User Manual

Lesson 19 Rotary Encoder

Introduction

A rotary encoder is an electro-mechanical device that converts the angular position or

motion of a shaft or axle to an analog or digital code. Rotary encoders are usually placed

at the side which is perpendicular to the shaft. Rotary encoders act as sensors for detecting

angle, speed, length, position and acceleration in automation field.

Components

- 1 * SunFounder Uno board

- 1 * USB data cable

- 1 * Rotary Encoder module

- Jumper wires

Experimental Principle

There are mainly two types of rotary encoder: absolute and incremental (relative) ones. The

output of absolute encoders indicates the current position of the shaft, making them angle

transducers. The output of incremental encoders provides information about the motion of

the shaft, which is typically further processed elsewhere into information such as speed,

distance, and position.

In this experiment, we will use the latter. An incremental encoder is a rotary sensor to turn

rotational displacement into a series of digital pulse signals which are then used to control

the angular displacement. It generates two-phase square waves whose phase difference is

90°. Usually the two-phase square waves are called channel A and channel B. See the

following figure for details.

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