sensor-hub

Hardware

This first version uses only two sensors : a current probe, and a temperature/humidity sensor :

1. SCT-013 : a current transformer. Gives 50mA out for a 100A current.
2. Bosch BME280 : measures temperature and humidity.

Current probe

Since we don't measure the mains' voltage, we cannot measure the power factor (phase between the current and voltage). So we use a hardware peak detector to ease the measuring work of the ESP32 chip. The peak detector is done with an op-amp and a diode, the simulations and schematics can be found in the hardware folder.

Temperature/Humidity

The BME280 can talk with the ESP8266 in I2C. That's what we do. I2C will work over tens of meters, with cheap ethernet cable.

Ressources

The following links were useful in this project :

• https://poweruc.com/blogs/news/non-invasive-sensor-yhdc-sct013-000-ct-used-with-arduino-sct-013
• https://learn.openenergymonitor.org/electricity-monitoring/ct-sensors/interface-with-arduino