4×3 LED Matrix with Arduino UNO — Running & Row/Column LED Effects

Project Title:

LED Matrix Control using Arduino UNO (4×3 LED Array)

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 Objective:

To design and control a 4×3 LED matrix using an Arduino UNO, implementing:

• Running LED effect
• Row-wise glow
• Column-wise glow

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 LED Matrix Design

 Hardware Components:

Component	Quantity
Arduino UNO	1
5mm  LEDs	12
220Ω Resistors	4
Breadboard / Simulation	1
Connecting Wires	As required

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Circuit Description:

The LED matrix consists of:

• 4 rows (cathodes) connected to pins 6, 7, 8, 9
• 3 columns (anodes) connected to pins 10, 11, 12

Each LED is addressed by:

• Setting an anode HIGH
• Setting a cathode LOW

This way, a specific LED can be turned ON while avoiding unwanted lighting .

                

                 

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 Working Principle:

Controlling a large number of LEDs directly is not practical. By using a matrix structure, we reduce the number of pins needed from 12 to 7 (4 rows + 3 columns). LEDs are controlled by multiplexing: turning on one LED at a time very fast to appear as if all are lit.

 

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Arduino Code Functionality

Features:

1. Running LED across the matrix one by one
2. Row-wise full glow
3. Column-wise full glow

const int cathodes[] = {6, 7, 8, 9};       // 4 rows

const int anodes[]   = {10, 11, 12};       // 3 columns

 

void setup() {

  for (int i = 0; i < 4; i++) pinMode(cathodes[i], OUTPUT);

  for (int i = 0; i < 3; i++) pinMode(anodes[i], OUTPUT);

}

 

void loop() {

  // 1. Running LED across all LEDs

  for (int row = 0; row < 4; row++) {

    for (int col = 0; col < 3; col++) {

      lightLED(row, col);

      delay(200);

      clearLEDs();

    }

  }

 

  delay(500);

 

  // 2. Glow entire row at once

  for (int row = 0; row < 4; row++) {

    glowRow(row);

    delay(500);

    clearLEDs();

  }

 

  delay(10);

 

  // 3. Glow entire column at once

  for (int col = 0; col < 3; col++) {

    glowColumn(col);

    delay(500);

    clearLEDs();

  }

 

  delay(1000);

}

 

// Light a single LED

void lightLED(int row, int col) {

  clearLEDs();

  digitalWrite(anodes[col], HIGH);     // Anode ON

  digitalWrite(cathodes[row], LOW);    // Cathode ON (sink)

}

 

// Glow all LEDs in one row

void glowRow(int row) {

  for (int i = 0; i < 3; i++)

    digitalWrite(anodes[i], HIGH);     // All columns ON

  digitalWrite(cathodes[row], LOW);    // Single row sinks current

}

 

// Glow all LEDs in one column

void glowColumn(int col) {

  digitalWrite(anodes[col], HIGH);     // One column ON

  for (int i = 0; i < 4; i++)

    digitalWrite(cathodes[i], LOW);    // All rows sink current

}

 

// Turn off all LEDs

void clearLEDs() {

  for (int i = 0; i < 3; i++) digitalWrite(anodes[i], LOW);

  for (int i = 0; i < 4; i++) digitalWrite(cathodes[i], HIGH);

}

 

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 Applications:

• LED Dot Matrix Displays
• LED Pattern Projects
• Multiplexed Lighting
• Educational Projects

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Conclusion:

This project demonstrates how a simple LED matrix can be controlled efficiently using row-column multiplexing with Arduino. It’s a basic foundation for developing scrolling text displays, animated icons, and digital signage boards.

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Future Improvements:

• Add buttons to switch display modes.
• Add brightness control using PWM.
• Use shift registers to expand LED count.
• Implement character display (A-Z) using lookup arrays.

I do not have exact reference sites, but I referred to YouTube videos, books, and ChatGPT  for understanding and building this project.