Rotary encoder is a sensor that tell rotation and direction.
It is used in volume knobs, motors, robot wheels and menu selections.
Arduino can read the encoder pulses and show value in serial monitor.
This project for KY040 Encoder Module Circuit with Arduino is very simple and beginner friendly.
Arduino Coding:
int clk = 6;
int dt = 7;
int counter = 0;
int lastState;
void setup() {
Serial.begin(9600);
pinMode(clk, INPUT);
pinMode(dt, INPUT);
lastState = digitalRead(clk);
}
void loop() {
int currentState = digitalRead(clk);
if (currentState != lastState) {
if (digitalRead(dt) != currentState) {
counter++;
} else {
counter--;
}
Serial.println(counter);
}
lastState = currentState;
}Coding Explanation:
- clk pin gives pulse when turning.
- dt pin tells direction.
- Arduino store last state.
- If state changes then rotation happen.
- If dt is different from clk then clockwise.
- If dt same then anticlockwise.
- Counter increase or decrease.
- Serial monitor show value.
Circuit Working:
Parts List:
| Part Name | Quantity |
|---|---|
| Arduino Uno | 1 |
| KY040 Rotatory Encoder module | 1 |
| USB cable | 1 |
Power goes from USB to Arduino.
Arduino gives 5V and GND to the rotary encoder.
Encoder knob turns and makes two pulse signals on CLK and DT pins.
Arduino reads change on CLK.
At that moment Arduino checks DT.
If DT is different from CLK clockwise.
If DT is same as CLK anticlockwise.
Arduino increases or decreases counter value.
Serial monitor shows the new counter value.
This is how the circuit reads rotation and direction.
Formula with Calculation:
Basic formula:
angle = steps × stepAngle
where,
- angle is the total rotation amount.
- steps means how many pulses the encoder counted
- stepAngle means degrees per one step (example: 18° per step)
So when knob turns Arduino counts steps.
Then multiply steps by degrees per step.
We get the total rotation angle from starting point.
Example:
steps = 5
stepAngle = 18°
angle = 5 × 18 = 90°
It means the knob rotated 90 degrees.
How to Build:
To build a KY040 Encoder Module Circuit with Arduino follow the below connection steps:
- Take all the parts as shown in circuit diagram above.
- Encoder GND pin goes to Arduino GND.
- Encoder + pin goes to Arduino 5V.
- Encoder CLK pin goes to Arduino pin 6.
- Encoder DT pin goes to Arduino pin 7.
- Encoder SW pin is not used in this example.
- If we want to see numbers on PC, then open serial monitor.
Conclusion:
KY040 Encoder Module Circuit with Arduino is easy.
Only two output pins needed.
Code read pulses and show count.
We can use this for menu, robot wheel, motor position and many projects.
Good for learning digital sensors and interrupts.
References:
Fully Working KY-040 Rotary Encoder Source Code, Fully Accurate (no jumps)