STM32 SDIO SD card initialization
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2025-02-05 1:03 AM
Hi,
I have an STM32F7 design with SD card connected via SDIO interface.
In many posts I read that SD cards have to be initialized with a 1 bit wide bus and a clock of 400 kHz. Switching the bus width from 1 to 4 bit using the command HAL_SD_ConfigWideBusOperation(&hsd1, SDMMC_BUS_WIDE_4B) is simple. However, I have some doubts about the clock frequency. Many examples inizialize the clock at higher frequencies in the first initialization. This seems to contradict the SD card specification.
Best regards
Jan
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2025-05-20 8:06 AM
Hi JBurg.5,
In our SD driver, in initialization API, we are forcing the card initialization to use 1bit @400Khz, then switching the user settings configured in init structure. I confirm that the Initialization is compliant with the SD Standard.
I hope that is clear now.
Best Regards,
Ismail
