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:


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 latitude and longitude

GPS altitude

GPS speed

Ground speed (using GPS/INS filter)

Air speed (from airspeed sensor)

GPS heading

X, Y, Z accelerations


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