KY-040 Rotary Encoder + Knob
by Generic
SKU: PSA-CMP-ENCODER
No reviews yetTypical India street price
₹30–₹80
Infinite-turn knob for menus, volume, robot heading.
Interface: 2-bit quadrature + switch
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Concept
Two switches 90° apart (A/B) tell you direction; shaft click is a button.
A little theory
Quadrature: 00-10-11-01. Debounce; use interrupts on A. In the classroom, treat KY-040 Rotary Encoder + Knob as a intermediate part using 2-bit quadrature + switch. Typical India street price is about ₹30–₹80. Always verify voltage and pin labels on your exact module — silk screens vary across clones. Start with a datasheet or trusted learn guide, power the part correctly, share GND with the MCU, and test with a simple blink/read sketch before building the full project. Measure voltages with a multimeter when something fails, and keep actuator current off the MCU regulator.
How it works in a project
Encoder library or attachInterrupt; SW as INPUT_PULLUP.
Classroom & project use
- Menu UI
- Motor setpoint
- Volume
Buying in India
Precautions
- Share a common GND with the microcontroller
- Verify polarity and voltage before powering the circuit
Specifications
| Type | Mechanical quadrature |
| Category | Sensors |
| Difficulty | Intermediate |
| Voltage | 3.3–5V |
| Interface | 2-bit quadrature + switch |
Pinout
See module silkscreen: typically VCC, GND, and signal pins. Confirm labels against the seller photo — clones vary.
