(Note: There’s no SI7021 sensor connected in the central photo - I added it in later when my extra female pin headers finally arrived!)
I’ve been running out of memory.
Whilst trying to develop/debug a Pro Mini 328P-based low-power temperature/humidity sensor node on The Things Network over LoRaWAN, I’ve been reaching the 32KB program memory limit and 2KB dynamic memory (SRAM) limit.
Then it occurred to me.
Why not test the pin-compatible, drop-in replacement benefit of the Pro Mini XL?
Essentially, all I needed was more program memory and SRAM.
So I updated the pin-mappings, replaced the 328P for the XL, recompiled.
Everything just worked!
And now my existing Arduino sketch was only using 20% of the program memory!
Now to add more sensors: GPS. Altimeter. Barometer.
Hmmm, what else could I fit, I wonder...?!
I began tinkering with all things LoRaWAN back in 2016 during a commercial farm monitoring project.
Farmer "Dave" needed to monitor the temperature and humidity of a 120+ acre farm.
But it was approx. half an hour’s drive away from the main HQ.
Initial research into low-power, long range radio transceivers led me to LoRa and LoRaWAN.