Hi,

I want to interface a 4×4 keypad to my philips microcontroller. The keys I enter should be displayed on LCD.
The key 1 for ex: if pressed once it should return ‘a’ and when pressed twice it should return ‘b’ and simillarly ‘c’ the third time. Just like in phones.

I have a code in C below, I tried but its not working. The connections are perfect. Please help me out here.. Thanks in advance.

CODE:

// Program to make alphabetical keypad similar to the one in mobiles
#includeltreg51.hgt
#include ltstring.hgt
#include ltstdio.hgt

#define port P1
#define dataport P2 //Data port for LCD
#define key P0 // Port for Keypad
#define sec 100
sbit rs = port^1;
sbit rw = port^2;
sbit en = port^3;

sbit col1=key^4;
sbit col2=key^5;
sbit col3=key^6;
sbit row1=key^0;
sbit row2=key^1;
sbit row3=key^2;
sbit row4=key^3;
unsigned char position=128,i=0;
int check_again[10]={0,0,0,0,0,0,0,0,0,0};

void delay(unsigned int msec);
void lcd_cmd(unsigned char item);
void lcd_data(unsigned char item);
void num_check(int a , int b);
void display(int a ,int b);

void delay(unsigned int msec) // Time delay function
{
int i,j ;
for(i=0;iltmsec;i++)
for(j=0;jlt1275;j++);
}

void lcd_cmd(unsigned char item)
{
dataport = item;
rs= 0;
rw=0;
en=1;
delay(1);
en=0;
return;
}

void lcd_data(unsigned char item)
{
lcd_cmd(0x0f);
delay(10);
dataport = item;
rs= 1;
rw=0;
en=1;
delay(1);
en=0;
return;
}

void num_check(int a , int b) //Check function
{
int j;
for(j=0;jlt10;j++)
{
if(j!=a)
{
check_again[j]=0;
}
}
if(check_again[a]==3)
check_again[a]=0;
check_again[11]=1;
check_again[12]=1;
}

void display(int a ,int b) // Display function
{
switch(b)
{
case 1:
{
switch(a)
{
case 1:{
if(check_again[a]gt1)
i–;
lcd_cmd(position+i);
lcd_data(‘a’);
delay(5);
num_check(1 ,check_again[1]);
break;
}
case 2:{
if(check_again[a]gt1)
i–;
lcd_cmd(position+i);
lcd_data(‘d’);
delay(5);
num_check(2 ,check_again[2]);
break;
}
case 3: {
if(check_again[a]gt1)
i–;
lcd_cmd(position+i);
lcd_data(‘g’);
delay(5);
num_check(3 ,check_again[3]);
break;
}
case 4:{
if(check_again[a]gt1)
i–;
lcd_cmd(position+i);
lcd_data(‘j’);
delay(5);
num_check(4 ,check_again[4]);
break;
}
case 5:{
if(check_again[a]gt1)
i–;
lcd_cmd(position+i);
lcd_data(‘m’);
delay(5);
num_check(5 ,check_again[5]);
break;
}
case 6:{
if(check_again[a]gt1)
i–;
lcd_cmd(position+i);
lcd_data(‘p’);
delay(5);
num_check(6 ,check_again[6]);
break;
}
case 7:{
if(check_again[a]gt1)
i–;
lcd_cmd(position+i);
lcd_data(‘s’);
delay(5);
num_check(7 ,check_again[7]);
break;
}
case 8:{
if(check_again[a]gt1)
i–;
lcd_cmd(position+i);
lcd_data(‘v’);
delay(5);
num_check(8 ,check_again[8]);
break;
}
case 9:{
if(check_again[a]gt1)
i–;
lcd_cmd(position+i);
lcd_data(‘y’);
delay(5);
num_check(9 ,check_again[9]);
break;
}
case 0:{
lcd_cmd(position+i);
lcd_data(‘ ‘);
delay(5);
num_check(10 ,check_again[10]);
break;
}
case 11:{
if((position+i)gt129)
{
i=i-2;
delay(5);
lcd_cmd(position+i+1);
num_check(11 ,check_again[11]);;
delay(5);
}
break;
}
case 12:{
delay(5);
lcd_cmd(position+i);
num_check(12 ,check_again[12]);
delay(5);
break;
}
}
break;
}
case 2:
{
switch(a)
{
case 1:{
if(check_again[a]gt1)
i–;
lcd_cmd(position+i);
lcd_data(‘b’);
delay(5);
num_check(1 ,check_again[1]);
break;
}
case 2:{
if(check_again[a]gt1)
i–;
lcd_cmd(position+i);
lcd_data(‘e’);
delay(5);
num_check(2 ,check_again[2]);
break;
}
case 3: {
if(check_again[a]gt1)
i–;
lcd_cmd(position+i);
lcd_data(‘h’);
delay(5);
num_check(3 ,check_again[3]);
break;
}
case 4:{
if(check_again[a]gt1)
i–;
lcd_cmd(position+i);
lcd_data(‘k’);
delay(5);
num_check(4 ,check_again[4]);
break;
}
case 5:{
if(check_again[a]gt1)
i–;
lcd_cmd(position+i);
lcd_data(‘n’);
delay(5);
num_check(5 ,check_again[5]);
break;
}
case 6:{
if(check_again[a]gt1)
i–;
lcd_cmd(position+i);
lcd_data(‘q’);
delay(5);
num_check(6 ,check_again[6]);
break;
}
case 7:{
if(check_again[a]gt1)
i–;
lcd_cmd(position+i);
lcd_data(‘t’);
delay(5);
num_check(7 ,check_again[7]);
break;
}
case 8:{
if(check_again[a]gt1)
i–;
lcd_cmd(position+i);
lcd_data(‘w’);
delay(5);
num_check(8 ,check_again[8]);
break;
}
case 9:{
if(check_again[a]gt1)
i–;
lcd_cmd(position+i);
lcd_data(‘z’);
delay(5);
num_check(9 ,check_again[9]);
break;
}
case 0:{
lcd_cmd(position+i);
lcd_data(‘-’);
num_check(10 ,check_again[10]);
break;
}
case 11:{
i–;
lcd_cmd(0×10);
delay(5);
break;
}
}
break;
}
case 3:
{
switch(a)
{
case 1:{
if(check_again[a]gt1)
i–;
lcd_cmd(position+i);
lcd_data(‘c’);
delay(5);
num_check(1 ,check_again[1]);
break;
}
case 2:{
if(check_again[a]gt1)
i–;
lcd_cmd(position+i);
lcd_data(‘f’);
delay(5);
num_check(2 ,check_again[2]);
break;
}
case 3: {
if(check_again[a]gt1)
i–;
lcd_cmd(position+i);
lcd_data(‘i’);
delay(5);
num_check(3 ,check_again[3]);
break;
}
case 4:{
if(check_again[a]gt1)
i–;
lcd_cmd(position+i);
lcd_data(‘l’);
delay(5);
num_check(4 ,check_again[4]);
break;
}
case 5:{
if(check_again[a]gt1)
i–;
lcd_cmd(position+i);
lcd_data(‘o’);
delay(5);
num_check(5 ,check_again[5])SPAN st