Datasheet

Arduino® UNO R4 WiFi

11 / 23 Arduino® UNO R4 WiFi Modiﬁed: 22/06/2023

ESP header (schematic)

6.2 USB Bridge

When programming the UNO R4 WiFi, the RA4M1 MCU is programmed via the ESP32-S3 module by default. The U2

and U6 switches can switch the USB communication to go directly to the RA4M1 MCU, by writing a high state to the

P408 pin (D40).

Soldering together the SJ1 pads permanently sets the USB communication directly to the RA4M1, bypassing the ESP32-

S3.