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…



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…


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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