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WebFlasher

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psonnera edited this page Jul 30, 2026 · 3 revisions

Installing from your web browser (Web Flasher)

Note

This is the simplest installation method: nothing to download or install, it works from a web page. It is also the only installation method for the Guition JC3248W535 display (which M5Burner does not support).

What you need

The Web Flasher runs on any desktop or laptop computer — the operating system does not matter, only the browser does:

  • Works: Google Chrome or Microsoft Edge, on Windows, Mac, Linux or ChromeOS. Other Chromium-based browsers generally work too (in Brave you must first enable Web Serial in the browser settings).
  • Does not work: Firefox and Safari (on any system — they do not support the Web Serial technology the flasher relies on).
  • Does not work: phones and tablets, including iPhone/iPad and Android, even with Chrome installed — mobile browsers have no Web Serial. For Android phones use the Android method instead.

Check the USB driver

Connect your device to the computer with a USB data cable (some cables are charge-only and will not work).

On Mac and Linux the needed drivers are already part of the system — normally nothing to install, whatever the device.

On Windows, a driver may be needed depending on the device:

  • M5Stack Basic / Gray / Fire: CP2104 driver, also available from SiLabs.
  • M5Stack Core2 / Tough (and most recent Basic units): CH9102 driver.
  • M5Stack CoreS3 / S3SE and Guition JC3248W535: no driver needed — these use the USB port built into the chip itself.

On Windows you can check in the device manager (right click on the Start button > Device Manager) that a new COM port appears under Ports (COM & LPT) when you plug the device. If it is already there, no driver is needed.

Flash the firmware

  1. Open the Web Flasher page: https://psonnera.github.io/M5_NightscoutMon/Flasher/

  2. Find the row matching your exact device model — the page shows the firmware version that will be installed. Read the warning on the page: picking the wrong model (for example the 16 MB firmware on an old 4 MB Basic) will not work.

  3. Click Install on that row.

  4. A popup lists the serial ports of your computer. Select your device's port and click Connect.

  5. On a first installation, choose the option to erase the device (this clears any previous settings). When re-flashing later you can keep the settings.

  6. Confirm and wait — flashing takes a minute or two. Do not unplug the device.

  7. The device restarts with M5_NightscoutMon installed.

Troubleshooting: if no serial port appears, check the driver (above) and try another USB cable or port. On the CoreS3 hold the reset button ~3 seconds until the green LED lights, then retry. On the Guition JC3248W535 hold the BOOT button while plugging in the cable, then retry. Close any program that could be using the port (Arduino IDE, serial monitor, M5Burner).

Congratulations, you programmed your device.

Continue with the setup here.

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