Project Overview: In this project, we will demonstrate how to interface a 1-key input button with an Arduino board to control the ON/OFF state of an LED. Each button press will toggle the LED’s state.

Hardware Required:

1. Arduino board (e.g., Arduino Uno)
2. 4-key input button module
3. LED Module
4. Jumper wires

Circuit Diagram: Connect the components as follows:

Note: The specific pin connections may vary depending on the type of 4-key input button module you have. Please refer to the datasheet or documentation of your button module for the appropriate connections.

Connection Table: Here’s a connection table for the button module, LED, and Arduino:

Below is the Arduino code to control the LED using the key input button:

//www.projectkitsandparts.com

// Define the button module pins connected to the Arduin o

const int keyPin1 = 8;

// Define the LED pins connected to the Arduino

const int ledPin1 = 5;

void setup() {

  // Set the button module pins as inputs

  pinMode(keyPin1, INPUT_PULLUP);

  // Set the LED pins as outputs

  pinMode(ledPin1, OUTPUT);

}

void loop() {

  // Read the button module pins

  bool buttonState1 = digitalRead(keyPin1);

  // Check if any button is pressed

  if (buttonState1 == LOW) {

    // If button 1 is pressed, turn on LED 1

    digitalWrite(ledPin1, LOW);

    delay(200);

  } else {

    // If no button is pressed, turn off all LEDs

    digitalWrite(ledPin1, HIGH);

  }

}

Code Explanation:

1. The code defines the pins connected to the button module (keyPin1) and the LED pins (ledPin1).
2. In the setup() function, the button module pins are set as inputs using pinMode(), and the LED pins are set as outputs.
3. In the loop() function, the state of each button is read using digitalRead() and stored in respective variables (buttonState1, buttonState2, etc.).
4. The code then checks which button is pressed by comparing the button states.
5. If a button is pressed, the corresponding LED is turned on by setting its pin to LOW using digitalWrite(), and a delay of 200 milliseconds is added for debounce.
6. If no button is pressed, all LEDs are turned off by setting their pins to HIGH.
7. The code continuously loops and checks the button states, allowing the LEDs to be controlled based on the button presses.

Project Steps:

• Connect the Arduino board to your computer via USB.
• Open the Arduino IDE (Integrated Development Environment) on your computer.
• Create a new sketch and copy-paste the code provided into the IDE.
• Make sure the correct Arduino board and port are selected under the “Tools” menu.
• Click the “Upload” button to compile and upload the code to the Arduino board.
• Connect the 4-key input button module to the Arduino using the specified pin connections.
• Connect the LEDs to the Arduino’s digital pins specified in the connection table.
• When the code runs, pressing each button will turn on the corresponding LED, and releasing the button will turn off the LED.
• If no button is pressed, LED will be turned off.