Retry issue of STM32F4-Discovery + USB host MSC + FatFS

[Jason Ro]

Posted on July 16, 2018 at 15:54

Hello!

My name is Jason.

I have been testing USB FatFS of STM32F4-Discovery board since last week.

And I tested reference source code of STMicro.

(STM32Cube_FW_F4_V1.21.0\Projects\STM32F4-Discovery\Applications\FatFs\FatFs_USBDisk)

It seems like normal operation works well.

And all of basic FatFS functions had no problem. (f_mount, f_open, f_write, f_close). 

But I found out there are too many retires between 

USBH_Process() and MSC_Application().

 

More than 100 retries occurred until APPLICATION_START is ready state.

I think this is the reason why 

MSC_Application() is located in the while() function.

Of course this can be a normal situation.

However, I never used while() function when I tested FatFS with SDIO 4-bit mode.

So I would like to know the reason why we have to use while() function for USB FatFS

Why should we use while() for 

MSC_Application() function?

Please refer to attached screenshot for more details.

Have a nice day!!!

Best regards,

Jason (GMT+9, Seoul, Korea)

[Tesla DeLorean]

If this is for a commercial project you might want to contact your local sales/support office and see if an FAE there can assist you.