STM32H7 SDMMC IDMA + MDMA

[Zed]

Hi everybody!

I have searched almost half of the Internet and couldn't find any working example of these kind of technology combination: STM32H7 SDMMC IDMA + MDMA. I must say that without MDMA, everything works good (I'm aware of cache problems). But in my project I keep important variables in DTCM_RAM and I need that data that I read from SD-card directly goes to DTCM_RAM. That is why I need MDMA. I have found some settings for CubeMX that initialize MDMA controller, but don't know what to do next.

So my question is:

Is there at least one example, that can be shared with this great Community, that utilize SDMMC, IDMA and MDMA on STM32H7 µC?

Please do not reply if your answer is "Check ST's example folder". I've already done it. There are lots of very useful examples there, but I didn't find a example that uses all three parts: SDMMC, IDMA, MDMA.

Thank you for all your kind help! 

[AScha.3]

Hi,

so maybe you are the first to use exactly this combination.

If using the normal DMA, everything working fine ->

you could just use a buffer area, to write the data by DMA , and then trigger the MDMA mem to mem, to copy this to the DTCM_RAM . This would do, what you want, SD data to DTCM_RAM, at almost same speed (because anyway the SD-card needs time in the ms range, to respond to a command, so adding some xx us changes almost nothing.

If this workaround doing what you want, you still can try, to do it with direct transfer by MDMA .