Has anyone here used the SPI port on the AT91SAM7SXXX parts? If so, have you observed the same problem I have?
It appears to me that the edge used to capture data is reversed from what the data sheet shows. I am using CPOL=0, NCPHA=1. According to the data sheet, this should cause the SPI clock to idle low, and to capture MISO data on rising clock edges, including the first rising edge.
On my scope I can see that the data is clearly low for the first rising edge of the clock, with plenty of room for both the setup and hold times on each side of the edge. It is also low for several other rising edges, during the
16-bit transfer. The data is high immediately before each falling edge. The data received in response to this transfer has all 16 bits being '1'.When I then set NCPHA=0 (still with CPOL=0) for exactly the same transfer, I then get data that makes sense, and agrees with what I am seeing on my scope. However, this behavior would be completely opposite both the waveform charts in section 29.6.2 of the data sheet, and the descriptions of CPOL and NCPHA in section 29.7.9.
I have scoured Atmel's web site and searched many other places on the web, and have found no mention of this.