STM32U5 USB MSC USBX standalone demo

This guide provides a comprehensive approach to build a bare-metal USB Mass Storage Class (MSC) device application on STM32U5G9J-DK1 using the Azure RTOS USBX stack.

Hardware & Software needed

Hardware:

• STM32U5G9J-DK1 development board
• eMMC interface embedded in the STM32U5G9J-DK1 board.

Software:

• EWARM v9.50.2
• STM32CubeMX V6.15.0
• STM32CubeU5 firmware package (includes USBX middleware)

Materials Provided

• STM32U5 USB MSC USBX standalone example project demonstrating USB MSC device implementation without ThreadX.

Setup

1. Connect the STM32U5G9J-DK1 board to your PC using a USB cable over CN5.
2. Build and flash the USB MSC standalone application onto the board.
3. The application initializes USBX by calling MX_USBX_Device_Init() in main().
4. The USBX_Device_Process() function is called continuously in the main loop to run the USBX stack.
5. Connect CN4 type C to your PC and see the magic

Enabling DMA Mode

If you would like to enable DMA mode, open main.h and uncomment the following define:

#define DMA

This enables DMA support for USB data transfers, which can improve performance.

Expected behavior

When plugged into a PC host, the STM32U5G9J-DK1 enumerates as a USB MSC device. During enumeration, the device provides all required descriptors (device descriptor, configuration descriptor, string descriptors) for host identification. Once enumeration completes successfully, a new removable drive appears on the host system. Standard read, write, and format operations can be performed as with any other removable drive.

Troubleshooting

Caution: never use status = UX_SUCCESS; in USBD_STORAGE_Read, USBD_STORAGE_Write, or similar USBX MSC callbacks. Use instead: status = UX_STATE_NEXT;

Note: The standalone USBX variant is enabled by MX code generated defining #define UX_STANDALONE in ux_user.h.

Two callback functions are required for the USBX mass storage class device:

• USBD_STORAGE_Read used to read data from the mass storage device.
• USBD_STORAGE_Write used to write data into the mass storage device.

Please check the knowledge base article for more details.

Caution : Issues and the pull-requests are not supported to submit problems or suggestions related to the software delivered in this repository. The example is being delivered as-is, and not necessarily supported by ST.

For any other question related to the product, the hardware performance or characteristics, the tools, the environment, you can submit it to the ST Community on the STM32 MCUs related page.