Creating variant for using UNO R4 WiFi in USB bridge bypass mode

Hardware UNO R4 UNO R4 WiFi
32

Here's how to reload the bootloader and the bridge code in case we bork that later.

:floppy_disk: bootloaders/UNO_R4

Compiled with

git clone GitHub - arduino/arduino-renesas-bootloader: A tinyusb based project implementing the bootloader for Uno R4 and Portenta C33 git clone GitHub - hathach/tinyusb: An open source cross-platform USB stack for embedded system cd tinyusb # This step is temporary patch -p1 < ../arduino-renesas-bootloader/0001-fix-arduino-bootloaders.patch python tools/get_deps.py ra cd .. cd arduino-renesas-bootloader TINYUSB_ROOT=$PWD/../tinyusb make -f Makefile.minima # TINYUSB_ROOT=$PWD/../tinyusb make -f Makefile.wifi

:rescue_worker_helmet: How to update ESP32-S3 firmware

Prerequisite: install esp-idf v5.0.0 (or newer) and run

. $esp-idf-path/export.sh

cd extras/uno-r4-wifi-usb-bridge

Restart the board in ESP download mode by shorting ESP_DOWNLOAD with GND, then power via USB The board will restart as Espressif USB JTAG/serial debug unit Then run

idf.py -p $portname flash

:rocket: How to load bootloader (UNO R4 WIFi)

Once the bridge is up and running, it will respond to two peculiar baud rates:

  • 1200bps: triggers the bootloader mode for RA4 chip
  • 2400bps: triggers ROM DFU mode

So, to reflash the bootloader, change the port baud to 2400

stty -F $portname 2400

Then flash the bootloader with rfp-cli

rfp-cli -device ra -port $portname -p dfu_wifi.hex

:rocket: How to load bootloader (UNO R4 Minima)

Reboot the board with BOOT shorted to GND The board will enumerate as Renesas RA USB Boot

Then flash the bootloader with rfp-cli

rfp-cli -device ra -port $portname -p dfu_minima.hex
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