A common trope for long-range pilots in the search for great performance and longer flights is to put the TX modules up in a pole or to use antenna trackers in order to increase the range by making the signals go over obstacles easier or by using high-gain antennas that has to point to the aircraft to be effective. Commercial systems like the Dragonlink, allow you to do that by providing standard SBUS and Mavilink protocols which can be retransmitted wirelessly to the radio using a wireless usually by a regular RC receiver and/or wifi-fi, Bluetooth allowing the user to stay out of the sun, use larger monitors for FPV, etc.
The technology used in the ExpressLRS TX modules gives us an enormous range and excellent penetration but, due to the characteristics of the protocol (CRFS), the TX module has to be physically attached to the radio, negating the benefits expressed above.
The objective of this project is to close this gap by creating a bidirectional converter for the CRFS protocol used in ExpressLSR and TBS Crossfire.
Using two cheap microcontroller boards, the relay will convert the CRFS protocol used to SBUS+SPORT and back allowing the mounting of the ExpresssLRS TX into a pole or tracker, greatly extending its range and mobility.
Currently, only RP2040-zero (and potentially Raspberry Pi Pico) is supported but other platforms with 3 serial ports can be used and may be supported in the future.
The authors can't take responsibility, personal or otherwise, by the use of this software. It is provided "as is".
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