LoRaWAN Sensor Node Firmware for Heltec WiFi LoRa 32 V2/V3

Features

• LoRaWAN 1.1.0 Class A, via RadioLib
• Deep sleep between uplinks
• OTAA join
• Sensor data is CayenneLPP encoded
• Default uplink interval: 20 minutes

Supported sensors

Built-in support is provided for the following sensors:

• DS18B20 Temperature Sensor
• HC-SR04 Ultrasonic Range Sensor
• HTU21D(F) Relative Humidity and Temperature Sensor
• BME280 Relative Humidity, Temperature and Barometric Pressure Sensor
• Internal battery voltage of the Heltec WiFi LoRa 32

Additional sensors can be added by implementing an Adafruit Unified Sensor compatible interface.

All sensors listed at Unified Sensor Drivers should be compatible.

See SensorCollection.cpp for a list of currently supported sensor types.

Supported devices

Currently, the following boards are supported:

• Heltec WiFi LoRa 32 V2
• Heltec WiFi LoRa 32 V3

Button

The node can be controlled by pushing the PRG button as follows:

• Press PRG for <1s: Show device info on the display.
• Press PRG for >1s and <5s: Immediately try to send an uplink message.
• Press PRG for >5s: Resets all node state and rejoins the network.

Uplink message format

Uplink messages are CayenneLPP formatted. See CayenneLPP by Electronic Cats - Library for Arduino.

Development

The firmware is developed using PlatformIO and the Arduino Environment.

Please refer to the PlatformIO manuals for details on development, compilation and flashing. The project contains a VSCode configuration for PlatformIO.

Provisioning a new sensor node

If you are using the things network, provision a new end device with the following settings:

• Input method: Enter end device specifics manually
• Frequency plan: Europe 863-870 Mhz
• LoRaWAN version: LoRaWAN Specification 1.1.0
• Regional Parameters version: RP001 Regional Parameters 1.1 revision A
• JoinEUI: 0000000000000000
• DevEUI / AppKey / NwkKey / End device ID: Generate random

Then, proceed as follows:

1. Copy include/lorawan-keys_example.h to include/lorawan-keys.h
2. Copy activation information from TTN to include/lorawan-keys.h
3. Modify includes/config.h as needed
4. Rebuild and flash the firmware

Links

• Kompost-Sensor: The previous firmware
• (German) Automatic compost monitoring using the Kompost-Sensor firmware
• (German) Using the integrated USB JTAG on the ESP32-S3 used in the Heltec WiFi LoRa 32 V3

License

See LICENSE.