SG90: a mini-servo motor

This is a a very handy and cheap servo motor with nice performances. It is suitable for many lightweight applications. We will use it to motorize a 2-DOF Tilt-Pan on which we will mount our preferred ultrasonic sonar sensor, namely the HC-SR04. Before proceeding let us review the main specs. 

Basics

Brand:             Tower Pro

Modulation:     Analog

Torque:           1.8 Kg.cm (at 4.8V)

Speed:             0.12 s/60° (at 4.8V)

Motor type:      3 poles

Gear type:        Plastic (Nylon)

Rot./Support:    Bushing

Supply voltage: 3V-6V

Pinout

Red wire:      +Vcc

Brown wire:  GND

Orange wire: Signal

Physical dimensions

Length: 23mm

Width:  12mm

Height:  29mm

Weight: 9g

Additional infos

Pulse width: 500-2400 μs

Rotational range: 180° (nominal)

Operation

The servo is controlled by sending pulses of width between 500 and 2400 μs. At each pulse the servo will rotate of 1°. Then, you should wait for 20ms for the servo to reach the position before sending the next pulse.

Programming
In order to experiment with the servo, you can use the Servo library at Arduino.cc. You can also follow this small tutorial/example.

Caveats

Remark that a servo is power consuming and that the Arduino can drive limited current (up to 40mA) per pin. Moreover, the total current output is 200mA. Therefore, it is not a good idea to drive directly more than two SG90, otherwise you risk to damage your Arduino.