Controls a PWM output on the machine by setting the duty cycle and optionally the frequency.
output_pwm(pin, duty) output_pwm(pin, duty, frequency)
Set output pin 1 to 50% duty cycle
output_pwm(1, 50);
Set output pin 2 to 75% duty cycle at 1 kHz
output_pwm(2, 75, 1000);
Set output pin 6 to 20% duty cycle at default frequency
output_pwm(6, 20);