I am trying to implement multiple virtual COM ports using one USB. I changed the no. of interfaces and device descriptors from 1 to 3 but is it still showing a single VCP. Would you tell me where I am lagging?

[ESzes.1]

As I understood the ST libraries doesn't support composite devices. I used a really good open source solution for it: https://github.com/IntergatedCircuits/USBDevice

This supports composite devices, you can find example projects there also.

[Rajesh Raturi]

I am doing this with threadX ( USBX ) help me to add a Virtual COM port

[gbm]

You didn't supply any detailed info, so just my wild guess: you re probably missing IAD, or Interface Association Descriptor - a component of the Configuration Descriptor. Find some info on the net regarding composite VCOM and its Config Desc. It won't work without IAD.

[TDK]

Related/duplicate:

https://community.st.com/s/question/0D53W00001FlHJJSA3/is-it-possible-to-create-multiple-virtual-com-ports-using-one-usb