. MP3 Clock Frequency
MPEG Version
Minimum MP3 Clock (MHz)
I
21
II
10.5
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4109H–8051–01/05
14.3 Audio Controls
14.3.1 Volume Control
The MP3 decoder implements volume control on both right and left channels. The
MP3VOR and MP3VOL registers allow a 32-step volume control according to Table 4.
Table 4. Volume Control
14.4.1 Equalization Control
VOL4:0 or VOR4:0
Volume Gain (dB)
00000
Mute
00001
-33
00010
-27
11110
-1.5
11111
0
Sound can be adjusted using a 3-band equalizer: a bass band under 750 Hz, a medium
band from 750 Hz to 3300 Hz and a treble band over 3300 Hz. The MP3BAS, MP3MED,
and MP3TRE registers allow a 32-step gain control in each band according to Table 5.
Table 5. Bass, Medium, Treble Control
BAS4:0 or MED4:0 or TRE4:0
Gain (dB)
00000
-∞
00001
-14
00010
-10
11110
+1
11111
+1.5
14.5.1 Special Effect
The MPBBST bit in MP3CON register allows enabling of a bass boost effect with the following characteristics: gain increase of +9 dB in the frequency under 375 Hz.
14.6 Decoding Errors
The three different errors that can appear during frame processing are detailed in the
following sections. All these errors can trigger an interrupt as explained in Section "Interrupt", page 68.
14.6.1 Layer Error
The ERRSYN flag in MP3STA is set when a non-supported layer is decoded in the
header of the frame that has been sent to the decoder.
14.6.2 Synchronization Error
The ERRSYN flag in MP3STA is set when no synchronization pattern is found in the
data that have been sent to the decoder.
14.6.3 CRC Error
When the CRC of a frame does not match the one calculated, the flag ERRCRC in
MP3STA is set. In this case, depending on the CRCEN bit in MP3CON, the frame is
played or rejected. In both cases, noise may appear at audio output.
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14.7 Frame Information
The MP3 frame header contains information on the audio data contained in the frame.
These informations is made available in the MP3STA register for you information.
MPVER and MPFS1:0 bits allow decoding of the sampling frequency according to
Table 8. MPVER bit gives the MPEG version (2 or 1).
Table 8. MP3 Frame Frequency Sampling
14.9 Ancillary Data
MPVER
MPFS1
MPFS0
Fs (kHz)
0
0
0
22.05 (MPEG II)
0
0
1
24 (MPEG II)
0
1
0
16 (MPEG II)
0
1
1
Reserved
1
0
0
44.1 (MPEG I)
1
0
1
48 (MPEG I)
1
1
0
32 (MPEG I)
1
1
1
Reserved
MP3 frames also contain data bits called ancillary data. These data are made available
in the MP3ANC register for each frame. As shown in Figure 47, the ancillary data are
available by Bytes when MPANC flag in MP3STA register is set. MPANC flag is set
when the ancillary buffer is not empty (at least one ancillary data is available) and is
cleared only when there is no more ancillary data in the buffer. This flag can generate an
interrupt as explained in Section "Interrupt", page 68. When set, software must read all
Bytes to empty the ancillary buffer.
Figure 47. Ancillary Data Block Diagram
Ancillary
Data To C51
8
MP3ANC
8
7-Byte
Ancillary Buffer
MPANC
MP3STA.7
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14.10 Interrupt
14.10.1 Description
As shown in Figure 48, the MP3 decoder implements five interrupt sources reported in
ERRCRC, ERRSYN, ERRLAY, MPREQ, and MPANC flags in MP3STA register.
All these sources are maskable separately using MSKCRC, MSKSYN, MSKLAY,
MSKREQ, and MSKANC mask bits respectively in MP3CON register.
The MP3 interrupt is enabled by setting EMP3 bit in IEN0 register. This assumes interrupts are globally enabled by setting EA bit in IEN0 register.
All interrupt flags but MPREQ and MPANC are cleared when reading MP3STA register.
The MPREQ flag is cleared by hardware when no more data is requested (see
Figure 45) and MPANC flag is cleared by hardware when the ancillary buffer becomes
empty.
Figure 48. MP3 Decoder Interrupt System
MPANC
MP3STA.7
MSKANC
MP3CON.4
MPREQ
MP3STA.6
MSKREQ
ERRLAY
MP3 Decoder
Interrupt Request
MP3CON.3
MP3STA.5
ERRSYN
MSKLAY
EMP3
MP3CON.2
IEN0.5
MP3STA.4
MSKSYN
ERRCRC
MP3CON.1
MP3STA.3
MSKCRC
MP3CON.0
14.10.2 Management
68
Reading the MP3STA register automatically clears the interrupt flags (acknowledgment)
except the MPREQ and MPANC flags. This implies that register content must be saved
and tested, interrupt flag by interrupt flag to be sure not to forget any interrupts.
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AT8xC51SND1C
Figure 49. MP3 Interrupt Service Routine Flow
MP3 Decoder
ISR
Read MP3STA
Data Request?
MPFREQ = 1?
Data Request
Handler
Write MP3 Data
to MP3DAT
Ancillary Data?(1)
MPANC = 1?
Ancillary Data
Handler
Sync Error?(1)
ERRSYN = 1?
Read ANN2:0 Ancillary
Bytes From MP3ANC
Synchro Error
Handler
Reload MP3 Frame
Through MP3DAT
Layer Error?(1)
ERRSYN = 1?
Layer Error
Handler
CRC Error
Handler
Load New MP3 Frame
Through MP3DAT
Note:
1. Test these bits only if needed (unmasked interrupt).
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14.11 Registers
Table 12. MP3CON Register
MP3CON (S:AAh) – MP3 Decoder Control Register
7
6
5
4
3
2
1
0
MPEN
MPBBST
CRCEN
MSKANC
MSKREQ
MSKLAY
MSKSYN
MSKCRC
Bit
Number
Bit
Mnemonic Description
MP3 Decoder Enable Bit
Set to enable the MP3 decoder.
Clear to disable the MP3 decoder.
7
MPEN
6
MPBBST
Bass Boost Bit
Set to enable the bass boost sound effect.
Clear to disable the bass boost sound effect.
5
CRCEN
CRC Check Enable Bit
Set to enable processing of frame that contains CRC error. Frame is played
whatever the error.
Clear to disable processing of frame that contains CRC error. Frame is skipped.
4
MSKANC
MPANC Flag Mask Bit
Set to prevent the MPANC flag from generating a MP3 interrupt.
Clear to allow the MPANC flag to generate a MP3 interrupt.
3
MSKREQ
MPREQ Flag Mask Bit
Set to prevent the MPREQ flag from generating a MP3 interrupt.
Clear to allow the MPREQ flag to generate a MP3 interrupt.
2
MSKLAY
ERRLAY Flag Mask Bit
Set to prevent the ERRLAY flag from generating a MP3 interrupt.
Clear to allow the ERRLAY flag to generate a MP3 interrupt.
1
MSKSYN
ERRSYN Flag Mask Bit
Set to prevent the ERRSYN flag from generating a MP3 interrupt.
Clear to allow the ERRSYN flag to generate a MP3 interrupt.
0
MSKCRC
ERRCRC Flag Mask Bit
Set to prevent the ERRCRC flag from generating a MP3 interrupt.
Clear to allow the ERRCRC flag to generate a MP3 interrupt.
Reset Value = 0011 1111b
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Table 13. MP3STA Register
MP3STA (S:C8h Read Only) – MP3 Decoder Status Register
7
6
5
4
3
2
1
0
MPANC
MPREQ
ERRLAY
ERRSYN
ERRCRC
MPFS1
MPFS0
MPVER
Bit
Number
Bit
Mnemonic Description
7
MPANC
Ancillary Data Available Flag
Set by hardware as soon as one ancillary data is available (buffer not empty).
Cleared by hardware when no more ancillary data is available (buffer empty).
6
MPREQ
MP3 Data Request Flag
Set by hardware when MP3 decoder request data.
Cleared when reading MP3STA.
5
ERRLAY
Invalid Layer Error Flag
Set by hardware when an invalid layer is encountered.
Cleared when reading MP3STA.
4
ERRSYN
Frame Synchronization Error Flag
Set by hardware when no synchronization pattern is encountered in a frame.
Cleared when reading MP3STA.
3
ERRCRC
CRC Error Flag
Set by hardware when a frame handling CRC is corrupted.
Cleared when reading MP3STA.
2-1
MPFS1:0
Frequency Sampling Bits
Refer to Table 8 for bits description.
0
MPVER
MPEG Version Bit
Set by the MP3 decoder when the loaded frame is a MPEG I frame.
Cleared by the MP3 decoder when the loaded frame is a MPEG II frame.
Reset Value = 0000 0001b
Table 14. MP3DAT Register
MP3DAT (S:ACh) – MP3 Data Register
7
6
5
4
3
2
1
0
MPD7
MPD6
MPD5
MPD4
MPD3
MPD2
MPD1
MPD0
Bit
Number
7-0
Bit
Mnemonic Description
MPD7:0
Input Stream Data Buffer
8-bit MP3 stream data input buffer.
Reset Value = 0000 0000b
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Table 15. MP3STA1 Register
MP3STA1 (S:AFh) – MP3 Decoder Status Register 1
7
6
5
4
3
2
1
0
-
-
-
MPFREQ
MPFREQ
-
-
-
Bit
Number
Bit
Mnemonic Description
Reserved
The value read from these bits is always 0. Do not set these bits.
7-5
-
4
MPFREQ
MP3 Frame Data Request Flag
Set by hardware when MP3 decoder request data.
Cleared when MP3 decoder no more request data .
3
MPBREQ
MP3 Byte Data Request Flag
Set by hardware when MP3 decoder request data.
Cleared when writing to MP3DAT.
2-0
-
Reserved
The value read from these bits is always 0. Do not set these bits.
Reset Value = 0001 0001b
Table 16. MP3ANC Register
MP3ANC (S:ADh Read Only) – MP3 Ancillary Data Register
7
6
5
4
3
2
1
0
AND7
AND6
AND5
AND4
AND3
AND2
AND1
AND0
Bit
Number
7-0
Bit
Mnemonic Description
AND7:0
Ancillary Data Buffer
MP3 ancillary data Byte buffer.
Reset Value = 0000 0000b
Table 17. MP3VOL Register
MP3VOL (S:9Eh) – MP3 Volume Left Control Register
7
6
5
4
3
2
1
0
-
-
-
VOL4
VOL3
VOL2
VOL1
VOL0
Bit
Number
Bit
Mnemonic Description
7-5
-
4-0
VOL4:0
Reserved
The value read from these bits is always 0. Do not set these bits.
Volume Left Value
Refer to Table 4 for the left channel volume control description.
Reset Value = 0000 0000b
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Table 18. MP3VOR Register
MP3VOR (S:9Fh) – MP3 Volume Right Control Register
7
6
5
4
3
2
1
0
-
-
-
VOR4
VOR3
VOR2
VOR1
VOR0
Bit
Number
Bit
Mnemonic Description
7-5
-
Reserved
The value read from these bits is always 0. Do not set these bits.
4-0
VOR4:0
Volume Right Value
Refer to Table 4 for the right channel volume control description.
Reset Value = 0000 0000b
Table 19. MP3BAS Register
MP3BAS (S:B4h) – MP3 Bass Control Register
7
6
5
4
3
2
1
0
-
-
-
BAS4
BAS3
BAS2
BAS1
BAS0
Bit
Number
Bit
Mnemonic Description
7-5
-
4-0
BAS4:0
Reserved
The value read from these bits is always 0. Do not set these bits.
Bass Gain Value
Refer to Table 5 for the bass control description.
Reset Value = 0000 0000b
Table 20. MP3MED Register
MP3MED (S:B5h) – MP3 Medium Control Register
7
6
5
4
3
2
1
0
-
-
MED5
MED4
MED3
MED2
MED1
MED0
Bit
Number
Bit
Mnemonic Description
7-6
-
5-0
MED5:0
Reserved
The value read from these bits is always 0. Do not set these bits.
Medium Gain Value
Refer to Table 5 for the medium control description.
Reset Value = 0000 0000b
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Table 21. MP3TRE Register
MP3TRE (S:B6h) – MP3 Treble Control Register
7
6
5
4
3
2
1
0
-
-
TRE5
TRE4
TRE3
TRE2
TRE1
TRE0
Bit
Number
Bit
Mnemonic Description
7-6
-
5-0
TRE5:0
Reserved
The value read from these bits is always 0. Do not set these bits.
Treble Gain Value
Refer to Table 5 for the treble control description.
Reset Value = 0000 0000b
Table 22. MP3CLK Register
MP3CLK (S:EBh) – MP3 Clock Divider Register
7
6
5
4
3
2
1
0
-
-
-
MPCD4
MPCD3
MPCD2
MPCD1
MPCD0
Bit
Number
Bit
Mnemonic Description
7-5
-
4-0
MPCD4:0
Reserved
The value read from these bits is always 0. Do not set these bits.
MP3 Decoder Clock Divider
5-bit divider for MP3 decoder clock generation.
Reset Value = 0000 0000b
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15. Audio Output
Interface
The AT8xC51SND1C implement an audio output interface allowing the audio bitstream
to be output in various formats. It is compatible with right and left justification PCM and
I2S formats and thanks to the on-chip PLL (see Section “Clock Controller”, page 12)
allows connection of almost all of the commercial audio DAC families available on the
market.
The audio bitstream can be from 2 different types:
15.1 Description
•
The MP3 decoded bitstream coming from the MP3 decoder for playing songs.
•
The audio bitstream coming from the MCU for outputting voice or sounds.
The C51 core interfaces to the audio interface through five special function registers:
AUDCON0 and AUDCON1, the Audio Control registers (see Table 11 and Table 12);
AUDSTA, the Audio Status register (see Table 13); AUDDAT, the Audio Data register
(see Table 14); and AUDCLK, the Audio Clock Divider register (see Table 15).
Figure 50 shows the audio interface block diagram, blocks are detailed in the following
sections.
Figure 50. Audio Interface Block Diagram
SCLK
AUD
CLOCK
DCLK
Clock Generator
0
DSEL
AUDEN
1
AUDCON1.0
Data Ready
HLR
DSIZ
AUDCON0.0
AUDCON0.1
POL
AUDCON0.2
Audio Data
From MP3
Decoder
16
MP3 Buffer
16
0
16
Sample
Request To
MP3 Decoder
DRQEN
AUDCON1.6
Data Converter
DOUT
1
JUST4:0
SRC
AUDCON0.7:3
AUDCON1.7
SREQ
Audio Data
From C51
8
Audio Buffer
AUDDAT
AUDSTA.7
UDRN
AUDSTA.6
AUBUSY
DUP1:0
AUDSTA.5
AUDCON1.2:1
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15.2 Clock Generator
The audio interface clock is generated by division of the PLL clock. The division factor is
given by AUCD4:0 bits in CLKAUD register. Figure 51 shows the audio interface clock
generator and its calculation formula. The audio interface clock frequency depends on
the incoming MP3 frames and the audio DAC used.
Figure 51. Audio Clock Generator and Symbol
AUDCLK
PLL
CLOCK
AUCD4:0
Audio Interface Clock
AUD
CLOCK
Audio Clock Symbol
PLLclk
AUDclk = --------------------------AUCD + 1
As soon as audio interface is enabled by setting AUDEN bit in AUDCON1 register, the
master clock generated by the PLL is output on the SCLK pin which is the DAC system
clock. This clock is output at 256 or 384 times the sampling frequency depending on the
DAC capabilities. HLR bit in AUDCON0 register must be set according to this rate for
properly generating the audio bit clock on the DCLK pin and the word selection clock on
the DSEL pin. These clocks are not generated when no data is available at the data
converter input.
For DAC compatibility, the bit clock frequency is programmable for outputting 16 bits or
32 bits per channel using the DSIZ bit in AUDCON0 register (see Section "Data Converter", page 76), and the word selection signal is programmable for outputting left
channel on low or high level according to POL bit in AUDCON0 register as shown in
Figure 52.
Figure 52. DSEL Output Polarity
15.3 Data Converter
76
POL = 0
Left Channel
Right Channel
POL = 1
Left Channel
Right Channel
The data converter block converts the audio stream input from the 16-bit parallel format
to a serial format. For accepting all PCM formats and I 2 S format, JUST4:0 bits in
AUDCON0 register are used to shift the data output point. As shown in Figure 53, these
bits allow MSB justification by setting JUST4:0 = 00000, LSB justification by setting
JUST4:0 = 10000, I2S Justification by setting JUST4:0 = 00001, and more than 16-bit
LSB justification by filling the low significant bits with logic 0.
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Figure 53. Audio Output Format
DSEL
Left Channel
DCLK
DOUT
1
2
3
Right Channel
13
14
15
LSB MSB B14
16
B1
1
2
3
13
14
15
LSB MSB B14
16
B1
I2S Format with DSIZ = 0 and JUST4:0 = 00001.
DSEL
Left Channel
DCLK
1
DOUT
2
Right Channel
3
17
MSB B14
LSB
18
32
1
2
3
17
MSB B14
LSB
18
32
I2S Format with DSIZ = 1 and JUST4:0 = 00001.
DSEL
Left Channel
DCLK
DOUT
1
2
3
Right Channel
13
14
MSB B14
15
B1
16
1
2
3
13
14
LSB MSB B15
15
B1
16
LSB
MSB/LSB Justified Format with DSIZ = 0 and JUST4:0 = 00000.
DSEL
DCLK
Left Channel
1
16
DOUT
17
Right Channel
18
31
MSB B14
B1
32
1
16
LSB
17
18
31
MSB B14
B1
32
LSB
16-bit LSB Justified Format with DSIZ = 1 and JUST4:0 = 10000.
DSEL
DCLK
DOUT
Left Channel
1
15
16
MSB B16
Right Channel
30
B2
31
B1
32
LSB
1
15
16
MSB B16
30
B2
31
B1
32
LSB
18-bit LSB Justified Format with DSIZ = 1 and JUST4:0 = 01110.
The data converter receives its audio stream from 2 sources selected by the SRC bit in
AUDCON1 register. When cleared, the audio stream comes from the MP3 decoder (see
Section “MP3 Decoder”, page 64) for song playing. When set, the audio stream is coming from the C51 core for voice or sound playing.
As soon as first audio data is input to the data converter, it enables the clock generator
for generating the bit and word clocks.
15.4 Audio Buffer
In voice or sound playing mode, the audio stream comes from the C51 core through an
audio buffer. The data is in 8-bit format and is sampled at 8 kHz. The audio buffer
adapts the sample format and rate. The sample format is extended to 16 bits by filling
the LSB to 00h. Rate is adapted to the DAC rate by duplicating the data using DUP1:0
bits in AUDCON1 register according to Table 5.
The audio buffer interfaces to the C51 core through three flags: the sample request flag
(SREQ in AUDSTA register), the under-run flag (UNDR in AUDSTA register) and the
busy flag (AUBUSY in AUDSTA register). SREQ and UNDR can generate an interrupt
request as explained in Section "Interrupt Request", page 78. The buffer size is 8 Bytes
large. SREQ is set when the samples number switches from 4 to 3 and reset when the
samples number switches from 4 to 5; UNDR is set when the buffer becomes empty signaling that the audio interface ran out of samples; and AUBUSY is set when the buffer is
full.
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Table 5. Sample Duplication Factor
DUP1
DUP0
Factor
0
0
No sample duplication, DAC rate = 8 kHz (C51 rate).
0
1
One sample duplication, DAC rate = 16 kHz (2 x C51 rate).
1
0
2 samples duplication, DAC rate = 32 kHz (4 x C51 rate).
1
1
Three samples duplication, DAC rate = 48 kHz (6 x C51 rate).
15.6 MP3 Buffer
In song playing mode, the audio stream comes from the MP3 decoder through a buffer.
The MP3 buffer is used to store the decoded MP3 data and interfaces to the decoder
through a 16-bit data input and data request signal. This signal asks for data when the
buffer has enough space to receive new data. Data request is conditioned by the
DREQEN bit in AUDCON1 register. When set, the buffer requests data to the MP3
decoder. When cleared no more data is requested but data are output until the buffer is
empty. This bit can be used to suspend the audio generation (pause mode).
15.7 Interrupt Request
The audio interrupt request can be generated by 2 sources when in C51 audio mode: a
sample request when SREQ flag in AUDSTA register is set to logic 1, and an under-run
condition when UDRN flag in AUDSTA register is set to logic 1. Both sources can be
enabled separately by masking one of them using the MSREQ and MUDRN bits in
AUDCON1 register. A global enable of the audio interface is provided by setting the
EAUD bit in IEN0 register.
The interrupt is requested each time one of the 2 sources is set to one. The source flags
are cleared by writing some data in the audio buffer through AUDDAT, but the global
audio interrupt flag is cleared by hardware when the interrupt service routine is
executed.
Figure 54. Audio Interface Interrupt System
UDRN
AUDSTA.6
Audio
Interrupt
Request
MUDRN
AUDCON1.4
SREQ
EAUD
AUDSTA.7
IEN0.6
MSREQ
AUDCON1.5
15.8 MP3 Song Playing
78
In MP3 song playing mode, the operations to do are to configure the PLL and the audio
interface according to the DAC selected. The audio clock is programmed to generate
the 256·Fs or 384·Fs as explained in Section "Clock Generator", page 76. Figure 55
shows the configuration flow of the audio interface when in MP3 song mode.
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AT8xC51SND1C
Figure 55. MP3 Mode Audio Configuration Flow
MP3 Mode
Configuration
Program Audio Clock
Configure Interface
HLR = X
DSIZ = X
POL = X
JUST4:0 = XXXXXb
SRC = 0
15.9 Voice or Sound
Playing
Enable DAC System
Clock
AUDEN = 1
Wait For
DAC Set-up Time
Enable Data Request
DRQEN = 1
In voice or sound playing mode, the operations required are to configure the PLL and
the audio interface according to the DAC selected. The audio clock is programmed to
generate the 256·Fs or 384·Fs as for the MP3 playing mode. The data flow sent by the
C51 is then regulated by interrupt and data is loaded 4 Bytes by 4 Bytes. Figure 56
shows the configuration flow of the audio interface when in voice or sound mode.
Figure 56. Voice or Sound Mode Audio Flows
Voice/Song Mode
Configuration
Program Audio Clock
Configure Interface
HLR = X
DSIZ = X
POL = X
JUST4:0 = XXXXXb
DUP1:0 = XX
Enable DAC System
Clock
AUDEN = 1
Note:
Audio Interrupt
Service Routine
Wait for DAC
Enable Time
Sample Request?
SREQ = 1?
Select Audio
SRC = 1
Load 4 Samples in the
Audio Buffer
Under-run Condition1
Load 8 Samples in the
Audio Buffer
Enable Interrupt
Set MSREQ & MUDRN1
EAUD = 1
1. An under-run occurrence signifies that C51 core did not respond to the previous sample request interrupt. It may never
occur for a correct voice/sound generation. It is the user’s responsibility to mask it or not.
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15.10 Registers
Table 11. AUDCON0 Register
AUDCON0 (S:9Ah) – Audio Interface Control Register 0
7
6
5
4
3
2
1
0
JUST4
JUST3
JUST2
JUST1
JUST0
POL
DSIZ
HLR
Bit
Number
Bit
Mnemonic Description
Audio Stream Justification Bits
Refer to Section "Data Converter", page 76 for bits description.
7-3
JUST4:0
2
POL
DSEL Signal Output Polarity
Set to output the left channel on high level of DSEL output (PCM mode).
Clear to output the left channel on the low level of DSEL output (I2S mode).
1
DSIZ
Audio Data Size
Set to select 32-bit data output format.
Clear to select 16-bit data output format.
0
HLR
High/Low Rate Bit
Set by software when the PLL clock frequency is 384·Fs.
Clear by software when the PLL clock frequency is 256·Fs.
Reset Value = 0000 1000b
Table 12. AUDCON1 Register
AUDCON1 (S:9Bh) – Audio Interface Control Register 1
7
6
5
4
3
2
1
0
SRC
DRQEN
MSREQ
MUDRN
-
DUP1
DUP0
AUDEN
Bit
Number
Bit
Mnemonic Description
7
SRC
Audio Source Bit
Set to select C51 as audio source for voice or sound playing.
Clear to select the MP3 decoder output as audio source for song playing.
6
DRQEN
MP3 Decoded Data Request Enable Bit
Set to enable data request to the MP3 decoder and to start playing song.
Clear to disable data request to the MP3 decoder.
5
MSREQ
Audio Sample Request Flag Mask Bit
Set to prevent the SREQ flag from generating an audio interrupt.
Clear to allow the SREQ flag to generate an audio interrupt.
4
MUDRN
Audio Sample Under-run Flag Mask Bit
Set to prevent the UDRN flag from generating an audio interrupt.
Clear to allow the UDRN flag to generate an audio interrupt.
3
-
2-1
DUP1:0
Audio Duplication Factor
Refer to Table 5 for bits description.
0
AUDEN
Audio Interface Enable Bit
Set to enable the audio interface.
Clear to disable the audio interface.
Reserved
The value read from this bit is always 0. Do not set this bit.
Reset Value = 1011 0010b
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Table 13. AUDSTA Register
AUDSTA (S:9Ch Read Only) – Audio Interface Status Register
7
6
5
4
3
2
1
0
SREQ
UDRN
AUBUSY
-
-
-
-
-
Bit
Number
Bit
Mnemonic Description
SREQ
Audio Sample Request Flag
Set in C51 audio source mode when the audio interface request samples (buffer
half empty). This bit generates an interrupt if not masked and if enabled in IEN0.
Cleared by hardware when samples are loaded in AUDDAT.
UDRN
Audio Sample Under-run Flag
Set in C51 audio source mode when the audio interface runs out of samples
(buffer empty). This bit generates an interrupt if not masked and if enabled in
IEN0.
Cleared by hardware when samples are loaded in AUDDAT.
5
AUBUSY
Audio Interface Busy Bit
Set in C51 audio source mode when the audio interface can not accept more
sample (buffer full).
Cleared by hardware when buffer is no more full.
4-0
-
7
6
Reserved
The value read from these bits is always 0. Do not set these bits.
Reset Value = 1100 0000b
Table 14. AUDDAT Register
AUDDAT (S:9Dh) – Audio Interface Data Register
7
6
5
4
3
2
1
0
AUD7
AUD6
AUD5
AUD4
AUD3
AUD2
AUD1
AUD0
Bit
Number
7-0
Bit
Mnemonic Description
AUD7:0
Audio Data
8-bit sampling data for voice or sound playing.
Reset Value = 1111 1111b
Table 15. AUDCLK Register
AUDCLK (S:ECh) – Audio Clock Divider Register
7
6
5
4
3
2
1
0
-
-
-
AUCD4
AUCD3
AUCD2
AUCD1
AUCD0
Bit
Number
Bit
Mnemonic Description
7-5
-
4-0
AUCD4:0
Reserved
The value read from these bits is always 0. Do not set these bits.
Audio Clock Divider
5-bit divider for audio clock generation.
Reset Value = 0000 0000b
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16. Universal Serial
Bus
The AT8xC51SND1C implements a USB device controller supporting full speed data
transfer. In addition to the default control endpoint 0, it provides 2 other endpoints, which
can be configured in control, bulk, interrupt or isochronous modes:
•
Endpoint 0: 32-Byte FIFO, default control endpoint
•
Endpoint 1, 2: 64-Byte Ping-pong FIFO,
This allows the firmware to be developed conforming to most USB device classes, for
example:
16.0.1 USB Mass Storage
Class Bulk-Only Transport
•
USB Mass Storage Class Bulk-only Transport, Revision 1.0 - September 31, 1999
•
USB Human Interface Device Class, Version 1.1 - April 7, 1999
•
USB Device Firmware Upgrade Class, Revision 1.0 - May 13, 1999
Within the Bulk-only framework, the Control endpoint is only used to transport classspecific and standard USB requests for device set-up and configuration. One Bulk-out
endpoint is used to transport commands and data from the host to the device. One Bulk
in endpoint is used to transport status and data from the device to the host.
The following AT8xC51SND1C configuration adheres to those requirements:
16.0.2 USB Device Firmware
Upgrade (DFU)
•
Endpoint 0: 32 Bytes, Control In-Out
•
Endpoint 1: 64 Bytes, Bulk-in
•
Endpoint 2: 64 Bytes, Bulk-out
The USB Device Firmware Update (DFU) protocol can be used to upgrade the on-chip
Flash memory of the AT89C51SND1C. This allows installing product enhancements
and patches to devices that are already in the field. 2 different configurations and
descriptor sets are used to support DFU functions. The Run-Time configuration co-exist
with the usual functions of the device, which is USB Mass Storage for AT89C51SND1C.
It is used to initiate DFU from the normal operating mode. The DFU configuration is
used to perform the firmware update after device re-configuration and USB reset. It
excludes any other function. Only the default control pipe (endpoint 0) is used to support
DFU services in both configurations.
The only possible value for the MaxPacketSize in the DFU configuration is 32 Bytes,
which is the size of the FIFO implemented for endpoint 0.
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16.1 Description
The USB device controller provides the hardware that the AT8xC51SND1C needs to
interface a USB link to a data flow stored in a double port memory.
It requires a 48 MHz reference clock provided by the clock controller as detailed in Section "Clock Controller", page 83. This clock is used to generate a 12 MHz Full Speed bit
clock from the received USB differential data flow and to transmit data according to full
speed USB device tolerance. Clock recovery is done by a Digital Phase Locked Loop
(DPLL) block.
The Serial Interface Engine (SIE) block performs NRZI encoding and decoding, bit stuffing, CRC generation and checking, and the serial-parallel data conversion.
The Universal Function Interface (UFI) controls the interface between the data flow and
the Dual Port RAM, but also the interface with the C51 core itself.
Figure 59 shows how to connect the AT8xC51SND1C to the USB connector. D+ and Dpins are connected through 2 termination resistors. Value of these resistors is detailed in
the section “DC Characteristics”.
Figure 57. USB Device Controller Block Diagram
USB
CLOCK
D+
D-
48 MHz
12 MHz
DPLL
USB
Buffer
UFI
To/From
C51 Core
SIE
Figure 58. USB Connection
VBUS
To Power Supply
D+
RUSB
D+
D-
RUSB
D-
GND
VSS
16.1.1 Clock Controller
The USB controller clock is generated by division of the PLL clock. The division factor is
given by USBCD1:0 bits in USBCLK register (see Table 24). Figure 59 shows the USB
controller clock generator and its calculation formula. The USB controller clock frequency must always be 48 MHz.
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Figure 59. USB Clock Generator and Symbol
USBCLK
PLL
CLOCK
USB
CLOCK
48 MHz USB Clock
USBCD1:0
USB Clock Symbol
PLLclk
USBclk = -------------------------------USBCD + 1
16.1.2 Serial Interface Engine
(SIE)
The SIE performs the following functions:
•
NRZI data encoding and decoding.
•
Bit stuffing and unstuffing.
