STM32 USB CDC: How to Customize COM Port Friendly Name on Windows Without INF File?

[luisfynn1]

Hello,

I am working on an STM32 USB CDC (Virtual COM Port) device using the STM32 USB Device Library (CubeMX-generated project).

My goal is to have the device appear on Windows as a custom COM port name such as:

MO3 Device (COMx)

However, I want to achieve this without using a custom INF file, since distributing and installing drivers on every PC is not practical for my use case.

From my current understanding:

• The Product String (iProduct) in usbd_desc.c can be modified
• The Interface String (iInterface) in the CDC descriptor may also influence the displayed name
• Windows typically uses usbser.sys and assigns "USB Serial Device (COMx)" by default
• Friendly Name seems to be controlled primarily via INF, not firmware

I have a few specific questions:

1. Is there any reliable way to influence or override the COM port Friendly Name purely from STM32 firmware (USB descriptors), without an INF file?
2. Does modifying iInterface (or using IAD / composite device descriptors) improve the likelihood of Windows using a custom name?
3. Are there known descriptor configurations that consistently result in Windows displaying the Product String as the COM port name?
4. Is this behavior dependent on specific Windows versions (e.g., Windows 10 vs 11)?

If complete control is not possible without INF, I would like to understand the exact limitations imposed by usbser.sys and Windows PnP behavior.

Any insights, practical workarounds, or reference implementations would be greatly appreciated.

Thank you.

[FBL]

Hi @luisfynn1 

Device naming is controlled by the host OS, driver binding, and its registry properties, not by the USB device alone. It can be changed. The behavior may vary across Windows versions, updates, and driver cache state.

From the device side, you can configure naming in product string descriptor as shown in this example.

[Charles522]

Hi ​@luisfynn1 

You may also want to check out the Prolific PL2303GC as another possible option.

It can customize the device name shown in Windows Device Manager and assign a specific COM port number from COM1 to COM65535, without modifying the INF file or going through WHQL certification again.

It might be useful for the kind of requirement you described.

[Charles522]

Hi ​@luisfynn1 
 

Just to add some context, our company has used the PL2303GC before, including its device-name customization feature.

For example, the device name and COM port can be configured as follows:

• MO3A Device (COM10)
• MO3B Device (COM100)
• MO3C Device (COM1000)
• MO3D Device (COM10000)