A Rotary Encoder is an electromechanical sensor used to convert the angular position or motion of a shaft into digital signals. Unlike potentiometers, rotary encoders provide infinite rotation and precise incremental or absolute position feedback, making them essential in IoT, robotics, automation, and research applications.

The most common type used in research and embedded systems is the Incremental Rotary Encoder (KY-040 or similar). It outputs two square wave signals (A and B), phase-shifted to indicate rotation direction and steps. Some variants also include a push-button switch for additional input functionality.

Key specifications (typical incremental encoder, KY-040):

• Type: Incremental rotary encoder

• Resolution (Steps): 20 pulses per revolution (PPR) (varies with model)

• Interface: Digital quadrature output (A & B channels)

• Push Button Switch: Integrated, normally open

• Operating Voltage: 3.3V – 5V logic level compatible

• Output: TTL-compatible square wave signals

• Rotational Life: >100,000 cycles

• Operating Temperature: -40°C to +85°C

• Mounting: Panel-mount or PCB mount

Research & application relevance:

• Robotics & Automation: Used for motor shaft position, speed measurement, and feedback control in PID systems.

• IoT Devices: Provides user input control (menu navigation, volume, parameter tuning) in smart devices.

• Mechatronics Research: Supports experiments on motion tracking, feedback systems, and control algorithms.

• Embedded Systems: Ideal for integration with Arduino, ESP32, STM32, and Raspberry Pi for rotational sensing.

Rotary encoders are valued in research for their precision, durability, and ability to provide real-time motion feedback, making them essential in motor control, robotics navigation, and human–machine interface (HMI) projects.