Rotary Encoder Module — CLK/DT/SW Output, 20 Detents, Arduino Compatible (KY-040)

Rotary Encoder Module — CLK/DT/SW Output, 20 Detents, Arduino Compatible (KY-040)

This rotary encoder module (KY-040 compatible) is an incremental position sensor that reports the direction and amount of shaft rotation, plus a pushbutton press when the shaft is depressed. It's the essential input device for Arduino menu navigation, volume control, and any application requiring continuous rotary input without a mechanical stop. The module includes a built-in pull-up resistor on the SW pin and a 5-pin header for direct connection to Arduino.

Module Specifications

• Type: Incremental rotary encoder (no absolute position)
• Detents per Revolution: 20 (20 clicks = 1 full rotation)
• Outputs: CLK (A), DT (B), SW (pushbutton)
• Operating Voltage: 3.3V – 5V DC
• Pushbutton: Active LOW (shaft press)
• Rotation: Continuous (no mechanical stop, infinite turns)
• PCB Dimensions: 26 × 20mm
• Shaft Height: 30mm total

5-Pin Header Connections

• GND: Ground
• +: VCC (3.3V or 5V)
• SW: Pushbutton output (active LOW) → Arduino digital input
• DT: Direction output (B phase, 90° lag) → Arduino digital input
• CLK: Clock output (A phase) → Arduino digital input

Direction Detection Logic

• Clockwise (CW): When CLK changes state, DT ≠ CLK
• Counter-Clockwise (CCW): When CLK changes state, DT = CLK
• Compare CLK and DT states on each CLK edge to determine rotation direction

Arduino Wiring

• GND → Arduino GND | + → 5V
• CLK → D6 | DT → D5 | SW → D7 (with INPUT_PULLUP)

Typical Applications

• LCD menu navigation: Scroll through menu items (rotate) and select (press) — the most common use case
• Volume / parameter control: Adjust audio volume, motor speed, or any continuous parameter
• Stepper motor control: Rotate encoder to drive stepper motor in same direction and amount
• Odometer / distance measurement: Attach wheel to shaft and count pulses for distance
• Position tracking: Track relative position from power-on reference point

Package Contents

• 1 × Rotary encoder module (KY-040 compatible) with 5-pin header

20 detents, infinite rotation, CLK/DT/SW outputs — the KY-040 rotary encoder module is the go-to input device for Arduino menu navigation, volume control, and continuous rotary position sensing.

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