Overview
The SERVO parameter group (often appearing as SERVOx_ or MOT_) configures the physical PWM / DShot / SBus outputs of the flight controller.
While RCMAP handles Input, the SERVO group handles Output. It defines what each pin on the servo rail actually does (e.g., Motor 1, Aileron, Camera Trigger, etc.) and how the signal is scaled.
Key Concepts
1. Servo Functions (SERVOx_FUNCTION)
The most important setting. Tells the autopilot what is plugged into the pin.
- 0: Disabled.
- 33: Motor 1 (Multicopter).
- 4: Aileron (Plane).
- 10: Camera Trigger.
- 51: RC Passthrough (Directly copies an input channel to this output).
2. Output Calibration (SERVOx_MIN, MAX, TRIM)
Defines the pulse-width limits (microseconds).
MIN: The "Low" endpoint (typically 1100us).MAX: The "High" endpoint (typically 1900us).TRIM: The "Neutral" position (typically 1500us).REVERSED: Flips the direction of travel (0=Normal, 1=Reversed).
3. BLHeli / DShot Pass-through (SERVO_BLH_...)
Configures the interface for BLHeli_32 ESCs, allowing the autopilot to perform firmware updates and read RPM telemetry (Bi-directional DShot).
Parameter Breakdown
SERVO_RATE: The update frequency for standard PWM servos (default 50Hz).SERVO_DSHOT_RATE: The speed of digital DShot outputs.SERVO_GPIO_MASK: Converts PWM pins into simple digital High/Low pins.
Integration Guide
Setting up a New Motor
- Connect ESC to Output 1.
- Set
SERVO1_FUNCTION = 33(Motor 1). - Set
MOT_PWM_TYPEto your desired protocol (e.g., DShot600). - Test: Use the "Motor Test" tab in the GCS to verify rotation direction. If wrong, use
SERVO1_REVERSED(for PWM) or BLHeliSuite (for DShot).
Developer Notes
- Library:
libraries/SRV_Channel. - Safety: PWM outputs are disabled until the vehicle is Armed or the Hardware Safety Switch is pressed.