Overview
The RC parameter group configures how the autopilot interprets signals from the Radio Control (RC) receiver. It handles channel calibration (Min/Max/Trim), reversal, and the assignment of auxiliary functions to transmitter switches.
ArduPilot supports up to 16 RC input channels.
Key Concepts
1. Channel Calibration (RCn_MIN, RCn_MAX, RCn_TRIM)
Defines the pulse-width range (PWM in microseconds) for each stick and switch.
MIN: Pulse width at lowest stick position (typically ~1000us).MAX: Pulse width at highest stick position (typically ~2000us).TRIM: Pulse width at center/neutral position (typically ~1500us).DZ: Deadzone. Small range around the center where stick movement is ignored to prevent "jitter" or "drift."
2. Auxiliary Functions (RCn_OPTION)
This is the most powerful feature of the RC system. You can map any of ArduPilot's hundreds of functions to a switch on your transmitter.
- Common Options:
- 7: Do Nothing.
- 22: Parachute Release.
- 28: Gripper.
- 300: Camera Trigger.
3. Failsafe (RC_FS_...)
Configures how the autopilot detects that the radio link has been lost.
RC_FS_TIMEOUT: How many seconds of no signal before triggering a failsafe action.
Parameter Breakdown
RC_PROTOCOLS: Bitmask to select which digital protocols to search for (SBUS, CRSF, FPort, etc.).RC_OPTIONS: Bitmask for specialized input behaviors (e.g., ignore receiver failsafe bit).RC_SPEED: Update rate for standard PWM inputs (Hz).
Integration Guide
- Calibration: Always perform "RC Calibration" in your GCS whenever you change your transmitter settings or receiver.
- Assignment: Use the "Radio Calibration" or "Extended Tuning" screens to assign switch functions (
RCn_OPTION). - Reverse: If the HUD shows the drone tilting the wrong way, use
RCn_REVERSED.
Developer Notes
- Library:
libraries/AP_RCProtocol. - Filtering: Input signals are low-pass filtered to reduce noise.