•
CRC generation and checking.
•
ACKs and NACKs automatic generation.
•
TOKEN type identifying.
•
Address checking.
•
Clock recovery (using DPLL).
Figure 60. SIE Block Diagram
End of Packet
Detector
SYNC Detector
Start of Packet
Detector
NRZI ‘ NRZ
Bit Unstuffing
Packet Bit Counter
Address Decoder
Serial to Parallel
Converter
D+
DUSB 48 MHz
CLOCK
Clock
Recover
PID Decoder
8
Data Out
SysClk
(12 MHz)
CRC5 & CRC16
Generator/Check
USB Pattern Generator
Parallel to Serial Converter
Bit Stuffing
NRZI Converter
CRC16 Generator
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16.1.3 Function Interface Unit
(UFI)
The Function Interface Unit provides the interface between the AT8xC51SND1C and
the SIE. It manages transactions at the packet level with minimal intervention from the
device firmware, which reads and writes the endpoint FIFOs.
Figure 62 shows typical USB IN and OUT transactions reporting the split in the hardware (UFI) and software (C51) load.
Figure 61. UFI Block Diagram
12 MHz DPLL
Transfer
Control
FSM
To/From SIE
Endpoint Control
USB side
Asynchronous Information
Endpoint 2
USBCON
USBADDR
USBINT
USBIEN
UEPNUM
UEPCONX
UEPSTAX
UEPRST
UEPINT
UEPIEN
UEPDATX
UBYCTX
UFNUMH
UFNUML
To/From C51 Core
Endpoint Control
C51 side
Endpoint 1
Endpoint 0
Figure 62. USB Typical Transaction Load
OUT Transactions:
HOST
OUT
DATA0 (n Bytes)
UFI
C51
OUT
ACK
DATA1
C51 interrupt
OUT
DATA1
NACK
ACK
Endpoint FIFO read (n Bytes)
IN Transactions:
HOST
UFI
C51
IN
IN
NACK
Endpoint FIFO Write
IN
DATA1
ACK
DATA1
C51 interrupt
Endpoint FIFO write
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16.2 Configuration
16.2.1 General Configuration
•
USB controller enable
Before any USB transaction, the 48 MHz required by the USB controller must be
correctly generated (See “Clock Controller” on page 19).
The USB controller should be then enabled by setting the EUSB bit in the USBCON
register.
•
Set address
After a Reset or a USB reset, the software has to set the FEN (Function Enable) bit
in the USBADDR register. This action will allow the USB controller to answer to the
requests sent at the address 0.
When a SET_ADDRESS request has been received, the USB controller must only
answer to the address defined by the request. The new address should be stored in
the USBADDR register. The FEN bit and the FADDEN bit in the USBCON register
should be set to allow the USB controller to answer only to requests sent at the new
address.
•
Set configuration
The CONFG bit in the USBCON register should be set after a
SET_CONFIGURATION request with a non-zero value. Otherwise, this bit should
be cleared.
16.2.2 Endpoint Configuration
•
Selection of an Endpoint
The endpoint register access is performed using the UEPNUM register. The
registers
–
UEPSTAX
–
UEPCONX
–
UEPDATX
–
UBYCTX
Theses registers correspond to the endpoint whose number is stored in the UEPNUM register. To select an Endpoint, the firmware has to write the endpoint number
in the UEPNUM register.
Figure 63. Endpoint Selection
Endpoint 0
UEPSTA0
UEPCON0
UEPDAT0
SFR Registers
0
UBYCT0
1
X
UEPSTAX
UEPCONX
UEPDATX
UBYCTX
Endpoint 2
UEPSTA2
UEPCON2
UEPDAT2
2
UBYCT2
UEPNUM
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•
Endpoint enable
Before using an endpoint, this must be enabled by setting the EPEN bit in the UEPCONX register.
An endpoint which is not enabled won’t answer to any USB request. The Default
Control Endpoint (Endpoint 0) should always be enabled in order to answer to USB
standard requests.
•
Endpoint type configuration
All Standard Endpoints can be configured in Control, Bulk, Interrupt or Isochronous
mode. The Ping-pong Endpoints can be configured in Bulk, Interrupt or Isochronous
mode. The configuration of an endpoint is performed by setting the field EPTYPE
with the following values:
–
Control:
EPTYPE = 00b
–
Isochronous: EPTYPE = 01b
–
Bulk:
EPTYPE = 10b
–
Interrupt:
EPTYPE = 11b
The Endpoint 0 is the Default Control Endpoint and should always be configured in
Control type.
•
Endpoint direction configuration
For Bulk, Interrupt and Isochronous endpoints, the direction is defined with the
EPDIR bit of the UEPCONX register with the following values:
–
IN:
EPDIR = 1b
–
OUT:
EPDIR = 0b
For Control endpoints, the EPDIR bit has no effect.
•
Summary of Endpoint Configuration:
Do not forget to select the correct endpoint number in the UEPNUM register before
accessing endpoint specific registers.
Table 3. Summary of Endpoint Configuration
Endpoint Configuration
EPEN
EPDIR
EPTYPE
UEPCONX
Disabled
0b
Xb
XXb
0XXX XXXb
Control
1b
Xb
00b
80h
Bulk-in
1b
1b
10b
86h
Bulk-out
1b
0b
10b
82h
Interrupt-In
1b
1b
11b
87h
Interrupt-Out
1b
0b
11b
83h
Isochronous-In
1b
1b
01b
85h
Isochronous-Out
1b
0b
01b
81h
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•
Endpoint FIFO reset
Before using an endpoint, its FIFO should be reset. This action resets the FIFO
pointer to its original value, resets the Byte counter of the endpoint (UBYCTX register), and resets the data toggle bit (DTGL bit in UEPCONX).
The reset of an endpoint FIFO is performed by setting to 1 and resetting to 0 the
corresponding bit in the UEPRST register.
For example, in order to reset the Endpoint number 2 FIFO, write 0000 0100b then
0000 0000b in the UEPRST register.
Note that the endpoint reset doesn’t reset the bank number for ping-pong endpoints.
16.4 Read/Write Data
FIFO
16.4.1 Read Data FIFO
The read access for each OUT endpoint is performed using the UEPDATX register.
After a new valid packet has been received on an Endpoint, the data are stored into the
FIFO and the Byte counter of the endpoint is updated (UBYCTX registers). The firmware
has to store the endpoint Byte counter before any access to the endpoint FIFO. The
Byte counter is not updated when reading the FIFO.
To read data from an endpoint, select the correct endpoint number in UEPNUM and
read the UEPDATX register. This action automatically decreases the corresponding
address vector, and the next data is then available in the UEPDATX register.
16.4.2 Write Data FIFO
The write access for each IN endpoint is performed using the UEPDATX register.
To write a Byte into an IN endpoint FIFO, select the correct endpoint number in UEPNUM and write into the UEPDATX register. The corresponding address vector is
automatically increased, and another write can be carried out.
Warning 1: The Byte counter is not updated.
Warning 2: Do not write more Bytes than supported by the corresponding endpoint.
16.4.3 FIFO Mapping
Figure 64. Endpoint FIFO Configuration
Endpoint 0
UEPSTA0
UEPCON0
UEPDAT0
SFR Registers
0
UBYCT0
1
X
UEPSTAX
UEPCONX
UEPDATX
UBYCTX
Endpoint 2
UEPSTA2
UEPCON2
UEPDAT2
2
UBYCT2
UEPNUM
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16.5 Bulk/Interrupt
Transactions
Bulk and Interrupt transactions are managed in the same way.
16.5.1 Bulk/Interrupt OUT
Transactions in Standard
Mode
Figure 65. Bulk/Interrupt OUT transactions in Standard Mode
HOST
OUT
C51
UFI
DATA0 (n Bytes)
ACK
RXOUTB0
Endpoint FIFO Read Byte 1
OUT
DATA1
Endpoint FIFO Read Byte 2
NAK
OUT
Endpoint FIFO Read Byte n
DATA1
Clear RXOUTB0
NAK
OUT
DATA1
ACK
RXOUTB0
Endpoint FIFO Read Byte 1
An endpoint should be first enabled and configured before being able to receive Bulk or
Interrupt packets.
When a valid OUT packet is received on an endpoint, the RXOUTB0 bit is set by the
USB controller. This triggers an interrupt if enabled. The firmware has to select the corresponding endpoint, store the number of data Bytes by reading the UBYCTX register. If
the received packet is a ZLP (Zero Length Packet), the UBYCTX register value is equal
to 0 and no data has to be read.
When all the endpoint FIFO Bytes have been read, the firmware should clear the
RXOUTB0 bit to allow the USB controller to accept the next OUT packet on this endpoint. Until the RXOUTB0 bit has been cleared by the firmware, the USB controller will
answer a NAK handshake for each OUT requests.
If the Host sends more Bytes than supported by the endpoint FIFO, the overflow data
won’t be stored, but the USB controller will consider that the packet is valid if the CRC is
correct and the endpoint Byte counter contains the number of Bytes sent by the Host.
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16.5.2 Bulk/Interrupt OUT
Transactions in Ping-pong
Mode
Figure 66. Bulk/Interrupt OUT Transactions in Ping-pong Mode
HOST
OUT
UFI
C51
DATA0 (n Bytes)
ACK
RXOUTB0
Endpoint FIFO bank 0 - Read Byte 1
OUT
Endpoint FIFO bank 0 - Read Byte 2
DATA1 (m Bytes)
ACK
Endpoint FIFO bank 0 - Read Byte n
Clear RXOUTB0
OUT
RXOUTB1
DATA0 (p Bytes)
Endpoint FIFO bank 1 - Read Byte 1
ACK
Endpoint FIFO bank 1 - Read Byte 2
Endpoint FIFO bank 1 - Read Byte m
Clear RXOUTB1
RXOUTB0
Endpoint FIFO bank 0 - Read Byte 1
Endpoint FIFO bank 0 - Read Byte 2
Endpoint FIFO bank 0 - Read Byte p
Clear RXOUTB0
An endpoint should be first enabled and configured before being able to receive Bulk or
Interrupt packets.
When a valid OUT packet is received on the endpoint bank 0, the RXOUTB0 bit is set by
the USB controller. This triggers an interrupt if enabled. The firmware has to select the
corresponding endpoint, store the number of data Bytes by reading the UBYCTX register. If the received packet is a ZLP (Zero Length Packet), the UBYCTX register value is
equal to 0 and no data has to be read.
When all the endpoint FIFO Bytes have been read, the firmware should clear the
RXOUB0 bit to allow the USB controller to accept the next OUT packet on the endpoint
bank 0. This action switches the endpoint bank 0 and 1. Until the RXOUTB0 bit has
been cleared by the firmware, the USB controller will answer a NAK handshake for each
OUT requests on the bank 0 endpoint FIFO.
When a new valid OUT packet is received on the endpoint bank 1, the RXOUTB1 bit is
set by the USB controller. This triggers an interrupt if enabled. The firmware empties the
bank 1 endpoint FIFO before clearing the RXOUTB1 bit. Until the RXOUTB1 bit has
been cleared by the firmware, the USB controller will answer a NAK handshake for each
OUT requests on the bank 1 endpoint FIFO.
The RXOUTB0 and RXOUTB1 bits are, alternatively, set by the USB controller at each
new valid packet receipt.
The firmware has to clear one of these 2 bits after having read all the data FIFO to allow
a new valid packet to be stored in the corresponding bank.
A NAK handshake is sent by the USB controller only if the banks 0 and 1 has not been
released by the firmware.
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If the Host sends more Bytes than supported by the endpoint FIFO, the overflow data
won’t be stored, but the USB controller will consider that the packet is valid if the CRC is
correct.
16.5.3 Bulk/Interrupt IN
Transactions in Standard
Mode
Figure 67. Bulk/Interrupt IN Transactions in Standard Mode
UFI
HOST
C51
Endpoint FIFO Write Byte 1
IN
Endpoint FIFO Write Byte 2
NAK
Endpoint FIFO Write Byte n
Set TXRDY
IN
DATA0 (n Bytes)
ACK
TXCMPL
Clear TXCMPL
Endpoint FIFO Write Byte 1
An endpoint should be first enabled and configured before being able to send Bulk or
Interrupt packets.
The firmware should fill the FIFO with the data to be sent and set the TXRDY bit in the
UEPSTAX register to allow the USB controller to send the data stored in FIFO at the
next IN request concerning this endpoint. To send a Zero Length Packet, the firmware
should set the TXRDY bit without writing any data into the endpoint FIFO.
Until the TXRDY bit has been set by the firmware, the USB controller will answer a NAK
handshake for each IN requests.
To cancel the sending of this packet, the firmware has to reset the TXRDY bit. The
packet stored in the endpoint FIFO is then cleared and a new packet can be written and
sent.
When the IN packet has been sent and acknowledged by the Host, the TXCMPL bit in
the UEPSTAX register is set by the USB controller. This triggers a USB interrupt if
enabled. The firmware should clear the TXCMPL bit before filling the endpoint FIFO with
new data.
The firmware should never write more Bytes than supported by the endpoint FIFO.
All USB retry mechanisms are automatically managed by the USB controller.
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16.5.4 Bulk/Interrupt IN
Transactions in Ping-pong
Mode
Figure 68. Bulk/Interrupt IN transactions in Ping-pong mode
HOST
C51
UFI
Endpoint FIFO bank 0 - Write Byte 1
IN
Endpoint FIFO bank 0 - Write Byte 2
NACK
Endpoint FIFO bank 0 - Write Byte n
Set TXRDY
IN
Endpoint FIFO bank 1 - Write Byte 1
DATA0 (n Bytes)
Endpoint FIFO bank 1 - Write Byte 2
ACK
Endpoint FIFO bank 1 - Write Byte m
TXCMPL
Clear TXCMPL
Set TXRDY
IN
DATA1 (m Bytes)
Endpoint FIFO bank 0 - Write Byte 1
Endpoint FIFO bank 0 - Write Byte 2
ACK
Endpoint FIFO bank 0 - Write Byte p
TXCMPL
Clear TXCMPL
Set TXRDY
IN
DATA0 (p Bytes)
Endpoint FIFO bank 1 - Write Byte 1
ACK
An endpoint should be first enabled and configured before being able to send Bulk or
Interrupt packets.
The firmware should fill the FIFO bank 0 with the data to be sent and set the TXRDY bit
in the UEPSTAX register to allow the USB controller to send the data stored in FIFO at
the next IN request concerning the endpoint. The FIFO banks are automatically
switched, and the firmware can immediately write into the endpoint FIFO bank 1.
When the IN packet concerning the bank 0 has been sent and acknowledged by the
Host, the TXCMPL bit is set by the USB controller. This triggers a USB interrupt if
enabled. The firmware should clear the TXCMPL bit before filling the endpoint FIFO
bank 0 with new data. The FIFO banks are then automatically switched.
When the IN packet concerning the bank 1 has been sent and acknowledged by the
Host, the TXCMPL bit is set by the USB controller. This triggers a USB interrupt if
enabled. The firmware should clear the TXCMPL bit before filling the endpoint FIFO
bank 1 with new data.
The bank switch is performed by the USB controller each time the TXRDY bit is set by
the firmware. Until the TXRDY bit has been set by the firmware for an endpoint bank,
the USB controller will answer a NAK handshake for each IN requests concerning this
bank.
Note that in the example above, the firmware clears the Transmit Complete bit
(TXCBulk-outMPL) before setting the Transmit Ready bit (TXRDY). This is done in order
to avoid the firmware to clear at the same time the TXCMPL bit for for bank 0 and the
bank 1.
The firmware should never write more Bytes than supported by the endpoint FIFO.
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16.6 Control
Transactions
16.6.1 Setup Stage
The DIR bit in the UEPSTAX register should be at 0.
Receiving Setup packets is the same as receiving Bulk Out packets, except that the
RXSETUP bit in the UEPSTAX register is set by the USB controller instead of the
RXOUTB0 bit to indicate that an Out packet with a Setup PID has been received on the
Control endpoint. When the RXSETUP bit has been set, all the other bits of the UEPSTAX register are cleared and an interrupt is triggered if enabled.
The firmware has to read the Setup request stored in the Control endpoint FIFO before
clearing the RXSETUP bit to free the endpoint FIFO for the next transaction.
16.6.2 Data Stage: Control
Endpoint Direction
The data stage management is similar to Bulk management.
A Control endpoint is managed by the USB controller as a full-duplex endpoint: IN and
OUT. All other endpoint types are managed as half-duplex endpoint: IN or OUT. The
firmware has to specify the control endpoint direction for the data stage using the DIR bit
in the UEPSTAX register.
•
If the data stage consists of INs, the firmware has to set the DIR bit in the UEPSTAX
register before writing into the FIFO and sending the data by setting to 1 the TXRDY
bit in the UEPSTAX register. The IN transaction is complete when the TXCMPL has
been set by the hardware. The firmware should clear the TXCMPL bit before any
other transaction.
•
If the data stage consists of OUTs, the firmware has to leave the DIR bit at 0. The
RXOUTB0 bit is set by hardware when a new valid packet has been received on the
endpoint. The firmware must read the data stored into the FIFO and then clear the
RXOUTB0 bit to reset the FIFO and to allow the next transaction.
To send a STALL handshake, see “STALL Handshake” on page 96.
16.6.3 Status Stage
The DIR bit in the UEPSTAX register should be reset at 0 for IN and OUT status stage.
The status stage management is similar to Bulk management.
•
For a Control Write transaction or a No-Data Control transaction, the status stage
consists of a IN Zero Length Packet (see “Bulk/Interrupt IN Transactions in
Standard Mode” on page 91). To send a STALL handshake, see “STALL
Handshake” on page 96.
•
For a Control Read transaction, the status stage consists of a OUT Zero Length
Packet (see “Bulk/Interrupt OUT Transactions in Standard Mode” on page 89).
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Isochronous Transactions
16.6.4 Isochronous OUT
Transactions in Standard
Mode
An endpoint should be first enabled and configured before being able to receive Isochronous packets.
When an OUT packet is received on an endpoint, the RXOUTB0 bit is set by the USB
controller. This triggers an interrupt if enabled. The firmware has to select the corre
Bulk-outsponding endpoint, store the number of data Bytes by reading the UBYCTX
register. If the received packet is a ZLP (Zero Length Packet), the UBYCTX register
value is equal to 0 and no data has to be read.
The STLCRC bit in the UEPSTAX register is set by the USB controller if the packet
stored in FIFO has a corrupted CRC. This bit is updated after each new packet receipt.
When all the endpoint FIFO Bytes have been read, the firmware should clear the
RXOUTB0 bit to allow the USB controller to store the next OUT packet data into the
endpoint FIFO. Until the RXOUTB0 bit has been cleared by the firmware, the data sent
by the Host at each OUT transaction will be lost.
If the RXOUTB0 bit is cleared while the Host is sending data, the USB controller will
store only the remaining Bytes into the FIFO.
If the Host sends more Bytes than supported by the endpoint FIFO, the overflow data
won’t be stored, but the USB controller will consider that the packet is valid if the CRC is
correct.
16.6.5 Isochronous OUT
Transactions in Ping-pong
Mode
An endpoint should be first enabled and configured before being able to receive Isochronous packets.
When a OUT packet is received on the endpoint bank 0, the RXOUTB0 bit is set by the
USB controller. This triggers an interrupt if enabled. The firmware has to select the corresponding endpoint, store the number of data Bytes by reading the UBYCTX register. If
the received packet is a ZLP (Zero Length Packet), the UBYCTX register value is equal
to 0 and no data has to be read.
The STLCRC bit in the UEPSTAX register is set by the USB controller if the packet
stored in FIFO has a corrupted CRC. This bit is updated after each new packet receipt.
When all the endpoint FIFO Bytes have been read, the firmware should clear the
RXOUB0 bit to allow the USB controller to store the next OUT packet data into the endpoint FIFO bank 0. This action switches the endpoint bank 0 and 1. Until the RXOUTB0
bit has been cleared by the firmware, the data sent by the Host on the bank 0 endpoint
FIFO will be lost.
If the RXOUTB0 bit is cleared while the Host is sending data on the endpoint bank 0, the
USB controller will store only the remaining Bytes into the FIFO.
When a new OUT packet is received on the endpoint bank 1, the RXOUTB1 bit is set by
the USB controller. This triggers an interrupt if enabled. The firmware empties the bank
1 endpoint FIFO before clearing the RXOUTB1 bit. Until the RXOUTB1 bit has been
cleared by the firmware, the data sent by the Host on the bank 1 endpoint FIFO will be
lost.
The RXOUTB0 and RXOUTB1 bits are alternatively set by the USB controller at each
new packet receipt.
The firmware has to clear one of these 2 bits after having read all the data FIFO to allow
a new packet to be stored in the corresponding bank.
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If the Host sends more Bytes than supported by the endpoint FIFO, the overflow data
won’t be stored, but the USB controller will consider that the packet is valid if the CRC is
correct.
16.6.6 Isochronous IN
Transactions in Standard
Mode
An endpoint should be first enabled and configured before being able to send Isochronous packets.
The firmware should fill the FIFO with the data to be sent and set the TXRDY bit in the
UEPSTAX register to allow the USB controller to send the data stored in FIFO at the
next IN request concerning this endpoint.
If the TXRDY bit is not set when the IN request occurs, nothing will be sent by the USB
controller.
When the IN packet has been sent, the TXCMPL bit in the UEPSTAX register is set by
the USB controller. This triggers a USB interrupt if enabled. The firmware should clear
the TXCMPL bit before filling the endpoint FIFO with new data.
The firmware should never write more Bytes than supported by the endpoint FIFO
16.6.7 Isochronous IN
Transactions in Ping-pong
Mode
An endpoint should be first enabled and configured before being able to send Isochronous packets.
The firmware should fill the FIFO bank 0 with the data to be sent and set the TXRDY bit
in the UEPSTAX register to allow the USB controller to send the data stored in FIFO at
the next IN request concerning the endpoint. The FIFO banks are automatically
switched, and the firmware can immediately write into the endpoint FIFO bank 1.
If the TXRDY bit is not set when the IN request occurs, nothing will be sent by the USB
controller.
When the IN packet concerning the bank 0 has been sent, the TXCMPL bit is set by the
USB controller. This triggers a USB interrupt if enabled. The firmware should clear the
TXCMPL bit before filling the endpoint FIFO bank 0 with new data. The FIFO banks are
then automatically switched.
When the IN packet concerning the bank 1 has been sent, the TXCMPL bit is set by the
USB controller. This triggers a USB interrupt if enabled. The firmware should clear the
TXCMPL bit before filling the endpoint FIFO bank 1 with new data.
The bank switch is performed by the USB controller each time the TXRDY bit is set by
the firmware. Until the TXRDY bit has been set by the firmware for an endpoint bank,
the USB controller won’t send anything at each IN requests concerning this bank.
The firmware should never write more Bytes than supported by the endpoint FIFO.
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16.7 Miscellaneous
16.7.1 USB Reset
The EORINT bit in the USBINT register is set by hardware when a End Of Reset has
been detected on the USB bus. This triggers a USB interrupt if enabled. The USB controller is still enabled, but all the USB registers are reset by hardware. The firmware
should clear the EORINT bit to allow the next USB reset detection.
16.7.2 STALL Handshake
This function is only available for Control, Bulk, and Interrupt endpoints.
The firmware has to set the STALLRQ bit in the UEPSTAX register to send a STALL
handshake at the next request of the Host on the endpoint selected with the UEPNUM
register. The RXSETUP, TXRDY, TXCMPL, RXOUTB0 and RXOUTB1 bits must be first
resseted to 0. The bit STLCRC is set at 1 by the USB controller when a STALL has been
sent. This triggers an interrupt if enabled.
The firmware should clear the STALLRQ and STLCRC bits after each STALL sent.
The STALLRQ bit is cleared automatically by hardware when a valid SETUP PID is
received on a CONTROL type endpoint.
Important note: when a Clear Halt Feature occurs for an endpoint, the firmware should
reset this endpoint using the UEPRST resgister in order to reset the data toggle
management.
16.7.3 Start of Frame
Detection
The SOFINT bit in the USBINT register is set when the USB controller detects a Start Of
Frame PID. This triggers an interrupt if enabled. The firmware should clear the SOFINT
bit to allow the next Start of Frame detection.
16.7.4 Frame Number
When receiving a Start Of Frame, the frame number is automatically stored in the
UFNUML and UFNUMH registers. The CRCOK and CRCERR bits indicate if the CRC of
the last Start Of Frame is valid (CRCOK set at 1) or corrupted (CRCERR set at 1). The
UFNUML and UFNUMH registers are automatically updated when receiving a new Start
of Frame.
16.7.5 Data Toggle Bit
The Data Toggle bit is set by hardware when a DATA0 packet is received and accepted
by the USB controller and cleared by hardware when a DATA1 packet is received and
accepted by the USB controller. This bit is reset when the firmware resets the endpoint
FIFO using the UEPRST register.
For Control endpoints, each SETUP transaction starts with a DATA0 and data toggling
is then used as for Bulk endpoints until the end of the Data stage (for a control write
transfer). The Status stage completes the data transfer with a DATA1 (for a control read
transfer).
For Isochronous endpoints, the device firmware should ignore the data-toggle.
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Suspend/Resume Management
16.7.6 Suspend
The Suspend state can be detected by the USB controller if all the clocks are enabled
and if the USB controller is enabled. The bit SPINT is set by hardware when an idle
state is detected for more than 3 ms. This triggers a USB interrupt if enabled.
In order to reduce current consumption, the firmware can put the USB PAD in idle mode,
stop the clocks and put the C51 in Idle or Power-down mode. The Resume detection is
still active.
The USB PAD is put in idle mode when the firmware clear the SPINT bit. In order to
avoid a new suspend detection 3ms later, the firmware has to disable the USB clock
input using the SUSPCLK bit in the USBCON Register. The USB PAD automatically
exits of idle mode when a wake-up event is detected.
The stop of the 48 MHz clock from the PLL should be done in the following order:
1. Disable of the 48 MHz clock input of the USB controller by setting to 1 the SUSPCLK bit in the USBCON register.
2. Disable the PLL by clearing the PLLEN bit in the PLLCON register.
16.7.7 Resume
When the USB controller is in Suspend state, the Resume detection is active even if all
the clocks are disabled and if the C51 is in Idle or Power-down mode. The WUPCPU bit
is set by hardware when a non-idle state occurs on the USB bus. This triggers an interrupt if enabled. This interrupt wakes up the CPU from its Idle or Power-down state and
the interrupt function is then executed. The firmware will first enable the 48 MHz generation and then reset to 0 the SUSPCLK bit in the USBCON register if needed.
The firmware has to clear the SPINT bit in the USBINT register before any other USB
operation in order to wake up the USB controller from its Suspend mode.
The USB controller is then re-activated.
Figure 69. Example of a Suspend/Resume Management
USB Controller Init
SPINT
Detection of a SUSPEND State
Clear SPINT
Set SUSPCLK
Disable PLL
microcontroller in Power-down
WUPCPU
Detection of a RESUME State
Enable PLL
Clear SUSPCLK
Clear WUPCPU Bit
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16.7.8 Upstream Resume
A USB device can be allowed by the Host to send an upstream resume for Remote
Wake-up purpose.
When the USB controller receives the SET_FEATURE request:
DEVICE_REMOTE_WAKEUP, the firmware should set to 1 the RMWUPE bit in the
USBCON register to enable this functionality. RMWUPE value should be 0 in the other
cases.
If the device is in SUSPEND mode, the USB controller can send an upstream resume by
clearing first the SPINT bit in the USBINT register and by setting then to 1 the SDRMWUP bit in the USBCON register. The USB controller sets to 1 the UPRSM bit in the
USBCON register. All clocks must be enabled first. The Remote Wake is sent only if the
USB bus was in Suspend state for at least 5ms. When the upstream resume is completed, the UPRSM bit is reset to 0 by hardware. The firmware should then clear the
SDRMWUP bit.
Figure 70. Example of REMOTE WAKEUP Management
USB Controller Init
SET_FEATURE: DEVICE_REMOTE_WAKEUP
Set RMWUPE
SPINT
Detection of a SUSPEND state
Suspend Management
need USB resume
enable clocks
Clear SPINT
UPRSM = 1
Set SDMWUP
UPRSM
upstream RESUME sent
Clear SDRMWUP
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16.8 USB Interrupt
System
16.8.1 Interrupt System
Priorities
D+
D-
Figure 71. USB Interrupt Control System
00
01
10
11
USB
Controller
EUSB
EA
IE1.6
IE0.7
IPH/L
Priority Enable
Interrupt Enable
Lowest Priority Interrupts
Table 1. Priority Levels
16.8.2 USB Interrupt Control
System
IPHUSB
IPLUSB
USB Priority Level
0
0
0..................Lowest
0
1
1
1
0
2
1
1
3..................Highest
As shown in Figure 72, many events can produce a USB interrupt:
•
TXCMPL: Transmitted In Data (Table 16 on page 105). This bit is set by hardware
when the Host accept a In packet.
•
RXOUTB0: Received Out Data Bank 0 (Table 16 on page 105). This bit is set by
hardware when an Out packet is accepted by the endpoint and stored in bank 0.
•
RXOUTB1: Received Out Data Bank 1 (only for Ping-pong endpoints) (Table 16 on
page 105). This bit is set by hardware when an Out packet is accepted by the
endpoint and stored in bank 1.
•
RXSETUP: Received Setup (Table 16 on page 105). This bit is set by hardware
when an SETUP packet is accepted by the endpoint.
•
STLCRC: STALLED (only for Control, Bulk and Interrupt endpoints) (Table 16 on
page 105). This bit is set by hardware when a STALL handshake has been sent as
requested by STALLRQ, and is reset by hardware when a SETUP packet is
received.
•
SOFINT: Start of Frame Interrupt (Table 12 on page 102). This bit is set by hardware
when a USB start of frame packet has been received.
•
WUPCPU: Wake-Up CPU Interrupt (Table 12 on page 102). This bit is set by
hardware when a USB resume is detected on the USB bus, after a SUSPEND state.
•
SPINT: Suspend Interrupt (Table 12 on page 102). This bit is set by hardware when
a USB suspend is detected on the USB bus.
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Figure 72. USB Interrupt Control Block Diagram
Endpoint X (X = 0..2)
TXCMP
UEPSTAX.0
RXOUTB0
UEPSTAX.1
RXOUTB1
EPXINT
UEPSTAX.6
UEPINT.X
RXSETUP
EPXIE
UEPSTAX.2
UEPIEN.X
STLCRC
UEPSTAX.3
NAKOUT
UEPCONX.5
NAKIN
UEPCONX.4
NAKIEN
UEPCONX.6
WUPCPU
EUSB
USBINT.5
EWUPCPU
IE1.6
USBIEN.5
EORINT
USBINT.4
EEORINT
USBIEN.4
SOFINT
USBINT.3
ESOFINT
USBIEN.3
SPINT
USBINT.0
ESPINT
USBIEN.0
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16.9 Registers
Table 10. USBCON Register
USBCON (S:BCh) – USB Global Control Register
7
6
5
4
3
2
1
0
USBE
SUSPCLK
SDRMWUP
-
UPRSM
RMWUPE
CONFG
FADDEN
Bit
Number
7
Bit
Mnemonic Description
USBE
USB Enable Bit
Set this bit to enable the USB controller.
