How to make an Arduino based Calculator using Keypad and LCD

In this tutorial, we’ll walk you through building a simple calculator using an Arduino, a 4x4 keypad, and an I2C LCD. This project is perfect for beginners looking to explore the basics of interfacing components with an Arduino.

Components Needed:

- Arduino Uno (or any other compatible board)

- 4x4 Keypad

- LCD I2C (16x2)

- Jumper wires

- Breadboard

- USB cable for programming

Step 1: Set Up Your Components

Connect the Keypad:

1. Place the keypad on your breadboard.

2. Connect the keypad's row and column pins to the Arduino. For instance:

- Row pins (R1, R2, R3, R4) to Arduino pins 9, 8, 7, 6

- Column pins (C1, C2, C3, C4) to Arduino pins 5, 4, 3, 2

Connect the LCD I2C:

1. Attach the I2C LCD to the breadboard.

2. Connect the LCD's SDA and SCL pins to the corresponding Arduino pins:

- SDA to A4

- SCL to A5

3. Connect the LCD's VCC to the 5V pin on the Arduino and GND to the GND pin on the Arduino.

Step 2: Install Required Libraries

Before coding, ensure you have the necessary libraries installed in your Arduino IDE:

1. Keypad Library:

- Go to Sketch > Include Library > Manage Libraries.

- Search for "Keypad" and install the Keypad library by Mark Stanley and Alexander Brevig.

2. LiquidCrystal I2C Library:

- Go to Sketch > Include Library > Manage Libraries.

- Search for "LiquidCrystal I2C" and install the library by Frank de Brabander.

Step 3: Write the Code

Here’s a sample code to get you started:

Step 4: Upload and Test

1. Connect your Arduino to your computer using the USB cable.

2. Open the Arduino IDE, paste the code, and upload it to your Arduino.

3. Once uploaded, your LCD should display "Calculator" initially. Use the keypad to enter numbers and operations. For example:

- Press `5`, then `A` (for addition), then `3`, and finally `#` to see the result `8` displayed.