PX4 Safety Switch

Safety Switch


A safety switch can be used to enable/disable the outputs to motors and servos.

LED meaning

  • Constant blinking – system is initialising
  • Intermittent blinking – system is ready. press the safety switch to enable output to the motors.
  • Solid – safety switch has been pressed, motors and servos are able to move once the vehicle is armed.

Configuring the Safety Switch


Using the Safety Switch to force I/O board firmware update

If the safety switch is held down for the first few seconds after a Pixhawk is powered up, the I/O firmware is reloaded.

This is normally not required but in some rare cases is required after a firmware upload if you hear the “Start up Failed” sound after startup (see Sounds wiki page).


A Pixhawk has two CPUs, the main CPU (aka FMU) is where ArduPilot runs. There is a separate I/O CPU which is responsible for some I/O including PWM outputs to the MAIN OUT channels. Pixracers only have the main CPU.

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