PX4 processes manual input from radio controls (RC) or other manual input devices into a standardized format (MANUAL_CONTROL topic). This format then serves either as input to the vehicle controllers or is (for fixed wing) directly passed into the mixer.
- RC_x_MIN, RC_x_TRIM, RC_x_MAX: These parameters are used to scale from PPM pulses to the standard -1..1 range for roll, pitch, yaw and 0..1 for throttle.
- RC_MAP_<function>: These parameters assign channel N to a function, e.g. channel 1 to roll. This is required as the channel order is not the same on all remote controls.
PX4 has these manual input function channels. These do NOT correspond to RC channels, but can be either mapped from one or multiple RC channels or from any other input device. The channels in bold are the minimum / mandator set. If the channel mapping is set to zero (0) for a channel, the input will be ignored. The mapping also allows multiple function channels to receive input from the same RC channel. This is handy for example on the Turnigy 9x to use only two switches: The three position switch for the MODE_SWITCH (which defines the main mode, which is MANUAL, ASSISTED or MISSION), and then the 2 position switch for the sub-mode (e.g. in ASSISTED the submodes SEATBELT or EASY).
Currently a maximum of 14 RC input channels is supported.