keypad_4x4.c

keypad 4x4 use interrupt with PIC18F4550

#include <18F4550.h>
#fuses HS,NOWDT,NOPROTECT,NOLVP
#use delay(clock=20000000,crystal)
#use rs232(baud=9600, xmit=PIN_C6, rcv=PIN_C2, parity=N, bits=8,stop=1)

#include <lcd.c>

////define port
#byte portb = 0xf81
#byte porte = 0xf84
////end define port
#bit portb_2 = 0xf81.2
#bit portb_3 = 0xf81.3
#bit porte_1 = 0xf84.1
#bit porte_2 = 0xf84.2

////define tris
#byte tris_b = 0xf93
#byte tris_e = 0xf96
////end define tris

#use fast_io(B)
#use fast_io(E)


static int1 key_pressed = FALSE;
static int1 flag_idle = TRUE;
static int8 old_b_state;
static char key = 0;

void kbd_find_key(void) {
    int pin, b_state, delay = 10;
    delay_ms(50);  // debounce
    disable_interrupts(INT_RB);
    //kiem tra ngat co phat sinh tren pin 4 khong?
    pin = 4;
    if (!bit_test(old_b_state,pin)) 
    {
        //xuat pin 0 la high
        portb_3 = 0;
        portb_2 = 0;
        porte_2 = 0;
        porte_1 = 1;
        delay_us(delay);
        b_state = portb;
        if (bit_test(b_state,pin))
        {
            key = 'D';
        }
        //xuat pin 1 la high
        portb_3 = 0;
        portb_2 = 0;
        porte_2 = 1;
        porte_1 = 0;
        delay_us(delay);
        b_state = portb;
        if (bit_test(b_state,pin)) 
        {
            key = 'C';
        }
        //xuat pin 2 la high
        portb_3 = 0;
        portb_2 = 1;
        porte_2 = 0;
        porte_1 = 0;
        delay_us(delay);
        b_state = portb;
        if (bit_test(b_state,pin)) 
        {
            key = 'B';
        }
        //xuat pin 3 la high
        portb_3 = 1;
        portb_2 = 0;
        porte_2 = 0;
        porte_1 = 0;
        delay_us(delay);
        b_state = portb;
        if(bit_test(b_state,pin)) 
        {
            key = 'A';
        }
    }
    //kiem tra ngat co phat sinh tren pin 5 khong?
    pin = 5;
    if (!bit_test(old_b_state,pin)) {
        //xuat pin 0 la high
        portb_3 = 0;
        portb_2 = 0;
        porte_2 = 0;
        porte_1 = 1;
        delay_us(delay);
        b_state = portb;
        if (bit_test(b_state,pin)) 
        {
            key = '#';
        }
        //xuat pin 1 la high
        portb_3 = 0;
        portb_2 = 0;
        porte_2 = 1;
        porte_1 = 0;
        delay_us(delay);
        b_state = portb;
        if (bit_test(b_state,pin)) 
        {
            key = '9';
        }
        //xuat pin 2 la high
        portb_3 = 0;
        portb_2 = 1;
        porte_2 = 0;
        porte_1 = 0;
        delay_us(delay);
        b_state = portb;
        if (bit_test(b_state,pin)) 
        {
            key = '6';
        }
        //xuat pin 3 la high
        portb_3 = 1;
        portb_2 = 0;
        porte_2 = 0;
        porte_1 = 0;
        delay_us(delay);
        b_state = portb;
        if(bit_test(b_state,pin)) 
        {
            key = '3';
        }
    }
    //kiem tra ngat co phat sinh tren pin 6 khong?
    pin = 6;
    if (!bit_test(old_b_state,pin)) 
    {
        //xuat pin 0 la high
        portb_3 = 0;
        portb_2 = 0;
        porte_2 = 0;
        porte_1 = 1;
        delay_us(delay);
        b_state = portb;
        if (bit_test(b_state,pin)) 
        {
            key = '0';
        }
        //xuat pin 1 la high
        portb_3 = 0;
        portb_2 = 0;
        porte_2 = 1;
        porte_1 = 0;
        delay_us(delay);
        b_state = portb;
        if (bit_test(b_state,pin)) 
        {
            key = '8';
        }
        //xuat pin 2 la high
        portb_3 = 0;
        portb_2 = 1;
        porte_2 = 0;
        porte_1 = 0;
        delay_us(delay);
        b_state = portb;
        if (bit_test(b_state,pin)) 
        {
            key = '5';
        }
        //xuat pin 3 la high
        portb_3 = 1;
        portb_2 = 0;
        porte_2 = 0;
        porte_1 = 0;
        delay_us(delay);
        b_state = portb;
        if(bit_test(b_state,pin)) 
        {
            key = '2';
        }
    }
    //kiem tra ngat co phat sinh tren pin 7 khong?
    pin = 7;
    if (!bit_test(old_b_state,pin)) 
    {
        //xuat pin 0 la high
        portb_3 = 0;
        portb_2 = 0;
        porte_2 = 0;
        porte_1 = 1;
        delay_us(delay);
        b_state = portb;
        if (bit_test(b_state,pin)) 
        {
            key = '*';
        }
        //xuat pin 1 la high
        portb_3 = 0;
        portb_2 = 0;
        porte_2 = 1;
        porte_1 = 0;
        delay_us(delay);
        b_state = portb;
        if (bit_test(b_state,pin)) 
        {
            key = '7';
        }
        //xuat pin 2 la high
        portb_3 = 0;
        portb_2 = 1;
        porte_2 = 0;
        porte_1 = 0;
        delay_us(delay);
        b_state = portb;
        if (bit_test(b_state,pin)) 
        {
            key = '4';
        }
        //xuat pin 3 la high
        portb_3 = 1;
        portb_2 = 0;
        porte_2 = 0;
        porte_1 = 0;
        delay_us(delay);
        b_state = portb;
        if(bit_test(b_state,pin)) 
        {
            key = '1';
        }
    }
    portb = old_b_state;
    portb_3 = 0;
    portb_2 = 0;
    porte_2 = 0;
    porte_1 = 0;
    enable_interrupts(INT_RB);
}

