If you're using a feather with a small flash size (like the Feather 32u4), you'll need a smaller library to experiment with than the one in this guide.
Enter TinyLoRa, an Arduino Library for Feathers and arduino-compatibles using the HopeRF RFM95/96W module. It's less than 8kB, making it perfect for smaller chips! It's also compatible with the Feather M0 LoRa, in case you want a smaller communications library for your speedy M0.
One of the trade-offs of using this tiny library (compared to a more featured library like the MCCI-LMIC Library) is that it uses a different method of device registration, Activation-by-Personalization (ABP). Instead of performing a secure join procedure, the security keys are hardcoded into the Sketch and "burned" into the Feather during compilation.
First, let's gather the parts required for this project.
Next, let's wire up our circuit.
Your Feather does not come with an antenna, but there are two ways of wiring one up.
For this guide, and to keep the build cost-effective, we soldered a small, 82mm wire to the ANT pad.
Make the following connections between the Feather 32u4 and the DHT22:
- Feather 3V to DHT22 Pin 1
- Feather Pin 10 to DHT22 Pin 2
- Feather Ground to DHT22 Pin 3
- Add a 10k ohm resistor between the DHT22's VCC (DHT Pin 1) and Data Pin (DHT Pin 2).