Power Meter for recording electricity usage at home using MicroPython on ESP8266.

Assumes your power meter has a flashing LED that flashes every e.g 1/1000th of a kWh and that you can place an optotransistor over the LED to trigger a pulse on a pin on the ESP8266.

Features

• Web page at / to get and set the kWh remaining on your prepaid electricity meter
• Prometheus /metrics endpoint to get details about power usage for display in Grafana
• Link to Home Assistant and Node-Red by publishing on the MQTT powermeter topic

Tested with

• MicroPython 1.13
• Wemos D1 Mini ESP8266

How to set up

Install USB to serial drivers on MacOS

https://learn.sparkfun.com/tutorials/how-to-install-ch340-drivers/all

How to install MicroPython on ESP8266 board

From https://docs.micropython.org/en/latest/esp8266/tutorial/intro.html Downloaded latest MicroPython 1.13: esp8266-20200911-v1.13.bin pip3 install esptool

esptool.py --help

esptool.py erase_flash

esptool.py --port /dev/tty.wchusbserial1410 --baud 460800 write_flash --flash_size=detect 0 ~/Downloads/esp8266-20200911-v1.13.bin

Connect to the boards REPL using WebREPL

http://micropython.org/webrepl/#10.0.0.146:8266

Using Ampy to connect to dev board

Command line tool for upload/download of files. Installation instructions at https://github.com/scientifichackers/ampy

• List files ampy -p /dev/tty.wchusbserial1410 -b 115200 ls
• Run a file (even if it's not yet uploaded) ampy -p /dev/tty.wchusbserial1410 -b 115200 run main.py
• Upload a file ampy -p /dev/tty.wchusbserial1410 -b 115200 put main.py
• Upload all the files: boot.py, main.py, config.json, index.html, metrics
• Note you will need to edit config_example.json to suit your requirements, and save as config.json

Use Screen to view terminal output

• screen /dev/tty.wchusbserial1410 115200
• To exit from Screen: CTRL+A CTRL+\
• To abort the currently running program, get back to REPL: CTRL+C
• To restart micro: CTRL+D

Where to buy

• Communica or Micro Robotics supply a cheap D1 Mini board
• Ambient light sensor, also from Communica, but pretty much any light dependent resistor (LDR) or optotransistor board will work

Learn More

I made a full presentation on Home Automation with MicroPython, the ESP8266 and Google Home at Google DevFest 2020. It includes my slides and YouTube presentation for building this Power Meter, as well as a short intro to MicroPython.