FrSky Telemetry Protocols

Protocol Information

ArduPilot has FrSky telemetry drivers to natively output autopilot information through the serial ports. It comes in two flavors:

  1. Repurposed FrSky telemetry (D and SmartPort), which reuses FrSky data IDs to transmit basic flight control information to the RC transmitter (e.g. T2 temperature message reused to transmit the number of GPS satellites and GPS status); and
  2. Passthrough telemetry (SmartPort), which leverages the new passthrough FrSky data IDs to send an extensive amount of autopilot specific information to the RC transmitter.

FrSky telemetry is also possible through the use of a MAVLink to FrSky converter.

The following table summarizes the information available using each protocol:

Feature Repurposed FrSky telemetry Passthrough FrSky telemetry
Vehicle/frame type  
Flight/control mode
Simple/super simple mode  
Throttle %    
Flight timer (automatically counting while in flight)  
Battery pack voltage
Battery failsafe voltage  
Battery failsafe capacity  
Battery failsafe trigger  
EKF failsafe trigger  
Instantaneous current consumption
Total current consumption  
Battery pack capacity (mAh)  
Battery pack capacity remaining (%)
GPS number of satellites visible
GPS fix status (e.g., 2D, 3D, DGPS, RTK)
GPS HDOP  
GPS latitude and longitude
GPS altitude
GPS speed  
Ground speed (using GPS/INS filter)  
Air speed (from airspeed sensor)  
GPS heading  
X, Y, Z accelerations    
Roll/pitch/yaw  
Barometric altitude    
Altitude from home (using GPS/INS filter, incl. barometer)
Rangefinder distance  
Direction to home  
Distance from home  
Vertical velocity  
Arming status  
Sensor health messages (e.g., Bad Compass Health)  
EKF error messages (e.g., Error compass variance)  
MAVLink status messages