Dedicated article for UNO R4 WiFi's with missing USB bridge firmware [HC-1549]

content/Hardware Support/UNO/Restore-the-USB-connectivity-firmware-on-UNO-R4-WiFi-with-espflash.md

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+---
+title: "Restore the USB connectivity firmware on UNO R4 WiFi with espflash"
+id: 16379769332892
+---
+
+The UNO R4 WiFi has a ESP32-S3 chip, which handles the USB-to-serial communication. The firmware for this chip can normally be upgraded [using Arduino IDE or Arduino Cloud](https://support.arduino.cc/hc/en-us/articles/9670986058780-Update-the-connectivity-module-firmware-on-UNO-R4-WiFi), but if this is not possible the firmware can be restored using **espflash**.
+
+You may want to use this procedure if:
+
+* Your UNO R4 WiFi is detected as a generic ESP32 board by Arduino IDE or Arduino Cloud.
+* Your UNO R4 WiFi isn't detected as any board by Arduino IDE or Arduino Cloud, despite being connected to your computer with a working data USB cable.
+
+---
+
+Follow these steps:
+
+1. Unplug UNO R4 WiFi and any non-essential USB devices from your computer.
+1. On the board, find the **GND** and **Download** pins on the 6-pin header next to the USB-C connector:
+
+   ![The GND and Download ESP32 pins.](img/esp32-data-pins.png)
+1. Connect the board to your computer while shorting the GND and Download pins.
+
+   * This can easily be done by connecting a female-to-female jumper wire between the two pins.
+   * If you don't have a female-to-female jumper wire, you can use some other pointy, conductive object (such as one end of a male-to-male jumper wire) and position to have contact with both pins. You can release the short after you've connected the board to your computer.
+1. The ESP32 should now be in Download mode, which allows firmware to be flashed.
+
+   * You may get a system message about a new device being connected. If prompted, allow it to connect.
+1. Download and extract the .ZIP file for your system:
+   * [unor4wifi-update-windows.zip](https://github.com/arduino/uno-r4-wifi-usb-bridge/releases/latest/download/unor4wifi-update-windows.zip){.link-download}
+   * [unor4wifi-update-macos.zip](https://github.com/arduino/uno-r4-wifi-usb-bridge/releases/latest/download/unor4wifi-update-macos.zip){.link-download}
+   * [unor4wifi-update-linux.zip](https://github.com/arduino/uno-r4-wifi-usb-bridge/releases/latest/download/unor4wifi-update-linux.zip){.link-download}
+1. Open your system's command line application inside the extracted folder.
+   * **Windows:** Hold <kbd>⇧Shift</kbd> and right-click any blank space inside the extracted folder. In the context menu, select **Open command window here / Open PowerShell window here**.
+   * **macOS:** Control-click on the extracted `unor4wifi-update-macos` folder and select "**New Terminal at Folder**" from the context menu. A terminal window will open.
+   * **Linux:** Open [a command line terminal](https://ubuntu.com/tutorials/command-line-for-beginners) in the extracted folder.
+1. Run the command:
+   * **Windows:** `bin\espflash write-bin -b 115200 0x0 (Get-Item .\firmware\UNOR4-WIFI-S3-*.bin).FullName`
+   * **macOS/Linux:** `./bin/espflash write-bin -b 115200 0x0 firmware/UNOR4-WIFI-S3-*.bin`
+     > [!NOTE]
+     > You may need to adjust your system's security settings to allow this command if you encounter a warning pop-up. To proceed, go to _System Preferences > Privacy & Security_, and under _Security_, click _Allow Anyway_ to allow espflash to run.
+
+1. The terminal window might now show a list of the serial ports present on your computer. Use the arrow keys on your keyboard to select the port for the board and then press the <kbd>**Enter**</kbd> key.
+   * **Windows:** The board will have a name like "USB Serial Device".
+   * **macOS:** The board will be named "USB JTAG_serial debug unit". Two ports with this name will be available, select the port that starts with `/dev/cu.usbmodem*`. <!-- TODO: Same for Linux, probably. Confirm this. -->
+   * If you can't find it, try following steps 1–3 again.
+
+1. The terminal window may show the following prompt:
+
+   ```text
+   ? Remember this serial port for future use? (y/n) ›
+   ```
+
+   Press the <kbd>**N**</kbd> key on your keyboard.
+1. The flashing process should now start. Wait for it to finish, as indicated by output that looks something like this:
+
+   ```text
+   [2023-07-11T08:59:44Z INFO ] Connecting...
+   [2023-07-11T08:59:45Z INFO ] Using flash stub
+   Chip type:         esp32s3 (revision v0.1)
+   Crystal frequency: 40MHz
+   Flash size:        8MB
+   Features:          WiFi, BLE
+   MAC address:       dc:54:75:c4:c6:54
+   [00:00:14] [========================================]     689/689     0x0
+   ```
+
+1. Close the terminal window.
+1. Disconnect the USB cable of the **UNO R4 WiFi** board from your computer.
+1. Ensure that the Download pin is no longer shorted.
+1. Connect the **UNO R4 WiFi** board to your computer with the USB cable again.