1. Rotary Encoders
Cedric Pinder
Major: Computer Engineering

2. What is a Rotary Encoder?
Wikipedia
A digital electronic device used to convert the angular position of a shaft or axle to a digital code.
Layman’s Term
Is a mechanism that converts a shaft (rotary) angle into an electrical signal.

3. Terms
Gray code- is a binary numeral system where two successive values differ in only one digit.
Detent- is a catch or lever that locks the movement of one part of a mechanism.

4. How is this possible?

5. When the rotary encoder is turned
How is this possible?
When the rotary encoder is turned
Why Gray code & Binary’
Rotary encoders are subject to wear and tear due to the turning of the shaft.
In due time the opening and closing timing of the internal switches won’t be in-sync.
If the switches are not in-sync, then incorrect position codes will be generated at the output of the logic devices connected to the encoder.
So, since Gray code only changes by one bit at a time and we can only close or open one switch of a rotary encoder at a time than this eliminates the problems.

6. Oscilloscope’s Results
Clockwise
Counter clockwise

7. Are they other encoders?
Absolute encoder- is a device that reports the shaft angle within a 360° range. An absolute encoder does not lose its position after a power-down and provides the absolute position upon power-up without requiring a home cycle or any shaft rotation.
Incremental encoder- is made up of 2 major parts: the disk and the sensor. The disk of an incremental encoder is patterned with a single track of repeating identical lines near the outside edge of the disk. The number of line pairs on the disk determines the encoder resolution (CPR).
Optical encoder- is a sensor that uses light to sense the speed, angle and direction of a rotary shaft. A linear encoder reads a linear strip instead of a disk to provide the same information for linear motion.

8. How is this beneficial to you?
This can be used in your final project for:
Volume and Tone Control for Audio Visual Equipment.
Tuner for Communication Units
Mode Selection for Measurement

9. Technical Specification
Encoder
360 degree, 12 detents,pulses per revolution
Voltage
5 Vdc
Current
1 mA

10. Circuit Diagram

11. References & Further information
technical documentation-
Embedded Design with the PIC18F452 Microcontroller, pg

12. Contact Info
Cedric Pinder
Phone: