STM32N6570-DK USBX Ux_Device_Video example not running / Windows Camera shows error

[Grace_04]

Hello ST Community,

I am working with the STM32N6570-DK and the USBX Ux_Device_Video example from
STM32Cube_FW_N6_V1.3.0\Projects\STM32N6570-DK\Applications\USBX\Ux_Device_Video.

I followed the README instructions exactly:

Built FSBL and Ux_Device_Video projects successfully in STM32CubeIDE

Generated FSBL.bin and Ux_Device_Video.bin

Signed both binaries using STM32_SigningTool_CLI

Programmed:

FSBL-trusted.bin at 0x70000000 (external flash)

Ux_Device_Video-trusted.bin at 0x70100000 (external flash)

Set BOOT0 and BOOT1 to boot from external flash and reset the board

However, the application does not run as expected. When the board is connected to a Windows PC, the Windows Camera application fails with the error:   
Can't start your camera
0xA00F4241 <CameraSwitchFailed> (0xC00DABE7)

From my understanding, the Ux_Device_Video example should enumerate as a USB UVC camera and stream video to the Windows Camera app. Since the camera app fails, it seems the firmware may not be executing correctly on the STM32 side (FSBL → application handoff).

Could you please clarify:

1. What is the expected runtime behavior/output of the Ux_Device_Video example?

2. How can we confirm that FSBL and the application are actually running (LED/UART/logs)?

3. Are there any additional configuration or validation steps missing from the README for external-flash boot?

4. Our final requirement is to use USB UVC to stream live camera video from the STM32N6570-DK to another monitor/PC.
Could you please confirm what hardware (camera sensor, display path) and software configuration are required on the STM32 side to achieve live video streaming using this example?

Any guidance would be appreciated.

Thank you.

[FBL]

Hi @Grace_04 

First, thank you for your feedback.

This might be an issue linked to Windows Camera not firmware/UVC issue. Would you test with another UVC tool? for instance VLC? or any other tools? Make sure to get it enumerated first in device manager.

[Grace_04]

Hi ,

Thank you for the response.

In our case, the device is not appearing in Windows Device Manager at all (neither as a camera nor as an unknown USB device). Because of this, we are unable to test with VLC or any other UVC tool at the moment, as USB enumeration itself does not seem to be happening.

What we are trying to understand clearly is the expected output and behavior of the Ux_Device_Video example:

We have not modified the example code in any way

There is no camera sensor–specific code integrated on our side

From the example description, it is not clear whether the application:

      streams a test pattern / dummy frames, or

      requires an external camera pipeline to be integrated by the user before any video output is expected

So our key questions are:

1. What exactly should the Ux_Device_Video example output by default?
2. Is it expected to enumerate as a UVC device with a dummy/test video stream, or is additional camera integration mandatory?

3. If no camera is connected or no camera pipeline is configured, should the device still enumerate as a USB UVC device in Device Manager?

4. Are there any simple indicators (LED toggling, UART logs, USB traces) to confirm that FSBL and the application are actually running when booting from external flash?

At the moment, since the device does not enumerate at all, we are unsure whether:

the issue is in FSBL → application handoff, or

USB initialization in the example, or

a missing prerequisite not mentioned in the README.

Clarification on whether the example is expected to enumerate and stream without additional camera integration would help us narrow this down.

Thank you for your support.

[FBL]

Hi @Grace_04 

1. Once the STM32N6570-DK USB device successfully completed the enumeration phase, you should be able to play a video from host side. It actually should output steam1 provided in MJPEG format.
2. For this example, there is no need for any camera. It should enumerates as UVC device and plays the stream. 

Let's narrow down the issue, which board revision do you have? the example has been developed based on  STM32N6570-DK boards revision MB1939-N6570-C01. I can see commits pushed 2 hours ago, it seems some. Would you make sure to test it using CubeN6v1.2? Maybe some updates are pushed when you are cloning the repository.

[Grace_04]

Hi ,

Thanks for the clarification.

I confirm that:

We have now tested the Ux_Device_Video example using STM32CubeN6 v1.2, as suggested.

The board in use is STM32N6570-DK.

The example code is used as-is, with no modifications and no camera pipeline integration.

However, even with CubeN6 v1.2, the device still does not enumerate on the host (it does not appear in Windows Device Manager as a UVC device or unknown USB device).

Thanks again for your support.

[FBL · Accepted solution]

Hi @Grace_04 

Thanks for confirming your setup.

You may need to provide board revision. It's marked on the board MB1939-N6570-C02 on my end. 

Each time you change boot settings, please perform a power-on reset on the board (fully power cycle the board, not just NRST).

Connect the board’s USB device port directly to the PC with a known-good USB cable (avoid hubs for debugging). If still not working, select the Ux_Device_Video workspace and run in mode debug so we can identify where it get's stuck.

On my end, it is working as expected.

[Grace_04]

Hi,

Thanks for the clarification.
We are using the MB1939-N6570-C02 , which is the same part number you mentioned and are currently using as well.

We will try it again, and if we face any issues, we will get back to you.

Thanks.