Happiness is SdFat with DMA SPI

Hardware Arduino Due
11

The return from spiRec are error bits, 0X2 means a timeout waiting for DMA to finish and 0X1 means SPI overrun was set.

I tried both changes with SdFat and it seems to work. I will stress test with some long file reads.

Can't say I feel confident, wish I understood the Bus Matrix and DMAC controller better.

At least a test with 100 MB which is about 200,000 block reads ran O.K.

Type is FAT16
File size 100MB
Buffer size 81920 bytes
Starting write test.
Write 4019.24 KB/sec
Maximum latency: 83141 usec, Minimum Latency: 19453 usec, Avg Latency: 20376 usec

Starting read test.
Read 4387.86 KB/sec
Maximum latency: 18959 usec, Minimum Latency: 18598 usec, Avg Latency: 18667 usec