SPECIFICATIONS

KY-040 Rotary Encoder Module 360 Degree 20 Pulse with Knob Cap 5V for Arduino DIY Electronics

Key Features & Benefits

🔄 360° Infinite Rotation: No mechanical stops – longer lifespan.

🎛️ 20 Pulses Per Revolution: High precision with direction detection.

🔘 Built-in Push Button: Press shaft for menu confirmation or reset.

🔌 5V Compatible: Onboard pull‑up resistors and debounce capacitors.

🎨 Knob Cap Included: Red/black cap, comfortable feel.

🧩 Plug & Play: 5‑pin header (GND, +, SW, DT, CLK).

Product Description

Need intuitive menu control for your Arduino project? KY‑040 rotary encoder module is the perfect choice. 360° infinite rotation, 20 pulses per revolution, built‑in push button. Onboard pull‑ups and debounce caps for clean signals. Includes comfortable knob cap. Perfect for digital volume controls, motor position sensing, Arduino menu navigation.

⚡ Quick Start Guide & Important Tips

🔹 What It Does & What You Need
✅ This product does:

Detects rotation direction and angle (incremental encoder)

20 pulses per revolution (20 PPR)

Built‑in push button for click actions

Digital output – direct MCU connection
❌ This product does NOT: Output analog value, remember position after power loss (incremental only), work directly with 3.3V systems
🔧 You will need: Arduino/5V MCU, jumper wires, 5V power supply
📦 Package includes: KY‑040 Module with Knob Cap × (as per SKU)

🔹 Pinout

⚠️ Critical Warnings:

Voltage: 5V only. For 3.3V systems (ESP32), use a level shifter.

Signal decoding: Must decode both CLK and DT to determine direction.

Contact bounce: Add software debouncing for reliable readings.

No absolute position: Code must maintain a counter; position lost on power loss.

🔹 Arduino Example Code

const int clkPin = 4;
const int dtPin = 3;
const int swPin = 2;
volatile int counter = 0;
volatile int lastClkState;
int lastSwState = HIGH;

void setup() {
Serial.begin(9600);
pinMode(clkPin, INPUT_PULLUP);
pinMode(dtPin, INPUT_PULLUP);
pinMode(swPin, INPUT_PULLUP);
lastClkState = digitalRead(clkPin);
attachInterrupt(digitalPinToInterrupt(clkPin), readEncoder, CHANGE);
}

void loop() {
int swState = digitalRead(swPin);
if (swState == LOW && lastSwState == HIGH) {
Serial.println("Button pressed!");
delay(50);
}
lastSwState = swState;
Serial.println(counter);
delay(100);
}

void readEncoder() {
int clkState = digitalRead(clkPin);
if (clkState != lastClkState) {
if (digitalRead(dtPin) != clkState) counter++;
else counter--;
}
lastClkState = clkState;
}

🔹 Common Questions

❓ Jumpy values when rotating?
Contact bounce – add software debouncing (e.g., small delay or filtering).

❓ Use with ESP32?
Not directly – 5V signal may damage 3.3V GPIO. Use level shifter.

❓ Position lost after power cycle?
Normal for incremental encoders. Save counter to EEPROM if needed.

❓ Knob cap included?
Yes – included and pre‑installed.

Specifications

Encoder Module (KY-040)

Model: KY-040

Voltage: 5V

Resolution: 20 PPR

Rotation: 360° infinite

Switch: Push button

Output Signals: CLK, DT, SW

Pins: 5 (GND, +, SW, DT, CLK)

Knob Cap: Included (ABS, ~15×16.5mm)

Module Size: ~30×19×29mm (without knob)

Shaft Length: ~20mm

Compatible: Arduino, 5V systems (level shifter needed for 3.3V)

Note: Manual measurement, allow 1‑3mm error. Colors may vary.