Clear this bit to disable and reset the USB controller, to disable the USB
transceiver an to disable the USB controllor clock inputs.
6
Suspend USB Clock Bit
SUSPCLK Set to disable the 48 MHz clock input (Resume Detection is still active).
Clear to enable the 48 MHz clock input.
5
Send Remote Wake-Up Bit
Set to force an external interrupt on the USB controller for Remote Wake UP
purpose.
SDRMWU
An upstream resume is send only if the bit RMWUPE is set, all USB clocks are
P
enabled AND the USB bus was in SUSPEND state for at least 5 ms. See
UPRSM below.
Cleared by software.
4
-
3
UPRSM
Reserved
The value read from this bit is always 0. Do not set this bit.
Upstream Resume Bit (read only)
Set by hardware when SDRMWUP has been set and if RMWUPE is enabled.
Cleared by hardware after the upstream resume has been sent.
2
Remote Wake-Up Enable Bit
Set to enabled request an upstream resume signaling to the host.
RMWUPE Clear after the upstream resume has been indicated by RSMINPR.
Note: Do not set this bit if the host has not set the DEVICE_REMOTE_WAKEUP
feature for the device.
1
CONFG
Configuration Bit
This bit should be set by the device firmware after a SET_CONFIGURATION
request with a non-zero value has been correctly processed.
It should be cleared by the device firmware when a SET_CONFIGURATION
request with a zero value is received. It is cleared by hardware on hardware
reset or when an USB reset is detected on the bus (SE0 state for at least 32 Full
Speed bit times: typically 2.7 µs).
FADDEN
Function Address Enable Bit
This bit should be set by the device firmware after a successful status phase of a
SET_ADDRESS transaction.
It should not be cleared afterwards by the device firmware. It is cleared by
hardware on hardware reset or when an USB reset is received (see above).
When this bit is cleared, the default function address is used (0).
0
Reset Value = 0000 0000b
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Table 11. USBADDR Register
USBADDR (S:C6h) – USB Address Register
7
6
5
4
3
2
1
0
FEN
UADD6
UADD5
UADD4
UADD3
UADD2
UADD1
UADD0
Bit
Number
Bit
Mnemonic Description
7
FEN
Function Enable Bit
Set to enable the function. The device firmware should set this bit after it has
received a USB reset and participate in the following configuration process with
the default address (FEN is reset to 0).
Cleared by hardware at power-up, should not be cleared by the device firmware
once set.
6-0
UADD6:0
USB Address Bits
This field contains the default address (0) after power-up or USB bus reset.
It should be written with the value set by a SET_ADDRESS request received by
the device firmware.
Reset Value = 0000 0000b
Table 12. USBINT Register
USBINT (S:BDh) – USB Global Interrupt Register
7
6
5
4
3
2
1
0
-
-
WUPCPU
EORINT
SOFINT
-
-
SPINT
Bit
Number
7-6
Bit
Mnemonic Description
-
Reserved
The value read from these bits is always 0. Do not set these bits.
5
WUPCPU
Wake Up CPU Interrupt Flag
Set by hardware when the USB controller is in SUSPEND state and is reactivated by a non-idle signal from USB line (not by an upstream resume). This
triggers a USB interrupt when EWUPCPU is set in the USBIEN.
Cleared by software after re-enabling all USB clocks.
4
EORINT
End of Reset Interrupt Flag
Set by hardware when a End of Reset has been detected by the USB controller.
This triggers a USB interrupt when EEORINT is set in USBIEN.
Cleared by software.
3
SOFINT
Start of Frame Interrupt Flag
Set by hardware when an USB Start of Frame packet (SOF) has been properly
received. This triggers a USB interrupt when ESOFINT is set in USBIEN.
Cleared by software.
2-1
-
0
SPINT
Reserved
The value read from these bits is always 0. Do not set these bits.
Suspend Interrupt Flag
Set by hardware when a USB Suspend (Idle bus for three frame periods: a J
state for 3 ms) is detected. This triggers a USB interrupt when ESPINT is set in
USBIEN.
Cleared by software.
Reset Value = 0000 0000b
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Table 13. USBIEN Register
USBIEN (S:BEh) – USB Global Interrupt Enable Register
7
6
5
4
3
2
1
0
-
-
EWUPCPU
EEORINT
ESOFINT
-
-
ESPINT
Bit
Number
Bit
Mnemonic Description
Reserved
The value read from these bits is always 0. Do not set these bits.
7-6
-
5
EWUPCP
U
Wake Up CPU Interrupt Enable Bit
Set to enable the Wake Up CPU interrupt.
Clear to disable the Wake Up CPU interrupt.
4
EEOFINT
End Of Reset Interrupt Enable Bit
Set to enable the End Of Reset interrupt. This bit is set after reset.
Clear to disable End Of Reset interrupt.
3
ESOFINT
Start Of Frame Interrupt Enable Bit
Set to enable the SOF interrupt.
Clear to disable the SOF interrupt.
2-1
-
0
ESPINT
Reserved
The value read from these bits is always 0. Do not set these bits.
Suspend Interrupt Enable Bit
Set to enable Suspend interrupt.
Clear to disable Suspend interrupt.
Reset Value = 0001 0000b
Table 14. UEPNUM Register
UEPNUM (S:C7h) – USB Endpoint Number
7
6
5
4
3
2
1
0
-
-
-
-
-
-
EPNUM1
EPNUM0
Bit
Number
7-2
1-0
Bit
Mnemonic Description
-
Reserved
The value read from these bits is always 0. Do not set these bits.
Endpoint Number Bits
EPNUM1:
Set this field with the number of the endpoint which should be accessed when
0
reading or writing to registers UEPSTAX, UEPDATX, UBYCTX or UEPCONX.
Reset Value = 0000 0000b
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Table 15. UEPCONX Register
UEPCONX (S:D4h) – USB Endpoint X Control Register (X = EPNUM set in UEPNUM)
7
6
5
4
3
2
1
0
EPEN
NAKIEN
NAKOUT
NAKIN
DTGL
EPDIR
EPTYPE1
EPTYPE0
Bit
Number
Bit
Mnemonic Description
Endpoint Enable Bit
Set to enable the endpoint according to the device configuration. Endpoint 0
should always be enabled after a hardware or USB bus reset and participate in
the device configuration.
Clear to disable the endpoint according to the device configuration.
7
EPEN
6
NAKIEN
NAK Interrupt enable
Set this bit to enable NAK IN or NAK OUT interrupt.
Clear this bit to disable NAK IN or NAK OUT Interrupt.
NAKOUT
NAK OUT received
This bit is set by hardware when an NAK handshake has been sent in response
of a OUT request from the Host. This triggers a USB interrupt when NAKIEN is
set.
This bit should be cleared by software.
4
NAKIN
NAK IN received
This bit is set by hardware when an NAK handshake has been sent in response
of a IN request from the Host. This triggers a USB interrupt when NAKIEN is set.
This bit should be cleared by software.
3
DTGL
Data Toggle Status Bit (Read-only)
Set by hardware when a DATA1 packet is received.
Cleared by hardware when a DATA0 packet is received.
2
EPDIR
Endpoint Direction Bit
Set to configure IN direction for Bulk, Interrupt and Isochronous endpoints.
Clear to configure OUT direction for Bulk, Interrupt and Isochronous endpoints.
This bit has no effect for Control endpoints.
5
1-0
Endpoint Type Bits
Set this field according to the endpoint configuration (Endpoint 0 should always
be configured as Control):
EPTYPE1:
00 Control endpoint
0
01 Isochronous endpoint
10 Bulk endpoint
11 Interrupt endpoint
Reset Value = 1000 0000b
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Table 16. UEPSTAX Register
UEPSTAX (S:CEh) – USB Endpoint X Status and Control Register (X = EPNUM set in UEPNUM)
7
6
5
4
3
2
1
0
DIR
RXOUTB1
STALLRQ
TXRDY
STLCRC
RXSETUP
RXOUTB0
TXCMP
Bit
Number
Bit
Mnemonic Description
Control Endpoint Direction Bit
This bit is relevant only if the endpoint is configured in Control type.
Set for the data stage. Clear otherwise.
7
6
DIR
Note: This bit should be configured on RXSETUP interrupt before any other bit is
changed. This also determines the status phase (IN for a control write and OUT
for a control read). This bit should be cleared for status stage of a Control Out
transaction.
Received OUT Data Bank 1 for Endpoints 1 and 2 (Ping-pong mode)
This bit is set by hardware after a new packet has been stored in the endpoint
FIFO data bank 1 (only in Ping-pong mode). Then, the endpoint interrupt is
triggered if enabled and all the following OUT packets to the endpoint bank 1 are
RXOUTB1
rejected (NAK’ed) until this bit has been cleared, excepted for Isochronous
Endpoints.
This bit should be cleared by the device firmware after reading the OUT data
from the endpoint FIFO.
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Bit
Number
5
4
3
Bit
Mnemonic Description
STALLRQ
Stall Handshake Request Bit
Set to send a STALL answer to the host for the next handshake. Clear otherwise.
TXRDY
TX Packet Ready Control Bit
Set after a packet has been written into the endpoint FIFO for IN data transfers.
Data should be written into the endpoint FIFO only after this bit has been cleared.
Set this bit without writing data to the endpoint FIFO to send a Zero Length
Packet, which is generally recommended and may be required to terminate a
transfer when the length of the last data packet is equal to MaxPacketSize (e.g.
for control read transfers).
Cleared by hardware, as soon as the packet has been sent for Isochronous
endpoints, or after the host has acknowledged the packet for Control, Bulk and
Interrupt endpoints.
STLCRC
Stall Sent Interrupt Flag/CRC Error Interrupt Flag
For Control, Bulk and Interrupt Endpoints:
Set by hardware after a STALL handshake has been sent as requested by
STALLRQ. Then, the endpoint interrupt is triggered if enabled in UEPIEN.
Cleared by hardware when a SETUP packet is received (see RXSETUP).
For Isochronous Endpoints:
Set by hardware if the last data received is corrupted (CRC error on data). Then,
the endpoint interrupt is triggered if enabled in UEPIEN.
Cleared by hardware when a non corrupted data is received.
2
Received SETUP Interrupt Flag
Set by hardware when a valid SETUP packet has been received from the host.
RXSETUP Then, all the other bits of the register are cleared by hardware and the endpoint
interrupt is triggered if enabled in UEPIEN.
Clear by software after reading the SETUP data from the endpoint FIFO.
1
Received OUT Data Bank 0 (see also RXOUTB1 bit for Ping-pong Endpoints)
This bit is set by hardware after a new packet has been stored in the endpoint
FIFO data bank 0. Then, the endpoint interrupt is triggered if enabled and all the
following OUT packets to the endpoint bank 0 are rejected (NAK’ed) until this bit
RXOUTB0 has been cleared, excepted for Isochronous Endpoints. However, for control
endpoints, an early SETUP transaction may overwrite the content of the endpoint
FIFO, even if its Data packet is received while this bit is set.
This bit should be cleared by the device firmware after reading the OUT data
from the endpoint FIFO.
0
TXCMP
Transmitted IN Data Complete Interrupt Flag
Set by hardware after an IN packet has been transmitted for Isochronous
endpoints and after it has been accepted (ACK’ed) by the host for Control, Bulk
and Interrupt endpoints. Then, the endpoint interrupt is triggered if enabled in
UEPIEN.
Clear by software before setting again TXRDY.
Reset Value = 0000 0000b
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Table 17. UEPRST Register
UEPRST (S:D5h) – USB Endpoint FIFO Reset Register
7
6
5
4
3
2
1
0
-
-
-
-
-
EP2RST
EP1RST
EP0RST
Bit
Number
Bit
Mnemonic Description
Reserved
The value read from these bits is always 0. Do not set these bits.
7-3
-
2
EP2RST
Endpoint 2 FIFO Reset
Set and clear to reset the endpoint 2 FIFO prior to any other operation, upon
hardware reset or when an USB bus reset has been received.
1
EP1RST
Endpoint 1 FIFO Reset
Set and clear to reset the endpoint 1 FIFO prior to any other operation, upon
hardware reset or when an USB bus reset has been received.
0
EP0RST
Endpoint 0 FIFO Reset
Set and clear to reset the endpoint 0 FIFO prior to any other operation, upon
hardware reset or when an USB bus reset has been received.
Reset Value = 0000 0000b
Table 18. UEPIEN Register
UEPIEN (S:C2h) – USB Endpoint Interrupt Enable Register
7
6
5
4
3
2
1
0
-
-
-
-
-
EP2INTE
EP1INTE
EP0INTE
Bit
Number
Bit
Mnemonic Description
Reserved
The value read from these bits is always 0. Do not set these bits.
7-3
-
2
EP2INTE
Endpoint 2 Interrupt Enable Bit
Set to enable the interrupts for endpoint 2.
Clear this bit to disable the interrupts for endpoint 2.
1
EP1INTE
Endpoint 1 Interrupt Enable Bit
Set to enable the interrupts for the endpoint 1.
Clear to disable the interrupts for the endpoint 1.
0
EP0INTE
Endpoint 0 Interrupt Enable Bit
Set to enable the interrupts for the endpoint 0.
Clear to disable the interrupts for the endpoint 0.
Reset Value = 0000 0000b
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Table 19. UEPINT Register
UEPINT (S:F8h Read-only) – USB Endpoint Interrupt Register
7
6
5
4
3
2
1
0
-
-
-
-
-
EP2INT
EP1INT
EP0INT
Bit
Number
7-3
2
Bit
Mnemonic Description
-
EP2INT
Reserved
The value read from these bits is always 0. Do not set these bits.
Endpoint 2 Interrupt Flag
This bit is set by hardware when an endpoint interrupt source has been detected
on the endpoint 2. The endpoint interrupt sources are in the UEPSTAX register
and can be: TXCMP, RXOUTB0, RXOUTB1, RXSETUP or STLCRC.
A USB interrupt is triggered when the EP2IE bit in the UEPIEN register is set.
This bit is cleared by hardware when all the endpoint interrupt sources are
cleared.
1
EP1INT
Endpoint 1 Interrupt Flag
This bit is set by hardware when an endpoint interrupt source has been detected
on the endpoint 1. The endpoint interrupt sources are in the UEPSTAX register
and can be: TXCMP, RXOUTB0, RXOUTB1, RXSETUP or STLCRC.
A USB interrupt is triggered when the EP1IE bit in the UEPIEN register is set.
This bit is cleared by hardware when all the endpoint interrupt sources are
cleared.
0
EP0INT
Endpoint 0 Interrupt Flag
This bit is set by hardware when an endpoint interrupt source has been detected
on the endpoint 0. The endpoint interrupt sources are in the UEPSTAX register
and can be: TXCMP, RXOUTB0, RXOUTB1, RXSETUP or STLCRC.
A USB interrupt is triggered when the EP0IE bit in the UEPIEN register is set.
This bit is cleared by hardware when all the endpoint interrupt sources are
cleared.
Reset Value = 0000 0000b
Table 20. UEPDATX Register
UEPDATX (S:CFh) – USB Endpoint X FIFO Data Register (X = EPNUM set in UEPNUM)
7
6
5
4
3
2
1
0
FDAT7
FDAT6
FDAT5
FDAT4
FDAT3
FDAT2
FDAT1
FDAT0
Bit
Number
7-0
Bit
Mnemonic Description
FDAT7:0
Endpoint X FIFO Data
Data Byte to be written to FIFO or data Byte to be read from the FIFO, for the
Endpoint X (see EPNUM).
Reset Value = XXh
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Table 21. UBYCTX Register
UBYCTX (S:E2h) – USB Endpoint X Byte Count Register (X = EPNUM set in UEPNUM)
7
6
5
4
3
2
1
0
-
BYCT6
BYCT5
BYCT4
BYCT3
BYCT2
BYCT1
BYCT0
Bit
Number
Bit
Mnemonic Description
7
-
6-0
BYCT7:0
Reserved
The value read from this bits is always 0. Do not set this bit.
Byte Count
Byte count of a received data packet. This Byte count is equal to the number of
data Bytes received after the Data PID.
Reset Value = 0000 0000b
Table 22. UFNUML Register
UFNUML (S:BAh, Read-only) – USB Frame Number Low Register
7
6
5
4
3
2
1
0
FNUM7
FNUM6
FNUM5
FNUM4
FNUM3
FNUM2
FNUM1
FNUM0
Bit
Number
7-0
Bit
Mnemonic Description
FNUM7:0
Frame Number
Lower 8 bits of the 11-bit Frame Number.
Reset Value = 00h
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Table 23. UFNUMH Register
UFNUMH (S:BBh, Read-only) – USB Frame Number High Register
7
6
5
4
3
2
1
0
-
-
CRCOK
CRCERR
-
FNUM10
FNUM9
FNUM8
Bit
Number
7-3
5
Bit
Mnemonic Description
-
CRCOK
Reserved
The value read from these bits is always 0. Do not set these bits.
Frame Number CRC OK Bit
Set by hardware after a non corrupted Frame Number in Start of Frame Packet is
received.
Updated after every Start Of Frame packet reception.
Note: The Start Of Frame interrupt is generated just after the PID receipt.
4
CRCERR
Frame Number CRC Error Bit
Set by hardware after a corrupted Frame Number in Start of Frame Packet is
received.
Updated after every Start Of Frame packet reception.
Note: The Start Of Frame interrupt is generated just after the PID receipt.
3
2-0
-
Reserved
The value read from this bits is always 0. Do not set this bit.
Frame Number
FNUM10:8 Upper 3 bits of the 11-bit Frame Number. It is provided in the last received SOF
packet. FNUM does not change if a corrupted SOF is received.
Reset Value = 00h
Table 24. USBCLK Register
USBCLK (S:EAh) – USB Clock Divider Register
7
6
5
4
3
2
1
0
-
-
-
-
-
-
USBCD1
USBCD0
Bit
Number
Bit
Mnemonic Description
7-2
-
1-0
USBCD1:0
Reserved
The value read from these bits is always 0. Do not set these bits.
USB Controller Clock Divider
2-bit divider for USB controller clock generation.
Reset Value = 0000 0000b
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AT8xC51SND1C
17. MultiMedia Card
Controller
The AT8xC51SND1C implements a MultiMedia Card (MMC) controller. The MMC is
used to store MP3 encoded audio files in removable Flash memory cards that can be
easily plugged or removed from the application.
17.1 Card Concept
The basic MultiMedia Card concept is based on transferring data via a minimum number
of signals.
17.1.1 Card Signals
The communication signals are:
17.1.2 Card Registers
•
CLK: with each cycle of this signal a one bit transfer on the command and data lines
is done. The frequency may vary from zero to the maximum clock frequency.
•
CMD: is a bi-directional command channel used for card initialization and data
transfer commands. The CMD signal has 2 operation modes: open-drain for
initialization mode and push-pull for fast command transfer. Commands are sent
from the MultiMedia Card bus master to the card and responses from the cards to
the host.
•
DAT: is a bi-directional data channel. The DAT signal operates in push-pull mode.
Only one card or the host is driving this signal at a time.
Within the card interface five registers are defined: OCR, CID, CSD, RCA and DSR.
These can be accessed only by the corresponding commands.
The 32-bit Operation Conditions Register (OCR) stores the VDD voltage profile of the
card. The register is optional and can be read only.
The 128-bit wide CID register carries the card identification information (Card ID) used
during the card identification procedure.
The 128-bit wide Card-Specific Data register (CSD) provides information on how to
access the card contents. The CSD defines the data format, error correction type, maximum data access time, data transfer speed, and whether the DSR register can be used.
The 16-bit Relative Card Address register (RCA) carries the card address assigned by
the host during the card identification. This address is used for the addressed host-card
communication after the card identification procedure.
The 16-bit Driver Stage Register (DSR) can be optionally used to improve the bus performance for extended operating conditions (depending on parameters like bus length,
transfer rate or number of cards).
17.2 Bus Concept
The MultiMedia Card bus is designed to connect either solid-state mass-storage memory or I/O-devices in a card format to multimedia applications. The bus implementation
allows the coverage of application fields from low-cost systems to systems with a fast
data transfer rate. It is a single master bus with a variable number of slaves. The MultiMedia Card bus master is the bus controller and each slave is either a single mass
storage card (with possibly different technologies such as ROM, OTP, Flash etc.) or an
I/O-card with its own controlling unit (on card) to perform the data transfer.
The MultiMedia Card bus also includes power connections to supply the cards.
The bus communication uses a special protocol (MultiMedia Card bus protocol) which is
applicable for all devices. Therefore, the payload data transfer between the host and the
cards can be bi-directional.
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17.2.1 Bus Lines
The MultiMedia Card bus architecture requires all cards to be connected to the same set
of lines. No card has an individual connection to the host or other devices, which
reduces the connection costs of the MultiMedia Card system.
The bus lines can be divided into three groups:
17.2.2 Bus Protocol
•
Power supply: VSS1 and VSS2, VDD – used to supply the cards.
•
Data transfer: MCMD, MDAT – used for bi-directional communication.
•
Clock: MCLK – used to synchronize data transfer across the bus.
After a power-on reset, the host must initialize the cards 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 which starts an operation. A command is
transferred serially from the host to the card on the MCMD line.
•
Response: a response is a token which is sent from an addressed card (or all
connected cards) to the host as an answer to a previously received command. It is
transferred serially on the MCMD line.
•
Data: data can be transferred from the card to the host or vice-versa. Data is
transferred serially on the MDAT line.
Card addressing is implemented using a session address assigned during the initialization phase, by the bus controller to all currently connected cards. Individual cards are
identified by their CID number. This method requires that every card will have an unique
CID number. To ensure uniqueness of CIDs the CID register contains 24 bits (MID and
OID fields) which are defined by the MMCA. Every card manufacturers is required to
apply for an unique MID (and optionally OID) number.
MultiMedia Card bus data transfers are composed of these tokens. One data transfer is
a bus operation. 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 MDAT
and the MCMD lines are transferred synchronous to the host clock.
2 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 MCMD 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 MCMD line similarly to the stream read.
Figure 73 through Figure 77 show the different types of operations, on these figures,
grayed tokens are from host to card(s) while white tokens are from card(s) to host.
Figure 73. Sequential Read Operation
Stop Command
MCMD
Command
Response
MDAT
Response
Data Stream
Data Transfer Operation
112
Command
Data Stop Operation
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Figure 74. (Multiple) Block Read Operation
Stop Command
MCMD
Command
Response
MDAT
Command
Response
Data Block CRC Data Block CRC Data Block CRC
Block Read Operation
Data Stop Operation
Multiple Block Read Operation
As shown in Figure 75 and Figure 76 the data write operation uses a simple busy signalling of the write operation duration on the data line (MDAT).
Figure 75. Sequential Write Operation
Stop Command
MCMD
Command
Response
Command
MDAT
Data Stream
Response
Busy
Data Transfer Operation
Data Stop Operation
Figure 76. Multiple Block Write Operation
Stop Command
MCMD
Command
Response
MDAT
Command
Data Block CRC Status Busy
Response
Data Block CRC Status Busy
Block Write Operation
Data Stop Operation
Multiple Block Write Operation
Figure 77. No Response and No Data Operation
MCMD
Command
Command
Response
MDAT
No Response Operation
17.2.3 Command Token
Format
No Data Operation
As shown in Figure 78, commands have a fixed code length of 48 bits. Each command
token is preceded by a Start bit: a low level on MCMD line and succeeded by an End bit:
a high level on MCMD line. The command content is preceded by a Transmission bit: a
high level on MCMD line for a command token (host to card) and succeeded by a 7 - bit
CRC so that transmission errors can be detected and the operation may be repeated.
Command content contains the command index and address information or parameters.
Figure 78. Command Token Format
0
1
Content
CRC
1
Total Length = 48 bits
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Table 3. Command Token Format
Bit Position
47
46
45:40
39:8
7:1
0
Width (Bits)
1
1
6
32
7
1
Value
‘0’
‘1’
-
-
-
‘1’
Start bit
Transmission
bit
Command
Index
Argument
CRC7
End bit
Description
17.3.1 Response Token
Format
There are five types of response tokens (R1 to R5). As shown in Figure 79, responses
have a code length of 48 bits or 136 bits. A response token is preceded by a Start bit: a
low level on MCMD line and succeeded by an End bit: a high level on MCMD line. The
command content is preceded by a Transmission bit: a low level on MCMD line for a
response token (card to host) and succeeded (R1,R2,R4,R5) or not (R3) by a 7 - bit
CRC.
Response content contains mirrored command and status information (R1 response),
CID register or CSD register (R2 response), OCR register (R3 response), or RCA register (R4 and R5 response).
Figure 79. Response Token Format
R1, R4, R5
0
0
Content
CRC
1
Total Length = 48 bits
R3
0
0
Content
1
Total Length = 48 bits
R2
0
0
Content = CID or CSD
CRC
1
Total Length = 136 bits
Table 4. R1 Response Format (Normal Response)
Bit Position
47
46
45:40
39:8
7:1
0
Width (bits)
1
1
6
32
7
1
Value
‘0’
‘0’
-
-
-
‘1’
Start bit
Transmission
bit
Command
Index
Card Status
CRC7
End bit
Description
Table 5. R2 Response Format (CID and CSD registers)
Bit Position
135
134
[133:128]
[127:1]
0
Width (bits)
1
1
6
32
1
Value
‘0’
‘0’
‘111111’
-
‘1’
Start bit
Transmission
bit
Reserved
Argument
End bit
Description
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Table 6. R3 Response Format (OCR Register)
Bit Position
47
46
[45:40]
[39:8]
[7:1]
0
Width (bits)
1
1
6
32
7
1
Value
‘0’
‘0’
‘111111’
-
‘1111111’
‘1’
Start bit
Transmission
bit
Reserved
OCR
register
Reserved
End bit
Description
Table 7. R4 Response Format (Fast I/O)
Bit Position
47
46
[45:40]
[39:8]
[7:1]
0
Width (bits)
1
1
6
32
7
1
Value
‘0’
‘0’
‘100111’
-
-
‘1’
Start bit
Transmission
bit
Command
Index
Argument
CRC7
End bit
Description
Table 8. R5 Response Format
Bit Position
47
46
[45:40]
[39:8]
[7:1]
0
Width (bits)
1
1
6
32
7
1
Value
‘0’
‘0’
‘101000’
-
-
‘1’
Start bit
Transmission
bit
Command
Index
Argument
CRC7
End bit
Description
17.8.1 Data Packet Format
There are 2 types of data packets: stream and block. As shown in Figure 80, stream
data packets have an indeterminate length while block packets have a fixed length
depending on the block length. Each data packet is preceded by a Start bit: a low level
on MCMD line and succeeded by an End bit: a high level on MCMD line. Due to the fact
that there is no predefined end in stream packets, CRC protection is not included in this
case. The CRC protection algorithm for block data is a 16-bit CCITT polynomial.
Figure 80. Data Token Format
Sequential Data
0
Block Data
0
Content
Content
1
CRC
1
Block Length
17.8.2 Clock Control
The MMC bus clock signal can be used by the host to turn the cards into energy saving
mode or to control the data flow (to avoid under-run or over-run conditions) on the bus.
The host is allowed to lower the clock frequency or shut it down.
There are a few restrictions the host must follow:
•
The bus frequency can be changed at any time (under the restrictions of maximum
data transfer frequency, defined by the cards, and the identification frequency
defined by the specification document).
•
It is an obvious requirement that the clock must be running for the card to output
data or response tokens. After the last MultiMedia Card bus transaction, the host is
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required, to provide 8 (eight) clock cycles for the card to complete the operation
before shutting down the clock. Following is a list of the various bus transactions:
17.9 Description
•
A command with no response. 8 clocks after the host command End bit.
•
A command with response. 8 clocks after the card command End bit.
•
A read data transaction. 8 clocks after the End bit of the last data block.
•
A write data transaction. 8 clocks after the CRC status token.
•
The host is allowed to shut down the clock of a “busy” card. The card will complete
the programming operation regardless of the host clock. However, the host must
provide a clock edge for the card to turn off its busy signal. Without a clock edge the
card (unless previously disconnected by a deselect command-CMD7) will force the
MDAT line down, forever.
The MMC controller interfaces to the C51 core through the following eight special function registers:
MMCON0, MMCON1, MMCON2, the three MMC control registers (see Table 16 to
Table 24); MMSTA, the MMC status register (see Table 19); MMINT, the MMC interrupt
register (see Table 20); MMMSK, the MMC interrupt mask register (see Table 21);
MMCMD, the MMC command register (see Table 22); MMDAT, the MMC data register
(see Table 23); and MMCLK, the MMC clock register (see Table 24).
As shown in Figure 81, the MMC controller is divided in four blocks: the clock generator
that handles the MCLK (formally the MMC CLK) output to the card, the command line
controller that handles the MCMD (formally the MMC CMD) line traffic to or from the
card, the data line controller that handles the MDAT (formally the MMC DAT) line traffic
to or from the card, and the interrupt controller that handles the MMC controller interrupt
sources. These blocks are detailed in the following sections.
Figure 81. MMC Controller Block Diagram
MCLK
OSC
CLOCK
Clock
Generator
Command Line
Controller
MCMD
Interrupt
Controller
Internal
Bus
17.10 Clock Generator
116
Data Line
Controller
8
MMC
Interrupt
Request
MDAT
The MMC clock is generated by division of the oscillator clock (FOSC) issued from the
Clock Controller block as detailed in Section "Oscillator", page 12. The division factor is
given by MMCD7:0 bits in MMCLK register, a value of 0x00 stops the MMC clock.
Figure 82 shows the MMC clock generator and its output clock calculation formula.
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Figure 82. MMC Clock Generator and Symbol
OSC
CLOCK
Controller Clock
OSCclk
MMCclk = ----------------------------MMCD + 1
MMCLK
MMCEN
MMCON2.7
MMCD7:0
MMC Clock
MMC
CLOCK
MMC Clock Symbol
As soon as MMCEN bit in MMCON2 is set, the MMC controller receives its system
clock. The MMC command and data clock is generated on MCLK output and sent to the
command line and data line controllers. Figure 83 shows the MMC controller configuration flow.
As exposed in Section “Clock Control”, page 115, MMCD7:0 bits can be used to dynamically increase or reduce the MMC clock.
Figure 83. Configuration Flow
MMC Controller
Configuration
Configure MMC Clock
MMCLK = XXh
MMCEN = 1
FLOWC = 0
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17.11 Command Line
Controller
As shown in Figure 84, the command line controller is divided in 2 channels: the command transmitter channel that handles the command transmission to the card through
the MCMD line and the command receiver channel that handles the response reception
from the card through the MCMD line. These channels are detailed in the following
sections.
