WiFi-based data logger for solar thermal collectors, developed on an ESP32 board.
| Physical quantity | Sensor | Interface | Board |
|---|---|---|---|
| Temperature | PT100/PT1000 | SPI | MAX31865 |
| Irradiance | Pyranometer | I2C | ADS1115 |
| RH | SHT20 | I2C | - |
| Flow | Pulse flowmeter | - | - |
| Wind speed | Pulse anemometer | - | - |
On each iteration of the main loop(), the ESP32 checks for connection status.
When the specified sampling interval has passed, all sensors are read and the measurement stats min, max, mean, stdev are calculated and stored in the Measurement object.
When the upload interval has passed, the JSON payload is updated with mean and stdev values.
The Measurenent stats are reset and the payload is published to the MQTT broker.
Set the WiFi network and MQTT broker credentials in src/credentials.h.
Configure the sampling and upload intervals as well as the sensors parameters (pins, labels etc) in the src/main.cpp.
Thats all!
To simplify the configuration process and avoid duplicate code, the project has been structured like this:
An MQTT broker is necessary to receive the payload and a really simple back end to insert the measurements to a database.
This project uses the Logger-stack, a dockerized Mosquitto+NodeRed+MySQL+Grafana server stack to receive, store and visualize measurements.