How to get DMA working for the last DWORDs from SDMMCx FIFO?

JHYBN.2056 · ‎2019-12-05

Hello,

I am working on SDMMC ReadBlock function using DMA with peripheral flow control enabled. When I try to transfer 512 Bytes block from the SD Card, I have last 3 DWORDs "mising" (CNDTR is 0xFF82 instead of expected 0xFF00). These DWORDs are transfered by DPSM (its DCOUNT is zero), but staying in FIFO, not transfered by DMA. So I have to transfer them by SW, instead by DMA.

Is there anyone, who knows how to persuade DMA to completely finish the transfer?

Some details about my setup:

memory buffer is 32 Bytes aligned
DMA burst transfer is INCR4 on both sides
SDMMC hardware flow enabled
transfer is finished with DATAEND flag

Thank you for any help,

Jarda

JHYBN.2056 · ‎2020-02-04

If somebody is interested in ...

My DMA problem has been solved after I set-up FIFO threshold level inside DMA_SxCR register to b'11 (full FIFO). From that moment all transfers are finished automatically. It's a pitty, that I do not get this idea from manual, but I have to follow the USB-FS MSC application example...

Jarda