ELRS on Pixhawk 2.4 with ardupilot

5月 04, 2023

I still have few old FC:3DR pixhawk

I have try to connect my ELRS 2.4G rx to it. since you got RC control and telemetry on one little receiver.

But ELRS is relatively recent, not much resource on it. There are also different version of clone. but when flashing with mission planner, it says this is FMUv2

I have set up and bind tested my ELRS https://ldsrc.blogspot.com/2023/05/crsf-lers-decode-with-arduino-leonardo.html

I know it works on RC channel output.

First thing is to know the Serial port Nr in mission planner mapping to the labels on my pixhawk. Lucky the mapping is quite straight forward.

Pixhawk FMUv2 / Cube FMU v3 Serial Mapping

The I follow this instruction: to set serial protocol at 23, and othe

https://www.expresslrs.org/quick-start/ardupilot-setup/

My ELRS is at V.3.2.1, we can set the baudrate, since we set 115 in pixhawk, I also set the same in ELRS RX.

then it's the chaos...I tried different ports, different baudrate, invert TX/RX(which is not necessary on both side)

At the end, I believe when you set serial protocol at 23, ardupilot will automatically set baudrate to 420 000, which you can't find in the serial baud selection.

So, I kept the serial baud at 115200 and change my elrs rx baud at 420k...

Then I got it worked at serial4. I can have RC input when goes to the rc calibration section.

Next step is the telemetry on T18

https://github.com/yaapu/FrskyTelemetryScript/wiki/Passthrough-over-CRSF-and-ExpressLRS

I have RC_options set for using passthrough for CRSF

I did the config it says, and get the yaapu lua 2.0.0 on my T18 have the elrs support enabled, but still get noting on the elrs debug...

I tested with purchased 2.4G one and my 915 TTGO V2, both has radio channel input, but get no telemetry data.