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OTA Updates

Update firmware over WiFi without a USB cable.

  1. Download sqmeter-firmware-vX.Y.Z.bin from GitHub Releases
  2. Open the web UI and go to System
  3. Under Firmware Update, select the .bin file
  4. Click Upload
  5. The device reboots automatically into the new firmware

Don't interrupt

Keep the browser open during upload. A power cut mid-flash can corrupt the active partition — the device will fall back to the previous app slot on next boot.

Web UI updates

To update the web UI (the dashboard/settings pages), flash sqmeter-littlefs-vX.Y.Z.bin via the web UI's Filesystem Update section, or use esptool directly. The web UI update doesn't touch the firmware.

Security

The current OTA endpoints are unauthenticated LAN endpoints. Anyone who can reach the device web UI can attempt firmware or filesystem uploads. Keep the device on a trusted network and do not expose it through port forwarding.

API Endpoints

The System page uses these endpoints:

Endpoint Purpose Artifact
POST /api/update Firmware OTA update sqmeter-firmware-vX.Y.Z.bin
POST /api/update/fs LittleFS/web UI update sqmeter-littlefs-vX.Y.Z.bin

Both endpoints expect multipart/form-data uploads and return JSON with success on completion or error on failure. The firmware endpoint reboots automatically after a successful upload.

Via ArduinoOTA

Command-line ArduinoOTA is disabled by default. To enable it, set both fields below in the device configuration and restart:

{
  "ota": {
    "enabled": true,
    "password": "use-a-long-random-password"
  }
}

Use the same password from your upload tool. If ota.enabled is false or ota.password is empty, the device will not start the ArduinoOTA listener.

Via esptool (USB)

If the device is unresponsive over WiFi, fall back to USB:

# Firmware only
esptool.py --chip esp32 --port PORT --baud 115200 \
  write_flash 0x10000 sqmeter-firmware-vX.Y.Z.bin

# Full reflash (nuclear option)
esptool.py --chip esp32 --port PORT --baud 115200 \
  write_flash 0x0 sqmeter-complete-flash-vX.Y.Z.bin

How OTA Works

The partition table has two app slots (app0 at 0x10000, app1 at 0x190000). OTA writes the new firmware to the inactive slot, then updates the otadata partition to point the bootloader at it on next boot. If the new firmware fails to boot, the bootloader stays on the old slot.

This means you always have a working rollback as long as you don't erase the flash.

The LittleFS filesystem update is separate from app OTA slots. It replaces the dashboard/settings assets and preserves NVS configuration, but an interrupted filesystem upload can leave the web UI unavailable until LittleFS is flashed again over USB or a later successful OTA filesystem upload.