Arduino 7 segment display counter | Rotary Encoder


arduino 7 segment display counter with rotary Encoder.
Arduino based coundown timer projects.

Arduino 7 segment display counter.

Hello viewers! In this blog you will find out the counter timer project which is base on arduino uno and 7 segment display and control the counter with help of rotary encoder.

This project is based on a countdown timer. You need to set the time by rotating the rotary encoder clockwise and then you need to press the button on the encoder.

 Component requirements: 

1. Arduino Uno - Buy
2. Rotary encoder. - Buy
3. 7 segment display(Anode). - Buy
4. Resistor (220om)   x   4
5. Breadboard. - Buy
6. Jumper Wires.

There are two type of 7 segment display.
1. Anode base.
2. Cathode base.
You can do this project either anode base or cathode base. The step-by-step instructions are provided below.

 Pinout Diagram: 

pinout of 7 segment display
Pinout of anode and cathode base 7 segment display

Circuit is based on an anode 7 segment display. For a cathode display the circuit would be different. The circuit for a cathode display can be found below.

 Circuit Diagram based on anode display: 

The circuit diagram for anode display.

 Pin Connection: 

1. Firstly, make a connection between the Arduino Uno and the 7 segment display.
  • The Arduino pin 13 should be connected to the 7 segment A pin.
  • The Arduino pin 12 should be connected to the 7 segment B pin.
  • The Arduino pin 11 should be connected to the 7 segment C pin.
  • The Arduino pin 10 should be connected to the 7 segment D pin.
  • The Arduino pin 9 should be connected to the 7 segment E pin.
  • The Arduino pin 8 should be connected to the 7 segment F pin.
  • The Arduino pin 7 should be connected to the 7 segment G pin.
2. The 7 segment COM pin is protected with a resistor, and the resistor's end is attached to the Arduino 5v pin. In order to protect the 7 segment LEDs, a 220 ohm resistor is used as a current limiter.
3. To connect the Arduino Uno and the rotary encoder, we have to make the following connections:
  • Connect the  encoder CLK pin to pin 2 of the Arduino.
  • Connect the encoder DT pin to pin 3 of the Arduino.
  • Connect the encoder SW pin to pin 4 of the Arduino.
  • Connect the encoder VCC pin to 5v pin of the Arduino.
  • Connect the encoder GND pin to GND pin of the Arduino.
Now the circuit is completed. Lets jump to the coding part.

 Circuit Diagram based on cathode display: 

Circuit diagram of cathode display.

 Pin Connection: 

This is a cathode base 7 segment display.
It is the same circuit as the anode display circuit, except that we need to add a 220 ohm resistor between the Arduino pins and the 7 segment display pins and also Connect the COM pin of 7 segment to arduino GND pin


1. Connect the Arduino uno to the PC using a USB cable for uploading the code.
2. Open the Arduino IDE and copy the code from below and paste it on Arduino IDE.
Note: In the code you need to change ledCathode to true if your display uses a cathode base 7 segment display.
3. In the arduino software goto tool --> then select your board and COM port after that Upload the code.

// C++ code
#define A  13
#define B  12
#define C  11
#define D  10
#define E  9
#define F  8
#define G  7

#define CLK 2
#define DT 3
#define SW 4

boolean ledCathode = false; //if you using anode 7 segment display, Make it true 

int currentStateCLK, lastStateCLK, start;
unsigned long lastButtonPress = 0;
unsigned int counter = 0;

int countDelay = 1000; // Countdown delay

byte numeral[11] = {
  B0111000 //F

const int segmentPins[7] = {G, F, E, D, C, B, A};

void setup()
  for (int i = 0; i < 7; i++)
    pinMode(segmentPins[i], OUTPUT);

  pinMode(CLK, INPUT);
  pinMode(DT, INPUT);
  pinMode(SW, INPUT_PULLUP);
  lastStateCLK = digitalRead(CLK);
  counter = 0;

void loop()
  currentStateCLK = digitalRead(CLK);
  if (currentStateCLK != lastStateCLK  && currentStateCLK == 1) {
    if (digitalRead(DT) != currentStateCLK) {
      counter --;
    } else {
      counter ++;
  lastStateCLK = currentStateCLK;
  if (counter > 0 && counter <= 10) {
  } else if (counter == 11) {
    counter = 0;
  } else {
    counter = 0;
  int btnState = digitalRead(SW);
  if (btnState == LOW) {
    if (millis() - lastButtonPress > 50) {
      Serial.println("Button pressed!");
      for (start = counter; start >= 0; start -- ) {
      counter = 0;
    lastButtonPress = millis();

void showDigit( int number)
  boolean isBitSet;
  for (int segment = 0; segment < 7; segment++)
    isBitSet = bitRead(numeral[number], segment);
    if (ledCathode == true) {
      isBitSet = ! isBitSet;
    digitalWrite( segmentPins[segment], isBitSet);

Once the code has been successfully uploaded, turn the rotary encoder clockwise to set the time from 0-9, by pressing the top of the rotary encoder to begin counting down.

Watch This Tutorial: 

Feel free to comment down if you have any problems and also tell me what next tutorial you would like to see?

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