Overview
In this tutorial, we will learn how to interfacing 4*4 keypad with Arduino by a single analog pin. The use of a lot of pins can be reduced by following this procedure. It helps to use rest of pins for another purpose. For this tutorial, we will use a single analog pin to interfacing keypad with Arduino.
You can watch the following video below:-
Components Required
The required components list for this tutorial given below:-
- Arduino Uno.
- 4*4 keypad.
- Three 4.7k resistors.
- Four 1k resistors.
- One 220ohm resistor.
- LCD display.
- 10k potentiometer.
- Some jumper wire.
Fig:1.1
Keypad Pinout
The following below figure shows 4*4 keypad pinout.
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| Fig 2.1: 4*4 Keypad Pinout |
Circuit Schematic
The given below schematic is single wire keypad with Arduino:-
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| Fig 3.1: One wire keypad with Arduino |
Circuit Description
One single analog pin keypad control based on basic voltage divider role. The voltage increase gradually from left to right (Fig: 4.1) in the row and up to down (Fig: 4.1) in the column. The voltage is minimum at the first-row first column and the maximum voltage is at point row 4 and column 4. Three 4.7k ohm resistors will gradually connect between row 1 to 2, 2 to 3, 3 to 4. Similarly, three 1k ohm resistors will connect between column 1 to 2, 2 to 3, and 3 to 4 respectively. The remaining one 1k ohm resistor will go to ground from column 1. Next +5V will connect with row 1 and analog input A0 pin from Arduino will connect with column 1.
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| Fig: 4.1 |
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| Fig 4.2: One wire keypad with LCD using Arduino |
Source Code
One wire keypad with Arduino source code is given below:-
One wire keypad with LCD using Arduino source code is given below:-
You can download the library here: https://github.com/AndrewMascolo/OnewireKeypad
You can download the library here: https://github.com/AndrewMascolo/OnewireKeypad
