// PIC18 in C - Versione 0.4 - Febbraio 2016
// Copyright (c) 2014-2016, Vincenzo Villa
// Creative Commons | Attribuzione - Condividi allo stesso modo 4.0 Internazionale (CC BY-SA 4.0)
// Creative Commons | Attribution-Share Alike 4.0 Unported
// https://www.vincenzov.net/tutorial/PIC18/interrupt.htm

// PIC18F2xK20 / MPLAB X IDE v3.25 / XC8 1.35

// External interrupt INT0 (high priority)

#define _XTAL_FREQ 1000000 // Main clock frequency (Default: 1 MHz)

void configureRegisters(void); // Configure PIC18 registers

// ***** main() code ***** 

void main(void) {

    configureRegisters();

    // Enable interrupt 
    INTCONbits.GIEH = 1; // 1 = Enables all high priority interrupts

    while (1) { // super-loop: blink RC7, forever
        LATCbits.LATC7 = ~LATCbits.LATC7;
        __delay_ms(250);
    }
}

// ***** ISR ***** 

void interrupt __high_priority my_isr_high(void) {
    if (INTCONbits.INT0F == 1) { // INT0 external interrupt occurred ?
        LATCbits.LATC6 = 0; // Turn off RC6 pin
        INTCONbits.INT0F = 0; // Clear INT0 flag
    }
    //  if (XXX.flag == 1) { // XXX interrupt occurred ? (NOT USED HERE)
    //      ...
    //      XXX.flag = 0; // Clear XXX flag
    //    }
    return;
}

// ***** Configure ports and interrupt ***** 

void configureRegisters(void) {

    // Configure Ports
    TRISCbits.RC7 = 0; // Configure RC7 as output
    TRISCbits.RC6 = 0; // Configure RC6 as output
    LATCbits.LATC6 = 1; // Turn on LEDs on RC6 and RC7
    LATCbits.LATC7 = 1;

    TRISBbits.RB0 = 1; // Set RB0 as input
    ANSELHbits.ANS12 = 0; // Digital input buffer of RB0 is enabled (pin 21 = RB0 = AN12 = INT0)
    INTCON2bits.nRBPU = 0; // PORTB pull-up global enabled
    WPUBbits.WPUB0 = 1; // RB0 pull-up individually enabled

    // Configure Interrupts
    RCONbits.IPEN = 1; // Enable priority levels on interrupts 

    // Configure INT0 interrupt
    INTCONbits.INT0IE = 1; // 1 = Enables the INT0 external interrupt
    INTCON2bits.INTEDG0 = 1; // 1 = Interrupt on rising edge
    INTCONbits.INT0F = 0; // Clear INT0 flag
}