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STM32F2 DMA-SDIO and excessive stall on writes

Question asked by JasonP on Jun 5, 2014
Latest reply on Jun 5, 2014 by JasonP
Hi All,

Using any type of SD card (SD,SDHC,SDXC) DMA reading from the cards works consistently (With an XC card, can obtain 12-15 MB/s)

Writes are typically 2-6 MB's, but every so often, the DMA-write stalls for up to 2 secs. It does not fail so therefore I have to assume it is the cards internals performing the physical write.

If I print the results out per-DMA-write, the time taken for each randomly-sized transaction seems quite consistent @ 4-6ms per transaction (even for up to 128 sectors in one transaction), except for every so often it stalls for up to 2 secs - which seems a LOT.

Has anyone else encountered this?