Custom RC Switch Functions with Arduino

Hello friends,

We are customizing a 3DR X8+ with a Pixhawk 4 and a separate Arduino Nano for a school project. We’re using Mission Planner 1.3.64 and want to use the triggers on our RC transmitter to run Arduino code.

The drone has a circular saw dangling from a pole. One goal is to be able to activate this saw using the triggers on our RC transmitter. It seems there are some preset functions available for RC6-8, but on our these ports are all occupied by propellers. Is there some way to use the other RC ports to perform custom functions?

Other than activating the saw, we also want to use the RC transmitter to activate a servo which would release the circular saw in case of an accident. For this we have the same question: how do we add in custom Arduino code that can be run from the transmitter switches?

Please let me know if any additional information is needed, I’m checking this post regularly. Any advice at all is welcome, thank you.