Where are all the samd21 chips

[bluejedi]

@chocotov1

I’ve done some experiments with the TinyLoRa library (GitHub - adafruit/TinyLoRa: LoRaWAN Library) on attiny85’s in the past. The attiny85 only has 8 kB of flash. The atmega328p of the UNO has 32 kB.

TinyLora is NoGo on V3.
This has been discussed on the Forum already.

@chocotov1

I’d encourage you to give the atmega328p (UNO) another chance! Benefits: Cheap, robust (no problems with 5 V), a lot less complicated than the SAMD21.

Bad advice. RAM and Flash memory on ATmega328 and ATmega32u4 is just too limited for LoRaWAN compliant stacks if you want to use them with SPI LoRa modules. And as already said you will need level shifters for almost everything (LoRa module and most sensors are 3.3V nowadays). You should not use these MCU’s for new LoRaWAN development in combination with SPI LoRa modules where the LoRaWAN stack has to run on the MCU.