STM32U5A9J-DK1 USB Device as mass storage standalone via sdmm1 emmc

[tod]

I want to use the EMMC as USB storage space, but I encountered another issue: I am trying to access the EMMC via SDMM1, and after implementing the MSC-related functions (read, write, USBD_STORAGE_GetMediaLastLba, USBD_STORAGE_GetMediaBlocklength) in ux_device_msc.c, the formatting operation on the PC side fails. The error message says: "Please insert a disk into the removable disk."
I have already verified that after initializing SDMM1, the EMMC can be accessed and read/write operations are successful.

What could be the reason for this issue?

The attached file is my project.

ux_device_msc.c：

[tod]

Hi @FBL 

Please help me analyze.

Thank you very much!

[tod]

Hi @FBL 

I can see an unallocated Disk 3 in Disk Management(3.64GB), but when trying to format it(FAT,size=512), I get the error: "The request could not be performed because of an I/O device error."

[FBL]

Hi @tod 

I will try to replicate the issue on my end. But, first, let me suggest you check this thread. It could be helpful.

[tod]

Hi @FBL 

You can use the project I provided (attachment: MSC_FIN.7z) to reproduce the issue.

I will check and try according to your suggestions and provide feedback.

Thank you very much!

[tod]

Hi @FBL 

I modified the read and write functions in ux_device_msc.c, but the formatting still cannot be performed correctly. Through GDB debugging, I found that during formatting, write operations are executed and the data is written correctly, but the formatting still fails.

[tod]

Hi @FBL 

Did you reproduce the issue? Is it a problem with my configuration or a bug in the code?

[tod]

Hi @FBL 

Has there been any progress on this issue? 

 I really do need your help！

Thank you so much!

[tod]

Hi @FBL 

I've tried different USB ports, replaced the data cable, and even used a different computer, but I still can't format it properly.
Please help me ! Thank you so much!

[FBL · Accepted solution]

Hi @tod 

Honestly it took me sometime to realize to never use status = UX_SUCCESS; and use  status = UX_STATE_NEXT; instead !

Now, here is a working example for eMMC !