STM32U575CIU6 USB CDC not working

ramamurth · ‎2026-01-16

Hi,

I'm working on custom board where i have to use the USB CDC class to demonstrate the USB virtual com port feature along with data transfer and receive.

We have generated the project using CubeMX 6.15 and STM32Cube IDE 2.0 but not able to detect the com port.

We are using PA11, PA12, PA9 pins for USB.

Kindly provide a step-by-step guide.

Thank you.

Ram

Andrew Neil · ‎2026-01-16

Welcome to the forum.

Please see How to write your question to maximize your chances to find a solution for best results.

@ramamurth wrote:
on custom board

You'll need to give details of that board - schematics, layout, etc.

Some good, clear photos may also help.

Do other things on the board work OK?

Before moving to a custom board, did you prove your code on a known-good board; eg, ST board?

A complex system that works is invariably found to have evolved from a simple system that worked.
A complex system designed from scratch never works and cannot be patched up to make it work.

Gyessine · ‎2026-01-19

Hello @ramamurth
First and to eliminate all software related issues
Can you try and run this firmware example and see if it works?
Keep in my mind that you will need 2 "DATA" USB cables.
BR
Gyessine

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FBL · ‎2026-01-19

Hi @ramamurth

Based on the project attached, you are not configuring your project in standalone (without ThreadX) properly: missing

ux_device_stack_tasks_run()

Here is a step by step KB article to implement standalone USBX.

To give better visibility on the answered topics, please click on Accept as Solution on the reply which solved your issue or answered your question.

Best regards,
FBL