SAM7S256_14 Datasheet, PDF (722/775 Pages) ATMEL Corporation – ARM-based Flash MCU

• 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.
40.21.8 Synchronous Serial Controller (SSC)
40.21.8.1 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.
40.21.8.2 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.
40.21.8.3 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.
Problem Fix/Workaround
The data need to be delayed for one bit clock period with an external assembly.
In the following schematic, TD, TK and NRST are SAM7S signals, TXD is the delayed data to connect to the
device.
SAM7S Series [DATASHEET]
6175M–ATARM–26-Oct-12
722