Figure 84. Command Line Controller Block Diagram
TX Pointer
CTPTR
MMCON0.4
5-Byte FIFO
Data Converter
// -> Serial
CRC7
Generator
MMCMD
Write
TX COMMAND Line
Finished State Machine
CFLCK
MMINT.5
EOCI
MMSTA.0
CMDEN
RX Pointer
CRPTR
MMCON0.5
MCMD
MMCON1.0
Command Transmitter
17 - Byte FIFO
Data Converter
Serial -> //
MMSTA.2
MMSTA.1
CRC7S
RESPFS
CRC7 and Format
Checker
MMCMD
Read
RX COMMAND Line
Finished State Machine
RESPEN
EORI
CRCDIS
MMCON1.1 MMCON0.1 MMCON0.0
Command Receiver
17.11.1 Command Transmitter
RFMT
MMINT.6
For sending a command to the card, user must load the command index (1 Byte) and
argument (4 Bytes) in the command transmit FIFO using the MMCMD register. Before
starting transmission by setting and clearing the CMDEN bit in MMCON1 register, user
must first configure:
•
RESPEN bit in MMCON1 register to indicate whether a response is expected or not.
•
RFMT bit in MMCON0 register to indicate the response size expected.
•
CRCDIS bit in MMCON0 register to indicate whether the CRC7 included in the
response will be computed or not. In order to avoid CRC error, CRCDIS may be set
for response that do not include CRC7.
Figure 85 summarizes the command transmission flow.
As soon as command transmission is enabled, the CFLCK flag in MMSTA is set indicating that write to the FIFO is locked. This mechanism is implemented to avoid command
overrun.
The end of the command transmission is signalled to you by the EOCI flag in MMINT
register becoming set. This flag may generate an MMC interrupt request as detailed in
Section "Interrupt", page 126. The end of the command transmission also resets the
CFLCK flag.
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User may abort command loading by setting and clearing the CTPTR bit in MMCON0
register which resets the write pointer to the transmit FIFO.
Figure 85. Command Transmission Flow
Command
Transmission
Configure Response
RESPEN = X
RFMT = X
CRCDIS = X
Load Command in
Buffer
MMCMD = index
MMCMD = argument
Transmit Command
CMDEN = 1
CMDEN = 0
17.11.2 Command Receiver
The end of the response reception is signalled to you by the EORI flag in MMINT register. This flag may generate an MMC interrupt request as detailed in Section "Interrupt",
page 126. When this flag is set, 2 other flags in MMSTA register: RESPFS and CRC7S
give a status on the response received. RESPFS indicates if the response format is correct or not: the size is the one expected (48 bits or 136 bits) and a valid End bit has been
received, and CRC7S indicates if the CRC7 computation is correct or not. These Flags
are cleared when a command is sent to the card and updated when the response has
been received.
User may abort response reading by setting and clearing the CRPTR bit in MMCON0
register which resets the read pointer to the receive FIFO.
According to the MMC specification delay between a command and a response (formally NCR parameter) can not exceed 64 MMC clock periods. To avoid any locking of
the MMC controller when card does not send its response (e.g. physically removed from
the bus), user must launch a time-out period to exit from such situation. In case of timeout user may reset the command controller and its internal state machine by setting and
clearing the CCR bit in MMCON2 register.
This time-out may be disarmed when receiving the response.
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17.12 Data Line
Controller
The data line controller is based on a 16-Byte FIFO used both by the data transmitter
channel and by the data receiver channel.
Figure 86. Data Line Controller Block Diagram
MMINT.0
MMINT.2
MMSTA.3
MMSTA.4
F1EI
F1FI
DATFS
CRC16S
CRC16 and Format
Checker
Data Converter
Serial -> //
8-Byte
TX Pointer
FIFO 1
DTPTR
MMCON0.6
RX Pointer
DRPTR
MMCON0.7
16-Byte FIFO
MMDAT
MCBI
CBUSY
MMINT.1
MMSTA.5
MDAT
Data Converter
// -> Serial
CRC16
Generator
8-Byte
MMINT.4
DATA Line
Finished State Machine
FIFO 2
F2EI
F2FI
MMINT.1
MMINT.3
DFMT
MBLOCK
DATEN
MMCON0.2
MMCON0.3
MMCON1.2
DATDIR
EOFI
BLEN3:0
MMCON1.3 MMCON1.7:4
17.12.1 FIFO Implementation
The 16-Byte FIFO is based on a dual 8-Byte FIFOs managed using 2 pointers and four
flags indicating the status full and empty of each FIFO.
Pointers are not accessible to user but can be reset at any time by setting and clearing
DRPTR and DTPTR bits in MMCON0 register. Resetting the pointers is equivalent to
abort the writing or reading of data.
F1EI and F2EI flags in MMINT register signal when set that respectively FIFO1 and
FIFO2 are empty. F1FI and F2FI flags in MMINT register signal when set that respectively FIFO1 and FIFO2 are full. These flags may generate an MMC interrupt request as
detailed in Section “Interrupt”.
17.12.2 Data Configuration
Before sending or receiving any data, the data line controller must be configured according to the type of the data transfer considered. This is achieved using the Data Format
bit: DFMT in MMCON0 register. Clearing DFMT bit enables the data stream format
while setting DFMT bit enables the data block format. In data block format, user must
also configure the single or multi-block mode by clearing or setting the MBLOCK bit in
MMCON0 register and the block length using BLEN3:0 bits in MMCON1 according to
Table 13. Figure 87 summarizes the data modes configuration flows.
Table 13. Block Length Programming
BLEN3:0
BLEN = 0000 to 1011
> 1011
120
Block Length (Byte)
Length = 2BLEN: 1 to 2048
Reserved: do not program BLEN3:0 > 1011
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Figure 87. Data Controller Configuration Flows
Data Stream
Configuration
Data Single Block
Configuration
Data Multi-Block
Configuration
Configure Format
DFMT = 0
Configure Format
DFMT = 1
MBLOCK = 0
BLEN3:0 = XXXXb
Configure Format
DFMT = 1
MBLOCK = 1
BLEN3:0 = XXXXb
17.13.1 Data Transmitter
Configuration
For transmitting data to the card user must first configure the data controller in transmission mode by setting the DATDIR bit in MMCON1 register.
Figure 88 summarizes the data stream transmission flows in both polling and interrupt
modes while Figure 89 summarizes the data block transmission flows in both polling
and interrupt modes, these flows assume that block length is greater than 16 data.
Data Loading
Data is loaded in the FIFO by writing to MMDAT register. Number of data loaded may
vary from 1 to 16 Bytes. Then if necessary (more than 16 Bytes to send) user must wait
that one FIFO becomes empty (F1EI or F2EI set) before loading 8 new data.
Data Transmission
Transmission is enabled by setting and clearing DATEN bit in MMCON1 register.
Data is transmitted immediately if the response has already been received, or is delayed
after the response reception if its status is correct. In both cases transmission is delayed
if a card sends a busy state on the data line until the end of this busy condition.
According to the MMC specification, the data transfer from the host to the card may not
start sooner than 2 MMC clock periods after the card response was received (formally
N WR parameter). To address all card types, this delay can be programmed using
DATD1:0 bits in MMCON2 register from 3 MMC clock periods when DATD1:0 bits are
cleared to 9 MMC clock periods when DATD1:0 bits are set, by step of 2 MMC clock
periods.
End of Transmission
The end of a data frame (block or stream) transmission is signalled to you by the EOFI
flag in MMINT register. This flag may generate an MMC interrupt request as detailed in
Section "Interrupt", page 126.
In data stream mode, EOFI flag is set, after reception of the End bit. This assumes user
has previously sent the STOP command to the card, which is the only way to stop
stream transfer.
In data block mode, EOFI flag is set, after reception of the CRC status token (see
Figure 79). 2 other flags in MMSTA register: DATFS and CRC16S report a status on the
frame sent. DATFS indicates if the CRC status token format is correct or not, and
CRC16S indicates if the card has found the CRC16 of the block correct or not.
Busy Status
As shown in Figure 79 the card uses a busy token during a block write operation. This
busy status is reported to you by the CBUSY flag in MMSTA register and by the MCBI
flag in MMINT which is set every time CBUSY toggles, i.e. when the card enters and
exits its busy state. This flag may generate an MMC interrupt request as detailed in Section "Interrupt", page 126.
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Figure 88. Data Stream Transmission Flows
Data Stream
Transmission
Data Stream
Initialization
FIFOs Filling
write 16 data to MMDAT
FIFOs Filling
write 16 data to MMDAT
Start Transmission
DATEN = 1
DATEN = 0
Unmask FIFOs Empty
F1EM = 0
F2EM = 0
FIFO Empty?
F1EI or F2EI = 1?
Start Transmission
DATEN = 1
DATEN = 0
FIFO Filling
write 8 data to MMDAT
No More Data
To Send?
Send
STOP Command
Data Stream
Transmission ISR
FIFO Empty?
F1EI or F2EI = 1?
FIFO Filling
write 8 data to MMDAT
No More Data
To Send?
Mask FIFOs Empty
F1EM = 1
F2EM = 1
Send
STOP Command
b. Interrupt mode
a. Polling mode
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Figure 89. Data Block Transmission Flows
Data Block
Transmission
Data Block
Initialization
FIFOs Filling
write 16 data to MMDAT
FIFOs Filling
write 16 data to MMDAT
Start Transmission
DATEN = 1
DATEN = 0
Unmask FIFOs Empty
F1EM = 0
F2EM = 0
FIFO Empty?
F1EI or F2EI = 1?
Start Transmission
DATEN = 1
DATEN = 0
FIFO Filling
write 8 data to MMDAT
No More Data
To Send?
Data Block
Transmission ISR
FIFO Empty?
F1EI or F2EI = 1?
FIFO Filling
write 8 data to MMDAT
No More Data
To Send?
Mask FIFOs Empty
F1EM = 1
F2EM = 1
b. Interrupt mode
a. Polling mode
17.13.2 Data Receiver
Configuration
To receive data from the card you must first configure the data controller in reception
mode by clearing the DATDIR bit in MMCON1 register.
Figure 90 summarizes the data stream reception flows in both polling and interrupt
modes while Figure 91 summarizes the data block reception flows in both polling and
interrupt modes, these flows assume that block length is greater than 16 Bytes.
Data Reception
The end of a data frame (block or stream) reception is signalled to you by the EOFI flag
in MMINT register. This flag may generate an MMC interrupt request as detailed in Section "Interrupt", page 126. When this flag is set, 2 other flags in MMSTA register: DATFS
and CRC16S give a status on the frame received. DATFS indicates if the frame format
is correct or not: a valid End bit has been received, and CRC16S indicates if the CRC16
computation is correct or not. In case of data stream CRC16S has no meaning and
stays cleared.
According to the MMC specification data transmission from the card starts after the
access time delay (formally NAC parameter) beginning from the End bit of the read command. To avoid any locking of the MMC controller when card does not send its data
(e.g. physically removed from the bus), you must launch a time-out period to exit from
such situation. In case of time-out you may reset the data controller and its internal state
machine by setting and clearing the DCR bit in MMCON2 register.
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This time-out may be disarmed after receiving 8 data (F1FI flag set) or after receiving
end of frame (EOFI flag set) in case of block length less than 8 data (1, 2 or 4).
Data Reading
Data is read from the FIFO by reading to MMDAT register. Each time one FIFO
becomes full (F1FI or F2FI set), user is requested to flush this FIFO by reading 8 data.
Figure 90. Data Stream Reception Flows
Data Stream
Reception
Data Stream
Initialization
Data Stream
Reception ISR
FIFO Full?
F1FI or F2FI = 1?
Unmask FIFOs Full
F1FM = 0
F2FM = 0
FIFO Full?
F1FI or F2FI = 1?
FIFO Reading
read 8 data from MMDAT
FIFO Reading
read 8 data from MMDAT
No More Data
To Receive?
No More Data
To Receive?
Send
STOP Command
Mask FIFOs Full
F1FM = 1
F2FM = 1
a. Polling mode
Send
STOP Command
b. Interrupt mode
124
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Figure 91. Data Block Reception Flows
Data Block
Reception
Data Block
Initialization
Data Block
Reception ISR
Start Transmission
DATEN = 1
DATEN = 0
Unmask FIFOs Full
F1FM = 0
F2FM = 0
FIFO Full?
F1EI or F2EI = 1?
FIFO Full?
F1EI or F2EI = 1?
Start Transmission
DATEN = 1
DATEN = 0
FIFO Reading
read 8 data from MMDAT
No More Data
To Receive?
FIFO Reading
read 8 data from MMDAT
Mask FIFOs Full
F1FM = 1
F2FM = 1
No More Data
To Receive?
a. Polling mode
17.13.3 Flow Control
b. Interrupt mode
To allow transfer at high speed without taking care of CPU oscillator frequency, the
FLOWC bit in MMCON2 allows control of the data flow in both transmission and
reception.
During transmission, setting the FLOWC bit has the following effects:
•
MMCLK is stopped when both FIFOs become empty: F1EI and F2EI set.
•
MMCLK is restarted when one of the FIFOs becomes full: F1EI or F2EI cleared.
During reception, setting the FLOWC bit has the following effects:
•
MMCLK is stopped when both FIFOs become full: F1FI and F2FI set.
•
MMCLK is restarted when one of the FIFOs becomes empty: F1FI or F2FI cleared.
As soon as the clock is stopped, the MMC bus is frozen and remains in its state until the
clock is restored by writing or reading data in MMDAT.
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17.14 Interrupt
17.14.1 Description
As shown in Figure 92, the MMC controller implements eight interrupt sources reported
in MCBI, EORI, EOCI, EOFI, F2FI, F1FI, and F2EI flags in MMCINT register. These
flags are detailed in the previous sections.
All these sources are maskable separately using MCBM, EORM, EOCM, EOFM, F2FM,
F1FM, and F2EM mask bits respectively in MMMSK register.
The interrupt request is generated each time an unmasked flag is set, and the global
MMC controller interrupt enable bit is set (EMMC in IEN1 register).
Reading the MMINT register automatically clears the interrupt flags (acknowledgment).
This implies that register content must be saved and tested interrupt flag by interrupt
flag to be sure not to forget any interrupts.
Figure 92. MMC Controller Interrupt System
MCBI
MMINT.7
MCBM
MMMSK.7
EORI
MMINT.6
EORM
EOCI
MMMSK.6
MMINT.5
EOCM
MMMSK.5
EOFI
MMINT.4
MMC Interface
Interrupt Request
EOFM
F2FI
MMMSK.4
EMMC
MMINT.3
F2FM
IEN1.0
MMMSK.3
F1FI
MMINT.2
F1FM
F2EI
MMMSK.2
MMINT.1
F2EM
MMMSK.1
F1EI
MMINT.0
F1EM
MMMSK.0
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17.15 Registers
Table 16. MMCON0 Register
MMCON0 (S:E4h) – MMC Control Register 0
7
6
5
4
3
2
1
0
DRPTR
DTPTR
CRPTR
CTPTR
MBLOCK
DFMT
RFMT
CRCDIS
Bit
Number
Bit
Mnemonic Description
7
DRPTR
Data Receive Pointer Reset Bit
Set to reset the read pointer of the data FIFO.
Clear to release the read pointer of the data FIFO.
6
DTPTR
Data Transmit Pointer Reset Bit
Set to reset the write pointer of the data FIFO.
Clear to release the write pointer of the data FIFO.
5
CRPTR
Command Receive Pointer Reset Bit
Set to reset the read pointer of the receive command FIFO.
Clear to release the read pointer of the receive command FIFO.
4
CTPTR
Command Transmit Pointer Reset Bit
Set to reset the write pointer of the transmit command FIFO.
Clear to release the read pointer of the transmit command FIFO.
3
MBLOCK
2
DFMT
Data Format Bit
Set to select the block-oriented data format.
Clear to select the stream data format.
1
RFMT
Response Format Bit
Set to select the 48-bit response format.
Clear to select the 136-bit response format.
0
CRCDIS
Multi-block Enable Bit
Set to select multi-block data format.
Clear to select single block data format.
CRC7 Disable Bit
Set to disable the CRC7 computation when receiving a response.
Clear to enable the CRC7 computation when receiving a response.
Reset Value = 0000 0000b
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Table 17. MMCON1 Register
MMCON1 (S:E5h) – MMC Control Register 1
7
6
5
4
3
2
1
0
BLEN3
BLEN2
BLEN1
BLEN0
DATDIR
DATEN
RESPEN
CMDEN
Bit
Number
Bit
Mnemonic Description
7-4
BLEN3:0
Block Length Bits
Refer to Table 13 for bits description. Do not program value > 1011b
3
DATDIR
Data Direction Bit
Set to select data transfer from host to card (write mode).
Clear to select data transfer from card to host (read mode).
2
DATEN
Data Transmission Enable Bit
Set and clear to enable data transmission immediately or after response has
been received.
1
RESPEN
Response Enable Bit
Set and clear to enable the reception of a response following a command
transmission.
0
CMDEN
Command Transmission Enable Bit
Set and clear to enable transmission of the command FIFO to the card.
Reset Value = 0000 0000b
Table 18. MMCON2 Register
MMCON2 (S:E6h) – MMC Control Register 2
7
6
5
4
3
2
1
0
MMCEN
DCR
CCR
-
-
DATD1
DATD0
FLOWC
Bit
Number
Bit
Mnemonic Description
MMC Clock Enable Bit
Set to enable the MCLK clocks and activate the MMC controller.
Clear to disable the MMC clocks and freeze the MMC controller.
7
MMCEN
6
DCR
Data Controller Reset Bit
Set and clear to reset the data line controller in case of transfer abort.
5
CCR
Command Controller Reset Bit
Set and clear to reset the command line controller in case of transfer abort.
4-3
-
2-1
DATD1:0
Data Transmission Delay Bits
Used to delay the data transmission after a response from 3 MMC clock periods
(all bits cleared) to 9 MMC clock periods (all bits set) by step of 2 MMC clock
periods.
0
FLOWC
MMC Flow Control Bit
Set to enable the flow control during data transfers.
Clear to disable the flow control during data transfers.
Reserved
The value read from these bits is always 0. Do not set these bits.
Reset Value = 0000 0000b
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Table 19. MMSTA Register
MMSTA (S:DEh Read Only) – MMC Control and Status Register
7
6
5
4
3
2
1
0
-
-
CBUSY
CRC16S
DATFS
CRC7S
RESPFS
CFLCK
Bit
Number
Bit
Mnemonic Description
Reserved
The value read from these bits is always 0. Do not set these bits.
7-6
-
5
CBUSY
Card Busy Flag
Set by hardware when the card sends a busy state on the data line.
Cleared by hardware when the card no more sends a busy state on the data line.
CRC16S
CRC16 Status Bit
Transmission mode
Set by hardware when the token response reports a good CRC.
Cleared by hardware when the token response reports a bad CRC.
Reception mode
Set by hardware when the CRC16 received in the data block is correct.
Cleared by hardware when the CRC16 received in the data block is not correct.
4
3
2
DATFS
CRC7S
Data Format Status Bit
Transmission mode
Set by hardware when the format of the token response is correct.
Cleared by hardware when the format of the token response is not correct.
Reception mode
Set by hardware when the format of the frame is correct.
Cleared by hardware when the format of the frame is not correct.
CRC7 Status Bit
Set by hardware when the CRC7 computed in the response is correct.
Cleared by hardware when the CRC7 computed in the response is not correct.
This bit is not relevant when CRCDIS is set.
1
0
RESPFS
CFLCK
Response Format Status Bit
Set by hardware when the format of a response is correct.
Cleared by hardware when the format of a response is not correct.
Command FIFO Lock Bit
Set by hardware to signal user not to write in the transmit command FIFO: busy
state.
Cleared by hardware to signal user the transmit command FIFO is available: idle
state.
Reset Value = 0000 0000b
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Table 20. MMINT Register
MMINT (S:E7h Read Only) – MMC Interrupt Register
7
6
5
4
3
2
1
0
MCBI
EORI
EOCI
EOFI
F2FI
F1FI
F2EI
F1EI
Bit
Number
Bit
Mnemonic Description
7
MCBI
MMC Card Busy Interrupt Flag
Set by hardware when the card enters or exits its busy state (when the busy
signal is asserted or deasserted on the data line).
Cleared when reading MMINT.
6
EORI
End of Response Interrupt Flag
Set by hardware at the end of response reception.
Cleared when reading MMINT.
5
EOCI
End of Command Interrupt Flag
Set by hardware at the end of command transmission.
Clear when reading MMINT.
4
EOFI
End of Frame Interrupt Flag
Set by hardware at the end of frame (stream or block) transfer.
Clear when reading MMINT.
3
F2FI
FIFO 2 Full Interrupt Flag
Set by hardware when second FIFO becomes full.
Cleared by hardware when second FIFO becomes empty.
2
F1FI
FIFO 1 Full Interrupt Flag
Set by hardware when first FIFO becomes full.
Cleared by hardware when first FIFO becomes empty.
1
F2EI
FIFO 2 Empty Interrupt Flag
Set by hardware when second FIFO becomes empty.
Cleared by hardware when second FIFO becomes full.
0
F1EI
FIFO 1 Empty Interrupt Flag
Set by hardware when first FIFO becomes empty.
Cleared by hardware when first FIFO becomes full.
Reset Value = 0000 0011b
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Table 21. MMMSK Register
MMMSK (S:DFh) – MMC Interrupt Mask Register
7
6
5
4
3
2
1
0
MCBM
EORM
EOCM
EOFM
F2FM
F1FM
F2EM
F1EM
Bit
Number
Bit
Mnemonic Description
7
MCBM
MMC Card Busy Interrupt Mask Bit
Set to prevent MCBI flag from generating an MMC interrupt.
Clear to allow MCBI flag to generate an MMC interrupt.
6
EORM
End Of Response Interrupt Mask Bit
Set to prevent EORI flag from generating an MMC interrupt.
Clear to allow EORI flag to generate an MMC interrupt.
5
EOCM
End Of Command Interrupt Mask Bit
Set to prevent EOCI flag from generating an MMC interrupt.
Clear to allow EOCI flag to generate an MMC interrupt.
4
EOFM
End Of Frame Interrupt Mask Bit
Set to prevent EOFI flag from generating an MMC interrupt.
Clear to allow EOFI flag to generate an MMC interrupt.
3
F2FM
FIFO 2 Full Interrupt Mask Bit
Set to prevent F2FI flag from generating an MMC interrupt.
Clear to allow F2FI flag to generate an MMC interrupt.
2
F1FM
FIFO 1 Full Interrupt Mask Bit
Set to prevent F1FI flag from generating an MMC interrupt.
Clear to allow F1FI flag to generate an MMC interrupt.
1
F2EM
FIFO 2 Empty Interrupt Mask Bit
Set to prevent F2EI flag from generating an MMC interrupt.
Clear to allow F2EI flag to generate an MMC interrupt.
0
F1EM
FIFO 1 Empty Interrupt Mask Bit
Set to prevent F1EI flag from generating an MMC interrupt.
Clear to allow F1EI flag to generate an MMC interrupt.
Reset Value = 1111 1111b
Table 22. MMCMD Register
MMCMD (S:DDh) – MMC Command Register
7
6
5
4
3
2
1
0
MC7
MC6
MC5
MC4
MC3
MC2
MC1
MC0
Bit
Number
7-0
Bit
Mnemonic Description
MC7:0
MMC Command Receive Byte
Output (read) register of the response FIFO.
MMC Command Transmit Byte
Input (write) register of the command FIFO.
Reset Value = 1111 1111b
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Table 23. MMDAT Register
MMDAT (S:DCh) – MMC Data Register
7
6
5
4
3
2
1
0
MD7
MD6
MD5
MD4
MD3
MD2
MD1
MD0
Bit
Number
7-0
Bit
Mnemonic Description
MD7:0
MMC Data Byte
Input (write) or output (read) register of the data FIFO.
Reset Value = 1111 1111b
Table 24. MMCLK Register
MMCLK (S:EDh) – MMC Clock Divider Register
7
6
5
4
3
2
1
0
MMCD7
MMCD6
MMCD5
MMCD4
MMCD3
MMCD2
MMCD1
MMCD0
Bit
Number
7-0
Bit
Mnemonic Description
MMCD7:0
MMC Clock Divider
8-bit divider for MMC clock generation.
Reset Value = 0000 0000b
132
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AT8xC51SND1C
18. IDE/ATAPI
Interface
The AT8xC51SND1C provides an IDE/ATAPI interface allowing connection of devices
such as CD-ROM reader, CompactFlash cards, Hard Disk Drive, etc. It consists of a 16bit data transfer (read or write) between the AT8xC51SND1C and the IDE device.
18.1 Description
The IDE interface mode is enabled by setting the EXT16 bit in AUXR (see Figure 9,
page 31). As soon as this bit is set, all MOVX instructions read or write are done in a 16bit mode compare to the standard 8-bit mode. P0 carries the low order multiplexed
address and data bus (A7:0, D7:0) while P2 carries the high order multiplexed address
and data bus (A15:8, D15:8). When writing data in IDE mode, the ACC contains D7:0
data (as in 8-bit mode) while DAT16H register (see Table 4) contains D15:8 data. When
reading data in IDE mode, D7:0 data is returned in ACC while D15:8 data is returned in
DAT16H.
Figure 93 shows the IDE read bus cycle while Figure 94 shows the IDE write bus cycle.
For simplicity, these figures depict the bus cycle waveforms in idealized form and do not
provide precise timing information. For IDE bus cycle timing parameters refer to the
Section “AC Characteristics”.
IDE cycle takes 6 CPU clock periods which is equivalent to 12 oscillator clock periods in
standard mode or 6 oscillator clock periods in X2 mode. For further information on X2
mode, refer to the Section “X2 Feature”, page 12.
Slow IDE devices can be accessed by stretching the read and write cycles. This is done
using the M0 bit in AUXR. Setting this bit changes the width of the RD and WR signals
from 3 to 15 CPU clock periods.
Figure 93. IDE Read Waveforms
CPU Clock
ALE
RD(1)
P0
P2
Notes:
P2
DPL or Ri
D7:0
DPH or P2(2),(3)
D15:8
P2
1. RD signal may be stretched using M0 bit in AUXR register.
2. When executing MOVX @Ri instruction, P2 outputs SFR content.
3. When executing MOVX @DPTR instruction, if DPHDIS is set (Page Access Mode),
P2 outputs SFR content instead of DPH.
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Figure 94. IDE Write Waveforms
CPU Clock
ALE
WR(1)
P0
P2
Notes:
18.1.1 IDE Device Connection
P2
DPL or Ri
D7:0
DPH or P2(2),(3)
D15:8
P2
1. WR signal may be stretched using M0 bit in AUXR register.
2. When executing MOVX @Ri instruction, P2 outputs SFR content.
3. When executing MOVX @DPTR instruction, if DPHDIS is set (Page Access Mode),
P2 outputs SFR content instead of DPH.
Figure 95 and Figure 96 show 2 examples on how to interface up to 2 IDE devices to the
AT8xC51SND1C. In both examples P0 carries IDE low order data bits D7:0, P2 carries
IDE high order data bits D15:8, while RD and WR signals are respectively connected to
the IDE nIOR and nIOW signals. Other IDE control signals are generated by the external address latch outputs in the first example while they are generated by some port
I/Os in the second one. Using an external latch will achieve higher transfer rate.
Figure 95. IDE Device Connection Example 1
AT8xC51SND1C
IDE Device 0
P2
IDE Device 1
D15-8
D15-8
D7:0
D7:0
A2:0
A2:0
ALE
nCS1:0
nCS1:0
Px.y
nRESET
nRESET
RD
WR
nIOR
nIOW
nIOR
nIOW
P0
Latch
Figure 96. IDE Device Connection Example 2
AT8xC51SND1C
IDE Device 1
P2/A15:8
D15-8
D15-8
P0/AD7:0
D7:0
D7:0
A2:0
nCS1:0
nRESET
nIOR
nIOW
A2:0
nCS1:0
nRESET
nIOR
nIOW
P4.2:0
P4.4:3
P4.5
RD
WR
134
IDE Device 0
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AT8xC51SND1C
Table 2. External Data Memory Interface Signals
18.3 Registers
Signal
Name
Type
Alternate
Function
A15:8
I/O
Address Lines
Upper address lines for the external bus.
Multiplexed higher address and data lines for the IDE interface.
P2.7:0
AD7:0
I/O
Address/Data Lines
Multiplexed lower address and data lines for the IDE interface.
P0.7:0
ALE
O
Address Latch Enable
ALE signals indicates that valid address information is available on lines
AD7:0.
RD
O
Read
Read signal output to external data memory.
P3.7
WR
O
Write
Write signal output to external memory.
P3.6
Description
-
Table 4. DAT16H Register
DAT16H (S:F9h) – Data 16 High Order Byte
7
6
5
4
3
2
1
0
D15
D14
D13
D12
D11
D10
D9
D8
Bit
Number
7-0
Bit
Mnemonic Description
D15:8
Data 16 High Order Byte
When EXT16 bit is set, DAT16H is set by software with the high order data Byte
prior any MOVX write instruction.
When EXT16 bit is set, DAT16H contains the high order data Byte after any
MOVX read instruction.
Reset Value =XXXX XXXXb
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19. Serial I/O Port
The serial I/O port in the AT8xC51SND1C provides both synchronous and asynchronous communication modes. It operates as a Synchronous Receiver and Transmitter in
one single mode (Mode 0) and operates as an Universal Asynchronous Receiver and
Transmitter (UART) in three full-duplex modes (Modes 1, 2 and 3). Asynchronous
modes support framing error detection and multiprocessor communication with automatic address recognition.
19.1 Mode Selection
SM0 and SM1 bits in SCON register (see Figure 11) are used to select a mode among
the single synchronous and the three asynchronous modes according to Table 2.
Table 2. Serial I/O Port Mode Selection
19.3 Baud Rate
Generator
SM0
SM1
Mode
Description
Baud Rate
0
0
0
Synchronous Shift Register
Fixed/Variable
0
1
1
8-bit UART
Variable
1
0
2
9-bit UART
Fixed
1
1
3
9-bit UART
Variable
Depending on the mode and the source selection, the baud rate can be generated from
either the Timer 1 or the Internal Baud Rate Generator. The Timer 1 can be used in
Modes 1 and 3 while the Internal Baud Rate Generator can be used in Modes 0, 1
and 3.
The addition of the Internal Baud Rate Generator allows freeing of the Timer 1 for other
purposes in the application. It is highly recommended to use the Internal Baud Rate
Generator as it allows higher and more accurate baud rates than Timer 1.
Baud rate formulas depend on the modes selected and are given in the following mode
sections.
19.3.1 Timer 1
When using Timer 1, the Baud Rate is derived from the overflow of the timer. As shown
in Figure 97 Timer 1 is used in its 8-bit auto-reload mode (detailed in Section "Mode 2
(8-bit Timer with Auto-Reload)", page 55). SMOD1 bit in PCON register allows doubling
of the generated baud rate.
