Auxiliary Function Switches

This article shows how to set up which features are invoked from the transmitter’s auxiliary function switches (Up to/including AC3.2.1 you could only set the Channel 7 and 8 options, From AC3.3 you can set options for channels 7 - 12).


AC3.3 introduces support for auxiliary functions on channels 9 ~ 12.


By default the auxiliary switches are disabled but you can assign features using the Mission Planner‘s Config/Tuning | Extended Tuning screen or by setting the CH7_OPT (or CH8_OPT) parameter directly.


Here are the options:

Option Description
Flip Vehicle will flip is on roll axis. Vehicle will rise for 1 second and then rapidly roll. The vehicle will not flip again until the switch is brought low and back to high. Give yourself at least 10m of altitude before trying flip for the first time!
Simple Mode

The copter moves left, right, forward and back as if it were facing in the same direction as when it took off regardless of the copter’s heading. See here for more details.


Return-to-Launch. The vehicle will first climb to a safe altitude (defined by RTL_ALT parameter), then return home, pause over home for 5 seconds (configurable by RTL_LOIT_TIME parameter) then descend to 2m or land (configurable by RTL_ALT_FINAL parameter).

Save Trim

Adjust the vehicle level position using the current roll and pitch stick inputs. See details here.</td>

Save WP Save the current location (including altitude) as a waypoint in the mission. If in AUTO mode no waypoint will be saved, instead the vehicle will RTL
Multi Mode


This option has been removed from AC3.3 (and higher).

Ch6 tuning knob position controls which of the following 3 functions is invoked when ch7 or ch8 switch put in the on position.

  • Ch6 <1200 : Flip
  • Ch6 1201 ~ 1799 : RTL
  • Ch6 > 1800 : Save Waypoint
Camera Trigger

Camera shutter will be activated. See more details here.

Sonar Sonar is disabled when switch is in low position, enabled when it high position.
Fence Fence is disabled when switch is in low position, enabled when it high position.
ResetToArmedYaw Vehicle will turn to face the same direction that it was facing when it was first armed (e.g. at take-off). An alternative to simple mode when you've lost orientation and need to bring the craft home.
Super Simple Mode

Similar to simple mode except controls are relative to the home position. Move the pitch stick forward and the copter will fly away from home, pull pitch back and it will return. Move roll stick left or right and the copter to orbit home regardless of the copter’s actual heading. See here for more details.

If mapped to a three-position switch then the function will allow Super-Simple and Simple modes to be enabled using the high and middle switch positions, respectively (a two-position switch will enable/disable Super Simple mode only).

Landing Gear

Retracts/Deploys landing gear. (AC3.3 only)
Lost Copter Alarm

Plays the lost copter alarm though the buzzer (AC3.3 only)

Emergency Stop Motors

Stops motors immediately (video). (AC3.3 only)

Motor Interlock

Opposite of Emergency stop (above) in that switch must be ON for motors to spin (video). (AC3.3 only)


Invokes the Brake flight mode when switch goes high. Bringing switch back to low will return the vehicle to the mode indicated by the ch5 flight mode switch. (AC3.3 only)

Check Ch7 & Ch8 PWM values reach 1800

Your channel 7 and/or channel 8 pwm value must reach at least 1800 PWM or the auxiliary function will not be activated. You can check that it surpasses this threshold using the Mission Planner’s radio config page.