PX4-Autopilot/docs/en/concept/pwm_limit.md

PWM_limit State Machine

ThePWM_limit State Machine controls PWM outputs as a function of pre-armed and armed inputs. Provides a delay between assertion of "armed" and a ramp-up of throttle on assertion of the armed signal.

Quick Summary

Inputs

• armed: asserted to enable dangerous behaviors such as spinning propellers
• pre-armed: asserted to enable benign behaviors such as moving control surfaces
• this input overrides the current state
• assertion of pre-armed immediately forces behavior of state ON, regardless of current state
• deassertion of pre-armed reverts behavior to current state

States

• INIT and OFF
  • pwm outputs set to disarmed values.
• RAMP
  • pwm outputs ramp from disarmed values to min values.
• ON
  • pwm outputs set according to control values.

State Transition Diagram