mLRS

This project initially made use of the AT Command firmware that comes flashed on the integrated STM32 MCU for the SeeedStudio LoRa-E5-HF chip. When reading documentation for this chip it may mention this AT Command firmware. This is no longer applicable as we have re-flashed both the Base Station and Purple Drone LoRa hardware with updated mLRS Firmware. Information on the mLRS project can be found here

For more specific information on using the mLRS firmware with the SeeedStudio LoRa-E5-HF chip see the documentation here. This documentation discusses using the Wio-E5 development board, which is a lightweight development board for the LoRa-E5-HF chip, however it is applicable to the daughter board on the Base Station as well.

Hardware Changes

In order to facilitate mLRS using the current hardware on the drone we had to re-map the UART connections used by the mLRS firmware. Information on re-mapping UARTs can be found here and instructions for building mLRS from source can be found here The new UART connection is as follows.

Pin	Purpose
PB7	RX
PB6	TX

This is the serial connection used to facilitate the MAVLink connection between the FC and the LoRa chip on the drone. The KiCAD files for the drone can be downloaded here.

Base Station LoRa

The UARTs on the Base Station LoRa were not re-mapped. The serial MAVLink data comes from the following UART Pins. The full KiCAD folder for the base station LoRa can be found here.

Pin	Purpose
PA3	RX
PA2	TX

On the Base Station side, we take that MAVLink stream coming from the mLRS LoRa device, and use an ESP32 to broadcast it over UDP to the Base Station Network. Information about this can be found here. The ESP32 sketch configured for used with the Base Station Wifi network can be found here