Hi all,

i use 89c52 to interface with 4*3 keypad, this is my code

char const columns[3] = {0xef, 0xdf,0xbf }; // var declaration


char key_get(void)
{

//int NO =0;

row =0;
column=0;


while(1)
{
// P0 = 0x0F;

P0 =columns[column];

delayms(10);


if( (P0&0x0F)!=0x0f )
{

delayms(10);
if( (P0&0x0F)== 0x0e) // row scan
{
row =0;
delayms(10); // for debouncing
return( KEYS[row][column]);
}

else if( (P0&0x0F)==0x0d) //scan row
{
row =1;
delayms(10);
lcd_data( KEYS[row][column]);
return( KEYS[row][column]);
}
else if( (P0&0x0F)==0x0b)
{
row =2;
delayms(10);
lcd_data( KEYS[row][column]);
return( KEYS[row][column]);

}

else if( (P0&0x0F)==0x07)
{
row =3;
delayms(10);
return( KEYS[row][column]);

}

}

delayms(1);
column++;
delayms(1);
if (column ==3)
{
column =0;
}

}

compiler iam using is keilc

problems i faced are

1. i used port 0 for keypad lsb for rows and msb for columns.all 1's when no keypressed 0 in row for key pressing, when i tried seeing the port0 using scope my port pins are 0 no change!

2. my crystal pin (xtal2 ) does not produce a sine wave of 5V amp it is only 2.5V.

note : i am trying to interface lcd & keypad whatever keys iam pressing that shoulkd be displayed in lcd

i also tried 8051 same problem exist

kindly give ur valuable suggestion

with thanks and regards
syed saleem. N