SAM7S256_14 Datasheet, PDF (620/775 Pages) ATMEL Corporation – ARM-based Flash MCU

40.6.9.5 SPI: Baudrate Set to 1
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.
Problem Fix/Workaround
None.
40.6.9.6 SPI: Disable In Slave Mode
The SPI disable is not possible in slave mode.
Problem Fix/Workaround
Read first the received data, then perform the software reset.
40.6.9.7 SPI: Bad Serial Clock Generation on 2nd Chip Select
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
• CPOL = 1 and NCPHA = 0
• Multiple chip selects are used with one transfer with Baud rate (SCBR) equal to 1 (i.e., when serial clock
frequency equals the system clock frequency) and the other transfers set with SCBR are not equal to 1
• Transmitting with the slowest chip select and then with the fastest one, then an additional pulse is generated
on output SPCK during the second transfer.
Problem Fix/Workaround
Do not use a multiple Chip Select configuration where at least one SCRx register is configured with SCBR = 1 and
the others differ from 1 if NCPHA = 0 and CPOL = 1.
If all chip selects are configured with Baudrate = 1, the issue does not appear.
40.6.10 Synchronous Serial Controller (SSC)
40.6.10.1 SSC: Periodic Transmission Limitations in Master Mode
If the Least Significant Bit is sent first (MSBF = 0), the first TAG during the frame synchro is not sent.
Problem Fix/Workaround
None.
40.6.10.2 SSC: Transmitter Limitations in Slave Mode
If TK is programmed as output and TF is programmed as input, it is impossible to emit data when the start of edge
(rising or falling) of synchro has a Start Delay equal to zero.
Problem Fix/Workaround
None.
40.6.10.3 SSC: Transmitter Limitations in Slave Mode
If TK is programmed as an input and TF is programmed as an output and requested to be set to low/high during
data emission, the Frame Synchro signal is generated one bit clock period after the data start and one data bit is
lost. This problem does not exist when generating a periodic synchro.
SAM7S Series [DATASHEET]
6175M–ATARM–26-Oct-12
620