Figure 97. Timer 1 Baud Rate Generator Block Diagram
PER
CLOCK
÷6
0
1
TL1
(8 bits)
T1
Overflow
÷2
0
To serial
Port
1
C/T1#
TMOD.6
SMOD1
INT1
GATE1
TMOD.7
TR1
PCON.7
TH1
(8 bits)
T1
CLOCK
TCON.6
136
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19.3.2 Internal Baud Rate
Generator
When using the Internal Baud Rate Generator, the Baud Rate is derived from the overflow of the timer. As shown in Figure 98 the Internal Baud Rate Generator is an 8-bit
auto-reload timer fed by the peripheral clock or by the peripheral clock divided by 6
depending on the SPD bit in BDRCON register (see Table 15). The Internal Baud Rate
Generator is enabled by setting BBR bit in BDRCON register. SMOD1 bit in PCON register allows doubling of the generated baud rate.
Figure 98. Internal Baud Rate Generator Block Diagram
PER
CLOCK
÷6
0
BRG
(8 bits)
1
Overflow
÷2
0
1
SPD
BRR
BDRCON.1
BDRCON.4
To serial
Port
SMOD1
PCON.7
BRL
(8 bits)
19.4 Synchronous Mode
(Mode 0)
IBRG
CLOCK
Mode 0 is a half-duplex, synchronous mode, which is commonly used to expand the I/0
capabilities of a device with shift registers. The transmit data (TXD) pin outputs a set of
eight clock pulses while the receive data (RXD) pin transmits or receives a Byte of data.
The 8-bit data are transmitted and received least-significant bit (LSB) first. Shifts occur
at a fixed Baud Rate (see Section "Baud Rate Selection (Mode 0)", page 138).
Figure 99 shows the serial port block diagram in Mode 0.
Figure 99. Serial I/O Port Block Diagram (Mode 0)
SCON.6
SCON.7
SM1
SM0
SBUF Tx SR
Mode Decoder
RXD
M3 M2 M1 M0
SBUF Rx SR
Mode
Controller
PER
CLOCK
19.4.1 Transmission (Mode 0)
TI
RI
SCON.1
SCON.0
BRG
CLOCK
Baud Rate
Controller
TXD
To start a transmission mode 0, write to SCON register clearing bits SM0, SM1.
As shown in Figure 100, writing the Byte to transmit to SBUF register starts the transmission. Hardware shifts the LSB (D0) onto the RXD pin during the first clock cycle
composed of a high level then low level signal on TXD. During the eighth clock cycle the
MSB (D7) is on the RXD pin. Then, hardware drives the RXD pin high and asserts TI to
indicate the end of the transmission.
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Figure 100. Transmission Waveforms (Mode 0)
TXD
Write to SBUF
RXD
D0
D1
D2
D3
D4
D5
D6
D7
TI
19.4.2 Reception (Mode 0)
To start a reception in mode 0, write to SCON register clearing SM0, SM1 and RI bits
and setting the REN bit.
As shown in Figure 101, Clock is pulsed and the LSB (D0) is sampled on the RXD pin.
The D0 bit is then shifted into the shift register. After eight samplings, the MSB (D7) is
shifted into the shift register, and hardware asserts RI bit to indicate a completed reception. Software can then read the received Byte from SBUF register.
Figure 101. Reception Waveforms (Mode 0)
TXD
Set REN, Clear RI
Write to SCON
RXD
D0
D1
D2
D3
D4
D5
D6
D7
RI
19.4.3 Baud Rate Selection
(Mode 0)
In mode 0, the baud rate can be either, fixed or variable.
As shown in Figure 102, the selection is done using M0SRC bit in BDRCON register.
Figure 103 gives the baud rate calculation formulas for each baud rate source.
Figure 102. Baud Rate Source Selection (mode 0)
PER
CLOCK
÷6
0
To Serial Port
1
IBRG
CLOCK
M0SRC
BDRCON.0
Figure 103. Baud Rate Formulas (Mode 0)
Baud_Rate=
Baud_Rate=
FPER
6
a. Fixed Formula
138
BRL= 256 -
6
6
2SMOD1 ⋅ FPER
⋅ 32 ⋅ (256 -BRL)
(1-SPD)
2SMOD1 ⋅ FPER
⋅ 32 ⋅ Baud_Rate
(1-SPD)
b. Variable Formula
AT8xC51SND1C
4109H–8051–01/05
AT8xC51SND1C
19.5 Asynchronous
The Serial Port has one 8-bit and 2 9-bit asynchronous modes of operation. Figure 104
Modes (Modes 1, 2 and 3) shows the Serial Port block diagram in such asynchronous modes.
Figure 104. Serial I/O Port Block Diagram (Modes 1, 2 and 3)
SCON.6
SCON.7
SCON.3
SM1
SM0
TB8
Mode Decoder
SBUF Tx SR
TXD
Rx SR
RXD
M3 M2 M1 M0
T1
CLOCK
Mode & Clock
Controller
IBRG
CLOCK
SBUF Rx
PER
CLOCK
Mode 1
RB8
SCON.2
SM2
TI
RI
SCON.4
SCON.1
SCON.0
Mode 1 is a full-duplex, asynchronous mode. The data frame (see Figure 105) consists
of 10 bits: one start, eight data bits and one stop bit. Serial data is transmitted on the
TXD pin and received on the RXD pin. When a data is received, the stop bit is read in
the RB8 bit in SCON register.
Figure 105. Data Frame Format (Mode 1)
Mode 1
D0
D1
D2
Start bit
Modes 2 and 3
D3
D4
D5
D6
D7
8-bit data
Stop bit
Modes 2 and 3 are full-duplex, asynchronous modes. The data frame (see Figure 106)
consists of 11 bits: one start bit, eight data bits (transmitted and received LSB first), one
programmable ninth data bit and one stop bit. Serial data is transmitted on the TXD pin
and received on the RXD pin. On receive, the ninth bit is read from RB8 bit in SCON
register. On transmit, the ninth data bit is written to TB8 bit in SCON register. Alternatively, you can use the ninth bit can be used as a command/data flag.
Figure 106. Data Frame Format (Modes 2 and 3)
D0
Start bit
D1
D2
D3
D4
9-bit data
D5
D6
D7
D8
Stop bit
19.5.1 Transmission (Modes 1,
2
and 3)
To initiate a transmission, write to SCON register, set the SM0 and SM1 bits according
to Table 2, and set the ninth bit by writing to TB8 bit. Then, writing the Byte to be transmitted to SBUF register starts the transmission.
19.5.2 Reception (Modes 1, 2
and 3)
To prepare for reception, write to SCON register, set the SM0 and SM1 bits according to
Table 2, and set the REN bit. The actual reception is then initiated by a detected high-tolow transition on the RXD pin.
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4109H–8051–01/05
19.5.3 Framing Error
Detection (Modes 1, 2 and 3)
Framing error detection is provided for the three asynchronous modes. To enable the
framing bit error detection feature, set SMOD0 bit in PCON register as shown in
Figure 107.
When this feature is enabled, the receiver checks each incoming data frame for a valid
stop bit. An invalid stop bit may result from noise on the serial lines or from simultaneous
transmission by 2 devices. If a valid stop bit is not found, the software sets FE bit in
SCON register.
Software may examine FE bit after each reception to check for data errors. Once set,
only software or a chip reset clear FE bit. Subsequently received frames with valid stop
bits cannot clear FE bit. When the framing error detection feature is enabled, RI rises on
stop bit instead of the last data bit as detailed in Figure 113.
Figure 107. Framing Error Block Diagram
Framing Error
Controller
FE
1
SM0/FE
0
SCON.7
SM0
SMOD0
PCON.6
19.5.4 Baud Rate Selection
(Modes 1 and 3)
In modes 1 and 3, the Baud Rate is derived either from the Timer 1 or the Internal Baud
Rate Generator and allows different baud rate in reception and transmission.
As shown in Figure 108 the selection is done using RBCK and TBCK bits in BDRCON
register.
Figure 109 gives the baud rate calculation formulas for each baud rate source while
Table 6 details Internal Baud Rate Generator configuration for different peripheral clock
frequencies and giving baud rates closer to the standard baud rates.
Figure 108. Baud Rate Source Selection (Modes 1 and 3)
T1
CLOCK
0
÷ 16
1
IBRG
CLOCK
To Serial
Rx Port
T1
CLOCK
IBRG
CLOCK
RBCK
BDRCON.2
0
To Serial
Tx Port
÷ 16
1
TBCK
BDRCON.3
Figure 109. Baud Rate Formulas (Modes 1 and 3)
Baud_Rate=
BRL= 256 -
2SMOD1 ⋅ FPER
6(1-SPD) ⋅ 32 ⋅ (256 -BRL)
6
2SMOD1 ⋅ FPER
⋅ 32 ⋅ Baud_Rate
(1-SPD)
a. IBRG Formula
140
Baud_Rate=
TH1= 256 -
2SMOD1 ⋅ FPER
6 ⋅ 32 ⋅ (256 -TH1)
2SMOD1 ⋅ FPER
192 ⋅ Baud_Rate
b. T1 Formula
AT8xC51SND1C
4109H–8051–01/05
AT8xC51SND1C
Table 6. Internal Baud Rate Generator Value
FPER = 6 MHz(1)
FPER = 8 MHz(1)
FPER = 10 MHz(1)
Baud Rate
SPD
SMOD1
BRL
Error %
SPD
SMOD1
BRL
Error %
SPD
SMOD1
BRL
Error %
115200
-
-
-
-
-
-
-
-
-
-
-
-
57600
-
-
-
-
1
1
247
3.55
1
1
245
1.36
38400
1
1
246
2.34
1
1
243
0.16
1
1
240
1.73
19200
1
1
236
2.34
1
1
230
0.16
1
1
223
1.36
9600
1
1
217
0.16
1
1
204
0.16
1
1
191
0.16
4800
1
1
178
0.16
1
1
152
0.16
1
1
126
0.16
FPER = 12 MHz(2)
FPER = 16 MHz(2)
FPER = 20 MHz(2)
Baud Rate
SPD
SMOD1
BRL
Error %
SPD
SMOD1
BRL
Error %
SPD
SMOD1
BRL
Error %
115200
-
-
-
-
1
1
247
3.55
1
1
245
1.36
57600
1
1
243
0.16
1
1
239
2.12
1
1
234
1.36
38400
1
1
236
2.34
1
1
230
0.16
1
1
223
1.36
19200
1
1
217
0.16
1
1
204
0.16
1
1
191
0.16
9600
1
1
178
0.16
1
1
152
0.16
1
1
126
0.16
4800
1
1
100
0.16
1
1
48
0.16
1
0
126
0.16
Notes:
1. These frequencies are achieved in X1 mode, FPER = FOSC ÷ 2.
2. These frequencies are achieved in X2 mode, FPER = FOSC.
19.6.1 Baud Rate Selection
(Mode 2)
In mode 2, the baud rate can only be programmed to 2 fixed values: 1/16 or 1/32 of the
peripheral clock frequency.
As shown in Figure 110 the selection is done using SMOD1 bit in PCON register.
Figure 111 gives the baud rate calculation formula depending on the selection.
Figure 110. Baud Rate Generator Selection (Mode 2)
PER
CLOCK
÷2
0
÷ 16
To Serial Port
1
SMOD1
PCON.7
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Figure 111. Baud Rate Formula (Mode 2)
Baud_Rate=
19.7 Multiprocessor
Communication (Modes
2 and 3)
2SMOD1 ⋅ FPER
32
Modes 2 and 3 provide a ninth-bit mode to facilitate multiprocessor communication. To
enable this feature, set SM2 bit in SCON register. When the multiprocessor communication feature is enabled, the serial Port can differentiate between data frames (ninth bit
clear) and address frames (ninth bit set). This allows the AT8xC51SND1C to function as
a slave processor in an environment where multiple slave processors share a single
serial line.
When the multiprocessor communication feature is enabled, the receiver ignores frames
with the ninth bit clear. The receiver examines frames with the ninth bit set for an
address match. If the received address matches the slaves address, the receiver hardware sets RB8 and RI bits in SCON register, generating an interrupt.
The addressed slave’s software then clears SM2 bit in SCON register and prepares to
receive the data Bytes. The other slaves are unaffected by these data Bytes because
they are waiting to respond to their own addresses.
19.8 Automatic Address
Recognition
The automatic address recognition feature is enabled when the multiprocessor communication feature is enabled (SM2 bit in SCON register is set).
Implemented in hardware, automatic address recognition enhances the multiprocessor
communication feature by allowing the Serial Port to examine the address of each
incoming command frame. Only when the Serial Port recognizes its own address, the
receiver sets RI bit in SCON register to generate an interrupt. This ensures that the CPU
is not interrupted by command frames addressed to other devices.
If desired, the automatic address recognition feature in mode 1 may be enabled. In this
configuration, the stop bit takes the place of the ninth data bit. Bit RI is set only when the
received command frame address matches the device’s address and is terminated by a
valid stop bit.
To support automatic address recognition, a device is identified by a given address and
a broadcast address.
Note:
19.8.1 Given Address
The multiprocessor communication and automatic address recognition features cannot
be enabled in mode 0 (i.e, setting SM2 bit in SCON register in mode 0 has no effect).
Each device has an individual address that is specified in SADDR register; the SADEN
register is a mask Byte that contains don’t care bits (defined by zeros) to form the
device’s given address. The don’t care bits provide the flexibility to address one or more
slaves at a time. The following example illustrates how a given address is formed.
To address a device by its individual address, the SADEN mask Byte must be
1111 1111b.
For example:
SADDR = 0101 0110b
SADEN = 1111 1100b
Given = 0101 01XXb
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AT8xC51SND1C
The following is an example of how to use given addresses to address different slaves:
Slave A:SADDR = 1111 0001b
SADEN = 1111 1010b
Given = 1111 0X0Xb
Slave B:SADDR = 1111 0011b
SADEN = 1111 1001b
Given = 1111 0XX1b
Slave C:SADDR = 1111 0011b
SADEN = 1111 1101b
Given = 1111 00X1b
The SADEN Byte is selected so that each slave may be addressed separately.
For slave A, bit 0 (the LSB) is a don’t-care bit; for slaves B and C, bit 0 is a 1. To communicate with slave A only, the master must send an address where bit 0 is clear (e.g.
1111 0000B).
For slave A, bit 1 is a 0; for slaves B and C, bit 1 is a don’t care bit. To communicate with
slaves A and B, but not slave C, the master must send an address with bits 0 and 1 both
set (e.g. 1111 0011B).
To communicate with slaves A, B and C, the master must send an address with bit 0 set,
bit 1 clear, and bit 2 clear (e.g. 1111 0001B).
19.8.2 Broadcast Address
A broadcast address is formed from the logical OR of the SADDR and SADEN registers
with zeros defined as don’t-care bits, e.g.:
SADDR = 0101 0110b
SADEN = 1111 1100b
(SADDR | SADEN)=1111 111Xb
The use of don’t-care bits provides flexibility in defining the broadcast address, however
in most applications, a broadcast address is FFh.
The following is an example of using broadcast addresses:
Slave A:SADDR = 1111 0001b
SADEN = 1111 1010b
Given = 1111 1X11b,
Slave B:SADDR = 1111 0011b
SADEN = 1111 1001b
Given = 1111 1X11b,
Slave C:SADDR = 1111 0010b
SADEN = 1111 1101b
Given = 1111 1111b,
For slaves A and B, bit 2 is a don’t care bit; for slave C, bit 2 is set. To communicate with
all of the slaves, the master must send the address FFh.
To communicate with slaves A and B, but not slave C, the master must send the
address FBh.
19.8.3 Reset Address
On reset, the SADDR and SADEN registers are initialized to 00h, i.e. the given and
broadcast addresses are XXXX XXXXb (all don’t care bits). This ensures that the Serial
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Port is backwards compatible with the 80C51 microcontrollers that do not support automatic address recognition.
144
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AT8xC51SND1C
19.9 Interrupt
The Serial I/O Port handles 2 interrupt sources that are the “end of reception” (RI in
SCON) and “end of transmission” (TI in SCON) flags. As shown in Figure 112 these
flags are combined together to appear as a single interrupt source for the C51 core.
Flags must be cleared by software when executing the serial interrupt service routine.
The serial interrupt is enabled by setting ES bit in IEN0 register. This assumes interrupts
are globally enabled by setting EA bit in IEN0 register.
Depending on the selected mode and weather the framing error detection is enabled or
disabled, RI flag is set during the stop bit or during the ninth bit as detailed in Figure 113.
Figure 112. Serial I/O Interrupt System
SCON.0
RI
Serial I/O
Interrupt Request
TI
SCON.1
ES
IEN0.4
Figure 113. Interrupt Waveforms
a. Mode 1
RXD
D0
D1
D2
Start Bit
D3
D4
D5
D6
D7
8-bit Data
Stop Bit
RI
SMOD0 = X
FE
SMOD0 = 1
b. Mode 2 and 3
RXD
D0
Start bit
D1
D2
D3
D4
9-bit data
D5
D6
D7
D8
Stop bit
RI
SMOD0 = 0
RI
SMOD0 = 1
FE
SMOD0 = 1
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19.10 Registers
Table 11. SCON Register
SCON (S:98h) – Serial Control Register
7
6
5
4
3
2
1
0
FE/SM0
OVR/SM1
SM2
REN
TB8
RB8
TI
RI
Bit
Number
Bit
Mnemonic Description
FE
7
Framing Error Bit
To select this function, set SMOD0 bit in PCON register.
Set by hardware to indicate an invalid stop bit.
Must be cleared by software.
SM0
Serial Port Mode Bit 0
Refer to Table 2 for mode selection.
SM1
Serial Port Mode Bit 1
Refer to Table 2 for mode selection.
5
SM2
Serial Port Mode Bit 2
Set to enable the multiprocessor communication and automatic address
recognition features.
Clear to disable the multiprocessor communication and automatic address
recognition features.
4
REN
Receiver Enable Bit
Set to enable reception.
Clear to disable reception.
3
TB8
Transmit Bit 8
Modes 0 and 1: Not used.
Modes 2 and 3: Software writes the ninth data bit to be transmitted to TB8.
2
RB8
Receiver Bit 8
Mode 0: Not used.
Mode 1 (SM2 cleared): Set or cleared by hardware to reflect the stop bit
received.
Modes 2 and 3 (SM2 set): Set or cleared by hardware to reflect the ninth bit
received.
1
TI
Transmit Interrupt Flag
Set by the transmitter after the last data bit is transmitted.
Must be cleared by software.
0
RI
Receive Interrupt Flag
Set by the receiver after the stop bit of a frame has been received.
Must be cleared by software.
6
Reset Value = 0000 0000b
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Table 12. SBUF Register
SBUF (S:99h) – Serial Buffer Register
7
6
5
4
3
2
1
0
SD7
SD6
SD5
SD4
SD3
SD2
SD1
SD0
Bit
Number
7-0
Bit
Mnemonic Description
SD7:0
Serial Data Byte
Read the last data received by the serial I/O Port.
Write the data to be transmitted by the serial I/O Port.
Reset value = XXXX XXXXb
Table 13. SADDR Register
SADDR (S:A9h) – Slave Individual Address Register
7
6
5
4
3
2
1
0
SAD7
SAD6
SAD5
SAD4
SAD3
SAD2
SAD1
SAD0
Bit
Number
7-0
Bit
Mnemonic Description
SAD7:0
Slave Individual Address
Reset Value = 0000 0000b
Table 14. SADEN Register
SADEN (S:B9h) – Slave Individual Address Mask Byte Register
7
6
5
4
3
2
1
0
SAE7
SAE6
SAE5
SAE4
SAE3
SAE2
SAE1
SAE0
Bit
Number
7-0
Bit
Mnemonic Description
SAE7:0
Slave Address Mask Byte
Reset Value = 0000 0000b
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4109H–8051–01/05
Table 15. BDRCON Register
BDRCON (S:92h) – Baud Rate Generator Control Register
7
6
5
4
3
2
1
0
-
-
-
BRR
TBCK
RBCK
SPD
M0SRC
Bit
Number
Bit
Mnemonic Description
Reserved
The value read from these bits are indeterminate. Do not set these bits.
7-5
-
4
BRR
Baud Rate Run Bit
Set to enable the baud rate generator.
Clear to disable the baud rate generator.
3
TBCK
Transmission Baud Rate Selection Bit
Set to select the baud rate generator as transmission baud rate generator.
Clear to select the Timer 1 as transmission baud rate generator.
2
RBCK
Reception Baud Rate Selection Bit
Set to select the baud rate generator as reception baud rate generator.
Clear to select the Timer 1 as reception baud rate generator.
1
SPD
0
M0SRC
Baud Rate Speed Bit
Set to select high speed baud rate generation.
Clear to select low speed baud rate generation.
Mode 0 Baud Rate Source Bit
Set to select the variable baud rate generator in Mode 0.
Clear to select fixed baud rate in Mode 0.
Reset Value = XXX0 0000b
Table 16. BRL Register
BRL (S:91h) – Baud Rate Generator Reload Register
7
6
5
4
3
2
1
0
BRL7
BRL6
BRL5
BRL4
BRL3
BRL2
BRL1
BRL0
Bit
Number
7-0
Bit
Mnemonic Description
BRL7:0
Baud Rate Reload Value
Reset Value = 0000 0000b
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AT8xC51SND1C
4109H–8051–01/05
AT8xC51SND1C
20. Synchronous
Peripheral Interface
The AT8xC51SND1C implements a Synchronous Peripheral Interface with master and
slave modes capability.
Figure 114 shows an SPI bus configuration using the AT8xC51SND1C as master connected to slave peripherals while Figure 115 shows an SPI bus configuration using the
AT8xC51SND1C as slave of an other master.
The bus is made of three wires connecting all the devices together:
•
Master Output Slave Input (MOSI): it is used to transfer data in series from the
master to a slave.
It is driven by the master.
•
Master Input Slave Output (MISO): it is used to transfer data in series from a slave
to the master.
It is driven by the selected slave.
•
Serial Clock (SCK): it is used to synchronize the data transmission both in and out
the devices through their MOSI and MISO lines. It is driven by the master for eight
clock cycles which allows to exchange one Byte on the serial lines.
Each slave peripheral is selected by one Slave Select pin (SS). If there is only one
slave, it may be continuously selected with SS tied to a low level. Otherwise, the
AT8xC51SND1C may select each device by software through port pins (Pn.x). Special
care should be taken not to select 2 slaves at the same time to avoid bus conflicts.
Figure 114. Typical Master SPI Bus Configuration
Pn.z
Pn.y
SS
Pn.x
AT8xC51SND1C
P4.0
P4.1
P4.2
SO
DataFlash 1
SI
SCK
SS DataFlash 2
SO
SI
SCK
SS
SO
LCD
Controller
SI
SCK
MISO
MOSI
SCK
Figure 115. Typical Slave SPI Bus Configuration
SSn
SS
SS1
SS0
MASTER
SS
SO
Slave 1
SI
SCK
SS
SO
Slave 2
AT8xC51SND1C
Slave n
SI
MISO MOSI SCK
SCK
MISO
MOSI
SCK
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4109H–8051–01/05
20.1 Description
The SPI controller interfaces with the C51 core through three special function registers:
SPCON, the SPI control register (see Table 6); SPSTA, the SPI status register (see
Table 7); and SPDAT, the SPI data register (see Table 8).
20.1.1 Master Mode
The SPI operates in master mode when the MSTR bit in SPCON is set.
Figure 116 shows the SPI block diagram in master mode. Only a master SPI module
can initiate transmissions. Software begins the transmission by writing to SPDAT. Writing to SPDAT writes to the shift register while reading SPDAT reads an intermediate
register updated at the end of each transfer.
The Byte begins shifting out on the MOSI pin under the control of the bit rate generator.
This generator also controls the shift register of the slave peripheral through the SCK
output pin. As the Byte shifts out, another Byte shifts in from the slave peripheral on the
MISO pin. The Byte is transmitted most significant bit (MSB) first. The end of transfer is
signaled by SPIF being set.
When the AT8xC51SND1C is the only master on the bus, it can be useful not to use SS
pin and get it back to I/O functionality. This is achieved by setting SSDIS bit in SPCON.
Figure 116. SPI Master Mode Block Diagram
MOSI/P4.1
I
8-bit Shift Register
SPDAT WR
SCK/P4.2
SPDAT RD
Q
Internal Bus
MISO/P4.0
SS/P4.3
MODF
SSDIS
SPCON.5
SPSTA.4
Control and Clock Logic
WCOL
SPSTA.6
PER
CLOCK
Bit Rate Generator
SPIF
SPSTA.7
SPEN
SPCON.6
Note:
150
SPR2:0
CPHA
CPOL
SPCON
SPCON.2
SPCON.3
MSTR bit in SPCON is set to select master mode.
AT8xC51SND1C
4109H–8051–01/05
AT8xC51SND1C
20.1.2 Slave Mode
The SPI operates in slave mode when the MSTR bit in SPCON is cleared and data has
been loaded in SPDAT.
Figure 117 shows the SPI block diagram in slave mode. In slave mode, before a data
transmission occurs, the SS pin of the slave SPI must be asserted to low level. SS must
remain low until the transmission of the Byte is complete. In the slave SPI module, data
enters the shift register through the MOSI pin under the control of the serial clock provided by the master SPI module on the SCK input pin. When the master starts a
transmission, the data in the shift register begins shifting out on the MISO pin. The end
of transfer is signaled by SPIF being set.
When the AT8xC51SND1C is the only slave on the bus, it can be useful not to use SS
pin and get it back to I/O functionality. This is achieved by setting SSDIS bit in SPCON.
This bit has no effect when CPHA is cleared (see Section "SS Management",
page 153).
Figure 117. SPI Slave Mode Block Diagram
MISO/P4.2
I
8-bit Shift Register
SPDAT WR
SPDAT RD
SCK/P4.2
Q
Internal Bus
MOSI/P4.1
Control and Clock Logic
SS/P4.3
SPIF
SPSTA.7
SSDIS
SPCON.5
Note:
CPHA
CPOL
SPCON.2
SPCON.3
1. MSTR bit in SPCON is cleared to select slave mode.
20.1.3 Bit Rate
The bit rate can be selected from seven predefined bit rates using the SPR2, SPR1 and
SPR0 control bits in SPCON according to Table 2. These bit rates are derived from the
peripheral clock (FPER) issued from the Clock Controller block as detailed in Section
"Oscillator", page 12.
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4109H–8051–01/05
Table 2. Serial Bit Rates
Bit Rate (kHz) Vs FPER
SPR1
SPR0
0
0
0
3000
4000
5000
6000
8000
10000
2
0
0
1
1500
2000
2500
3000
4000
5000
4
0
1
0
750
1000
1250
1500
2000
2500
8
0
1
1
375
500
625
750
1000
1250
16
1
0
0
187.5
250
312.5
375
500
625
32
1
0
1
93.75
125
156.25
187.5
250
312.5
64
1
1
0
46.875
62.5
78.125
93.75
125
156.25
128
1
1
1
6000
8000
10000
12000
16000
20000
1
FPER Divider
1. These frequencies are achieved in X1 mode, FPER = FOSC ÷ 2.
2. These frequencies are achieved in X2 mode, FPER = FOSC.
Notes:
20.2.1 Data Transfer
6 MHz(1) 8 MHz(1) 10 MHz(1) 12 MHz(2) 16 MHz(2) 20 MHz(2)
SPR2
The Clock Polarity bit (CPOL in SPCON) defines the default SCK line level in idle
state(1) while the Clock Phase bit (CPHA in SPCON) defines the edges on which the
input data are sampled and the edges on which the output data are shifted (see
Figure 118 and Figure 119). The SI signal is output from the selected slave and the SO
signal is the output from the master. The AT8xC51SND1C captures data from the SI line
while the selected slave captures data from the SO line.
For simplicity, Figure 118 and Figure 119 depict the SPI waveforms in idealized form
and do not provide precise timing information. For timing parameters refer to the Section
“AC Characteristics”.
Note:
1. When the peripheral is disabled (SPEN = 0), default SCK line is high level.
Figure 118. Data Transmission Format (CPHA = 0)
1
2
3
4
5
6
7
8
MSB
bit 6
bit 5
bit 4
bit 3
bit 2
bit 1
LSB
bit 6
bit 5
bit 4
bit 3
bit 2
bit 1
LSB
SCK Cycle Number
SPEN (Internal)
SCK (CPOL = 0)
SCK (CPOL = 1)
MOSI (From Master)
MISO (From Slave)
MSB
SS (to slave)
Capture point
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Figure 119. Data Transmission Format (CPHA = 1)
1
2
3
4
5
6
7
8
MOSI (from master)
MSB
bit 6
bit 5
bit 4
bit 3
bit 2
bit 1
LSB
MISO (from slave)
MSB
bit 6
bit 5
bit 4
bit 3
bit 2
bit 1
SCK cycle number
SPEN (internal)
SCK (CPOL = 0)
SCK (CPOL = 1)
LSB
SS (to slave)
Capture point
20.2.2 SS Management
Figure 118 shows an SPI transmission with CPHA = 0, where the first SCK edge is the
MSB capture point. Therefore the slave starts to output its MSB as soon as it is
selected: SS asserted to low level. SS must then be deasserted between each Byte
transmission (see Figure 120). SPDAT must be loaded with a data before SS is
asserted again.
Figure 119 shows an SPI transmission with CPHA = 1, where the first SCK edge is used
by the slave as a start of transmission signal. Therefore, SS may remain asserted
between each Byte transmission (see Figure 120).
Figure 120. SS Timing Diagram
SI/SO
Byte 1
Byte 2
Byte 3
SS (CPHA = 0)
SS (CPHA = 1)
20.2.3 Error Conditions
The following flags signal the SPI error conditions:
•
MODF in SPSTA signals a mode fault.
MODF flag is relevant only in master mode when SS usage is enabled (SSDIS bit
cleared). It signals when set that an other master on the bus has asserted SS pin
and so, may create a conflict on the bus with 2 master sending data at the same
time.
•
A mode fault automatically disables the SPI (SPEN cleared) and configures the SPI
in slave mode (MSTR cleared).
MODF flag can trigger an interrupt as explained in Section "Interrupt", page 154.
MODF flag is cleared by reading SPSTA and re-configuring SPI by writing to
SPCON.
•
WCOL in SPSTA signals a write collision.
WCOL flag is set when SPDAT is loaded while a transfer is on-going. In this case
data is not written to SPDAT and transfer continue uninterrupted. WCOL flag does
not trigger any interrupt and is relevant jointly with SPIF flag.
WCOL flag is cleared after reading SPSTA and writing new data to SPDAT while no
transfer is on-going.
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20.3 Interrupt
The SPI handles 2 interrupt sources that are the “end of transfer” and the “mode fault”
flags.
As shown in Figure 121, these flags are combined toghether to appear as a single interrupt source for the C51 core. The SPIF flag is set at the end of an 8-bit shift in and out
and is cleared by reading SPSTA and then reading from or writing to SPDAT.
