Keypad interfacing with microcontroller use Mikro C keypad library

In this tutorial I am show you how to interface keypad with PIC16F877A microcontroller. In this project I am use 4x3 matrix keypad. In this project I am use Mikro C Pro For Pic Compiler for source code editing. Mikro c provide a keypad library working with 4x4 matrix keypad. You can watch this video or read the written tutorial below.

MATRIX KEYPAD

Before I interface the keypad with PIC16F877A microcontroller , frist we need to understand how to working matrix keypad.
Keypad is set of button. It contain digits,symbols&alphabetical letters. It can be (4x4),(4x3) & (3x2). 4x3 it means 3 column and 4 row. Matrix keypads are commonly used in calculator , digital scale, security systems ,electronic device etc. Matrix keypad is array of push switch. Push button switch leg are connected to columns and rows. 4x4 matrix keypad contain (4*4)=16 push button switch. If we are use 3x4 matrix there are (3*4)=12 push button switch. 4x4 matrix keypad has (4+4)=8 pin connection and 3x4 matrix keypad (3+4)=7 pin connection.

4X4 MATRIX KEYPAD STRUCTURE

When press the any key than any column & row are connected each other at a time. Than current flowing column to row.

3x4 matrix keypad

CIRCUIT DIAGRAM OF KEYPAD INTERFACING

3x4 matrix keypad and Lm16x2 Lcd display

Keypad Library

The mikroC PRO for PIC provides a library for working with 4x4 keypad. The library routines can also be used with 4x1, 4x2, or 4x3 keypad. For connections explanation see schematic at the bottom of this page.

Library routines

Keypad_Init
Keypad_Key_Click
Keypad_Key_Press

LCD INTERFACING

In this project I am use LM16x02 LCD display. If you don't know how to interface Lcd display with microcontroller than click here for more details.

SOURCE CODE FOR Mikro C

	unsigned short kp; // kp is a variable
	// keypad module connections
	char keypadPort at PORTD;
	// End keypad module connections

	// Lcd module connections
	sbit LCD_RS at RB0_bit;
	sbit LCD_EN at RB1_bit;
	sbit LCD_D4 at RB2_bit;
	sbit LCD_D5 at RB3_bit;
	sbit LCD_D6 at RB4_bit;
	sbit LCD_D7 at RB5_bit;

	sbit LCD_RS_Direction at TRISB0_bit;
	sbit LCD_EN_Direction at TRISB1_bit;
	sbit LCD_D4_Direction at TRISB2_bit;
	sbit LCD_D5_Direction at TRISB3_bit;
	sbit LCD_D6_Direction at TRISB4_bit;
	sbit LCD_D7_Direction at TRISB5_bit;
	// End Lcd module connections
	void main() {
	Lcd_Init(); // initialize Lcd module
	Keypad_Init(); // initilize keypad module
	Lcd_Cmd(_LCD_CLEAR); // Lcd clear
	Lcd_Out(1,3, "WELCOME TO");
	Lcd_Out(2,1, "MINA TECHNOLOGY");
	delay_ms(1000); // 1s delay
	Lcd_Cmd(_LCD_CLEAR); // clear Lcd
	while(1){ // loop started
	kp = 0 ; // Reset the key code variable
	// wait for key to be pressed and relised
	do
	kp = Keypad_Key_Click(); // Store key code in kp varible
	while(!kp);

	switch(kp){
	case 1 : kp = 49 ; break ; // 1
	case 2 : kp = 50 ; break ; // 2
	case 3 : kp = 51 ; break ; // 3
	case 5 : kp = 52 ; break ; // 4
	case 6 : kp = 53 ; break ; // 5
	case 7 : kp = 54 ; break ; // 6
	case 9 : kp = 55 ; break ; // 7
	case 10 : kp = 56 ; break ; // 8
	case 11 : kp = 57 ; break ; // 9
	case 13 : kp = 42 ; break ; // *
	case 14 : kp = 48 ; break ; // 0
	case 15 : kp = 35 ; break ; // #
	}
	Lcd_Chr_Cp(kp); // print lcd with cursor position
	}


	}