Sonoff-Tasmota and ESPurna are the two main open source firmware used in home automation devices, such as Sonoff wireless switches, based on Espressif ESP8266 WiSoC. Xose Pérez – aka Tinkerman – has recently purchased “dumb” power meters / kill-a-watt meters, added WiFi to them with ESP-01 module and Wemos D1 mini board, and implemented support in ESPurna firmware leveraging earlier reverse-engineering work by Karl Hagström.
The power meter above looks exactly like the one I’ve been using for review for over two years, and has been more more reliable than other models, such as Broadlink SP2 (with built-in WiFi) that gave up on me after a few months.
Xose actually noticed that old and newer models of the power meters were based on different solutions. Karl’s meter relied on ECH1560, while Xose’s new meter was instead based on Vango V9261F, which has a public datasheet, and was already being worked on by Domoticz community.
While he connect ESP-01 to one of the meter, he found Wemos D1 mini was much easier to connect thanks to a built-in 5V support. He still had to include a Hilink AC to 5V DC power supply module, a baseboard for the Wemos board with an optocoupler and resistor. Finally (not shown in pictures), he hot-glued all cabling to make sure nothing move, and that’s important as you don’t want anything bad happens with AC voltages…
The power meter can then be calibrated and configure in ESPurna user interface, and you can also handle the data through MQTT, Domoticz, a REST API, and/or Home Assistant. Support for V9261F has been implemented and tested, but while the older ECH1560 solutions have been implemented, they have yet to be tested.