I'm trying to control an APM using Mavlink and a joystick.
I understand that the Mavlink message I need to send for this is RC_CHANNELS_OVERRIDE. Some of the fields in this message are obscure to me.
I notice that Mission Planner sets SystemID=255 and ComponentID=190 in the packet header, and in the body of the message itself sets target_system=220 and target_component=5.
Where do these numbers come from? Are they important? Are they constants? Do they change with APM configuration? Mavlink documentation says precious little about these.