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Arduino DIY Calculator using a 4*4 Keypad and 16*2 LCD Display

Updated: Mar 19

Keypads are generally used as input devices that take input from the users and process it. Membrane keyboards are characterized by the use of keys that are pressure pads with symbols printed on them. This is in contrast to a mechanical keyboard, which features separate and individual keys. Because of their design, membrane keyboards are smaller and more compact than their mechanical counterpart. In this project, we use a 16*2 LCD which contains 16 columns and 2 rows which will show the final result of the arithmetic operation assigned to the calculator.

A list of components required to implement the circuit both manually and using TinkerCAD is given below.

Hardware Requirements:

1. 4x4 Keypad:

4x4 membrane keypad
4x4 membrane keypad

A 4x4 matrix keypad is used as an input device that takes inputs from the users. It consists of 16 pins in total with four rows and four columns. On pressing a key, a connection will be established between the corresponding row and column between which the switch is placed.

2. Arduino UNO:

Arduino UNO
Arduino UNO

The Arduino is a programmable #microcontroller, it's an open-source electronics proto-type platform. It interacts with the user by receiving input with the aid of sensors and provides the output employing LED, buzzer, etc.,

To know more about the Arduino UNO, go through this article.

3. 16*2 LCD: LCD- Liquid Crystal Display is an electronic module that uses liquid crystal to produce a visible image. It is the basic module that is generally used in DIY's and circuits. The display segments are affordable and simply programmable.

4. Jumping Wires: Jumper wires are used to establish connections between different components in the circuit.

Software Requirements:

TinkerCAD Software:

TinkerCAD Software
TinkerCAD Software

It is an easy-to-use online simulation software that is equipped with all the essential components which are required to build the circuit and analyze it.

Visit the TinkerCAD website.

Circuit Connection and its Working:

Circuit connection involves the following steps:

  • In the keypad, there are 8 pins in total out of which 4 pins correspond to the Rows (viz., R1, R2, R3, R4) and the other four correspond to the Columns (viz., C1, C2, C3, C4).

  • These 8 row and column pins of the keypad are connected from 0-7 PWM pins of the Arduino board respectively.

  • DB 4-DB7 pins of the LCD are connected to 11-8 pins of the Arduino respectively.

  • The 12th port of the Arduino is connected to Enable pin of the LCD and the 13th port of the Arduino is connected to Rs of the LCD.

  • LED 1 of the LCD is connected to the ground pin of the Arduino through a 1-kilo-ohm resistor. Further, the Vo and ground pins of the LCD are also connected to the ground pin of the Arduino.

  • Vo and RW pins of the LCD are shorted (i.e., grounded)

  • Vcc and the other LED of the LCD are short-circuited and connected to 5V pin of the Arduino


Video by - Sri Harshitha

Simulation software plays a leading role in designing huge circuits which help to understand, analyze and provide outputs for a large set of input values which would be hectic doing it manually. It helps in avoiding any damage to the hardware by going beyond the rated value.

Validate your new circuit ideas and know the scope and boundaries of your circuit.


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LearnElectronics India's explanation is spot-on. Great work!


Anushka Gupta
Anushka Gupta
Jul 25, 2023

Wow! This Arduino calculator tutorial by Learn Electronics India is a true treasure for the DIY electronics community. Building a calculator was always on my to-do list, and thanks to this blog, I finally accomplished it successfully.



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