FrSky Telemetry Protocols

Protocol Information

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

• Repurposed FrSky Telemetry Protocol
• Passthrough FrSky Telemetry Protocol

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		●