Fundamentlas of Microcontroller

Hello ..
How r u all ?
i'm an electronic engineering student ..

i ahve a question regarding the Keil assembly ..
i'm doning a lab ,, i just finish doing it .. i need help to write a report ..
its about interfacing to a keypad, which includes these part: a keypad scanning routine, a code conversion routine and creating include file ..

so, anyone could help .?
much appreciated

1.Make four pin as input and four pin as output.
2. put a high voltage at first input pin .
3.Scan all the out put pin, which pin is high
4.pass the high voltage in to another input pin
5.scan the output pins
6.rtepeat the same procedure.

Control the input pins and scan the outputs?

Maybe the other way around?

ok;
you are correct
you can select any way

There is another methode which depends on the number of keys you want to scan:
Use one channel of ADC and read the voltages: this frees lots of pin ports.

check **broken link removed**.. this shud help!!

hi can u help me with 4x3 keypad interfacing in zilog?
thanks!!

Hai,
Here i post a program for 4*3 keypad with LCD display make necessary changes.

unsigned short kp, cnt, oldstate = 0;
char txt[5];

void main()
{
cnt = 0;
trisc=0x00;
trisb=0xf0;
Lcd8_Config(&portc,&portd,1,3,2,7,6,5,4,3,2,1,0);
Lcd8_Cmd(LCD_CLEAR); // Clear display
Lcd8_Cmd(LCD_CURSOR_OFF); // Cursor off
Lcd8_Out(1,1,"start");

while(1)
{
portb=0x01;
while(portb.f4==1)
{
Lcd8_Cmd(lcd_clear);
Lcd8_Out(1,1,"1");
}
while(portb.f5==1)
{
Lcd8_Cmd(lcd_clear);
Lcd8_Out(1,1,"5");
}
while(portb.f6==1)
{
Lcd8_Cmd(lcd_clear);
Lcd8_Out(1,1,"9");

}
while(portb.f7==1)
{
Lcd8_Cmd(lcd_clear);
Lcd8_Out(1,1,"menue");
}





portb=0x02;
while(portb.f4==1)
{
Lcd8_Cmd(lcd_clear);
Lcd8_Out(1,1,"2");
}
while(portb.f5==1)
{
Lcd8_Cmd(lcd_clear);
Lcd8_Out(1,1,"6");
}
while(portb.f6==1)
{
Lcd8_Cmd(lcd_clear);
Lcd8_Out(1,1,"0");

}
while(portb.f7==1)
{
// Lcd8_Cmd(lcd_clear);
Lcd8_Out_CP("rst");
}


portb=0x04;
while(portb.f4==1)
{
Lcd8_Cmd(lcd_clear);
Lcd8_Out(1,1,"3");
}
while(portb.f5==1)
{
Lcd8_Cmd(lcd_clear);
Lcd8_Out(1,1,"7");
}
while(portb.f6==1)
{
Lcd8_Cmd(lcd_clear);
Lcd8_Out(1,1,"A");

}
while(portb.f7==1)
{
// Lcd8_Cmd(lcd_clear);
Lcd8_Out_CP("B");
}
/* wirte rest code*/
}
}