Chapter 15: Flight controller

【Introduction】

• This article will conclude an user manual for FlightControllerKey.

【Basic Information】

• You can use KeyConnection to get the connection status of a flight controller. Since the flight controller is non-removable on an aircraft which mean it also represents the connection status of an aircraft.
• You can use KeyIsFlying to know if the aircraft is flying. It means the motor is running and altitude is not 0.
• You can use KeyFlightTimeInSeconds to know the total flying time after the first start of the motor. This value will be reset if the power is switched off.
• You can use KeyAircraftLocation3D to know the 3D location in WGS84 coordinate system. The altitude means the relative altitude to the take off point.
• You can use KeyAircraftAttitude and KeyAircraftVelocity to know the attitude and velocity of an aircraft in N-E-D system.
• You can use KeyTakeoffLocationAltitude to know the altitude above sea level but this data is inaccurate.
• You can use KeySerialNumber to get the serial number of this flight controller, it normally also represents the product serial number.

【Sensor】

• You can use KeyGPSSatelliteCount to get the total detected GPS satellites number, normally you can detect at least 12 when flying. It is good to detect about 18 or 19 satellites.
• You can use KeyGPSSignalLevel to get the GPS signal level. Normally you need at least level 4 to start a waypointMission. Level 10 means the GPS data is mixed with the RTK data(Not all aircraft will have a level 10, this definition is for reference only).
• You can use KeyCompassCount to know the total number of compasses and KeyCompassHeading for compass heading. Its 0 degree means the magnetic North. If the KeyCompassHasError is true, you need to call KeyStartCompassCalibration to start the compass calibration and use KeyCompassCalibrationStatus to monitor the calibration status.
• You can use KeyUltrasonicHeight to know the ultrasonic module's distance measurement from the bottom of an aircraft.
• You can use KeyWindWarning to get the wind warning, use KeyWindSpeed to get the wind speed and KeyWindDirection for win direction.

【Basic configuration】

• You can set KeyMultipleFlightModeEnabled which means the flight mode is allowed to switch. When this key returns true, it is effectless when you switch the flight mode switch on an RC.
• You can use KeyIsFailSafe to know if the aircraft is executing a fail safe action. You can use KeyFailsafeAction to set the fail sate action. It will be triggered when the connection link is broken between the RC and the aircraft.
• You can use KeyLowBatteryWarningThreshold to set the low battery warning threshold in a range of 15% to 50%. The low battery warning will be triggered if the battery level is lower than this threshold. You can use KeySeriousLowBatteryWarningThreshold to set the serious low battery warning threshold. The default value is 10% and the return home function will be triggered if the battery level is lower than this threshold.
• You can use KeyLEDsSettings to control the forearm lights, status indicators and night lights.
• You can use KeyAreMotorsOn to know if the motor is running. You can use KeyLockMotors to lock the motor. You can not use the control stick to start the motor if KeyLockMotors returns true. Set the KeyESCBeepEnabled as true will start the ESC beep sound to help you find the missing aircraft.
• Set the KeyCoordinatedTurnEnabled as true will enable the coordinated turn. When the aircraft turns, the node follows the flight direction. There is no sideslip flight, and the resistance of flight is smaller.

【Basic operation】

• Call KeyStartTakeoff will make the aircraft take off.
• Call KeyStartAutoLanding will make the aircraft land. It will hover in air when it is 0.7m above the ground. Then the KeyIsLandingConfirmationNeeded turns to true and you can call KeyConfirmLanding to finally land the aircraft.
  

【Return home function】

• You can use KeyHomeLocation to set the return home point, call KeyIsHomeLocationSet to know if the return home point is set . Normally the aircraft will set its take off point as the return home point. You can use KeyHomeLocationUsingCurrentAircraftLocation to set the current aircraft location as the return home point. You can also use KeyHomeLocationUsingCurrentRemoteControllerLocation to set the current RC location as the return home point. Since the RC does not contain an GPS module, it usually uses Android system API to the Android device location through internet.
• You can use KeyGoHomeHeight to set the return home height which is relative to the take off point. You can know the setting range by using KeyGoHomeHeightRange. If the horizontal disatance between the return home point and aircraft is below 50m, the aircraft will ignore the KeyGoHomeHeight and return to home in its current height. If the visual system is not working properly now, the aircraft will use the KeyGoHomeHeight to return home anyway.
• You can use KeyStartGoHome or press the go home button to start return home function.
• You can use KeyLowBatteryRTHEnabled to determine whether or not the low battery return home function is enabled. We recommend you not to disable it.