The MODF flag is set in case of mode fault error and is cleared by reading SPSTA and
then writing to SPCON.
The SPI interrupt is enabled by setting ESPI bit in IEN1 register. This assumes interrupts are globally enabled by setting EA bit in IEN0 register.
Figure 121. SPI Interrupt System
SPIF
SPI Controller
Interrupt Request
SPSTA.7
MODF
SPSTA.4
ESPI
IEN1.2
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20.4 Configuration
The SPI configuration is made through SPCON.
20.4.1 Master Configuration
The SPI operates in master mode when the MSTR bit in SPCON is set.
20.4.2 Slave Configuration
The SPI operates in slave mode when the MSTR bit in SPCON is cleared and data has
been loaded is SPDAT.
20.4.3 Data Exchange
There are 2 possible methods to exchange data in master and slave modes:
20.4.4 Master Mode with
Polling Policy
•
polling
•
interrupts
Figure 122 shows the initialization phase and the transfer phase flows using the polling
method. Using this flow prevents any overrun error occurrence.
The bit rate is selected according to Table 2. The transfer format depends on the slave
peripheral.
SS may be deasserted between transfers depending also on the slave peripheral.
SPIF flag is cleared when reading SPDAT (SPSTA has been read before by the “end of
transfer” check).
This polling method provides the fastest effective transmission and is well adapted when
communicating at high speed with other microcontrollers. However, the procedure may
then be interrupted at any time by higher priority tasks.
Figure 122. Master SPI Polling Flows
SPI Initialization
Polling Policy
SPI Transfer
Polling Policy
Disable interrupt
SPIE = 0
Select Slave
Pn.x = L
Select Master Mode
MSTR = 1
Start Transfer
write data in SPDAT
Select Bit Rate
program SPR2:0
End Of Transfer?
SPIF = 1?
Select Format
program CPOL & CPHA
Get Data Received
read SPDAT
Enable SPI
SPEN = 1
Last Transfer?
Deselect Slave
Pn.x = H
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20.4.5 Master Mode with
Interrupt
Figure 123 shows the initialization phase and the transfer phase flows using the interrupt. Using this flow prevents any overrun error occurrence.
The bit rate is selected according to Table 2.
The transfer format depends on the slave peripheral.
SS may be deasserted between transfers depending also on the slave peripheral.
Reading SPSTA at the beginning of the ISR is mandatory for clearing the SPIF flag.
Clear is effective when reading SPDAT.
Figure 123. Master SPI Interrupt Flows
SPI Initialization
Interrupt Policy
SPI Interrupt
Service Routine
Select Master Mode
MSTR = 1
Read Status
Read SPSTA
Select Bit Rate
program SPR2:0
Get Data Received
read SPDAT
Select Format
program CPOL & CPHA
Start New Transfer
write data in SPDAT
Enable interrupt
ESPI =1
Last Transfer?
Enable SPI
SPEN = 1
Deselect Slave
Pn.x = H
Select Slave
Pn.x = L
Disable interrupt
SPIE = 0
Start Transfer
write data in SPDAT
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20.4.6 Slave Mode with Polling
Policy
Figure 124 shows the initialization phase and the transfer phase flows using the polling.
The transfer format depends on the master controller.
SPIF flag is cleared when reading SPDAT (SPSTA has been read before by the “end of
reception” check).
This provides the fastest effective transmission and is well adapted when communicating at high speed with other Microcontrollers. However, the process may then be
interrupted at any time by higher priority tasks.
Figure 124. Slave SPI Polling Flows
SPI Initialization
Polling Policy
Disable interrupt
SPIE = 0
SPI Transfer
Polling Policy
Data Received?
SPIF = 1?
Select Slave Mode
MSTR = 0
Get Data Received
read SPDAT
Select Format
program CPOL & CPHA
Prepare Next Transfer
write data in SPDAT
Enable SPI
SPEN = 1
Prepare Transfer
write data in SPDAT
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20.4.7 Slave Mode with
Interrupt Policy
Figure 123 shows the initialization phase and the transfer phase flows using the
interrupt.
The transfer format depends on the master controller.
Reading SPSTA at the beginning of the ISR is mandatory for clearing the SPIF flag.
Clear is effective when reading SPDAT.
Figure 125. Slave SPI Interrupt Policy Flows
SPI Initialization
Interrupt Policy
SPI Interrupt
Service Routine
Select Slave Mode
MSTR = 0
Get Status
Read SPSTA
Select Format
program CPOL & CPHA
Get Data Received
read SPDAT
Enable interrupt
ESPI =1
Prepare New Transfer
write data in SPDAT
Enable SPI
SPEN = 1
Prepare Transfer
write data in SPDAT
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20.5 Registers
Table 6. SPCON Register
SPCON (S:C3h) – SPI Control Register
7
6
5
4
3
2
1
0
SPR2
SPEN
SSDIS
MSTR
CPOL
CPHA
SPR1
SPR0
Bit
Number
Bit
Mnemonic Description
7
SPR2
SPI Rate Bit 2
Refer to Table 2 for bit rate description.
6
SPEN
SPI Enable Bit
Set to enable the SPI interface.
Clear to disable the SPI interface.
5
SSDIS
Slave Select Input Disable Bit
Set to disable SS in both master and slave modes. In slave mode this bit has no
effect if CPHA = 0.
Clear to enable SS in both master and slave modes.
4
MSTR
Master Mode Select
Set to select the master mode.
Clear to select the slave mode.
3
CPOL
2
CPHA
1-0
SPR1:0
SPI Clock Polarity Bit(1)
Set to have the clock output set to high level in idle state.
Clear to have the clock output set to low level in idle state.
SPI Clock Phase Bit
Set to have the data sampled when the clock returns to idle state (see CPOL).
Clear to have the data sampled when the clock leaves the idle state (see CPOL).
SPI Rate Bits 0 and 1
Refer to Table 2 for bit rate description.
Reset Value = 0001 0100b
Note:
1. When the SPI is disabled, SCK outputs high level.
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Table 7. SPSTA Register
SPSTA (S:C4h) – SPI Status Register
7
6
5
4
3
2
1
0
SPIF
WCOL
-
MODF
-
-
-
-
Bit
Number
Bit
Mnemonic Description
7
SPIF
6
WCOL
5
-
4
MODF
3-0
-
SPI Interrupt Flag
Set by hardware when an 8-bit shift is completed.
Cleared by hardware when reading or writing SPDAT after reading SPSTA.
Write Collision Flag
Set by hardware to indicate that a collision has been detected.
Cleared by hardware to indicate that no collision has been detected.
Reserved
The value read from this bit is indeterminate. Do not set this bit.
Mode Fault
Set by hardware to indicate that the SS pin is at an appropriate level.
Cleared by hardware to indicate that the SS pin is at an inappropriate level.
Reserved
The value read from these bits is indeterminate. Do not set these bits.
Reset Value = 00000 0000b
Table 8. SPDAT Register
SPDAT (S:C5h) – Synchronous Serial Data Register
7
6
5
4
3
2
1
0
SPD7
SPD6
SPD5
SPD4
SPD3
SPD2
SPD1
SPD0
Bit
Number
7-0
Bit
Mnemonic Description
SPD7:0
Synchronous Serial Data.
Reset Value = XXXX XXXXb
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21. Two-wire
Interface (TWI)
Controller
The AT8xC51SND1C implements a TWI controller supporting the four standard master
and slave modes with multimaster capability. Thus, it allows connection of slave devices
like LCD controller, audio DAC, etc., but also external master controlling where the
AT8xC51SND1C is used as a peripheral of a host.
The TWI bus is a bi-directional TWI serial communication standard. It is designed primarily for simple but efficient integrated circuit control. The system is comprised of 2 lines,
SCL (Serial Clock) and SDA (Serial Data) that carry information between the ICs connected to them. The serial data transfer is limited to 100 Kbit/s in low speed mode,
however, some higher bit rates can be achieved depending on the oscillator frequency.
Various communication configurations can be designed using this bus. Figure 126
shows a typical TWI bus configuration using the AT8xC51SND1C in master and slave
modes. All the devices connected to the bus can be master and slave.
Figure 126. Typical TWI Bus Configuration
AT8xC51SND1C
Master/Slave
LCD
Display
Rp
Audio
DAC
Rp
P1.6/SCL
P1.7/SDA
21.1 Description
HOST
Microprocessor
SCL
SDA
The CPU interfaces to the TWI logic via the following four 8-bit special function registers: the Synchronous Serial Control register (SSCON SFR, see Table 10), the
Synchronous Serial Data register (SSDAT SFR, see Table 12), the Synchronous Serial
Status register (SSSTA SFR, see Table 11) and the Synchronous Serial Address register (SSADR SFR, see Table 13).
SSCON is used to enable the controller, to program the bit rate (see Table 10), to
enable slave modes, to acknowledge or not a received data, to send a START or a
STOP condition on the TWI bus, and to acknowledge a serial interrupt. A hardware
reset disables the TWI controller.
SSSTA contains a status code which reflects the status of the TWI logic and the TWI
bus. The three least significant bits are always zero. The five most significant bits contains the status code. There are 26 possible status codes. When SSSTA contains F8h,
no relevant state information is available and no serial interrupt is requested. A valid status code is available in SSSTA after SSI is set by hardware and is still present until SSI
has been reset by software. Table 3 to Table 131 give the status for both master and
slave modes and miscellaneous states.
SSDAT contains a Byte of serial data to be transmitted or a Byte which has just been
received. It is addressable while it is not in process of shifting a Byte. This occurs when
TWI logic is in a defined state and the serial interrupt flag is set. Data in SSDAT remains
stable as long as SSI is set. While data is being shifted out, data on the bus is simultaneously shifted in; SSDAT always contains the last Byte present on the bus.
SSADR may be loaded with the 7 - bit slave address (7 most significant bits) to which
the controller will respond when programmed as a slave transmitter or receiver. The
LSB is used to enable general call address (00h) recognition.
Figure 127 shows how a data transfer is accomplished on the TWI bus.
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Figure 127. Complete Data Transfer on TWI Bus
SDA
MSB
Slave Address
SCL
1
2
R/W
ACK
direction signal
bit
from
receiver
8
Nth data Byte
9
S
1
2
ACK
signal
from
receiver
8
9
Clock Line Held Low While Serial Interrupts Are Serviced
P/S
The four operating modes are:
•
Master transmitter
•
Master receiver
•
Slave transmitter
•
Slave receiver
Data transfer in each mode of operation are shown in Figure 128 through Figure 131.
These figures contain the following abbreviations:
A
Acknowledge bit (low level at SDA)
A
Not acknowledge bit (high level on SDA)
Data
8-bit data Byte
S
START condition
P
STOP condition
MR
Master Receive
MT
Master Transmit
SLA
Slave Address
GCA
General Call Address (00h)
R
Read bit (high level at SDA)
W
Write bit (low level at SDA)
In Figure 128 through Figure 131, circles are used to indicate when the serial interrupt
flag is set. The numbers in the circles show the status code held in SSSTA. At these
points, a service routine must be executed to continue or complete the serial transfer.
These service routines are not critical since the serial transfer is suspended until the
serial interrupt flag is cleared by software.
When the serial interrupt routine is entered, the status code in SSSTA is used to branch
to the appropriate service routine. For each status code, the required software action
and details of the following serial transfer are given in Table 3 through Table 131.
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21.1.1 Bit Rate
The bit rate can be selected from seven predefined bit rates or from a programmable bit
rate generator using the SSCR2, SSCR1, and SSCR0 control bits in SSCON (see
Table 10). The predefined bit rates are derived from the peripheral clock (FPER) issued
from the Clock Controller block as detailed in section "Oscillator", page 12, while bit rate
generator is based on timer 1 overflow output.
Table 2. Serial Clock Rates
SSCRx
2
1
0
FPER = 6 MHz
FPER = 8 MHz
FPER = 10 MHz
FPER Divided By
0
0
0
47
62.5
78.125
128
0
0
1
53.5
71.5
89.3
112
0
1
0
62.5
83
104.2(1)
96
0
1
1
75
100
125(1)
80
1
0
0
12.5
16.5
20.83
480
1
0
1
100
133.3(1)
166.7(1)
60
1
1
0
200(1)
266.7(1)
333.3(1)
30
1
1
1
0.5 < ⋅ < 125(1)
0.67 < ⋅ <
166.7(1)
0.81 < ⋅ <
208.3(1)
96 ⋅ (256 – reload value Timer 1)
Note:
21.2.1 Master Transmitter
Mode
Bit Frequency (kHz)
1. These bit rates are outside of the low speed standard specification limited to 100 kHz
but can be used with high speed TWI components limited to 400 kHz.
In the master transmitter mode, a number of data Bytes are transmitted to a slave
receiver (see Figure 128). Before the master transmitter mode can be entered, SSCON
must be initialized as follows:
SSCR2
SSPE
SSSTA
SSSTO
SSI
SSAA
SSCR1
SSCR0
Bit Rate
1
0
0
0
X
Bit Rate
Bit Rate
SSCR2:0 define the serial bit rate (see Table 2). SSPE must be set to enable the controller. SSSTA, SSSTO and SSI must be cleared.
The master transmitter mode may now be entered by setting the SSSTA bit. The TWI
logic will now monitor the TWI bus and generate a START condition as soon as the bus
becomes free. When a START condition is transmitted, the serial interrupt flag (SSI bit
in SSCON) is set, and the status code in SSSTA is 08h. This status must be used to
vector to an interrupt routine that loads SSDAT with the slave address and the data
direction bit (SLA+W). The serial interrupt flag (SSI) must then be cleared before the
serial transfer can continue.
When the slave address and the direction bit have been transmitted and an acknowledgment bit has been received, SSI is set again and a number of status code in SSSTA
are possible. There are 18h, 20h or 38h for the master mode and also 68h, 78h or B0h if
the slave mode was enabled (SSAA = logic 1). The appropriate action to be taken for
each of these status code is detailed in Table 3. This scheme is repeated until a STOP
condition is transmitted.
SSPE and SSCR2:0 are not affected by the serial transfer and are not referred to in
Table 3. After a repeated START condition (state 10h) the controller may switch to the
master receiver mode by loading SSDAT with SLA+R.
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21.2.2 Master Receiver Mode
In the master receiver mode, a number of data Bytes are received from a slave transmitter (see Figure 129). The transfer is initialized as in the master transmitter mode. When
the START condition has been transmitted, the interrupt routine must load SSDAT with
the 7 - bit slave address and the data direction bit (SLA+R). The serial interrupt flag
(SSI) must then be cleared before the serial transfer can continue.
When the slave address and the direction bit have been transmitted and an acknowledgment bit has been received, the serial interrupt flag is set again and a number of
status code in SSSTA are possible. There are 40h, 48h or 38h for the master mode and
also 68h, 78h or B0h if the slave mode was enabled (SSAA = logic 1). The appropriate
action to be taken for each of these status code is detailed in Table 131. This scheme is
repeated until a STOP condition is transmitted.
SSPE and SSCR2:0 are not affected by the serial transfer and are not referred to in
Table 131. After a repeated START condition (state 10h) the controller may switch to
the master transmitter mode by loading SSDAT with SLA+W.
21.2.3 Slave Receiver Mode
In the slave receiver mode, a number of data Bytes are received from a master transmitter (see Figure 130). To initiate the slave receiver mode, SSADR and SSCON must be
loaded as follows:
SSA6
SSA5
SSA4
←⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯
SSA3
SSA2
SSA1
SSA0
⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯→
Own Slave Address
SSGC
X
The upper 7 bits are the addresses to which the controller will respond when addressed
by a master. If the LSB (SSGC) is set, the controller will respond to the general call
address (00h); otherwise, it ignores the general call address.
SSCR2
SSPE
SSSTA
SSSTO
SSI
SSAA
SSCR1
SSCR0
X
1
0
0
0
1
X
X
SSCR2:0 have no effect in the slave mode. SSPE must be set to enable the controller.
The SSAA bit must be set to enable the own slave address or the general call address
acknowledgment. SSSTA, SSSTO and SSI must be cleared.
When SSADR and SSCON have been initialized, the controller waits until it is
addressed by its own slave address followed by the data direction bit which must be
logic 0 (W) for operating in the slave receiver mode. After its own slave address and the
W bit has been received, the serial interrupt flag is set and a valid status code can be
read from SSSTA. This status code is used to vector to an interrupt service routine, and
the appropriate action to be taken for each of these status code is detailed in Table 131
and Table 7. The slave receiver mode may also be entered if arbitration is lost while the
controller is in the master mode (see states 68h and 78h).
If the SSAA bit is reset during a transfer, the controller will return a not acknowledge
(logic 1) to SDA after the next received data Byte. While SSAA is reset, the controller
does not respond to its own slave address. However, the TWI bus is still monitored and
address recognition may be resumed at any time by setting SSAA. This means that the
SSAA bit may be used to temporarily isolate the controller from the TWI bus.
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21.2.4 Slave Transmitter Mode
In the slave transmitter mode, a number of data Bytes are transmitted to a master
receiver (see Figure 131). Data transfer is initialized as in the slave receiver mode.
When SSADR and SSCON have been initialized, the controller waits until it is
addressed by its own slave address followed by the data direction bit which must be
logic 1 (R) for operating in the slave transmitter mode. After its own slave address and
the R bit have been received, the serial interrupt flag is set and a valid status code can
be read from SSSTA. This status code is used to vector to an interrupt service routine,
and the appropriate action to be taken for each of these status code is detailed in
Table 7. The slave transmitter mode may also be entered if arbitration is lost while the
controller is in the master mode (see state B0h).
If the SSAA bit is reset during a transfer, the controller will transmit the last Byte of the
transfer and enter state C0h or C8h. The controller is switched to the not addressed
slave mode and will ignore the master receiver if it continues the transfer. Thus the master receiver receives all 1’s as serial data. While SSAA is reset, the controller does not
respond to its own slave address. However, the TWI bus is still monitored and address
recognition may be resumed at any time by setting SSAA. This means that the SSAA bit
may be used to temporarily isolate the controller from the TWI bus.
21.2.5 Miscellaneous States
There are 2 SSSTA codes that do not correspond to a defined TWI hardware state (see
Table 8). These are discussed below.
Status F8h indicates that no relevant information is available because the serial interrupt
flag is not yet set. This occurs between other states and when the controller is not
involved in a serial transfer.
Status 00h indicates that a bus error has occurred during a serial transfer. A bus error is
caused when a START or a STOP condition occurs at an illegal position in the format
frame. Examples of such illegal positions are during the serial transfer of an address
Byte, a data Byte, or an acknowledge bit. When a bus error occurs, SSI is set. To
recover from a bus error, the SSSTO flag must be set and SSI must be cleared. This
causes the controller to enter the not addressed slave mode and to clear the SSSTO
flag (no other bits in S1CON are affected). The SDA and SCL lines are released and no
STOP condition is transmitted.
Note:
The TWI controller interfaces to the external TWI bus via 2 port 1 pins: P1.6/SCL (serial
clock line) and P1.7/SDA (serial data line). To avoid low level asserting and conflict on
these lines when the TWI controller is enabled, the output latches of P1.6 and P1.7 must
be set to logic 1.
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Figure 128. Format and States in the Master Transmitter Mode
MT
Successful transmission to a slave receiver
S
SLA
W
A
08h
Data
18h
A
P
28h
Next transfer started with
a repeated start condition
S
SLA
W
10h
R
Not acknowledge received
after the slave address
A
P
MR
20h
Not acknowledge received
after a data Byte
A
P
30h
Arbitration lost in slave
address or data Byte
A or A
Other master
continues
38h
Arbitration lost and
addressed as slave
A
From slave to master
166
Data
nnh
Other master
continues
38h
Other master
continues
68h 78h B0h
From master to slave
A or A
A
To corresponding
states in slave mode
Any number of data Bytes and their associated
acknowledge bits
This number (contained in SSSTA) corresponds
to a defined state of the TWI bus
AT8xC51SND1C
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Figure 129. Format and States in the Master Receiver Mode
MR
Successful reception
from a slave transmitter
S
SLA
08h
R
A
Data
A
40h
50h
Data
A
P
58h
Next transfer started with
a repeated start condition
S
SLA
R
10h
W
Not acknowledge received
after the slave address
A
P
MT
48h
Arbitration lost in slave
address or data Byte
A or A
Other master
continues
38h
Arbitration lost and
addressed as slave
A
From slave to master
Data
nnh
Other master
continues
38h
Other master
continues
68h 78h B0h
From master to slave
A
A
To corresponding
states in slave mode
Any number of data Bytes and their associated
acknowledge bits
This number (contained in SSSTA) corresponds
to a defined state of the TWI bus
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Figure 130. Format and States in the Slave Receiver Mode
Reception of the own slave
address and one or more
data Bytes.
All are acknowledged
S
SLA
W
A
Data
60h
A
Data
80h
Last data Byte received
is not acknowledged
A
P or S
80h
A0h
A
P or S
88h
Arbitration lost as master and
addressed as slave
A
68h
Reception of the general call
address and one or more data Bytes
General Call
A
Data
70h
Last data Byte received
is not acknowledged
A
90h
Data
A
P or S
90h
A0h
A
P or S
98h
Arbitration lost as master and
addressed as slave by general call
A
78h
From master to slave
From slave to master
168
Data
nnh
A
Any number of data Bytes and their associated
acknowledge bits
This number (contained in SSSTA) corresponds
to a defined state of the TWI bus
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Figure 131. Format and States in the Slave Transmitter Mode
Reception of the own slave
address and transmission
of one or more data Bytes.
S
SLA
R
A
Data
A8h
Arbitration lost as master and
addressed as slave
A
B8h
Data
A
P or S
C0h
A
B0h
Last data Byte transmitted.
Switched to not addressed
slave (SSAA = 0).
A
All 1’s
P or S
C8h
From master to slave
From slave to master
Data
nnh
A
Any number of data Bytes and their associated
acknowledge bits
This number (contained in SSSTA) corresponds
to a defined state of the TWI bus
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Table 3. Status for Master Transmitter Mode
Application Software Response
Status
Code
SSSTA
To SSCON
Status of the TWI Bus
and TWI Hardware
To/From SSDAT
08h
A START condition has Write SLA+W
been transmitted
10h
A repeated START
condition has been
transmitted
Write SLA+W
Write SLA+R
Write data Byte
18h
SLA+W has been
transmitted; ACK has
been received
No SSDAT action
No SSDAT action
No SSDAT action
Write data Byte
20h
SLA+W has been
transmitted; NOT ACK
has been received
No SSDAT action
No SSDAT action
No SSDAT action
Write data Byte
28h
Data Byte has been
transmitted; ACK has
been received
No SSDAT action
No SSDAT action
No SSDAT action
Write data Byte
30h
Data Byte has been
transmitted; NOT ACK
has been received
No SSDAT action
No SSDAT action
No SSDAT action
No SSDAT action
38h
170
Arbitration lost in
SLA+W or data Bytes
No SSDAT action
SSSTA
SSSTO
SSI
SSAA
Next Action Taken by TWI Hardware
X
0
0
X
X
0
0
X
X
0
0
X
0
0
0
X
1
0
0
X
0
1
0
X
STOP condition will be transmitted and SSSTO flag
will be reset.
1
1
0
X
STOP condition followed by a START condition will
be transmitted and SSSTO flag will be reset.
0
0
0
X
1
0
0
X
0
1
0
X
STOP condition will be transmitted and SSSTO flag
will be reset.
1
1
0
X
STOP condition followed by a START condition will
be transmitted and SSSTO flag will be reset.
0
0
0
X
1
0
0
X
0
1
0
X
STOP condition will be transmitted and SSSTO flag
will be reset.
1
1
0
X
STOP condition followed by a START condition will
be transmitted and SSSTO flag will be reset.
0
0
0
X
1
0
0
X
0
1
0
X
STOP condition will be transmitted and SSSTO flag
will be reset.
1
1
0
X
STOP condition followed by a START condition will
be transmitted and SSSTO flag will be reset.
0
0
0
X
TWI bus will be released and not addressed slave
mode will be entered.
1
0
0
X
A START condition will be transmitted when the bus
becomes free.
SLA+W will be transmitted.
SLA+W will be transmitted.
SLA+R will be transmitted.
Logic will switch to master receiver mode
Data Byte will be transmitted.
Repeated START will be transmitted.
Data Byte will be transmitted.
Repeated START will be transmitted.
Data Byte will be transmitted.
Repeated START will be transmitted.
Data Byte will be transmitted.
Repeated START will be transmitted.
AT8xC51SND1C
4109H–8051–01/05
AT8xC51SND1C
Table 4. Status for Master Receiver Mode
Application Software Response
Status
Code
SSSTA
To SSCON
Status of the TWI Bus
and TWI Hardware
To/From SSDAT
SSSTA
SSSTO
SSI
SSAA
X
0
0
X
X
0
0
X
X
0
0
X
SLA+W will be transmitted.
Logic will switch to master transmitter mode.
0
0
0
X
TWI bus will be released and not addressed slave
mode will be entered.
1
0
0
X
A START condition will be transmitted when the bus
becomes free.
No SSDAT action
0
0
0
0
Data Byte will be received and NOT ACK will be
returned.
No SSDAT action
0
0
0
1
Data Byte will be received and ACK will be returned.
1
0
0
X
0
1
0
X
STOP condition will be transmitted and SSSTO flag
will be reset.
1
1
0
X
STOP condition followed by a START condition will
be transmitted and SSSTO flag will be reset.
08h
A START condition has Write SLA+R
been transmitted
10h
A repeated START
condition has been
transmitted
38h
40h
Arbitration lost in
SLA+R or NOT ACK
bit
SLA+R has been
transmitted; ACK has
been received
Write SLA+R
Write SLA+W
No SSDAT action
No SSDAT action
No SSDAT action
48h
50h
SLA+R will be transmitted.
SLA+R will be transmitted.
Repeated START will be transmitted.
SLA+R has been
transmitted; NOT ACK
has been received
No SSDAT action
Data Byte has been
received; ACK has
been returned
Read data Byte
0
0
0
0
Data Byte will be received and NOT ACK will be
returned.
Read data Byte
0
0
0
1
Data Byte will be received and ACK will be returned.
1
0
0
X
0
1
0
X
STOP condition will be transmitted and SSSTO flag
will be reset.
1
1
0
X
STOP condition followed by a START condition will
be transmitted and SSSTO flag will be reset.
No SSDAT action
Read data Byte
58h
Next Action Taken by TWI Hardware
Data Byte has been
received; NOT ACK
has been returned
Read data Byte
Read data Byte
Repeated START will be transmitted.
171
4109H–8051–01/05
Table 5. Status for Slave Receiver Mode with Own Slave Address
Application Software Response
Status
Code
SSSTA
60h
68h
80h
To SSCON
Status of the TWI Bus
and TWI Hardware
To/From SSDAT
SSSTA
SSSTO
SSI
SSAA
Own SLA+W has been
received; ACK has
been returned
No SSDAT action
X
0
0
0
Data Byte will be received and NOT ACK will be
returned.
No SSDAT action
X
0
0
1
Data Byte will be received and ACK will be returned.
Arbitration lost in
SLA+R/W as master;
own SLA+W has been
received; ACK has
been returned
No SSDAT action
X
0
0
0
Data Byte will be received and NOT ACK will be
returned.
X
0
0
1
Previously addressed
with own SLA+W; data
has been received;
ACK has been
returned
Read data Byte
X
0
0
0
X
0
0
1
0
0
0
0
0
0
0
1
Data Byte will be received and ACK will be returned.
No SSDAT action
Read data Byte
Read data Byte
Previously addressed
with own SLA+W; data
has been received;
NOT ACK has been
returned
Read data Byte
1
0
0
0
Read data Byte
1
0
0
1
No SSDAT action
No SSDAT action
A0h
A STOP condition or
repeated START
condition has been
received while still
addressed as slave
0
0
0
0
0
0
0
1
1
0
0
0
1
0
0
1
No SSDAT action
No SSDAT action
172
Data Byte will be received and NOT ACK will be
returned.
Data Byte will be received and ACK will be returned.
Read data Byte
88h
Next Action Taken by TWI Hardware
Switched to the not addressed slave mode; no
recognition of own SLA or GCA.
Switched to the not addressed slave mode; own
SLA will be recognized; GCA will be recognized if
SSGC = logic 1.
Switched to the not addressed slave mode; no
recognition of own SLA or GCA. A START condition
will be transmitted when the bus becomes free.
Switched to the not addressed slave mode; own
SLA will be recognized; GCA will be recognized if
SSGC = logic 1. A START condition will be
transmitted when the bus becomes free.
Switched to the not addressed slave mode; no
recognition of own SLA or GCA.
Switched to the not addressed slave mode; own
SLA will be recognized; GCA will be recognized if
SSGC = logic 1.
Switched to the not addressed slave mode; no
recognition of own SLA or GCA. A START condition
will be transmitted when the bus becomes free.
Switched to the not addressed slave mode; own
SLA will be recognized; GCA will be recognized if
SSGC = logic 1. A START condition will be
transmitted when the bus becomes free.
AT8xC51SND1C
4109H–8051–01/05
AT8xC51SND1C
Table 6. Status for Slave Receiver Mode with General Call Address
Application Software Response
Status
Code
SSSTA
70h
78h
90h
To SSCON
Status of the TWI Bus
and TWI Hardware
To/From SSDAT
General call address
has been received;
ACK has been
returned
No SSDAT action
Arbitration lost in
SLA+R/W as master;
general call address
has been received;
ACK has been
returned
No SSDAT action
Previously addressed
with general call; data
has been received;
ACK has been
returned
Read data Byte
No SSDAT action
SSSTA
SSSTO
SSI
SSAA
X
0
0
0
X
0
0
1
X
0
0
0
X
0
0
1
X
0
0
0
X
0
0
1
Read data Byte
98h
0
0
0
0
0
0
0
1
1
0
0
0
1
0
0
1
0
0
0
0
0
0
0
1
Read data Byte
Read data Byte
No SSDAT action
No SSDAT action
A0h
A STOP condition or
repeated START
condition has been
received while still
addressed as slave
Data Byte will be received and ACK will be returned.
Data Byte will be received and NOT ACK will be
returned.
Data Byte will be received and NOT ACK will be
returned.
Data Byte will be received and ACK will be returned.
Read data Byte
Previously addressed
with general call; data
has been received;
NOT ACK has been
returned
Data Byte will be received and NOT ACK will be
returned.
Data Byte will be received and ACK will be returned.
No SSDAT action
Read data Byte
Next Action Taken by TWI Hardware
No SSDAT action
1
0
0
0
No SSDAT action
1
0
0
1
Switched to the not addressed slave mode; no
recognition of own SLA or GCA.
Switched to the not addressed slave mode; own
SLA will be recognized; GCA will be recognized if
SSGC = logic 1.
Switched to the not addressed slave mode; no
recognition of own SLA or GCA. A START condition
will be transmitted when the bus becomes free.
