Receiver RSSI Sensing Pin (RSSI_ANA_PIN)

Description

RSSI_ANA_PIN tells the autopilot where to look for the "Signal Strength" wire from your radio receiver.

This is only used if you are physically wiring an RSSI output from your receiver to the flight controller.

• Analog Input: Use an ADC-capable pin (like an analog airspeed port).
• PWM Input: Use a digital GPIO pin (typically a servo output pin configured as a GPIO).

Tuning & Behavior

• Default: -1 (Disabled).
• Calibration: You must also set the RSSI_PIN_LOW and RSSI_PIN_HIGH voltages to calibrate the signal correctly.
• Note: If you are using MAVLink-based RSSI (common with ELRS/Crossfire), this parameter is ignored.

RSSI Strong Signal PWM (RSSI_CHAN_HIGH)

Description

RSSI_CHAN_HIGH calibrates the "Maximum" point for PWM-based RSSI sensors or auxiliary channels.

If your receiver is sending RSSI as a PWM signal, this parameter defines the 100% threshold.

Tuning & Behavior

• Default: 2000.
• Calibration: Place your transmitter near the drone and observe the RSSI PWM value in the GCS. Enter that value here.

RSSI Weak Signal PWM (RSSI_CHAN_LOW)

Description

RSSI_CHAN_LOW calibrates the "Minimum" point for PWM-based RSSI sensors or auxiliary channels.

If your receiver is sending RSSI as a PWM signal (where a shorter pulse means a weaker signal), this parameter defines the 0% threshold.

Tuning & Behavior

• Default: 1000.
• Calibration: Turn off your transmitter and observe the RSSI PWM value in the GCS status tab. Enter that value here.

RSSI Strong Signal Voltage (RSSI_PIN_HIGH)

Description

RSSI_PIN_HIGH calibrates the "100% Signal" point for analog RSSI sensors.

You measure this by placing the transmitter immediately next to the drone's receiver. The maximum voltage output by the sensor is entered here.

Tuning & Behavior

• Default: 3.3V.
• Accuracy: Correctly setting this ensures your GCS shows a full signal bar when you are flying nearby.

RSSI Weak Signal Voltage (RSSI_PIN_LOW)

Description

RSSI_PIN_LOW calibrates the "0% Signal" point for analog RSSI sensors.

You measure this by powering on the drone but keeping the transmitter turned off (or at extreme distance). The voltage reported by the sensor at this state is entered here.

Tuning & Behavior

• Inversion: If your receiver outputs a higher voltage for a weaker signal (inverted), simply set RSSI_PIN_LOW to the high voltage and RSSI_PIN_HIGH to the low voltage.

RSSI_TYPE: RSSI Type

Description

Radio Receiver RSSI type. This selects the method used to read the signal strength (RSSI) from your radio link.

Values

• Default: 0

Description

RSSI_TYPE tells the autopilot how to measure the "health" of your radio control link.

• Receiver Protocol (3): The modern standard. If you are using ELRS, Crossfire, or FrSky FPort, the RSSI is sent digitally inside the data stream. Set this to 3 and no other wiring is needed.
• RC Channel (2): Common for older FrSky setups where you map RSSI to an auxiliary channel (e.g., Channel 8 or 16).
• Analog (1): Used for very old receivers that output a 0-3.3V signal.

Source Code

ardupilot/libraries/AP_RSSI/AP_RSSI.cpp