SD card operation on STM32N6570-DK

ERROR · ‎2025-06-25

Hi,

1. I have my own application (migrated from H7 to N6) with FileX writing to the SD card in real-time.

And I see that 4-bit data bus is unusable at all (a lot of disk errors).

The 1-bit data bus in NORMAL mode works sometimes. HIGH-SPEED is not working properly.

The same data throughput was recorded on STM32H747I-DISCO perfectly via 4-bit bus.

Could you please advise on this?

2. Looking at STM32CubeN6\Projects\STM32N6570-DK\Applications\FileX\Fx_MultiAccess example,
I see that 1-bit data bus in Normal mode is used.

Is there any issue with the SDMMC on STM32N6 chip or STM32N6570-DK board (signal integrity)?

Regards,

A

GAA · ‎2025-06-27

Hello @ERROR ,

To work with UHS, first ensure that the voltage switches from 3.3 V to 1.8 V, either via a transceiver or through the VDD supply, you can verify the completion of the voltage switch sequence by checking the BUSYD0 register.
A similar example is already available in the STM32H7RS Cube firmware at the following link for bus wide 4bit:
STM32CubeH7RS/Projects/STM32H7S78-DK/Applications/FatFs/FatFs_MultiAccess
Recommendation: Verify that you are using the correct pins for the 4bit bus width. You can refer to this project as an example for the SDMMC1 instance, which can be found in the MSP file here:
STM32CubeH7RS/Projects/STM32H7S78-DK/Examples/SD/SD_ReadWrite_DMA

Best regards,

ERROR · ‎2025-06-28

Hi GAA,

Thank you for your support. I'll check by the end of July.

Regards,
A