Switched to the not addressed slave mode; own
SLA will be recognized; GCA will be recognized if
SSGC = logic 1. A START condition will be
transmitted when the bus becomes free.
Switched to the not addressed slave mode; no
recognition of own SLA or GCA.
Switched to the not addressed slave mode; own
SLA will be recognized; GCA will be recognized if
SSGC = logic 1.
Switched to the not addressed slave mode; no
recognition of own SLA or GCA. A START condition
will be transmitted when the bus becomes free.
Switched to the not addressed slave mode; own
SLA will be recognized; GCA will be recognized if
SSGC = logic 1. A START condition will be
transmitted when the bus becomes free.
173
4109H–8051–01/05
Table 7. Status for Slave Transmitter Mode
Application Software Response
Status
Code
SSSTA
A8h
B0h
B8h
Status of the TWI Bus
and TWI Hardware
To SSCON
To/From SSDAT
SSSTA
SSSTO
SSI
SSAA
Own SLA+R has been
received; ACK has
been returned
Write data Byte
X
0
0
0
Last data Byte will be transmitted.
Write data Byte
X
0
0
1
Data Byte will be transmitted.
Arbitration lost in
SLA+R/W as master;
own SLA+R has been
received; ACK has
been returned
Write data Byte
X
0
0
0
X
0
0
1
Data Byte in SSDAT
has been transmitted;
ACK has been
received
Write data Byte
X
0
0
0
X
0
0
1
Last data Byte will be transmitted.
Data Byte will be transmitted.
Write data Byte
Write data Byte
No SSDAT action
No SSDAT action
C0h
Data Byte in SSDAT
has been transmitted;
NOT ACK has been
received
0
0
0
0
0
0
0
1
1
0
0
0
1
0
0
1
0
0
0
0
0
0
0
1
No SSDAT action
No SSDAT action
No SSDAT action
No SSDAT action
C8h
Next Action Taken by TWI Hardware
Last data Byte in
SSDAT has been
transmitted
(SSAA= 0); ACK has
been received
No SSDAT action
1
0
0
0
No SSDAT action
1
0
0
1
SSI
SSAA
Last data Byte will be transmitted.
Data Byte will be transmitted.
Switched to the not addressed slave mode; no
recognition of own SLA or GCA.
Switched to the not addressed slave mode; own
SLA will be recognized; GCA will be recognized if
SSGC = logic 1.
Switched to the not addressed slave mode; no
recognition of own SLA or GCA. A START condition
will be transmitted when the bus becomes free.
Switched to the not addressed slave mode; own
SLA will be recognized; GCA will be recognized if
SSGC = logic 1. A START condition will be
transmitted when the bus becomes free.
Switched to the not addressed slave mode; no
recognition of own SLA or GCA.
Switched to the not addressed slave mode; own
SLA will be recognized; GCA will be recognized if
SSGC = logic 1.
Switched to the not addressed slave mode; no
recognition of own SLA or GCA. A START condition
will be transmitted when the bus becomes free.
Switched to the not addressed slave mode; own
SLA will be recognized; GCA will be recognized if
SSGC = logic 1. A START condition will be
transmitted when the bus becomes free.
Table 8. Status for Miscellaneous States
Application Software Response
Status
Code
SSSTA
To SSCON
Status of the TWI Bus
and TWI Hardware
To/From SSDAT
No relevant state
information available;
SSI = 0
No SSDAT action
F8h
Bus error due to an
illegal START or STOP
condition
No SSDAT action
00h
174
SSSTA
SSSTO
Next Action Taken by TWI Hardware
Wait or proceed current transfer.
No SSCON action
0
1
0
X
Only the internal hardware is affected, no STOP
condition is sent on the bus. In all cases, the bus is
released and SSSTO is reset.
AT8xC51SND1C
4109H–8051–01/05
AT8xC51SND1C
21.9 Registers
Table 10. SSCON Register
SSCON (S:93h) – Synchronous Serial Control Register
7
6
5
4
3
2
1
0
SSCR2
SSPE
SSSTA
SSSTO
SSI
SSAA
SSCR1
SSCR0
Bit
Number
Bit
Mnemonic Description
Synchronous Serial Control Rate Bit 2
Refer to Table 2 for rate description.
7
SSCR2
6
SSPE
Synchronous Serial Peripheral Enable Bit
Set to enable the controller.
Clear to disable the controller.
5
SSSTA
Synchronous Serial Start Flag
Set to send a START condition on the bus.
Clear not to send a START condition on the bus.
4
SSSTO
Synchronous Serial Stop Flag
Set to send a STOP condition on the bus.
Clear not to send a STOP condition on the bus.
3
SSI
Synchronous Serial Interrupt Flag
Set by hardware when a serial interrupt is requested.
Must be cleared by software to acknowledge interrupt.
Synchronous Serial Assert Acknowledge Flag
Set to enable slave modes. Slave modes are entered when SLA or GCA (if
SSGC set) is recognized.
Clear to disable slave modes.
Master Receiver Mode in progress
Clear to force a not acknowledge (high level on SDA).
Set to force an acknowledge (low level on SDA).
Master Transmitter Mode in progress
This bit has no specific effect when in master transmitter mode.
Slave Receiver Mode in progress
Clear to force a not acknowledge (high level on SDA).
Set to force an acknowledge (low level on SDA).
Slave Transmitter Mode in progress
Clear to isolate slave from the bus after last data Byte transmission.
Set to enable slave mode.
2
SSAA
1
SSCR1
Synchronous Serial Control Rate Bit 1
Refer to Table 2 for rate description.
0
SSCR0
Synchronous Serial Control Rate Bit 0
Refer to Table 2 for rate description.
Reset Value = 0000 0000b
175
4109H–8051–01/05
Table 11. SSSTA Register
SSSTA (S:94h) – Synchronous Serial Status Register
7
6
5
4
3
2
1
0
SSC4
SSC3
SSC2
SSC1
SSC0
0
0
0
Bit
Number
Bit
Mnemonic Description
7:3
SSC4:0
2:0
0
Synchronous Serial Status Code Bits 0 to 4
Refer to Table 3 to Table 131 for status description.
Always 0.
Reset Value = F8h
Table 12. SSDAT Register
SSDAT (S:95h) – Synchronous Serial Data Register
7
6
5
4
3
2
1
0
SSD7
SSD6
SSD5
SSD4
SSD3
SSD2
SSD1
SSD0
Bit
Number
Bit
Mnemonic Description
7:1
SSD7:1
Synchronous Serial Address bits 7 to 1 or Synchronous Serial Data Bits 7
to 1
0
SSD0
Synchronous Serial Address bit 0 (R/W) or Synchronous Serial Data Bit 0
Reset Value = 1111 1111b
Table 13. SSADR Register
SSADR (S:96h) – Synchronous Serial Address Register
7
6
5
4
3
2
1
0
SSA7
SSA6
SSA5
SSA4
SSA3
SSA2
SSA1
SSGC
Bit
Number
Bit
Mnemonic Description
7:1
SSA7:1
Synchronous Serial Slave Address Bits 7 to 1
0
SSGC
Synchronous Serial General Call Bit
Set to enable the general call address recognition.
Clear to disable the general call address recognition.
Reset Value = 1111 1110b
176
AT8xC51SND1C
4109H–8051–01/05
AT8xC51SND1C
22. Analog to Digital
Converter
The AT8xC51SND1C implement a 2-channel 10-bit (8 true bits) analog to digital converter (ADC). First channel of this ADC can be used for battery monitoring while the
second one can be used for voice sampling at 8 kHz.
22.1 Description
The A/D converter interfaces with the C51 core through four special function registers:
ADCON, the ADC control register (see Table 4); ADDH and ADDL, the ADC data registers (see Table 6 and Table 7); and ADCLK, the ADC clock register (see Table 5).
As shown in Figure 132, the ADC is composed of a 10-bit cascaded potentiometric digital to analog converter, connected to the negative input of a comparator. The output
voltage of this DAC is compared to the analog voltage stored in the Sample and Hold
and coming from AIN0 or AIN1 input depending on the channel selected (see Table 2).
The 10-bit ADDAT converted value (see formula in Figure 132) is delivered in ADDH
and ADDL registers, ADDH is giving the 8 most significant bits while ADDL is giving the
2 least significant bits. ADDAT
Figure 132. ADC Structure
ADCON.5
ADCON.3
ADEN
ADSST
ADC
Interrupt
Request
ADCON.4
ADEOC
ADC
CLOCK
CONTROL
EADC
IEN1.3
AIN1
0
AIN0
1
8
ADDH
2
ADDL
+
SAR
AVSS
ADCS
Sample and Hold
10
ADCON.0
R/2R DAC
1023 ⋅ V IN
ADDAT = --------------------------V REF
AREFP AREFN
Figure 133 shows the timing diagram of a complete conversion. For simplicity, the figure
depicts the waveforms in idealized form and do not provide precise timing information.
For ADC characteristics and timing parameters refer to the section “AC Characteristics”.
Figure 133. Timing Diagram
CLK
TADCLK
ADEN
TSETUP
ADSST
TCONV
ADEOC
177
4109H–8051–01/05
22.1.1 Clock Generator
The ADC clock is generated by division of the peripheral clock (see details in
section “X2 Feature”, page 12). The division factor is then given by ADCP4:0 bits in
ADCLK register. Figure 134 shows the ADC clock generator and its calculation
formula(1).
Figure 134. ADC Clock Generator and Symbol Caution:
ADCLK
PER
CLOCK
÷2
ADCD4:0
ADC
CLOCK
ADC Clock
ADC Clock Symbol
PERclk
ADCclk = ------------------------2 ⋅ ADCD
Note:
1. In all cases, the ADC clock frequency may be higher than the maximum FADCLK
parameter reported in the section “Analog to Digital Converter”, page 202.
2. The ADCD value of 0 is equivalent to an ADCD value of 32.
22.1.2 Channel Selection
The channel on which conversion is performed is selected by the ADCS bit in ADCON
register according to Table 2.
Table 2. ADC Channel Selection
22.2.1 Conversion Precision
178
Channel
0
AIN1
1
AIN0
The 10-bit precision conversion is achieved by stopping the CPU core activity during
conversion for limiting the digital noise induced by the core. This mode called the
Pseudo-Idle mode(1),(2) is enabled by setting the ADIDL bit in ADCON register(3). Thus,
when conversion is launched (see Section "Conversion Launching", page 179), the
CPU core is stopped until the end of the conversion (see Section "End Of Conversion",
page 179). This bit is cleared by hardware at the end of the conversion.
Notes:
22.2.2 Configuration
ADCS
1. Only the CPU activity is frozen, peripherals are not affected by the Pseudo-Idle
mode.
2. If some interrupts occur during the Pseudo-Idle mode, they will be delayed and processed, according to their priority after the end of the conversion.
3. Concurrently with ADSST bit.
The ADC configuration consists in programming the ADC clock as detailed in the Section "Clock Generator", page 178. The ADC is enabled using the ADEN bit in ADCON
register. As shown in Figure 93, user must wait the setup time (TSETUP) before launching
any conversion.
AT8xC51SND1C
4109H–8051–01/05
AT8xC51SND1C
Figure 135. ADC Configuration Flow
ADC
Configuration
Program ADC Clock
ADCD4:0 = xxxxxb
Enable ADC
ADIDL = x
ADEN = 1
Wait Setup Time
22.2.3 Conversion Launching
The conversion is launched by setting the ADSST bit in ADCON register, this bit
remains set during the conversion. As soon as the conversion is started, it takes 11
clock periods (TCONV) before the data is available in ADDH and ADDL registers.
Figure 136. ADC Conversion Launching Flow
ADC
Conversion Start
Select Channel
ADCS = 0-1
Start Conversion
ADSST = 1
22.2.4 End Of Conversion
The end of conversion is signalled by the ADEOC flag in ADCON register becoming set
or by the ADSST bit in ADCON register becoming cleared. ADEOC flag can generate an
interrupt if enabled by setting EADC bit in IEN1 register. This flag is set by hardware and
must be reset by software.
179
4109H–8051–01/05
22.3 Registers
Table 4. ADCON Register
ADCON (S:F3h) – ADC Control Register
7
6
5
4
3
2
1
0
-
ADIDL
ADEN
ADEOC
ADSST
-
-
ADCS
Bit
Number
Bit
Mnemonic Description
Reserved
The value read from this bit is always 0. Do not set this bit.
7
-
6
ADIDL
ADC Pseudo-Idle Mode
Set to suspend the CPU core activity (pseudo-idle mode) during conversion.
Clear by hardware at the end of conversion.
5
ADEN
ADC Enable Bit
Set to enable the A to D converter.
Clear to disable the A to D converter and put it in low power stand by mode.
4
ADEOC
End Of Conversion Flag
Set by hardware when ADC result is ready to be read. This flag can generate an
interrupt.
Must be cleared by software.
3
ADSST
Start and Status Bit
Set to start an A to D conversion on the selected channel.
Cleared by hardware at the end of conversion.
2-1
-
0
ADCS
Reserved
The value read from these bits is always 0. Do not set these bits.
Channel Selection Bit
Set to select channel 0 for conversion.
Clear to select channel 1 for conversion.
Reset Value = 0000 0000b
Table 5. ADCLK Register
ADCLK (S:F2h) – ADC Clock Divider Register
7
6
5
4
3
2
1
0
-
-
-
ADCD4
ADCD3
ADCD2
ADCD1
ADCD0
Bit
Number
Bit
Mnemonic Description
7-5
-
4-0
ADCD4:0
Reserved
The value read from these bits is always 0. Do not set these bits.
ADC Clock Divider
5-bit divider for ADC clock generation.
Reset Value = 0000 0000b
180
AT8xC51SND1C
4109H–8051–01/05
AT8xC51SND1C
Table 6. ADDH Register
ADDH (S:F5h Read Only) – ADC Data High Byte Register
7
6
5
4
3
2
1
0
ADAT9
ADAT8
ADAT7
ADAT6
ADAT5
ADAT4
ADAT3
ADAT2
Bit
Number
7-0
Bit
Mnemonic Description
ADAT9:2
ADC Data
8 Most Significant Bits of the 10-bit ADC data.
Reset Value = 0000 0000b
Table 7. ADDL Register
ADDL (S:F4h Read Only) – ADC Data Low Byte Register
7
6
5
4
3
2
1
0
-
-
-
-
-
-
ADAT1
ADAT0
Bit
Number
Bit
Mnemonic Description
7-2
-
1-0
ADAT1:0
Reserved
The value read from these bits is always 0. Do not set these bits.
ADC Data
2 Least Significant Bits of the 10-bit ADC data.
Reset Value = 0000 0000b
181
4109H–8051–01/05
23. Keyboard
Interface
The AT8xC51SND1C implement a keyboard interface allowing the connection of a 4 x n
matrix keyboard. It is based on 4 inputs with programmable interrupt capability on both
high or low level. These inputs are available as alternate function of P1.3:0 and allow
exit from idle and power down modes.
23.1 Description
The keyboard interfaces with the C51 core through 2 special function registers: KBCON,
the keyboard control register (see Table 3); and KBSTA, the keyboard control and status register (see Table 4).
The keyboard inputs are considered as 4 independent interrupt sources sharing the
same interrupt vector. An interrupt enable bit (EKB in IEN1 register) allows global
enable or disable of the keyboard interrupt (see Figure 137). As detailed in Figure 138
each keyboard input has the capability to detect a programmable level according to
KINL3:0 bit value in KBCON register. Level detection is then reported in interrupt flags
KINF3:0 in KBSTA register.
A keyboard interrupt is requested each time one of the four flags is set, i.e. the input
level matches the programmed one. Each of these four flags can be masked by software using KINM3:0 bits in KBCON register and is cleared by reading KBSTA register.
This structure allows keyboard arrangement from 1 by n to 4 by n matrix and allow
usage of KIN inputs for any other purposes.
Figure 137. Keyboard Interface Block Diagram
KIN0
Input Circuitry
KIN1
Input Circuitry
KIN2
Input Circuitry
KIN3
Input Circuitry
Keyboard Interface
Interrupt Request
EKB
IEN1.4
Figure 138. Keyboard Input Circuitry
0
KIN3:0
KINF3:0
1
KBSTA.3:0
KINM3:0
KINL3:0
KBCON.3:0
KBCON.7:4
23.1.1 Power Reduction Mode
KIN3:0 inputs allow exit from idle and power-down modes as detailed in section “Power
Management”, page 48. To enable this feature, KPDE bit in KBSTA register must be set
to logic 1.
Due to the asynchronous keypad detection in power down mode (all clocks are
stopped), exit may happen on parasitic key press. In this case, no key is detected and
software must enter power down again.
182
AT8xC51SND1C
4109H–8051–01/05
AT8xC51SND1C
23.2 Registers
Table 3. KBCON Register
KBCON (S:A3h) – Keyboard Control Register
7
6
5
4
3
2
1
0
KINL3
KINL2
KINL1
KINL0
KINM3
KINM2
KINM1
KINM0
Bit
Number
Bit
Mnemonic Description
7-4
KINL3:0
Keyboard Input Level Bit
Set to enable a high level detection on the respective KIN3:0 input.
Clear to enable a low level detection on the respective KIN3:0 input.
3-0
KINM3:0
Keyboard Input Mask Bit
Set to prevent the respective KINF3:0 flag from generating a keyboard interrupt.
Clear to allow the respective KINF3:0 flag to generate a keyboard interrupt.
Reset Value = 0000 1111b
Table 4. KBSTA Register
KBSTA (S:A4h) – Keyboard Control and Status Register
7
6
5
4
3
2
1
0
KPDE
-
-
-
KINF3
KINF2
KINF1
KINF0
Bit
Number
Bit
Mnemonic Description
7
KPDE
6-4
-
3-0
KINF3:0
Keyboard Power Down Enable Bit
Set to enable exit of power down mode by the keyboard interrupt.
Clear to disable exit of power down mode by the keyboard interrupt.
Reserved
The value read from these bits is always 0. Do not set these bits.
Keyboard Input Interrupt Flag
Set by hardware when the respective KIN3:0 input detects a programmed level.
Cleared when reading KBSTA.
Reset Value = 0000 0000b
183
4109H–8051–01/05
24. Electrical Characteristics
24.1 Absolute Maximum Rating
Storage Temperature ......................................... -65 to +150°C
Voltage on any other Pin to VSS
.................................... -0.3
*NOTICE:
to +4.0 V
IOL per I/O Pin ................................................................. 5 mA
Power Dissipation ............................................................. 1 W
Stressing the device beyond the “Absolute Maximum Ratings” may cause permanent damage.
These are stress ratings only. Operation beyond
the “operating conditions” is not recommended
and extended exposure beyond the “Operating
Conditions” may affect device reliability.
Operating Conditions
Ambient Temperature Under Bias........................ -40 to +85°C
VDD ........................................................................................................................ 4.0V
24.2 DC Characteristics
24.2.1 Digital Logic
Table 3. Digital DC Characteristics
VDD = 2.7 to 3.3 V, TA = -40 to +85°C
Symbol
VIL
VIH1(2)
Min
Input Low Voltage
Input High Voltage (except RST, X1)
Typ(1)
Max
Units
-0.5
0.2·VDD - 0.1
V
0.2·VDD + 1.1
VDD
V
0.7·VDD
VDD + 0.5
V
Test Conditions
VIH2
Input High Voltage (RST, X1)
VOL1
Output Low Voltage
(except P0, ALE, MCMD, MDAT, MCLK,
SCLK, DCLK, DSEL, DOUT)
0.45
V
IOL= 1.6 mA
VOL2
Output Low Voltage
(P0, ALE, MCMD, MDAT, MCLK, SCLK,
DCLK, DSEL, DOUT)
0.45
V
IOL= 3.2 mA
VOH1
Output High Voltage
(P1, P2, P3, P4 and P5)
VDD - 0.7
V
IOH= -30 µA
VOH2
Output High Voltage
(P0, P2 address mode, ALE, MCMD,
MDAT, MCLK, SCLK, DCLK, DSEL,
DOUT, D+, D-)
VDD - 0.7
V
IOH= -3.2 mA
IIL
Logical 0 Input Current (P1, P2, P3, P4
and P5)
-50
µA
VIN= 0.45 V
ILI
Input Leakage Current (P0, ALE, MCMD,
MDAT, MCLK, SCLK, DCLK, DSEL,
DOUT)
10
µA
0.45< VIN< VDD
ITL
Logical 1 to 0 Transition Current
(P1, P2, P3, P4 and P5)
-650
µA
VIN= 2.0 V
200
kΩ
RRST
CIO
VRET
184
Parameter
Pull-Down Resistor
Pin Capacitance
VDD Data Retention Limit
50
90
10
pF
1.8
TA= 25°C
V
AT8xC51SND1C
4109H–8051–01/05
AT8xC51SND1C
Table 3. Digital DC Characteristics
VDD = 2.7 to 3.3 V, TA = -40 to +85°C
Symbol
Parameter
Min
AT89C51SND1C
Operating Current
IDD
Typ(1)
Max
(3)
X1 / X2 mode
6.5 / 10.5
8 / 13.5
9.5 / 17
AT83SND1C
Operating Current
X1 / X2 mode
6.5 / 10.5
8 / 13.5
9.5 / 17
AT80C51SND1C
Idle Mode Current
X1 / X2 mode
6.5 / 10.5
8 / 13.5
9.5 / 17
AT89C51SND1C
(3)
Idle Mode Current
IDL
IPD
IFP
Units
X1 / X2 mode
5.3 / 8.1
6.4 / 10.3
7.5 / 13
Test Conditions
VDD < 3.3 V
mA
12 MHz
16 MHz
20 MHz
VDD < 3.3 V
mA
12 MHz
16 MHz
20 MHz
VDD < 3.3 V
mA
12 MHz
16 MHz
20 MHz
VDD < 3.3 V
mA
12 MHz
16 MHz
20 MHz
VDD < 3.3 V
AT83SND1C
Idle Mode Current
X1 / X2 mode
5.3 / 8.1
6.4 / 10.3
7.5 / 13
AT80C51SND1C
Idle Mode Current
X1 / X2 mode
5.3 / 8.1
6.4 / 10.3
7.5 / 13
mA
mA
12 MHz
16 MHz
20 MHz
VDD < 3.3 V
12 MHz
16 MHz
20 MHz
AT89C51SND1C
Power-Down Mode Current
20
500
µA
VRET < VDD < 3.3 V
AT83SND1C
Power-Down Mode Current
20
500
µA
VRET < VDD < 3.3 V
AT80C51SND1C
Power-Down Mode Current
20
500
µA
VRET < VDD < 3.3 V
15
mA
VDD < 3.3 V
AT89C51SND1C
Flash Programming Current
Notes:
1. Typical values are obtained using VDD= 3 V and TA= 25°C. They are not tested and
there is no guarantee on these values.
2. Flash retention is guaranteed with the same formula for VDD min down to 0V.
3. See Table 4 for typical consumption in player mode.
Table 4. Typical Reference Design AT89C51SND1C Power Consumption
Player Mode
IDD
Test Conditions
Stop
10 mA
AT89C51SND1C at 16 MHz, X2 mode, VDD= 3 V
No song playing
Playing
30 mA
AT89C51SND1C at 16 MHz, X2 mode, VDD= 3 V
MP3 Song with Fs= 44.1 KHz, at any bit rates (Variable Bit Rate)
185
4109H–8051–01/05
IDD, IDL and IPD Test Conditions
Figure 139. IDD Test Condition, Active Mode
VDD
VDD
RST
(NC)
Clock Signal
VDD
PVDD
UVDD
AVDD
X2
X1
IDD
VDD
P0
VSS
PVSS
UVSS
AVSS
VSS
TST
All other pins are unconnected
Figure 140. IDL Test Condition, Idle Mode
VDD
RST
VSS
(NC)
Clock Signal
VDD
PVDD
UVDD
AVDD
X2
X1
IDL
VDD
P0
VSS
PVSS
UVSS
AVSS
VSS
TST
All other pins are unconnected
Figure 141. IPD Test Condition, Power-Down Mode
VDD
RST
VSS
(NC)
X2
X1
VSS
PVSS
UVSS
AVSS
VSS
186
VDD
PVDD
UVDD
AVDD
IPD
VDD
P0
MCMD
MDAT
TST
All other pins are unconnected
AT8xC51SND1C
4109H–8051–01/05
AT8xC51SND1C
24.4.1 A to D Converter
Table 5. A to D Converter DC Characteristics
VDD = 2.7 to 3.3 V, TA = -40 to +85°C
Symbol
Parameter
Min
Typ
Max
Units
3.3
V
Test Conditions
AVDD
Analog Supply Voltage
AIDD
Analog Operating Supply
Current
600
µA
AVDD= 3.3V
AIN1:0= 0 to AVDD
ADEN= 1
AIPD
Analog Standby Current
2
µA
AVDD= 3.3V
ADEN= 0 or PD= 1
AVIN
Analog Input Voltage
AVSS
AVDD
V
Reference Voltage
AREFN
AREFP
AVSS
2.4
AVDD
10
30
KΩ
TA= 25°C
10
pF
TA= 25°C
AVREF
2.7
AREF Input Resistance
RREF
CIA
V
Analog Input capacitance
24.5.1 Oscillator & Crystal
Schematic
Figure 142. Crystal Connection
X1
C1
Q
C2
VSS
Note:
Parameters
X2
For operation with most standard crystals, no external components are needed on X1
and X2. It may be necessary to add external capacitors on X1 and X2 to ground in special cases (max 10 pF). X1 and X2 may not be used to drive other circuits.
Table 6. Oscillator & Crystal Characteristics
VDD = 2.7 to 3.3 V, TA = -40 to +85°C
Symbol
Parameter
Min
Typ
Max
Unit
CX1
Internal Capacitance (X1 - VSS)
10
pF
CX2
Internal Capacitance (X2 - VSS)
10
pF
CL
Equivalent Load Capacitance (X1 - X2)
5
pF
DL
Drive Level
50
µW
Crystal Frequency
20
MHz
RS
Crystal Series Resistance
40
Ω
CS
Crystal Shunt Capacitance
6
pF
F
187
4109H–8051–01/05
24.6.1 Phase Lock Loop
Schematic
Figure 143. PLL Filter Connection
FILT
R
C2
C1
VSS
Parameters
VSS
Table 7. PLL Filter Characteristics
VDD = 2.7 to 3.3 V, TA = -40 to +85°C
Symbol
Parameter
Min
Typ
Max
Unit
R
Filter Resistor
100
Ω
C1
Filter Capacitance 1
10
nF
C2
Filter Capacitance 2
2.2
nF
24.7.1 USB Connection
Schematic
Figure 144. USB Connection
To Power Supply
RUSB
VBUS
D+
D-
D+
D-
RUSB
GND
VSS
Parameters
Table 8. USB Termination Characteristics
VDD = 2.7 to 3.3 V, TA = -40 to +85°C
Symbol
RUSB
Parameter
Min
USB Termination Resistor
Typ
Max
Unit
Ω
27
24.8.1 In System Programming
Schematic
Figure 145. ISP Pull-Down Connection
ISP
RISP
VSS
Parameters
Table 9. ISP Pull-Down Characteristics
VDD = 2.7 to 3.3 V, TA = -40 to +85°C
Symbol
RISP
188
Parameter
ISP Pull-Down Resistor
Min
Typ
2.2
Max
Unit
KΩ
AT8xC51SND1C
4109H–8051–01/05
AT8xC51SND1C
24.10 AC Characteristics
24.10.1 External Program Bus Cycles
Definition of Symbols
Table 11. External Program Bus Cycles Timing Symbol Definitions
Signals
Timings
Conditions
A
Address
H
High
I
Instruction In
L
Low
L
ALE
V
Valid
P
PSEN
X
No Longer Valid
Z
Floating
Test conditions: capacitive load on all pins= 50 pF.
Table 12. External Program Bus Cycle - Read AC Timings
VDD = 2.7 to 3.3 V, TA = -40 to +85°C
Variable Clock
Standard Mode
Symbol
Parameter
TCLCL
Clock Period
TLHLL
ALE Pulse Width
TAVLL
Min
Max
Variable Clock
X2 Mode
Min
Max
Unit
50
50
ns
2·TCLCL-15
TCLCL-15
ns
Address Valid to ALE Low
TCLCL-20
0.5·TCLCL20
ns
TLLAX
Address hold after ALE Low
TCLCL-20
0.5·TCLCL20
ns
TLLIV
ALE Low to Valid Instruction
4·TCLCL-35
2·TCLCL-35
ns
TPLPH
PSEN Pulse Width
3·TCLCL-25
1.5·TCLCL25
ns
TPLIV
PSEN Low to Valid Instruction
TPXIX
Instruction Hold After PSEN High
TPXIZ
Instruction Float After PSEN High
TCLCL-10
0.5·TCLCL10
ns
TAVIV
Address Valid to Valid Instruction
5·TCLCL-35
2.5·TCLCL35
ns
TPLAZ
PSEN Low to Address Float
10
10
ns
1.5·TCLCL35
3·TCLCL-35
0
0
ns
ns
189
4109HS–8051–01/05
Waveforms
Figure 146. External Program Bus Cycle - Read Waveforms
ALE
TLHLL
TPLPH
TLLPL
PSEN
TPLIV
TPLAZ
TAVLL TLLAX
P0
D7:0
TPXAV
TPXIZ
TPXIX
A7:0
D7:0
A7:0
D7:0
Instruction In
P2
Instruction In
A15:8
A15:8
24.12.1 External Data 8-bit Bus Cycles
Definition of Symbols
Table 13. External Data 8-bit Bus Cycles Timing Symbol Definitions
Signals
Timings
Conditions
A
Address
H
High
D
Data In
L
Low
L
ALE
V
Valid
Q
Data Out
X
No Longer Valid
R
RD
Z
Floating
W
WR
Test conditions: capacitive load on all pins= 50 pF.
