SDIO partial block DMA transfer possible?

infoinfo980 · ‎2012-01-19

Posted on January 19, 2012 at 22:57

Hi,

I'd like to transfer less than a full block of data (i.e. less than 512 bytes) from the SDIO FIFO to another peripheral that's mapped into an FSMC address directly using DMA without having to first transfer the full block to SRAM then again out to the FSMC address.

Is that possible? The SDIO spec hints at partial block transfers being possible but I don't see the capability in ST's driver code.

Regards,

- Andy

infoinfo989 · ‎2012-01-22

Posted on January 22, 2012 at 17:26

I certainly believe you can. The blocksize is only ''fixed'' for SDHC cards at 512 bytes - older cards can have a wide variety of blocksizes, and the SDIO SDIO_DCTRL register contains a ''data block size'' field that allows you to select any power-of-2 blocksize from 1 byte to 16 kB.