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
