UVC HS on Nucleo-H755 with USB3300: Windows Camera App Error 0xA00F4243
- March 3, 2026
- 1 reply
- 312 views
Hello,
I am working on a UVC (USB Video Class) project using a Nucleo-H755ZI-Q board and Azure RTOS USBX.
I have successfully tested the ux_device_video (FS) example on the board. Now, I am trying to migrate this example to High Speed (HS) using an external USB3300 ULPI PHY.
[Current Status]
Hardware: Nucleo-H755ZI-Q + USB3300 (ULPI interface).
Software Stack: X-CUBE-AZRTOS-H7 (USBX).
Enumeration: The device is correctly recognized as a "Camera" in the Windows Device Manager without any yellow exclamation marks.
Issue: When I open the Windows "Camera" app, it fails with the following error code:
0xA00F4243 <CameraReservedByAnotherApp>
(0xC00D3704)
[Modifications Made]
Modified the USB configuration to use High Speed with external PHY (ULPI).
Updated the USBX descriptors (Device Descriptor, Configuration Descriptor) to support HS, including the Device Qualifier Descriptor.
Ensured the ULPI pins are correctly configured in the HAL initialization.
[Observations]
The FS version works perfectly. The issue only occurs when using the HS configuration with the USB3300. It seems the host can see the device, but fails to start the stream or handle the UVC-specific requests (Probe/Commit control) at High Speed.
[Questions]
Are there specific common pitfalls when migrating the ux_device_video example from FS to HS on the STM32H7 series?
Could this be related to the USBX descriptor settings (e.g., wMaxPacketSize for HS) or DMA/Cache coherency issues on the H7?
Does the Windows Camera app error 0xA00F4243 specifically point to a failure in the SET_INTERFACE or UVC PROBE/COMMIT request handling?
Any advice or guidance on how to debug this would be greatly appreciated.
Best regards,