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…

Requirements:

Circuit:

How to Make an Arduino Calculator?
Circuit Diagram.

According to the diagram, make all the connections.

For Keypad:

  • 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. 
To download the library, open Arduino IDE and goto:-

  • 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.

You can download the code from here: Arduino_Calculator.ino

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

A = + (Addition)
B = – (Subtraction)
C = * (Multiplication)
D = / (Division)

Symbol * and # are used as ‘Cancel’ and ‘Equals to’ Respectively.

That’s all for this tutorial. Hope you like it.

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