What would cause inbound (peripheral to internal memory) PDCA transfer data to wrap?
I can't explain it. On a UC3C2512C, I'm using the PDCA to read SPI data from an external device. After the PDCA writes the data to a memory buffer, I see the data shifted and wrapped in that memory buffer. All of the data I expect is contained inside the memory buffer, but the data is shifted and wrapped.
For example, using an oscilloscope, I see the following on the MISO line:
0x00 0x01 0x02 0x03 0x04 0x05 0x06 0x07 0x08 0x09
and in the memory buffer I see the last three bytes wrapped:
0x07 0x08 0x09 0x00 0x01 0x02 0x03 0x04 0x05 0x06
As well, when I increase the SPI clock rate I see more wrapping. The frequency of SPI transfers also seems to change the number of wrapped bytes. In some cases, I can see the number of wrapped bytes toggle between X and X plus one, as if just at a threshold.
Any ideas what could cause this?