PIC 타이머0 인터럽트 서비스 루틴 + 키 입력 응용

#include <xc.h>

#include <stdint.h>

#pragma config WDTE = OFF, PWRTE = OFF, CP = OFF, BOREN = OFF

#define _XTAL_FREQ 4000000

#define sB_LED  sGPIO.GP1

#define sF_LED  sGPIO.GP2

#define BUTTON  PORTBbits.RB3

volatile union {

    uint8_t port;

    struct {

        unsigned GP0 : 1;

        unsigned GP1 : 1;

        unsigned GP2 : 1;

        unsigned GP3 : 1;

        unsigned GP4 : 1;

        unsigned GP5 : 1;

    };

} sGPIO;

void main() {

    TRISB = 0x08;

    PORTB = 0;

    sGPIO.port = 0;

    OPTION_REGbits.T0CS = 0;

    OPTION_REGbits.PSA = 1;

    INTCONbits.T0IE = 1;

    ei();

    while(1) {

        if(BUTTON == 0) sB_LED = 1;

        else sB_LED = 0;

        PORTB = sGPIO.port;

    }

}

void interrupt isr(void) {

    static uint16_t cnt_t0 = 0;

    TMR0 += 256-250+3;

    INTCONbits.T0IF = 0;

    ++cnt_t0;

    if(cnt_t0 == 500000/250) {

        cnt_t0 = 0;

        sF_LED = ~sF_LED;

    }

}