How to connect STM32 Virtual COM Port (USB CDC) to RS485 bus using external converter

[Sujith]

Hi,
I’m using an STM32L412RB where the USB DM/DP lines are already configured as a Virtual COM Port (USB CDC device).

Now I want to communicate with an RS485 bus without changing the existing board hardware.
My idea is to build a small adapter board that connects the STM32 USB DM/DP pins to an external USB-to-RS485 converter (which has DM and DP lines).

Is it possible to design such an adapter to convert the STM32’s USB VCP interface to RS485?
Can the STM32 (configured as a USB device) send and receive RS485 data through this path:

STM32 (USB CDC Device) → USB DM/DP → USB-to-RS485 Converter → RS485 Bus

Any guidance or reference designs would be helpful.

Thanks,
Sujith

[AScha.3]

Hi,

>Can the STM32 (configured as a USB device) send and receive RS485 data through this ..

No. (At least would need another cpu, like STM32 , to be USB host and send on its uart...) :)

Use an uart with rs485 (DE) capability, look what uarts on L412 can do it

....then connect a rs485 driver/transceiver here; clear and simple.

[FBL]

Hi @Sujith 

Unfortunately, there are no specific examples in the provided context for implementing this bridge with STM32.