Published December 27, 2024 © CERN-OHL2

Key-controlled 3x3 LED Matrix

Use Arduino UNO to control a 3x3 LED matrix where each keypad button press lights the corresponding LED.

BeginnerProtip2 hours26

Things used in this project

Hardware components

Arduino UNO

5 mm LED: Yellow

Resistor 10k ohm

DFRobot Gravity:Digital Push Button (Yellow)

Software apps and online services

PCBX Online Simulation

Hand tools and fabrication machines

Arduino Materia 101

Story

This project involves creating an interactive keypad-controlled LED matrix using an Arduino UNO development board. The goal is to design a system where pressing any button in a 3x3 matrix keypad will light up the corresponding LED in a 3x3 LED matrix.

Components Required

Arduino UNO Development Board: The brain of the project that will read inputs from the keypad and control the LEDs.

LEDs (9): To form a 3x3 LED matrix for visual feedback.

Push Buttons (9): To form a 3x3 keypad matrix for user input.

Resistors: To limit the current and prevent damage for LEDs.

Code Analysis

The code provided is a straightforward implementation of the project requirements. Let's break down the key parts of the code:

1.Pins Definition:

led_row and led_col arrays define the pins connected to the rows and columns of the LED matrix.

btn_row and btn_col arrays define the pins connected to the rows and columns of the keypad matrix.

2.Setup Function:

Initializes all the keypad row pins as outputs and column pins as inputs.

Initializes all the LED row pins as outputs and column pins as outputs.

3. Loop Function:

The loop() function contains the main logic of the project.

It performs row scanning by setting the current row's keypad buttons to high.

It then performs column scanning within each row. If a button is pressed (detected as high), the corresponding LED is lit up for 500 milliseconds.

After the delay, the LED is turned off, and the row is reset for the next scan.

How It Works

When the circuit is powered and the code is uploaded to the Arduino UNO, the device will continuously scan each row of the keypad matrix. When a button is pressed, the corresponding LED in the LED matrix will light up for a brief period, providing immediate visual feedback to the user.

Additional Notes

Debounce Handling: The current implementation does not include debounce logic, which might be necessary in a real-world application to handle the mechanical bounce of buttons.

Enhancements: Additional features like multiple LED lighting patterns or interactive effects could be added to enhance user experience.

Scalability: The code structure allows for easy scaling up to larger matrices by adjusting the pin arrays and loop logic accordingly.

Code

Key-controlled 3x3 LED Matrix

// Define the pins for the 3x3 LED matrix
int led_row[3] = {A5, A4, A3}; // Connect to the rows of the LED matrix
int led_col[3] = {A2, A1, A0}; // Connect to the columns of the LED matrix

// Define the pins for the 3x3 matrix keypad
int btn_row[3] = {8, 9, 10}; // Connect to the rows of the keypad
int btn_col[3] = {11, 12, 13}; // Connect to the columns of the keypad

void setup() {
    for (int i = 0; i < 3; i++) {
        pinMode(btn_row[i], OUTPUT);
        pinMode(btn_col[i], INPUT);
    }
    
    for (int i = 0; i < 3; i++) {
        pinMode(led_row[i], OUTPUT);
        pinMode(led_col[i], OUTPUT);
    }
}

void loop() {
for (int row = 0; row < 3; row++) { // Row scanning
    digitalWrite(btn_row[row], HIGH); // Set the buttons of the current row to high level
    digitalWrite(led_row[row], HIGH); // Set the cathode of the LEDs in the current row to 1
    for (int col = 0; col < 3; col++) { // Column scanning     
        if (digitalRead(btn_col[col]) == HIGH) { // A button in the current column of the current row is pressed
            digitalWrite(led_row[row], LOW); // Set the cathode of the LEDs in the current row to 0
            digitalWrite(led_col[col], HIGH); // Set the anode of the corresponding column's LED to 1, lighting up the LED at the corresponding coordinate
            delay(500); // Keep the LED lit for 500 milliseconds
            digitalWrite(led_col[col], LOW); // Set the anode of the corresponding column's LED to 0, turning off the LED
            digitalWrite(led_row[row], HIGH); // Reset the cathode of the LEDs in the current row to 1
        }
    }
    digitalWrite(btn_row[row], LOW); // Reset the buttons in the current row to high level
    }
}

Credits

lois li

8 projects • 0 followers