Servo

Servos are controlled via PWM.

The PWM signal is typically 50Hz (20ms) with a pulse width of 1-2ms (1000-2000us), with a center position at 1.5ms (1500us).

The pulse-width encodes the position, and the presence of a pulsing signal is used to indicate that the motor should move (and potentially how fast it should move).

This is in contrast with other types of motors which are controlled via varying the duty-cycle. The overall duty-cycle is not relevant to servos.

Other things, such as the Talon or Jaguar modules, use a similar control system.