In previous tutorials, we learned about display modules and keypad. In this article, I will share how to make an Arduino Calculator using a LCD display and keypad module. Using this calculator we can do simple addition, subtraction, multiplication and division. So without wasting any more time, let’s begin…

## Circuit:

According to the diagram, make all the connections.

• R1 = 2
• R2 = 3
• R3 = 4
• R4 = 5
• C1 = 6
• C2 = 7
• C3 = 8
• C4 = 9

For LCD:

• First connect LCD on breadboard.
• Now connect pins RW, LED cathode and Vss or GND to the GND rail of breadboard.
• Connect the Vcc to the +ve rail of breadboard. Also connect the LED anode pin (Right next to cathode) to +ve rail through a 220 ohm resistor.
• Connect the contrast pin labeled as V0 to middle terminal of the potentiometer. Connect other two terminals of the pot to +ve and GND.
• Now connect the following pin in order:
• D4 = 13
• D5 = 12
• D6 = 11
• D7 = 10

After connections are made, we can upload the code on to the board…

## Coding:

Before you can start coding you have to install a library to us the keypad and LCD.

• Sketch >> Include Library >> Manage Libraries.
• In the search bar type “Keypad.h” and scroll down to find “Keypad library by Mark Stanley version 3.1.1”
• Also check if LiquidCrystal library is installed. If not, you can find it using same method.
• Install the libraries and restart the IDE.

To use the calculator simply upload the code, The Alphabets are used as follows:-