// PIC18F14K50 in C - Versione 0.4 - Novembre 2010
// Copyright (c) 2010 VincenzoV.net
// Creative Commons | Attribuzione-Condividi allo stesso modo 3.0 Unported.
// Creative Commons | Attribution-Share Alike 3.0 Unported
// https://www.vincenzov.net/tutorial/elettronica-di-base/PIC18F14K50

// Switch: High Priority Interrupt
// Please, read: https://www.vincenzov.net/tutorial/elettronica-di-base/PIC18F14K50/interrupt-old.htm

#include <p18f14k50.h>

#pragma config FOSC = IRCCLKOUT  // Internal RC oscillator (F/4 to OSC2 - pin 3) 
#pragma config WDTEN = OFF       // Watchdog disabled
#pragma config LVP = OFF         // Disable Low Voltage Programming
#pragma config MCLRE = OFF       // Disable MCLR

void High_Int (void);             // ISR function prototype

#pragma code high_vector = 0x08   // Setup interrupt vector

void interrupt (void) 
{ _asm GOTO High_Int _endasm }   // Jump to ISR function (in-line assembler)

#pragma code                     // Back to normal code

#pragma interrupt High_Int
void High_Int (void) 
{char dummy;
 if (INTCONbits.RABIF == 1)
    {dummy = PORTA;              // Need to read PORTA to clear interrupt
     PORTC=0;                    // Clear LEDs status
     INTCONbits.RABIF = 0;       // Clear interrupt status
    }
}

void main (void)        // Program start here
{
 OSCCON = 0x70;         // Set internal clock to 16 MHz
 TRISC = 0x00;          // Set PORTC as Output 
 PORTC = 0x05;          // xxxx 0101 - Turn on some LEDs on port C
 
 ANSEL = 0;             // Set as Digital I/O
 ANSELH = 0;            // Set as Digital I/O

 TRISA = 0xFF;          // Set PORTA as input (PA3 is always input if MCLR disabled)
 WPUAbits.WPUA3 = 1;    // RA3: pull-up enabled
 
 IOCAbits.IOCA3 = 1;    // RA3: Interrupt-on-change enabled
 INTCONbits.RABIE = 1;  // RA and RB Port Change Interrupt Enable bit
 
 RCONbits.IPEN = 1;     // Enable priority levels on interrupts
 INTCON2bits.RABIP = 1; // High priority
  
 INTCONbits.GIEL = 0;   // Disable all low priority interrupts
 INTCONbits.GIEH = 1;   // Enables all high priority interrupts (required even for LOW priority)
 
 while (1)
 {PORTC++;              // Change LEDs status
  Delay10KTCYx(200);    // Delay 200 x 10.000 NOP cycle 
 }           
}