User manual

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Chapter20 Servo Motor

Controlling a servo motor with an Arduino or other type of microcontroller is probably the easiest

way to get started in robotics, motion art, or any other reason you may have to make your

electronic project interact with the real world. Servos are very simple to interact with and in this

post I’ll show you how to connect one to an Arduino.

Servo motors are a specific type of motor, often used in hobby RC cars and planes, that rotate to

a specific angle when a corresponding signal is applied to the pulse pin. Servo motors are very

easy to program and very strong for their size. This makes them useful for a wide array of

applications. The internal components of a servo motor consist of a regular DC motor, which does

the actual work, a system of gears to increase the torque to the output shaft, and a circuit board

and sensors to control the movement of the motor.

Wiring:

To get started controlling a servo with your Arduino, you only need to connect three pins. There

are two pins for power and ground. For a small servo or just for testing, you can connect these

directly to the Arduino. If you are controlling a large servo motor, you might want to use an

external power source. Just remember to connect the ground from the external source to the

ground of the Arduino.

The third pin is the pulse, or signal pin. This accepts the signal from your controller that tells it

what angle to turn to. The control signal is fairly simple compared to that of a stepper motor. It is

just a pulse of varying lengths. The length of the pulse corresponds to the angle the motor turns

to. Typically a pulse of 1.25 milliseconds causes the motor to rotate to 0 degrees and a pulse of

1.75 milliseconds turns it 180 degrees. Any length of pulse in between will rotate the servo shaft