f_open(&fil, "w_test.txt", FA_CREATE_ALWAYS | FA_WRITE)

[OLYMPIA]

Could you show me that "f_open(&fil, "w_test.txt", FA_CREATE_ALWAYS | FA_WRITE)" get "NOT READY FR_OK" ?

When I used "NUCLEO F722", I get "NOT READY FR_OK". But when I used "NUCLEO L476", I get FR_OK.

I checked wiring so many times.

[SofLit]

Hello,

STM32F7 and STM32F4 are not the same product.

Answering to your question according to what provided is not obvious.

Meanwhile, I suggest you to refer to this video how to setup FatFs with SDCard on F7 product.

[Andrew Neil]

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@OLYMPIA wrote:

I get "NOT READY FR_OK".

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Do you mean FR_NOT_READY ?

http://elm-chan.org/fsw/ff/doc/rc.html#:~:text=FR_NOT_READY,device%20has%20broken.

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@OLYMPIA wrote:

When I used "NUCLEO F722", I get "NOT READY FR_OK". But when I used "NUCLEO L476", I get FR_OK.

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So step through both, and see where they differ.

Have you used a logic analyser to see what's going on in the hardware?

[Tesla DeLorean]

You can't debug the block IO furnished via the DISKIO layer at the top-level.

There's more involved than wiring.. but you've presented none of that.

Not Ready is usually from the GPIO pin associated with the socket card detection switch, but can also come from the card itself.