PX4 FAQ
Cannot Arm the Drone?#
Check for any (Preflight checks fail) error messages from QGC.
Check for the throttle position (it must be "low").
Check whether you are using Arming Gesture or Arming Buttom/Switch (they are either or). More info here
Check the parameter COM_RC_IN_MODE, it should be the default value 0.
more information regarding PX4 mixing and geometry file https://github.com/jlecoeur/servo_mix_matrix
https://github.com/PX4/PX4-Devguide/issues/435
https://github.com/PX4/PX4-Devguide/issues/511
Radio channel twitches in QGroundControl#
Check if you are using manually inverted SBUS signal. Try to use the original signal pad from the receiver.
Past experience with frsky r-xsr is that if we manually solder the wire from the inverted SBUS pad, it may have the twitching problem. If we use the original SBUS signal wire connect to the flight controller SBUS pad then all is good.
Drone slowly spins after takeoff#
Check RC calibration. If you copy the param from another drone, you may encounter this. Just try to re-calibrate your RC from QGroundControl.