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Does STM32F7xx SDIO port contain HW support for the card to signal busy

Question asked by David Harrison on Feb 5, 2018

Hi, all. On this web page : the author, someone called Frank, states that "The STM32F2xx SDIO port contains hardware support for the card to signal busy". Apparently, it does so by holding the SDIO D0 line low until it is ready to accept data when writing to it.

Does anyone know if this is also true for the SDMMC port on the STM32F7xx series?


I have tried sending the CMD13 “SEND_STATUS” and reading the value of bit 8 as he suggests, but that doesn't seem to be working reliably either. So I am wondering about monitoring the level of the SDIO DO pin using another GPIO pin.


I am having timing issues with writing to the SD card over the 4-bit SDMMC interface and I am wondering if I am seeing what this Frank gentleman is reporting.