The ESP USB Bridge project converts ESP32-S2 or ESP32-S3 into a USB to UART/JTAG chip

Espressif’s ESP USB Bridge is an ESP-IDF based project that leverages the ESP32-S2 or ESP32-S3 USB interface to use the board as a USB to UART or USB to JTAG debug board.

It can serve as a substitute for CH340 or CP2104 based USB to TTL debug boards for example, be used with OpenOCD in JTAG bridge mode, and also flash the UF2 firmware file to the target board.

Host computer, ESP32-S2/S3 board running ESP USB Bridge firmware and target board with USB and/or JTAG

As we just mentioned, there are three main use cases:

  • Serial bridge mode with a terminal program or a firmware flash tool like esptool. In this case it works like your typical USB to TTL debug board
  • JTAG bridge mode for JTAG debugging with OpenOCD, and if the target board is ESP32 based, you can use the openocd-esp32 project
  • Mass storage device where the map is accessible by a file manager on the host computer. One of the specific use cases in this mode is to copy a UF2 firmware file which can then be flashed to the target microcontroller by ESP32-S2/S3. Currently, the ESP USB Bridge only supports UF2 flashing to Espressif microcontrollers.

Source code, released under an Apache 2.0 license, and instructions can be found on Github. You will need an ESP32-S2 or ESP32-S3 board that exposes the USB DM/DP pins as well as the UART and/or JTAG interfaces. Something like Lolin S2 Mini should do the job as a USB to UART board with both USB and UART available on the headers, but if you need JTAG the ESP32-S3-USB-OTG board should be a better option . ESP-IDF 4.3 or above is required to build the project.

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Steven L. Nielsen