It evolved from the same Ideentron code base on which TinyLoRa is based. I threw away almost everything except the AES routines and implemented
large parts the basic parts of the LoRaWAN 1.0.3 spec. Check out the readme to see what’s supported.
The sample project is currently heavily optimized for the ATtiny85 MCU so that a whole LoRaWAN 1.0.3 stack with support for various sensors runs on an ATtiny85 MCU with only 5 data pins, 8K of flash memory, 512 bytes of EEPROM, 512 bytes of SRAM and without an external clock.
It should not be too much work to support Arduinos and other ATtiny or ATmega MCUs. I am happy to create a fork of the SlimLoRa “library” code to make it a real library supporting more MCUs if someone wants to contribute.