/*  Name     : main.c
 *  Purpose  : Source code for KEYPAD Interfacing with AT89C52.
 *  Author   : Gemicates
 *  Date     : 2014-01-19
 *  Website  : www.gemicates.org
 *  Revision : None
 */
 
#include <REGX52.H>											// header file for AT89c52 series
#define keypad P0
#define Lcd_port P2											// GPIO direction register declaration

sbit rs = P3^7;  											// register select pin
sbit rw = P3^6;  											// read write pin
sbit en = P3^5;  											// enable pin

 													// Row and Column pins declaration
sbit R1 = keypad^0;
sbit R2 = keypad^1;
sbit R3 = keypad^2;
sbit R4 = keypad^3;
sbit C1 = keypad^4;
sbit C2 = keypad^5;
sbit C3 = keypad^6;

 				                                                                        // Function declarations
void delay(unsigned int count);
void lcdcmd_address(unsigned char cmd);
void lcddata(unsigned char send_data);
void lcd_string(unsigned char str[10]);
void lcd_data_string(unsigned char *str);

void check_column_one();
void check_column_two();
void check_column_three();
void output(int key);

void main()											       // main function
{
	lcdcmd_address(0x38);  									       // for using 8-bit 2 row mode and 5x7 Dots of LCD
	lcdcmd_address(0x0E);  									       // turn display ON for cursor blinking
	
	lcdcmd_address(0x01);  									       // clear screen
	lcdcmd_address(0x06);  									       // display ON
	delay(10);
			
	lcdcmd_address(0x86);  									       // bring cursor to position 6 of ROW 1	
	lcddata('H');
	lcdcmd_address(0x87);  													
	lcddata('I');
	lcddata('!');
	delay(10);
	lcdcmd_address(0xC3);								               // bring cursor to position 3 of ROW 2
	lcd_string("**GUYS**");
	delay(50);
	lcdcmd_address(0x01);  									       // clear screen
				
	lcdcmd_address(0x83);									       // bring cursor to position 3 of ROW 1
	lcd_string("WELCOME TO");
	delay(100);
	lcdcmd_address(0xC3);									       // bring cursor to position 3 of ROW 2
	lcd_string("GEMICATES");
	lcdcmd_address(0x01);  									       // clear screen
	lcdcmd_address(0x0C);									       // Display On cursor Off
		
	C1=C2=C3=1;									               // The output of all the columns will be high
	while(1)
	{
		R1=R2=R3=R4=0;									       // made all the rows zero
		if(C1==0)
			check_column_one();							       // check pressed key is a column one?
		else if(C2==0)
			check_column_two();							       // check pressed key is a column two?
		else if(C3==0)
			check_column_three();							       // check pressed key is a column three?
	}
}

void delay(unsigned int count)
{
	int m,n;
	for(m=0;m<count;m++)
	for(n=0;n<1275;n++);
}

void lcdcmd_address(unsigned char cmd)  			                                       // Function to send command to LCD
{
	Lcd_port = cmd;
	rs= 0;
	rw= 0;
	en= 1;
	delay(5);
	en= 0;
	return;
}

void lcddata(unsigned char send_data)   				                              // Function to send data to LCD
{
	Lcd_port = send_data;
	rs= 1;
	rw=0;
	en=1;
	delay(5);
	en=0;
	return;
}
 
void lcd_string(unsigned char str[10])  			                                     // Funtion to Initialize LCD
{ 
	lcd_data_string(str);
}

void lcd_data_string(unsigned char *str) 			                                     // Function to send string on LCD
{
int i=0;
	while(str[i]!='\0')
	{
		lcddata(str[i]);
		i++;
		delay(10);
	}
return;
}

void check_column_one() 									    // Detecting column one?
{
	R1=R2=R3=R4=1;										    // After detecting column All rows set to high

	R1=0;
	if((R1==0)&&(C1==0))
		output(1);
	R1=1;
	
	R2=0;
	if((R2==0)&&(C1==0))
		output(4);
	R2=1;
	
	R3=0;
	if((R3==0)&&(C1==0))
		output(7);
	R3=1;
	
	R4=0;
	if((R4==0)&&(C1==0))
		output(10);
	R4=1;
}
	
void check_column_two() 								          // Detecting column two?
{
	R1=R2=R3=R4=1;										  // After detecting column All rows set to high
	 
	R1=0;
	if((R1==0)&&(C2==0))
		output(2);
	R1=1;
	
	R2=0;
	if((R2==0)&&(C2==0))
		output(5);
	R2=1;
	
	R3=0;
	if((R3==0)&&(C2==0))
		output(8);
	R3=1;
	
	R4=0;
	if((R4==0)&&(C2==0))
		output(11);
	R4=1;
}

void check_column_three() 								        // Detecting column three?
{
	R1=R2=R3=R4=1;									        // After detecting column All rows set to high
	
	R1=0;
	if((R1==0)&&(C3==0))
		output(3);
	R1=1;
	
	R2=0;
	if((R2==0)&&(C3==0))
		output(6);
	R2=1;
	
	R3=0;
	if((R3==0)&&(C3==0))
		output(9);
	R3=1;
	
	R4=0;
	if((R4==0)&&(C3==0))
		output(12);
	R4=1;
}	

void output(int key)
{
	lcdcmd_address(0x01);								        // clear screen
	lcdcmd_address(0x86);								        // bring cursor to position 3 of ROW 1
	switch(key)
	{
		case 1:
			lcd_string("ONE");
		break;
		
		case 2:
			lcd_string("TWO");
		break;
		
		case 3:
			lcd_string("THREE");
		break;
		
		case 4:
			lcd_string("FOUR");
		break;
		
		case 5:
			lcd_string("FIVE");
		break;
		
		case 6:
			lcd_string("SIX");
		break;
		
		case 7:
			lcd_string("SEVEN");
		break;
		
		case 8:
			lcd_string("EIGHT");
		break;
		
		case 9:
			lcd_string("NINE");
		break;
		
		case 10:
			lcd_string("TEN");
		break;
		
		case 11:
			lcd_string("ELEVEN");
		break;
		
		case 12:
			lcd_string("TWELVE");
		break;
	}
}