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For developers: building ESPHome components

Home Assistant Connect AUX-2 has an unlocked bootloader, so you can test your own ESPHome component for serial or Modbus on it.

  1. Compile ESPHome with your custom component for Connect AUX-2, starting from the firmware source.
  2. Use ewt-gen to offer a web-based installer for your firmware. You can automate this with the example GitHub Actions workflow.

To return to the factory firmware, see Custom firmware and restoring factory firmware.

Consider an integration instead

Home Assistant prefers generic ESPHome-based proxies, with the protocol knowledge living in Home Assistant. With that split, new device protocols reach users through Home Assistant updates or the Home Assistant Marketplace, without a firmware upgrade on the ESPHome device. This is part of the Open Home Foundation's Proxy all the things effort.

If you have an ESPHome component today, consider how it would work as a Home Assistant integration. If your ESPHome device isn't time-constrained and has no other requirements that need protocol knowledge on the device, consider running the stock Connect AUX-2 firmware and moving the device logic into Home Assistant. See Building serial and Modbus integrations.