Before you connect
- Browser — Chrome, Edge, or Brave on a desktop or laptop. Web Serial doesn't exist in Safari, and not at all on iPhone or iPad. There's no workaround for that.
- Cable — a USB-C cable that carries data, not a charge-only one.
- Board — M5Stack AtomS3 Lite.
- Bootloader mode — hold the side button, plug in the cable, keep holding for about 2 seconds after it powers up. AtomS3 Lite has no auto-reset circuit, so this manual step is needed every time you flash.
Connect & flash
Still holding the button? Click connect, choose the matching serial port from the browser prompt, then let go.