AT91SAM7S256D-AU Atmel, AT91SAM7S256D-AU Datasheet - Page 683

• Manufacturer Part Number: AT91SAM7S256D-AU
• Description: ARM Microcontrollers - MCU 256K Flash SRAM 64K ARM based MCU
• Manufacturer: Atmel
• Series: SAM7S256r

Specifications of AT91SAM7S256D-AU

• Rohs: yes
• Core: ARM
• Processor Series: AT91SAM
• Data Bus Width: 16 bit/32 bit
• Maximum Clock Frequency: 55 MHz
• Program Memory Size: 256 KB
• Data Ram Size: 64 KB
• On-chip Adc: Yes
• Operating Supply Voltage: 3 V to 3.6 V
• Operating Temperature Range: - 40 C to + 85 C
• Package / Case: LQFP-64
• Mounting Style: SMD/SMT
• Interface Type: 2-Wire, I2S, SPI, USART
• Length: 7 mm

40.16.8.5
40.16.8.6
40.16.8.7
40.16.8.8
40.16.8.9
40.16.8.10
40.16.8.11
In fixed Mode, if a transfer is performed through a PDC on a Chip select different from the Chip select 0, the output
spi_size sampled by the PDC will depend on the field, BITS (Bits per Transfer) of SPI_CSR0 register, whatever the
selected Chip select is. For example, if SPI_CSR0 is configured for a 10-bit transfer whereas SPI_CSR1 is config-
ured for an 8-bit transfer, when a transfer is performed in Fixed mode through the PDC, on Chip select 1, the
transfer will be considered as a HalfWord transfer.
If a PDC transfer has to be performed in 8 bits, on a Chip select y (y as different from 0), the BITS field of the
SPI_CSR0 must be configured in 8 bits, in the same way as the BITS field of the CSRy Register.
When Baudrate is set at 1 (i.e. when serial clock frequency equals the system clock frequency) and when the BITS
field of the SPI_CSR register (number of bits to be transmitted) equals an ODD value (in this case 9,11,13 or 15),
an additional pulse will be generated on output SPCK.
Everything is OK if the BITS field equals 8,10,12,14 or 16 and Baudrate = 1.
None.
The SPI disable is not possible in slave mode.
Read first the received data, then perform the software reset.
The SPI Command “SPI Disable” is not possible during a transfer, it must be performed only after TX_EMPTY ris-
ing else there is everlasting dummy transfers occur.
None.
The SPI Command “software reset” does not reset the SPIEN config bit. Therefore rewriting an SPI enable com-
mand does not set TX_READY, TX_EMPTY flags.
Send SPI disable command after a software reset.
If CSAAT = 1 for current access and there is no more TX request for a time greater than DLYBCT + DLYBCS, then
if an access is requested on another slave, the NPCS bus switches from one CS to the one requested without
DLYBCS. External Slaves may reach a contention on SPI_MISO line for a short period.
Assert the Last Transfer Command (NPCS de-activation) for the last character of each slave.
Bad Serial clock generation on the 2nd chip select when SCBR = 1, CPOL = 1 and NCPHA = 0.
This occurs using SPI with the following conditions:
• Master Mode
Problem Fix/Workaround
Problem Fix/Workaround
Problem Fix/Workaround
Problem Fix/Workaround
Problem Fix/Workaround
Problem Fix/Workaround
SPI: Chip Select and Fixed Mode
SPI: Baudrate Set to 1
SPI: Disable In Slave Mode
SPI: Disable Issue
SPI: Software Reset and SPIEN Bit
SPI: CSAAT = 1 and Delay
SPI: Bad Serial Clock Generation on 2nd Chip Select
SAM7S Series [DATASHEET]
6175M–ATARM–26-Oct-12
683