This project utilizes a WeMos D1 mini Pro, u.FL to SMA antenna whip, and an external antenna in a 3D-printed enclosure to indicate presense when powered on and attached to MQTT.

The included Arduino code is setup to work with Home Assistant MQTT Discovery to automatically create a binary_sensor device which will indicate the connection status of the device. The device should be powered from your car’s ignition so it’s only on when the car is running. When the device powers on, it will attempt to connect to the defined MQTT broker, publishes a discovery message, and configures a Last Will and Testament. When the device is powered off (or you drive out of WiFi range), the Last Will and Testament is sent by your broker to update subscribed automation system(s).

The included Home Assistant automation example utilizes this information to open or close a connected garage door.”