Table 14. External Data 8-bit Bus Cycle - Read AC Timings
VDD = 2.7 to 3.3 V, TA = -40 to +85°C
Variable Clock
Standard Mode
Symbol
190
Parameter
TCLCL
Clock Period
TLHLL
ALE Pulse Width
TAVLL
Min
Max
Variable Clock
X2 Mode
Min
Max
Unit
50
50
ns
2·TCLCL-15
TCLCL-15
ns
Address Valid to ALE Low
TCLCL-20
0.5·TCLCL-20
ns
TLLAX
Address hold after ALE Low
TCLCL-20
0.5·TCLCL-20
ns
TLLRL
ALE Low to RD Low
3·TCLCL-30
1.5·TCLCL-30
ns
AT8xC51SND1C
4109HS–8051–01/05
AT8xC51SND1C
Variable Clock
Standard Mode
Symbol
Parameter
TRLRH
RD Pulse Width
TRHLH
RD high to ALE High
TAVDV
Address Valid to Valid Data In
TAVRL
Address Valid to RD Low
TRLDV
RD Low to Valid Data
TRLAZ
RD Low to Address Float
TRHDX
Data Hold After RD High
TRHDZ
Instruction Float After RD High
Min
Max
6·TCLCL-25
TCLCL-20
Variable Clock
X2 Mode
Min
Max
3·TCLCL-25
TCLCL+20
0.5·TCLCL-20
9·TCLCL-65
4·TCLCL-30
Unit
ns
0.5·TCLCL+2
0
ns
4.5·TCLCL-65
ns
2·TCLCL-30
ns
5·TCLCL-30
2.5·TCLCL-30
ns
0
0
ns
0
0
2·TCLCL-25
ns
TCLCL-25
ns
191
4109HS–8051–01/05
Table 15. External Data 8-bit Bus Cycle - Write AC Timings
VDD = 2.7 to 3.3 V, TA = -40 to +85°C
Variable Clock
Standard Mode
Symbol
Waveforms
Parameter
TCLCL
Clock Period
TLHLL
ALE Pulse Width
TAVLL
Min
Variable Clock
X2 Mode
Max
Min
Max
Unit
50
50
ns
2·TCLCL-15
TCLCL-15
ns
Address Valid to ALE Low
TCLCL-20
0.5·TCLCL-20
ns
TLLAX
Address hold after ALE Low
TCLCL-20
0.5·TCLCL-20
ns
TLLWL
ALE Low to WR Low
3·TCLCL-30
1.5·TCLCL-30
ns
TWLWH
WR Pulse Width
6·TCLCL-25
3·TCLCL-25
ns
TWHLH
WR High to ALE High
TAVWL
Address Valid to WR Low
4·TCLCL-30
2·TCLCL-30
ns
TQVWH
Data Valid to WR High
7·TCLCL-20
3.5·TCLCL-20
ns
TWHQX
Data Hold after WR High
TCLCL-15
0.5·TCLCL-15
ns
TCLCL-20
TCLCL+20
0.5·TCLCL-20
0.5·TCLCL+2
0
ns
Figure 147. External Data 8-bit Bus Cycle - Read Waveforms
ALE
TLHLL
TLLRL
TRLRH
TRHLH
RD
TRLDV
TRHDZ
TRLAZ
TAVLL
P0
TLLAX
TRHDX
A7:0
D7:0
TAVRL
Data In
TAVDV
P2
192
A15:8
AT8xC51SND1C
4109HS–8051–01/05
AT8xC51SND1C
Figure 148. External Data 8-bit Bus Cycle - Write Waveforms
ALE
TLHLL
TLLWL
TWHLH
TWLWH
WR
TAVWL
TAVLL
P0
TLLAX
TQVWH
A7:0
TWHQX
D7:0
Data Out
P2
A15:8
24.15.1 External IDE 16-bit Bus Cycles
Definition of Symbols
Table 16. External IDE 16-bit Bus Cycles Timing Symbol Definitions
Signals
Conditions
A
Address
H
High
D
Data In
L
Low
L
ALE
V
Valid
Q
Data Out
X
No Longer Valid
R
RD
Z
Floating
W
WR
193
4109HS–8051–01/05
Timings
Test conditions: capacitive load on all pins= 50 pF.
Table 17. External IDE 16-bit Bus Cycle - Data Read AC Timings
VDD = 2.7 to 3.3 V, TA = -40 to +85°C
Variable Clock
Standard Mode
Symbol
Parameter
TCLCL
Clock Period
TLHLL
ALE Pulse Width
TAVLL
Min
Max
Variable Clock
X2 Mode
Min
Max
Unit
50
50
ns
2·TCLCL-15
TCLCL-15
ns
Address Valid to ALE Low
TCLCL-20
0.5·TCLCL-20
ns
TLLAX
Address hold after ALE Low
TCLCL-20
0.5·TCLCL-20
ns
TLLRL
ALE Low to RD Low
3·TCLCL-30
1.5·TCLCL-30
ns
TRLRH
RD Pulse Width
6·TCLCL-25
3·TCLCL-25
ns
TRHLH
RD high to ALE High
TAVDV
Address Valid to Valid Data In
TAVRL
Address Valid to RD Low
TRLDV
RD Low to Valid Data
TRLAZ
RD Low to Address Float
TRHDX
Data Hold After RD High
TRHDZ
Instruction Float After RD High
TCLCL-20
TCLCL+20
0.5·TCLCL-20
9·TCLCL-65
4·TCLCL-30
0.5·TCLCL+2
0
ns
4.5·TCLCL-65
ns
2·TCLCL-30
ns
5·TCLCL-30
2.5·TCLCL-30
ns
0
0
ns
0
0
2·TCLCL-25
ns
TCLCL-25
ns
Table 18. External IDE 16-bit Bus Cycle - Data Write AC Timings
VDD = 2.7 to 3.3 V, TA = -40 to +85°C
Variable Clock
Standard Mode
Symbol
194
Parameter
TCLCL
Clock Period
TLHLL
ALE Pulse Width
TAVLL
Min
Max
Variable Clock
X2 Mode
Min
Max
Unit
50
50
ns
2·TCLCL-15
TCLCL-15
ns
Address Valid to ALE Low
TCLCL-20
0.5·TCLCL-20
ns
TLLAX
Address hold after ALE Low
TCLCL-20
0.5·TCLCL-20
ns
TLLWL
ALE Low to WR Low
3·TCLCL-30
1.5·TCLCL-30
ns
TWLWH
WR Pulse Width
6·TCLCL-25
3·TCLCL-25
ns
TWHLH
WR High to ALE High
TAVWL
Address Valid to WR Low
4·TCLCL-30
2·TCLCL-30
ns
TQVWH
Data Valid to WR High
7·TCLCL-20
3.5·TCLCL-20
ns
TWHQX
Data Hold after WR High
TCLCL-15
0.5·TCLCL-15
ns
TCLCL-20
TCLCL+20
0.5·TCLCL-20
0.5·TCLCL+2
0
ns
AT8xC51SND1C
4109HS–8051–01/05
AT8xC51SND1C
Waveforms
Figure 149. External IDE 16-bit Bus Cycle - Data Read Waveforms
ALE
TLHLL
TLLRL
TRLRH
TRHLH
RD
TRLDV
TRHDZ
TRLAZ
TAVLL
P0
TLLAX
TRHDX
A7:0
D7:0
TAVRL
Data In
TAVDV
P2
D15:8(1)
A15:8
Data In
Note:
1. D15:8 is written in DAT16H SFR.
Figure 150. External IDE 16-bit Bus Cycle - Data Write Waveforms
ALE
TLHLL
TLLWL
TWLWH
TWHLH
WR
TAVWL
TAVLL
P0
TLLAX
TQVWH
A7:0
TWHQX
D7:0
Data Out
P2
A15:8
D15:8(1)
Data Out
Note:
1. D15:8 is the content of DAT16H SFR.
24.19 SPI Interface
Definition of Symbols
Table 20. SPI Interface Timing Symbol Definitions
Signals
Conditions
C
Clock
H
High
I
Data In
L
Low
O
Data Out
V
Valid
X
No Longer Valid
Z
Floating
195
4109HS–8051–01/05
Timings
Test conditions: capacitive load on all pins= 50 pF.
Table 21. SPI Interface Master AC Timing
VDD = 2.7 to 3.3 V, TA = -40 to +85°C
Symbol
Parameter
Min
Max
Unit
Slave Mode
TCHCH
Clock Period
TCHCX
2
TPER
Clock High Time
0.8
TPER
TCLCX
Clock Low Time
0.8
TPER
TSLCH, TSLCL
SS Low to Clock edge
100
ns
TIVCL, TIVCH
Input Data Valid to Clock Edge
40
ns
TCLIX, TCHIX
Input Data Hold after Clock Edge
40
ns
TCLOV, TCHOV
Output Data Valid after Clock Edge
TCLOX, TCHOX
Output Data Hold Time after Clock Edge
0
ns
TCLSH, TCHSH
SS High after Clock Edge
0
ns
TSLOV
SS Low to Output Data Valid
50
ns
TSHOX
Output Data Hold after SS High
50
ns
TSHSL
SS High to SS Low
TILIH
Input Rise Time
2
µs
TIHIL
Input Fall Time
2
µs
TOLOH
Output Rise time
100
ns
TOHOL
Output Fall Time
100
ns
40
ns
(1)
Master Mode
TCHCH
Clock Period
TCHCX
2
TPER
Clock High Time
0.8
TPER
TCLCX
Clock Low Time
0.8
TPER
TIVCL, TIVCH
Input Data Valid to Clock Edge
20
ns
TCLIX, TCHIX
Input Data Hold after Clock Edge
20
ns
TCLOV, TCHOV
Output Data Valid after Clock Edge
TCLOX, TCHOX
Output Data Hold Time after Clock Edge
TILIH
Input Data Rise Time
2
µs
TIHIL
Input Data Fall Time
2
µs
TOLOH
Output Data Rise time
50
ns
TOHOL
Output Data Fall Time
50
ns
Note:
196
40
0
ns
ns
1. Value of this parameter depends on software.
AT8xC51SND1C
4109HS–8051–01/05
AT8xC51SND1C
Waveforms
Figure 151. SPI Slave Waveforms (SSCPHA= 0)
SS
(input)
TSLCH
TSLCL
TCHCH
SCK
(SSCPOL= 0)
(input)
TCHCX
TCLCH
TSHSL
TCLCX
TCHCL
SCK
(SSCPOL= 1)
(input)
TCLOX
TCHOX
TCLOV
TCHOV
TSLOV
MISO
(output)
TCLSH
TCHSH
SLAVE MSB OUT
BIT 6
TSHOX
SLAVE LSB OUT
(1)
TIVCH TCHIX
TIVCL TCLIX
MOSI
(input)
Note:
MSB IN
BIT 6
LSB IN
1. Not Defined but generally the MSB of the character which has just been received.
Figure 152. SPI Slave Waveforms (SSCPHA= 1)
SS
(input)
TSLCH
TSLCL
SCK
(SSCPOL= 0)
(input)
TCHCH
TCHCX
TSHSL
TCLCX
TCHCL
SCK
(SSCPOL= 1)
(input)
TCHOV
TCLOV
TSLOV
MISO
(output)
TCLCH
TCLSH
TCHSH
(1)
SLAVE MSB OUT
BIT 6
TCHOX
TCLOX
TSHOX
SLAVE LSB OUT
TIVCH TCHIX
TIVCL TCLIX
MOSI
(input)
Note:
MSB IN
BIT 6
LSB IN
1. Not Defined but generally the LSB of the character which has just been received.
197
4109HS–8051–01/05
Figure 153. SPI Master Waveforms (SSCPHA= 0)
SS
(output)
TCHCH
SCK
(SSCPOL= 0)
(output)
TCHCX
TCLCH
TCLCX
TCHCL
SCK
(SSCPOL= 1)
(output)
TIVCH TCHIX
TIVCL TCLIX
MOSI
(input)
MSB IN
BIT 6
LSB IN
TCLOX
TCLOV
TCHOV
MISO
(output)
Port Data
Note:
MSB OUT
TCHOX
BIT 6
LSB OUT
Port Data
1. SS handled by software using general purpose port pin.
Figure 154. SPI Master Waveforms (SSCPHA= 1)
SS(1)
(output)
TCHCH
SCK
(SSCPOL= 0)
(output)
TCHCX
TCLCH
TCLCX
TCHCL
SCK
(SSCPOL= 1)
(output)
TIVCH TCHIX
TIVCL TCLIX
MOSI
(input)
MISO
(output)
Note:
198
MSB IN
BIT 6
TCLOV
TCLOX
TCHOX
TCHOV
Port Data
MSB OUT
BIT 6
LSB IN
LSB OUT
Port Data
1. SS handled by software using general purpose port pin.
AT8xC51SND1C
4109HS–8051–01/05
AT8xC51SND1C
24.21.1 Two-wire Interface
Timings
Table 22. TWI Interface AC Timing
VDD = 2.7 to 3.3 V, TA = -40 to +85°C
INPUT
Min
Max
OUTPUT
Min
Max
Start condition hold time
14·TCLCL(4)
4.0 µs(1)
TLOW
SCL low time
16·TCLCL(4)
4.7 µs(1)
THIGH
SCL high time
14·TCLCL(4)
4.0 µs(1)
TRC
SCL rise time
1 µs
-(2)
TFC
SCL fall time
0.3 µs
0.3 µs(3)
TSU; DAT1
Data set-up time
250 ns
20·TCLCL(4)TRD
TSU; DAT2
SDA set-up time (before repeated START condition)
250 ns
1 µs(1)
TSU; DAT3
SDA set-up time (before STOP condition)
250 ns
8·TCLCL(4)
THD; DAT
Data hold time
0 ns
8·TCLCL(4) - TFC
TSU; STA
Repeated START set-up time
14·TCLCL(4)
4.7 µs(1)
TSU; STO
STOP condition set-up time
14·TCLCL(4)
4.0 µs(1)
TBUF
Bus free time
14·TCLCL(4)
4.7 µs(1)
TRD
SDA rise time
1 µs
-(2)
TFD
SDA fall time
0.3 µs
0.3 µs(3)
Symbol
THD; STA
Notes:
Waveforms
Parameter
1. At 100 kbit/s. At other bit-rates this value is inversely proportional to the bit-rate of
100 kbit/s.
2. Determined by the external bus-line capacitance and the external bus-line pull-up
resistor, this must be < 1 µs.
3. Spikes on the SDA and SCL lines with a duration of less than 3·TCLCL will be filtered
out. Maximum capacitance on bus-lines SDA and
SCL= 400 pF.
4. TCLCL= TOSC= one oscillator clock period.
Figure 155. Two Wire Waveforms
Repeated START condition
START or Repeated START condition
START condition
STOP condition
Trd
Tsu;STA
0.7 VDD
0.3 VDD
SDA
(INPUT/OUTPUT)
Tsu;STO
Tfd
Trc
Tfc
Tbuf
Tsu;DAT3
0.7 VDD
0.3 VDD
SCL
(INPUT/OUTPUT)
Thd;STA
Tlow Thigh Tsu;DAT1
Thd;DAT
Tsu;DAT2
199
4109HS–8051–01/05
24.22.1 MMC Interface
Definition of symbols
Table 23. MMC Interface Timing Symbol Definitions
Signals
Timings
Conditions
C
Clock
H
High
D
Data In
L
Low
O
Data Out
V
Valid
X
No Longer Valid
Table 24. MMC Interface AC timings
VDD = 2.7 to 3.3 V, TA = -40 to +85°C, CL ≤ 100pF (10 cards)
Symbol
Waveforms
Parameter
Min
Max
Unit
TCHCH
Clock Period
50
ns
TCHCX
Clock High Time
10
ns
TCLCX
Clock Low Time
10
ns
TCLCH
Clock Rise Time
10
ns
TCHCL
Clock Fall Time
10
ns
TDVCH
Input Data Valid to Clock High
3
ns
TCHDX
Input Data Hold after Clock High
3
ns
TCHOX
Output Data Hold after Clock High
5
ns
TOVCH
Output Data Valid to Clock High
5
ns
Figure 156. MMC Input-Output Waveforms
TCHCH
TCHCX
TCLCX
MCLK
TCHCL
TCHIX
TCLCH
TIVCH
MCMD Input
MDAT Input
TCHOX
TOVCH
MCMD Output
MDAT Output
200
AT8xC51SND1C
4109HS–8051–01/05
AT8xC51SND1C
24.24.1 Audio Interface
Definition of symbols
Table 25. Audio Interface Timing Symbol Definitions
Signals
Timings
Conditions
C
Clock
H
High
O
Data Out
L
Low
S
Data Select
V
Valid
X
No Longer Valid
Table 26. Audio Interface AC timings
VDD = 2.7 to 3.3 V, TA = -40 to +85°C, CL≤ 30pF
Symbol
Min
Max
Unit
(1)
TCHCH
Clock Period
TCHCX
Clock High Time
30
ns
TCLCX
Clock Low Time
30
ns
TCLCH
Clock Rise Time
10
ns
TCHCL
Clock Fall Time
10
ns
TCLSV
Clock Low to Select Valid
10
ns
TCLOV
Clock Low to Data Valid
10
ns
Note:
Waveforms
Parameter
325.5
ns
1. 32-bit format with Fs= 48 KHz.
Figure 157. Audio Interface Waveforms
TCHCH
TCHCX
TCLCX
DCLK
TCHCL
TCLCH
TCLSV
DSEL
Right
Left
TCLOV
DDAT
201
4109HS–8051–01/05
24.26.1 Analog to Digital Converter
Definition of symbols
Table 27. Analog to Digital Converter Timing Symbol Definitions
Signals
Characteristics
Conditions
C
Clock
H
High
E
Enable (ADEN bit)
L
Low
S
Start Conversion
(ADSST bit)
Table 28. Analog to Digital Converter AC Characteristics
VDD = 2.7 to 3.3 V, TA = -40 to +85°C
Symbol
TCLCL
Clock Period
TEHSH
Start-up Time
TSHSL
Min
Max
Unit
µs
4
4
µs
Conversion Time
11·TCLCL
µs
DLe
Differential nonlinearity error(1)(2)
1
LSB
ILe
Integral nonlinearity errorss(1)(3)
2
LSB
OSe
Offset error(1)(4)
4
LSB
4
LSB
Ge
Notes:
Waveforms
Parameter
Gain error
(1)(5)
1. AVDD= AVREFP= 3.0 V, AVSS= AVREFN= 0 V. ADC is monotonic with no missing code.
2. The differential non-linearity is the difference between the actual step width and the
ideal step width (see Figure 159).
3. The integral non-linearity is the peak difference between the center of the actual step
and the ideal transfer curve after appropriate adjustment of gain and offset errors
(see Figure 159).
4. The offset error is the absolute difference between the straight line which fits the
actual transfer curve (after removing of gain error), and the straight line which fits the
ideal transfer curve (see Figure 159).
5. The gain error is the relative difference in percent between the straight line which fits
the actual transfer curve (after removing of offset error), and the straight line which
fits the ideal transfer curve (see Figure 159).
Figure 158. Analog to Digital Converter Internal Waveforms
CLK
TCLCL
ADEN Bit
TEHSH
ADSST Bit
TSHSL
202
AT8xC51SND1C
4109HS–8051–01/05
AT8xC51SND1C
Figure 159. Analog to Digital Converter Characteristics
Offset Gain
Error Error
OSe
Ge
Code Out
1023
1022
1021
1020
1019
1018
Ideal Transfer curve
Example of an actual transfer curve
7
6
5
Center of a step
4
Integral non-linearity (ILe)
3
Differential non-linearity (DLe)
2
1
1 LSB
(ideal)
0
0
1
2
3
4
5
6
7
AVIN
(LSB ideal)
1018 1019 1020 1021 1022 1023 1024
Offset
Error OSe
24.28.1 Flash Memory
Definition of symbols
Table 29. Flash Memory Timing Symbol Definitions
Signals
Timings
Conditions
S
ISP
L
Low
R
RST
V
Valid
B
FBUSY flag
X
No Longer Valid
Table 30. Flash Memory AC Timing
VDD = 2.7 to 3.3 V, TA = -40 to +85°C
Symbol
Parameter
Min
Typ
Max
Unit
TSVRL
Input ISP Valid to RST Edge
50
ns
TRLSX
Input ISP Hold after RST Edge
50
ns
TBHBL
FLASH Internal Busy (Programming) Time
NFCY
Number of Flash Write Cycles
TFDR
Flash Data Retention Time
10
ms
100K
Cycle
10
Years
203
4109HS–8051–01/05
Waveforms
Figure 160. FLASH Memory - ISP Waveforms
RST
TSVRL
TRLSX
(1)
ISP
Note:
1. ISP must be driven through a pull-down resistor (see Section “In System Programming”, page 188).
Figure 161. FLASH Memory - Internal Busy Waveforms
FBUSY bit
TBHBL
24.30.1 External Clock Drive and Logic Level References
Definition of symbols
Table 31. External Clock Timing Symbol Definitions
Signals
C
Timings
Conditions
Clock
H
High
L
Low
X
No Longer Valid
Table 32. External Clock AC Timings
VDD = 2.7 to 3.3 V, TA = -40 to +85°C
Symbol
Parameter
Unit
Clock Period
50
ns
TCHCX
High Time
10
ns
TCLCX
Low Time
10
ns
TCLCH
Rise Time
3
ns
TCHCL
Fall Time
3
ns
Cyclic Ratio in X2 mode
40
60
%
Figure 162. External Clock Waveform
TCLCH
VDD - 0.5
0.45 V
VIH1
TCHCX
TCLCX
VIL
TCHCL
204
Max
TCLCL
TCR
Waveforms
Min
TCLCL
AT8xC51SND1C
4109HS–8051–01/05
AT8xC51SND1C
Figure 163. AC Testing Input/Output Waveforms
INPUTS
VDD - 0.5
0.45 V
Note:
OUTPUTS
0.7 VDD
VIH min
0.3 VDD
VIL max
1. During AC testing, all inputs are driven at VDD -0.5 V for a logic 1 and 0.45 V for a
logic 0.
2. Timing measurements are made on all outputs at VIH min for a logic 1 and VIL max for
a logic 0.
Figure 164. Float Waveforms
VLOAD
VLOAD + 0.1 V
VLOAD - 0.1 V
Note:
Timing Reference Points
VOH - 0.1 V
VOL + 0.1 V
For timing purposes, a port pin is no longer floating when a 100 mV change from load
voltage occurs and begins to float when a 100 mV change from the loading VOH/VOL level
occurs with IOL/IOH= ±20 mA.
205
4109HS–8051–01/05
25. Ordering Information
Part Number
Memory
Size
Supply
Voltage
Temperature
Range
Max
Frequency
Package(2)
Packing
Product
Marking
AT89C51SND1C-ROTIL
64K Flash
3V
Industrial
40 MHz
TQFP80
Tray
89C51SND1C-IL
AT89C51SND1C-7HTIL
64K Flash
3V
Industrial
40 MHz
BGA81
Tray
89C51SND1C-IL
AT89C51SND1C-DDV
64K Flash
3V
Industrial
40 MHz
Dice
Tray
-
AT83SND1Cxxx(1)-ROTIL
64K ROM
3V
Industrial
40 MHz
TQFP80
Tray
89C51SND1C-IL
AT83SND1Cxxx(1)-7HTIL
64K ROM
3V
Industrial
40 MHz
BGA81
Tray
89C51SND1C-IL
AT83SND1Cxxx-DDV
64K ROM
3V
Industrial
40 MHz
Dice
Tray
-
AT80C51SND1C-ROTIL
ROMless
3V
Industrial
40 MHz
TQFP80
Tray
89C51SND1C-IL
AT80C51SND1C-7HTIL
ROMless
3V
Industrial
40 MHz
BGA81
Tray
89C51SND1C-IL
AT80C51SND1C-DDV
ROMless
3V
Industrial
40 MHz
Dice
Tray
-
Notes:
206
1. Refers to ROM code.
2. PLCC84 package only available for development board.
AT8xC51SND1C
4109HS–8051–01/05
AT8xC51SND1C
26. Package Information
26.1 TQFP80
207
4109H–8051–01/05
26.2 BGA81
208
AT8xC51SND1C
4109H–8051–01/05
AT8xC51SND1C
26.3 PLCC84
209
4109H–8051–01/05
27. Datasheet Change Log for AT8xC51SND1C
27.1 Changes from
4109D-10/02 to 4109E06/03
1. Additional information on AT83SND1C product.
2. Added BGA81 package.
3. Updated AC/DC characteristics for AT89C51SND1C product.
4. Changed the endurance of Flash to 100, 000 Write/Erase cycles.
5. Added note on Flash retention formula for VIH1, in Section "DC Characteristics",
page 184.
27.2 Changes from
4109E-06/03 to 4109F01/04
1. Added AT80C51SND1C ROMless product.
27.3 Changes from
4109F-01/04 to 4109G07/04
1. UART bootloader now flagged as option in Features section.
2. Updated DC characteristics for AT83SND1C product.
2. Add USB connection schematic in USB section.
3. Add USB termination characteristics in DC Characteristics section.
4. Page access mode clarification in Data Memory section.
27.4 Changes from
4109G-07/04 to 4109H01/05
210
1. Clarify EA pin not present on packages but on dice.
2. Interrupt priority number clarification to match number defined by development
tools
AT8xC51SND1C
4109H–8051–01/05
AT8xC51SND1C
211
4109H–8051–01/05
Table of Contents
1. Features ............................................................................................. 1
2. Description ........................................................................................ 2
3. Typical Applications ......................................................................... 2
4. Block Diagram ................................................................................... 2
5. Pin Description .................................................................................. 3
5.1 Pinouts ........................................................................................................... 3
5.2 Signals............................................................................................................. 6
5.3 Internal Pin Structure.................................................................................... 11
6. Clock Controller .............................................................................. 12
6.1 Oscillator ...................................................................................................... 12
6.2 X2 Feature.................................................................................................... 12
6.3 PLL ............................................................................................................... 13
6.4 Registers ....................................................................................................... 15
7. Program/Code Memory .................................................................. 17
7.1 ROMLESS Memory Architecture................................................................... 18
7.2 ROM Memory Architecture ........................................................................... 19
7.3 Flash Memory Architecture .......................................................................... 19
7.4 Hardware Security System ............................................................................ 21
7.5 Boot Memory Execution ............................................................................... 21
7.6 Preventing Flash Corruption......................................................................... 22
7.7 Registers ....................................................................................................... 23
7.8 Hardware Bytes ............................................................................................. 24
8. Data Memory ................................................................................... 25
8.1 Internal Space .............................................................................................. 25
8.2 External Space .............................................................................................. 27
8.3 Dual Data Pointer ......................................................................................... 29
8.4 Registers ...................................................................................................... 30
9. Special Function Registers ............................................................ 32
10. Interrupt System ........................................................................... 38
10.1 Interrupt System Priorities .......................................................................... 38
10.2 External Interrupts ...................................................................................... 41
10.3 Registers ..................................................................................................... 42
i
AT8xC51SND1C
11. Power Management ...................................................................... 48
11.1 Reset .......................................................................................................... 48
11.2 Reset Recommendation to Prevent Flash Corruption ................................ 49
11.3 Idle Mode .................................................................................................... 49
11.4 Power-down Mode...................................................................................... 50
11.5 Registers......................................................................................................52
12. Timers/Counters ........................................................................... 53
12.1 Timer/Counter Operations .......................................................................... 53
12.2 Timer Clock Controller ................................................................................ 53
12.3 Timer 0........................................................................................................ 54
12.4 Timer 1........................................................................................................ 56
12.5 Interrupt ...................................................................................................... 57
12.6 Registers......................................................................................................58
13. Watchdog Timer ............................................................................ 61
13.1 Description.................................................................................................. 61
13.2 Watchdog Clock Controller ......................................................................... 61
13.3 Watchdog Operation....................................................................................62
13.4 Registers......................................................................................................63
14. MP3 Decoder ................................................................................. 64
14.1 Decoder ...................................................................................................... 64
14.2 Audio Controls .............................................................................................66
14.3 Decoding Errors.......................................................................................... 66
14.4 Frame Information .......................................................................................67
14.5 Ancillary Data.............................................................................................. 67
14.6 Interrupt .......................................................................................................68
14.7 Registers......................................................................................................70
15. Audio Output Interface ................................................................. 75
15.1 Description.................................................................................................. 75
15.2 Clock Generator...........................................................................................76
15.3 Data Converter ........................................................................................... 76
15.4 Audio Buffer ................................................................................................ 77
15.5 MP3 Buffer.................................................................................................. 78
15.6 Interrupt Request ........................................................................................ 78
15.7 MP3 Song Playing ...................................................................................... 78
15.8 Voice or Sound Playing .............................................................................. 79
15.9 Registers......................................................................................................80
16. Universal Serial Bus ..................................................................... 82
16.1 Description...................................................................................................83
16.2 Configuration .............................................................................................. 86
16.3 Read/Write Data FIFO ................................................................................ 88
16.4 Bulk/Interrupt Transactions......................................................................... 89
ii
4109H–8051–01/05
16.5 Control Transactions................................................................................... 93
16.6 Isochronous Transactions............................................................................94
16.7 Miscellaneous ..............................................................................................96
16.8 Suspend/Resume Management ..................................................................97
16.9 USB Interrupt System ................................................................................. 99
16.10 Registers..................................................................................................101
17. MultiMedia Card Controller ........................................................ 111
17.1 Card Concept............................................................................................ 111
17.2 Bus Concept ............................................................................................. 111
17.3 Description................................................................................................ 116
17.4 Clock Generator........................................................................................ 116
17.5 Command Line Controller......................................................................... 118
17.6 Data Line Controller...................................................................................120
17.7 Interrupt .....................................................................................................126
17.8 Registers....................................................................................................127
18. IDE/ATAPI Interface .................................................................... 133
18.1 Description................................................................................................ 133
18.2 Registers................................................................................................... 135
19. Serial I/O Port .............................................................................. 136
19.1 Mode Selection ......................................................................................... 136
19.2 Baud Rate Generator................................................................................ 136
19.3 Synchronous Mode (Mode 0) ................................................................... 137
19.4 Asynchronous Modes (Modes 1, 2 and 3) .................................................139
19.5 Multiprocessor Communication (Modes 2 and 3) ..................................... 142
19.6 Automatic Address Recognition................................................................ 142
19.7 Interrupt .....................................................................................................145
19.8 Registers....................................................................................................146
20. Synchronous Peripheral Interface ............................................ 149
20.1 Description.................................................................................................150
20.2 Interrupt .................................................................................................... 154
20.3 Configuration .............................................................................................155
20.4 Registers....................................................................................................159
21. Two-wire Interface (TWI) Controller .......................................... 161
21.1 Description................................................................................................ 161
21.2 Registers................................................................................................... 175
22. Analog to Digital Converter ....................................................... 177
22.1 Description................................................................................................ 177
22.2 Registers....................................................................................................180
23. Keyboard Interface ..................................................................... 182
iii
AT8xC51SND1C
4109H–8051–01/05
AT8xC51SND1C
23.1 Description................................................................................................ 182
23.2 Registers....................................................................................................183
24. Electrical Characteristics ........................................................... 184
24.1 Absolute Maximum Rating........................................................................
24.2 DC Characteristics....................................................................................
24.3 AC Characteristics ....................................................................................
24.4 SPI Interface .............................................................................................
184
184
189
195
25. Ordering Information .................................................................. 206
26. Package Information .................................................................. 207
26.1 TQFP80 .................................................................................................... 207
26.2 BGA81 ...................................................................................................... 208
26.3 PLCC84 .................................................................................................... 209
27. Datasheet Change Log for AT8xC51SND1C ............................ 210
27.1 Changes from 4109D-10/02 to 4109E-06/03............................................
27.2 Changes from 4109E-06/03 to 4109F-01/04 ............................................
27.3 Changes from 4109F-01/04 to 4109G-07/04............................................
27.4 Changes from 4109G-07/04 to 4109H-01/05 ...........................................
210
210
210
210
iv
4109H–8051–01/05
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4109H–8051–01/05
/0M