Using the analog output of an IR sensor, the revolutions of a Ferraris electricity meter are detected. The total meter reading (KWh) and current consumption (Watt) are displayed on an embedded web page and optionally published via MQTT. As visual feedback the blue LED on the Wemos D1 mini board blinks if the red marker has been detected. An embedded web server helps to adjust various parameters to fine-tune the sensor setup and also offers a simple RESTful interface to retrieve the meter reading. The total consumption reading and sensor settings are frequently saved to (pseudo) EEPROM to migate counter resets due to possible intermediate power failures.

https://github.com/lrswss/esp8266-wifi-power-meter