emcniece / rak-mqtt-soil-monitor

A solar-powered MQTT soil moisture and temperature monitor, featuring RAKwireless Wisblocks

RAKWireless MQTT Soil Monitor

This project features RAKWireless boards and modules (mini base board with solar and LiPo power, soil moisture probe, temperature/humidity sensor) that publishes state over MQTT. Designed for integration with Home Assistant.

Hardware

• RAK11200 ESP32-WROVER WisBlock WiFi Module
• RAK19003 WisBlock Mini Base Board
• RAK1901 WisBlock Temperature and Humidity Sensor
• RAK12023 WisBlock Soil Moisture Sensor Connector Module
  • May be replaced by RAK12028
• RAK12035 WisBlock Soil Moisture Sensor Module
• Solar Board
• Battery connector wires
• 18650 Battery Holder Case
• Reconditioned 18650 cells

Software

• MQTT Explorer

Arduino Boards

Add these URLs to the "Additional board manager URLs" in the Arduino IDE preferences:

https://raw.githubusercontent.com/RAKwireless/RAKwireless-Arduino-BSP-Index/main/package_rakwireless_index.json
https://raw.githubusercontent.com/RAKwireless/RAKwireless-Arduino-BSP-Index/main/package_rakwireless.com_rui_index.json

Following this you can search for "RAKwireless ESP32 Modules" (or keyword: RAK11200) in the board manager, then install.

Arduino Libraries

• knolleary/PubSubClient (download & import .zip)
• SparkFun SHTC3 Humidity and Temperature Sensor Library (install from library manager)

Setup

• Install Arduino boards via manager
• Install Arduino libraries via manager (or download and import .zip)
• Solder male header pins into BOOT and GND

Programming

The RAK11200 ESP32 module has a BOOT pin that must be pulled to GND to enable upload/programming mode. The RAK19003 Mini Base Board exposes this pin on the edge headers. A wire may be used to short BOOT and GND, or you can solder male header pins and use a jumper (provided with the base board kit) to enable boot mode. A small SPST tactile pushbutton switch can be soldered to leads of female headers, creating a dedicated boot switch.

Programming sequence:

1. Hold BOOT switch / short BOOT pin to GND
2. Press reset button
3. Release BOOT switch / disconnect BOOT-GND short
4. Click "upload" from Arduino IDE
5. Wait for Hard resetting via RTS pin... log line
6. Press reset button again

Now your ESP32 module should be running your code. Open the Arduino IDE serial monitor at 115200 baud to view printed output.

References & External Documentation

• https://github.com/RAKWireless/WisBlock/tree/master/examples/RAK11200/solutions/mqtt_subscribe_publish
• https://docs.rakwireless.com/Product-Categories/WisBlock/RAK11200/Datasheet/#hardware
• https://github.com/knolleary/pubsubclient

ToDo

• Cleaner MQTT publishing method (wrap string formatting and serial printing)
• Low-power operation
• Soil moisture sensor
• Improved battery measurement curve
• MQTT topic updatable from MQTT message
• Linting & tests