Why 2 SD cards with the same characteristics won't work the same way on SDMMC1 peripheral (STM32H743ZI)

[M.CHN]

Hello everyone,

I am facing a strange issue. I am working with a nucleo-h743ZI2 biard using SDMMC1with fatfs to write data on µSD card. I have 2 SD card with apparently the same characteristics : 4GB, SDHC, class 10. SDMMC is set in 1 bit mode (4 bit mode returns rxoverrun when I mount a card) and my code works on one card and it return Data_Timeout with the other card.

Do you know the reason(s) of this difference ?

Best Regards

Mathieu

[TDK]

Hard to answer these questions without much detail. Maybe the cards are not as similar as you think.

Debug the problem with the one card and you'll likely find the answer.

[Tesla DeLorean]

You'd perhaps want to inspect the CSD Register content, and not the label on the packaging.

The Card Specific Data describes the parameters you're interested in.

Some of ST's code makes choices based on the reported features of the cards