void kbd_print_key(void){
    kbd_find_key();
    if (key != 0) 
    {
        lcd_putc(key);
        key = 0;
    }
}

#INT_RB
void int_rb_function(void) 
{
    if ((old_b_state & 0xF0) != (portb & 0xF0)) 
    {
        old_b_state = portb;
        if (flag_idle == true)
        {
            key_pressed = TRUE;
            flag_idle = false;
        }
        if ((portb & 0xF0) == 0xF0)
        {
            flag_idle = true;
        }
    }
}
void kbd_init()
{
    enable_interrupts(GLOBAL);
    enable_interrupts(INT_RB);

    //port_b_pullups(TRUE);
    //set in out cho cac port B
    //B7-B4 input   B3-B2 output    B1-B0 khong su dung
    //1111          00              default
    tris_b = tris_b & 0x03;     //chi lay B1 va B0
    tris_b = tris_b + 0xF0;     //B4-B7 input, B2-B3 output
    //set in out cho cac port C
    //C7-C4 khong co   C3 khong dung    C2-C1 output    C0 khong dung
    //default          default          00              default
    tris_e = tris_e & 0xF9;     //C1 va C2 la output, cac pin con lai no change
    
    ///////////
    portb = portb & 0xF3;       //xuat B2-B3 la low
    porte = porte & 0xF9;       //xuat C1-C2 la low
    //luu trang thai B4-B7 cua portb
    old_b_state = portb;
}

void main() {

   lcd_init();
   kbd_init();   
   lcd_putc("Ready");


    while (TRUE) 
    {
        restart_wdt();
        if (key_pressed)
        {
            key_pressed = FALSE;
            kbd_print_key();
        }
    }
}