Private LoRa Protocol Source code for RS485-LN. The RS485_LN_PingPong_v1.0.hex is pre-built firmware which can be and upgrade to RS485-LN directly, upgrade method is the same as per instruction in RS485-LN.
See http://wiki.dragino.com/xwiki/bin/view/Main/Firmware%20Compile%20Instruction%20--%20STM32/