ESP8266 Hygrometer

To help colleagues at my FH course, here is an example-code for measuring soil humidity.

The basic concept is that an analog reading of the hygrometer sensor is taken and sent via MQTT to a central server. From there, Node Red is used to collect data and send notifications if the level dips down too low.

Version "internal ADC, 1 sensor": Hygrometer - Single

Version "external ADC, 4 sensors": Hygrometer - Quad

Used for the project:

  • Arduino IDE
  • ESP8266
  • ADS1115 I2C ADC (for the quad version)
  • MQTT server for data transport

Downloads:

Hygrometer.cpp

Hygrometer_Quad.cpp

Script for google-patents search Emisar D4 / Nichia Optisolis driver