USB CDC-ACM bridge

Overview

This sample app demonstrates use of a USB CDC-ACM to bridge a standard hardware UART on a supported board. This sample can be found under samples/subsys/usb/cdc_acm_bridge in the Zephyr project tree.

Requirements

This project requires an USB device driver, which is available for multiple boards supported in Zephyr.

The board has to have an USB interface as well as hardware UART, the device node for the hardware UART is board specific so each supported board needs an explicit overlay.

Building and Running

Reel Board

To see the console output of the app, open a serial port emulator and attach it to the USB to TTL Serial cable. Build and flash the project:

west build -b reel_board samples/subsys/usb/cdc_acm_bridge
west flash

Running

Plug the board into a host device, for example, a PC running Linux, the board should enumerate as a CDC-ACM device, the CDC-ACM input and output should be echoed back to the real UART, and configuration changes to the CDC-ACM uart such as bitrate will be propagated to the hardware port.

If the hardware port is connected to an on-board debugger then the output should be echoed between the two ports, if it’s connected to some pins on the boards the pins can be shorted together to test that the driver is working correctly.