01 Interfacing Push Button.md

Arduino Button and LCD (I2C) Display Interaction

Aim

To detect button presses using a push button and display a message ("TOUCHED") on an LCD (I2C interface) whenever the button is pressed.

---

Components Required

• Arduino board (e.g., Arduino Uno)
• 16x2 LCD with I2C interface
• Push button
• Resistors (if required)
• Jumper wires
• Breadboard

---

Circuit Diagram

Connections:

1. LCD (I2C Interface):

   • VCC: Connect to Arduino 5V.
   • GND: Connect to Arduino GND.
   • SDA: Connect to Arduino A4 (Uno).
   • SCL: Connect to Arduino A5 (Uno).

2. Push Button:

   • One terminal: Connect to Arduino pin 7.
   • Other terminal: Connect to GND.
   • Enable internal pull-up by configuring pin 7 as INPUT_PULLUP.

---

Video Simulation

---

Program

Code

#include <LiquidCrystal_I2C.h>

LiquidCrystal_I2C lcd(0x3F, 16, 2); // Initialize the LCD with I2C address 0x3F, 16 columns, 2 rows

const int BUTTON_PIN = 7; // Pin connected to the push button
int lastState = LOW; // Stores the last state of the button
int currentState;

void setup() {
  Serial.begin(9600); // Initialize serial communication for debugging
  pinMode(BUTTON_PIN, INPUT_PULLUP); // Set the button pin as input with an internal pull-up resistor
  lcd.init(); // Initialize the LCD
  lcd.backlight(); // Turn on the LCD backlight
}

void loop() {
  currentState = digitalRead(BUTTON_PIN); // Read the current state of the button

  // Check if the button is pressed (transition from not pressed to pressed)
  if (lastState == HIGH && currentState == LOW) { 
    Serial.println("Button pressed");
    lcd.clear(); // Clear the LCD display
    lcd.setCursor(0, 0); // Set the cursor to the first row, first column
    lcd.print("TOUCHED"); // Display "TOUCHED" on the LCD
    delay(500); // Keep the message for 500ms
    lcd.clear(); // Clear the LCD display
  }

  lastState = currentState; // Update the last state
}

---

How It Works

1. Button Detection:

   • The push button is connected to pin 7 with an internal pull-up resistor enabled (INPUT_PULLUP).
   • When the button is pressed, the state changes from HIGH to LOW, and this transition is detected in the code.

2. LCD Interaction:

   • The LCD (16x2) is initialized using the I2C library with address 0x3F.
   • Upon button press, the message "TOUCHED" is displayed briefly before clearing the screen.

3. Serial Monitoring:

   • Each button press is logged in the Serial Monitor with the message "Button pressed" for debugging purposes.

---

Steps to Execute

1. Setup the Circuit:

   • Connect the components as described in the Circuit Diagram section.

2. Upload the Code:

   • Open the Arduino IDE.
   • Copy the code into the IDE.
   • Upload the code to the Arduino board.

3. Test the Setup:

   • Power the Arduino board.
   • Press the push button and observe the LCD displaying "TOUCHED" briefly.
   • Open the Serial Monitor at a baud rate of 9600 to see the button press messages.

---

How It Works

1. When the button is pressed, it triggers a state change from HIGH to LOW.
2. This triggers a message "TOUCHED" to be displayed on the LCD.
3. The message is shown for 500ms and then cleared to be ready for the next button press.

---

Troubleshooting

1. No Response on Button Press:

   • Verify the button connections.
   • Ensure the correct pin number is defined for the button (BUTTON_PIN).
   • Check the internal pull-up resistor setting (INPUT_PULLUP).

2. No Display on LCD:

   • Confirm the I2C address of the LCD (0x3F in this case).
   • Ensure proper connections to SDA and SCL pins.

3. Serial Monitor Not Showing Output:

   • Verify the baud rate of the Serial Monitor matches the code (9600).
   • Check the USB connection between the Arduino and your computer.

---

Additional Notes

• If your LCD I2C address is different, scan for the correct address using an I2C scanner sketch.
• Adjust the delay times as needed for better user experience.

---