What Is an Arduino® Servo?

Jo Dunaway

Arduino is the registered trademark name for a type of marketed servo. A servo is a short name in widespread usage for a serverino or servomechanism. An Arduino® servo is an electrical or partially electronic automatic device that uses negative feedback error-correction to move and change mechanical positions when mounted on a board. The servo may be attached as well to a servomotor or not have a motor attached at all. The most common usage for an Arduino® servo is for position control and can have a servomotor to furnish the mechanical force to rotate a potentiometer arm to a specified position, as used in mini-robotics.


An Arduino® servo has its own library of instruction and error-correction codes that can be downloaded from the website after purchase. It is an open-source embedded system platform, and the coding is generally considered simple to learn and use. Prices are moderate, but some users like to make their own by buying the components from Arduino® and constructing simple servomechanisms, often for less than $5 US Dollars (USD). Once constructed, the programming instructions can be downloaded, the bootloader can be unlocked to program the fuses, the bootloader burnt, and then the bootloader relocked. Many mini-robotics hobby uses are built in just such fashion after purchasing Arduino® servos and components.

Servos can be controlled by use of a pulse of a width specified from the control wire. These pulses have a minimum and maximum limit as well as a repeater rate. Different servos will have different minimum and maximums rates, however, they all have a neutral that has identical clockwise and counterclockwise force that keeps the arm still. Angles of movement are controlled by the length of the pulses, as the length determines how far rotations turn. These servos can be powered by a simple 9V battery, or for longer periods can be powered by larger batteries. To preserve batteries, the Arduino® servos can be put into a sleep mode.

The first uses of servomechanisms were military in marine navigation equipment and fire-position control systems. More modern uses are for satellite-tracking antennas, anti-aircraft gun control positions, and automatic machine tools. Hard disk drives have a servo system with micro-positioning reliability and accuracy parameters. Servos are used in remote controlled airplanes and boats, as well as fly-by-wire systems in aircraft. Complex motions in industrial machines on assembly lines are powered by servos, among a few of more modern uses of an Arduino® servo.

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