Here is my very old code for E32-868T20D and E32-868T30D (both are equally designed but second one have amplifier transistor):
Both OTAA and ADR modes are supported.
Some weather sensors - are supported: bme280, bmp280 and bmp180.
Also analogue data is sent (battery voltage). and state of UART pins (if UART is disabled).
Data is packed by cayenne lpp which is umpacks automatically by TTN.
DevEUI is auto-generated from device’s unique ID value.
Pulling down M0 triggers UART-based configuration UI.
More info on github. Please note that project is frozen as-is, because STM8 have low-precision clock (HSI clock) which is hard to count exactly specific time intervals as well as receiving acknowledgement at exact reception window.