The Arduino UNO R3 (COM5) driver allows Windows to recognize the board’s USB serial connection so development tools can communicate with it. With the correct driver installed, you can upload sketches and exchange serial data on Windows 11, 10, 8, or 7. “COM5” identifies the port currently assigned to the board; Windows may assign a different number when you reconnect it.

Key Features

• USB serial communication: Provides the connection used by the Arduino IDE and compatible applications to send and receive data through the board’s USB interface.
• Sketch upload support: Enables development software to communicate with the UNO R3 bootloader when transferring programs to the board.
• Serial monitoring: Supports viewing messages from running sketches and sending input through a serial terminal, using the baud rate configured in your code.
• Windows device recognition: Helps Windows identify the board and make its serial port available in Device Manager under Ports (COM & LPT).

How to Install

1. Choose a compatible driver. Obtain the Arduino UNO R3 driver intended for your version of Windows. Check any package requirements before installing, particularly on Windows 7 or 8. Some Windows configurations recognize the board automatically without a separate installation.

1. Connect the board. Plug the UNO R3 into your computer with a USB data cable. A charge-only cable will not support communication. If detection fails, try another cable or a different USB port.

1. Install the driver if needed. Run the supplied installer and follow its prompts. If the download contains driver files instead, extract them, open Device Manager, right-click the unrecognized board, and select Update driver. Choose the option to browse your computer and point Windows to the extracted folder.

1. Confirm the port assignment. Expand Ports (COM & LPT) in Device Manager and locate the Arduino board. Verify that it appears without a warning icon, then note its assigned COM port.

1. Test communication. Open the Arduino IDE, select Arduino Uno as the board, and choose COM5—or the port shown in Device Manager. Upload a simple example such as Blink to confirm the connection.

If your board is an UNO-compatible model with a different USB-to-serial chip, it may require that chip manufacturer’s driver rather than the standard Arduino UNO R3 driver.

Common Issues and Fixes

• Device not detected / COM5 missing: Check Device Manager under Ports for “Arduino UNO” or “USB Serial Device.” Try a data-capable USB cable and another port, then reinstall the correct driver: official Arduino USB driver for ATmega16U2-based UNO R3, or CH340 driver for clone boards. Reselect Tools > Port > COM5 in the Arduino IDE.
• Driver install fails: Run the installer as administrator. If Windows blocks an unsigned package, use the signed vendor driver or temporarily disable driver signature enforcement, then reinstall and reboot.
• Version conflicts (Code 10/43): Uninstall old Arduino/CH340/FTDI drivers and delete the driver package in Device Manager. Reinstall only the matching UNO R3 driver, reboot, and confirm COM5 is assigned; if needed, change the COM port in Device Manager.