LCD Logic Gate System

by devkrishnavhora in Circuits > Arduino

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LCD Logic Gate System

The LCD Logic Gate System is an interactive electronics project based on an Arduino Uno and a 16×2 LCD display.

The project allows the user to select different digital logic gates and change the input values using push buttons. The Arduino processes the selected logic operation and displays the gate name, inputs, and output on the LCD.

The built-in LED is also used to represent the logic output.

Supplies

Deshbot Shield

Arduino Uno

16×2 LCD Display

Push Buttons

Pin Connections


16×2 LCD

LCD PinArduino

RS - A4

EN - A3

D4 - A2

D5 - A1

D6 - A0

D7 - D13

Push Buttons

ButtonArduino

Button 1 - D10

Button 2 - D12

Logic Output

ComponentArduino

Built-in LED - LED_BUILTIN

. Working Principle

. Working Principle

The Arduino generates the logic-gate operations internally.

The LCD displays the currently selected logic gate and its input/output values.

The user can interact with the system using two buttons.

  1. D10 button is used to change the gate/input selection.
  2. D12 button is used to change the input state.
  3. The built-in LED indicates the logic output.

The system supports common digital logic gates such as:

  1. AND
  2. OR
  3. NOT
  4. NAND
  5. NOR
  6. XOR
  7. XNOR

Logic Gate Operation

AND Gate

The output is HIGH only when both inputs are HIGH.

ABOutput

0

0

0

0

1

0

1

0

0

1

1

1

OR Gate

The output is HIGH when at least one input is HIGH.

NOT Gate

The NOT gate reverses the input.

InputOutput

0

1

1

0

NAND Gate

NAND is the opposite of AND.

NOR Gate

NOR is the opposite of OR.

XOR Gate

XOR gives HIGH when the two inputs are different.

XNOR Gate

XNOR gives HIGH when the two inputs are the same.

LCD Display

The LCD can display information such as:

AND
A:1 B:1 OUT:1

For another gate:

XOR
A:1 B:0 OUT:1

For the NOT gate:

NOT
A:1 OUT:0

System Flow

START
↓
Initialize LCD
↓
Select Logic Gate
↓
Set Input A / B
↓
Calculate Logic Output
↓
Display on LCD
↓
LED shows output
↓
User changes input
↓
Repeat Operation

Features

  1. 16×2 LCD user interface
  2. Push-button control
  3. Multiple logic gates
  4. Real-time logic output
  5. Built-in LED output indication
  6. Interactive learning system
  7. Simple Arduino-based implementation

Programming Concepts Used

Digital Input

The push buttons are configured as digital inputs using Arduino pinMode().

Digital Output

The built-in LED is configured as a digital output.

Conditional Statements

if statements are used to detect button presses and process the selected logic gate.

Switch-Case

A switch-case structure can be used to select and execute different logic gates.

Boolean Logic

The program uses logical operations to calculate the output of each gate.

LCD Programming

The Arduino sends text and values to the 16×2 LCD using the LiquidCrystal library.

Downloads

lcd_logic_gate.ino

Conclusion


The LCD Logic Gate System is a practical Arduino project that demonstrates the fundamentals of digital logic.

By using push buttons, an LCD, and the Arduino's built-in LED, the user can interactively test different logic gates and observe their outputs.

This project combines digital electronics, Arduino programming, Boolean logic, user input, and LCD interfacing into one simple learning system.