SAM7X256 Atmel Corporation, SAM7X256 Datasheet - Page 663

• Manufacturer Part Number: SAM7X256
• Manufacturer: Atmel Corporation

Specifications of SAM7X256

• Flash (kbytes): 256 Kbytes
• Pin Count: 100
• Max. Operating Frequency: 55 MHz
• Cpu: ARM7TDMI
• Hardware Qtouch Acquisition: No
• Max I/o Pins: 62
• Ext Interrupts: 62
• Usb Transceiver: 1
• Usb Speed: Full Speed
• Usb Interface: Device
• Spi: 2
• Twi (i2c): 1
• Uart: 3
• Can: 1
• Ssc: 1
• Ethernet: 1
• Graphic Lcd: No
• Video Decoder: No
• Camera Interface: No
• Adc Channels: 8
• Adc Resolution (bits): 10
• Adc Speed (ksps): 384
• Resistive Touch Screen: No
• Temp. Sensor: No
• Crypto Engine: No
• Sram (kbytes): 64
• Self Program Memory: NO
• Dram Memory: No
• Nand Interface: No
• Picopower: No
• Temp. Range (deg C): -40 to 85
• I/o Supply Class: 3.3
• Operating Voltage (vcc): 3.0 to 3.6
• Fpu: No
• Mpu / Mmu: no / no
• Timers: 3
• Output Compare Channels: 3
• Input Capture Channels: 3
• Pwm Channels: 4
• 32khz Rtc: Yes
• Calibrated Rc Oscillator: No

41.5.9.3
41.5.9.4
41.5.9.5
41.5.10
41.5.10.1
41.5.10.2
41.5.10.3
6120I–ATARM–06-Apr-11
Universal Synchronous Asynchronous Receiver Transmitter (USART)
USART: CTS in Hardware Handshaking
USART: Hardware Handshaking – Two Characters Sent
USART: RXBRK Flag Error in Asynchronous Mode
TWI: NACK Status Bit Lost
TWI: Possible Receive Holding Register Corruption
TWI: Software Reset
During a master frame, if TWI_SR is read between the Non Acknowledge condition detection
and the TXCOMP bit rising in the TWI_SR, the NACK bit is not set.
The user must wait for the TXCOMP status bit by interrupt and must not read the TWI_SR as
long as transmission is not completed.
TXCOMP and NACK fields are set simultaneously and the NACK field is reset after the read of
the TWI_SR.
When loading the TWI_RHR, the transfer direction is ignored. The last data byte received in the
TWI_RHR is corrupted at the end of the first subsequent transmit data byte. Neither RXRDY nor
OVERRUN status bits are set if this occurs.
The user must be sure that received data is read before transmitting any new data.
when a software reset is performed during a frame and when TWCK is low, it is impossible to ini-
tiate a new transfer in READ or WRITE mode.
None.
When Hardware Handshaking is used and if CTS goes low near the end of the start bit, a char-
acter can be lost.
CTS must not go high during a time slot occurring between 2 Master Clock periods before and
16 Master Clock periods after the rising edge of the start bit.
None.
If CTS switches from 0 to 1 during the TX of a character and if the holding register (US_THR) is
not empty, the content of US_THR will also be transmitted.
Don't use the PDC in transmit mode and do not fill US_THR before TXEMPTY is set at 1.
In receiver mode, when there are two consecutive characters (without time guard in between),
RXBRK is not taken into account. As a result, the RXBRK flag is not enabled correctly and the
frame error flag is set
Constraints on the transmitter device connected to the SAM7X USART receiver side:
Problem Fix/Workaround
Problem Fix/Workaround
Problem Fix/Workaround
Problem Fix/Workaround
Problem Fix/Workaround
Problem Fix/Workaround
SAM7X512/256/128
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