Using FatFs to access SD Card and USB Mass Storage Device

[Andrew Hazelton]

Posted on October 18, 2017 at 05:57

Compiler:           IAR Workbench v8.11.3

Middleware�s:   FatFs & STM32_USB_Host

Hardware:          STM32746G Discovery Board

HAL Version:      V1.8.0

Demo Projects:   C:\STM32Cube_FW_F7_V1.8.0\Projects\STM32746G-Discovery\Applications\USB_Host\MSC_Standalone  AND  C:\STM32Cube_FW_F7_V1.8.0\Projects\STM32746G-Discovery\Applications\FatFs\FatFs_uSD

Project:

I have merged together the below two STM32Cube_FW_F7_V1.8.0 Discovery Applications into the one project (attached):

1)  MSC_

Standalone � USB host mass storage class demo project.

2)  FatFs_uSD � File system using micro SD card.

My goal is to use the FatFs to open both the USB memory stick and the micro SD card. Then to transfer a .txt file from the USB memory stick to the micro SD card.

Problem:

All of the functions f_open(), f_read(), f_write() and f_close() will only work on the first storage device (SD or USB) that you use the FATFS_LinkDriver() and f_mount() on. How do you tell the hardware drivers disk_read() and disk_write() which storage device (SD or USB) you intend to use when you call the f_open() function?

If you have already used the FATFS_LinkDriver() and f_mount() function to link the micro SD card, do you then have to use the FATFS_UnLinkDriver() function to unlink the hardware SD drivers before you can then link the USB Host drivers?

I have already set �_VOLUMES   2� in ffconf.h

Attachment: 

Please un-zip the attached project into the below directory:

C:\STM32Cube_FW_F7_V1.8.0\Projects\STM32746G-Discovery\Applications\USB_Host

#fatfs #usb-mass-storage-device #sd-card

[bbee · Accepted solution]

Posted on October 19, 2017 at 07:34

See

http://elm-chan.org/fsw/ff/doc/filename.html

 

You can pass the drive number in the path name or change the default drive with f_chdrive.

When you use both, a SD drive and a USB drive then you have to link each drive to its driver using FATFS_LinkDriver. In that case you should have two Diskio_drvTypeDef instances (one for SD and one for USB) and it is possible to access both drives without to use unlink and link again.

[Andrew Hazelton]

Posted on October 20, 2017 at 13:19

Hi ra hummel.

Thanks for that I got it working. I re-attached the working project above if anyone wants to try it.

1)  Insert USB memory stick with a file called 'tfile.txt'. Make sure it has lots of text.

2)  Insert micro SD card into the board.

[Gregoire de Chasteigner]

Posted on December 07, 2017 at 12:01

Hi Andrew, I have test your code and it work well but when I tried to merge it with my own application, it doesn't work. So I am wondering what you have modified in the librairies to get it work?

Thanks

[Andrew Hazelton]

Posted on December 08, 2017 at 12:55

Hi Gregoire,

I have not made any changes to any of the libraries. What hardware are you using?

[Nikhil Gayke]

Can you share working code​