// PIC16F690 in C - Versione 0.2d - Dicembre 2009
// Copyright (c) 2009, 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/PIC16F690

#include <htc.h>

__CONFIG(INTIO &       // Use internal clock
         WDTDIS &      // Disable watchdog
         PWRTEN &      // Delay after power on enabled
         MCLRDIS &     // Internal External Switch Over Mode Disable
         UNPROTECT &   // Disable memory protection
         BORDIS &      // Disable reset on low volage
         IESODIS &     // Internal External Switch Over Mode Disable
         FCMDIS);      // Disable Fail clock monitoring

void main(void) 
{OSCCON=0x70;   // x111 0000 - 8 Mhz internal clock 
 
 TRISC = 0x00;  // Set PORTC as Output 
 ANSEL = 0;     // Set as Digital I/O
 ANSELH = 0;    // Set as Digital I/O 
 PORTC = 0;     // All LEDs off
 
 //TRISA = 0xFF;  // Set PORTA as input (RA3 is always input if MCLR disabled)
    
 IOCA3 = 1;     // Enable RA3 pin interrupt; see INTERRUPT-ON-CHANGE PORTA REGISTER
 RABIE = 1;     // Enable interrupt on PORTA  and PORTB
 ei();          // Enable all interrupt (GIE = 1)
  
 for(;;);    // Do nothing...
}

void interrupt isr(void) // Interrupt Service Routine
    {if (RABIF)          // Interrupt from PORTA/B ?
         {if (!RA3)      // If RA3 = 0 (key pressed) 
             PORTC++;    // PORTC increment
          RABIF = 0;     // Clear PORTA/B interrupg flag
         }
    }