Before you begin, use a data-capable USB cable, charge or power your device, and close any apps that might use serial ports (Arduino IDE, serial terminals, 3D printer hosts, etc.).
Flash your device
Open the Web Flasher
Open the Web Flasher in your browser:
Open Web Flasher
The Web Flasher requires a browser with Web Serial API support. Use the latest versions of Chrome, Edge, or Safari.
Connect your device
Plug your OSSM or RADR into your computer with a USB cable. When prompted, select your device’s serial port (often shown as “CP210x USB to UART Bridge”).
The Web Flasher shows your selected port and enables the Connect/Flash controls.
Verify the update
- Reconnect the device in the Web Flasher to confirm it is detected without errors.
- For OSSM, wait for the homing routine to complete after reboot.
- For RADR, continue with pairing and controls in the Quick Start guide: RADR Quick Start.
Troubleshooting
Device not detected
Device not detected
If your computer doesn’t recognize the device, you may need a USB-to-UART driver (especially on Windows). Also try:
- Use a different USB port or a known data-capable cable
- Disconnect and reconnect the device, then refresh the Web Flasher page
- Close other apps that might hold the serial port (Arduino IDE, serial consoles)
- Windows
- macOS / Linux
Download and install the CP210x drivers from Silicon Labs:
Browser not supported or no serial prompt
Browser not supported or no serial prompt
- Use the latest Chrome, Edge, or Safari
- If you previously blocked serial permissions, click your browser’s site permissions (lock icon) and allow serial ports, then reload
- Firefox does not currently support the Web Serial API—switch to a supported browser
Flashing fails or gets stuck
Flashing fails or gets stuck
- Unplug the device, wait 10 seconds, and reconnect
- Try a different USB port/cable and refresh the flasher page
- Restart your browser or computer and try again
- Ensure no other app is using the serial port

