It was based on The Things Uno with Microchip RN2903 (for USA market), so the project is available here:
https://www.arduino.cc/en/Main/Software
https://github.com/thethingsnetwork/examples
One notable addition in the project is the need to mask the channels, because we connected to an 8-ch gateway whereas RN2903 normally defaults to a full 64-ch setup. You'll see an additional setup step in the code example to do that.
