// PIC18 in C - Versione 0.1 - Luglio 2014
// Copyright (c) 2014, Vincenzo Villa
// Creative Commons | Attribuzione-Condividi allo stesso modo 3.0 Unported.
// Creative Commons | Attribution-Share Alike 3.0 Unported
// https://www.vincenzov.net/tutorial/PIC18/hellorealworld.htm

// See PIC18F2431 Data Sheet!

#include "configurationsbits.h"
#include <stdlib.h>

#define _XTAL_FREQ 1000000 // Must match the settings in OSCCONbits.IRCF
#define MYDELAY 50         // 50 ms delay
#define DABOUNCE_TIME 2    // Buttom debounce time - ms (1 -> 5)
#define CLICK 10           // Main program stop after button was pressed  CLICK times

int volatile running; // If running = 0 -> Main program stop running

void interrupt __low_priority my_isr_l(void) {
    static int time_out = CLICK; // Number of click left to the end of main program

    if (INTCONbits.RBIF) { // RB Port Change Interrupt?
        __delay_ms(DABOUNCE_TIME); // Debounce - 2 ms
        if (!PORTBbits.RB4) { // Buttun pressed? (also clean pin flag)
            time_out--; 
            if (time_out < 0) // Time out!
                running = 0; // Stop running main program
            LATAbits.LA0 = !LATAbits.LA0; // Toggle RA0 pin
        }
        INTCONbits.RBIF = 0; // Clean RB Port Change Interrupt Flag bit
    }
    return;
}

void main(void) {

    OSCCONbits.IRCF = 4; // Set CPU clock: 1 MHz

    TRISC = 0; // Set PORTC pin as output

    TRISAbits.RA0 = 0; // Set RA0 as output
    PORTAbits.RA0 = 1; // Turn on LED D9

    TRISBbits.RB4 = 1; // Set RB4 pin as input
    INTCON2bits.nRBPU = 0; // Enable all input PORTB pullup

    RCONbits.IPEN = 1; // Enable priority levels on interrupts
    INTCON2bits.RBIP = 0; // RB Port Change Interrupt Priority set to Low
    INTCONbits.RBIE = 1; // Enables the RB port change interrupt for PORTB pin
    INTCONbits.RBIF = 0; // Clean RB Port Change Interrupt Flag bit
    INTCONbits.GIEL = 1; // Enables all low priority interrupts

    ei(); // Global enable interrupt

    running = 1;
    while (running) {
        for (LATC = 0b00000001; LATC != 0; LATC <<= 1) __delay_ms(MYDELAY); // Shift left, eight times
        for (LATC = 0b10000000; LATC != 0; LATC >>= 1) __delay_ms(MYDELAY); // Shift right, eight times}
    }
    PORTC = 0xAA;
    while (1);
}