stm32f407 SDIO and USART together

[xt]

when I use the usart6's DMA, my SDIO can't write to the SD card properly

[Andrew Neil]

What, exactly, don't you understand?

You'll need to give a lot more detail for people to be able to help you - see: How to write your question to maximize your chances to find a solution

Or, if you're happy that the problem is solved, just mark your previous post as the solution:

https://community.st.com/t5/community-guidelines/help-others-to-solve-their-issues/ta-p/575256

[xt]

why usart6'dma must use the FIFO mode.  if I not use ,the data recived by usart6 is whole,then I write to the SD,the data in SD is loss

[Andrew Neil]

Again, you'd need to give more details.

You haven't shown any code - so impossible to know where the mistake might be.

Instrument your code so that you can see what's going on in both the working and non-working cases.

Compare & contrast.

Look into where & when this "loss" occurs

Use a logic analyser on the SDIO to see what's actually happening in the hardware