// 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
         
volatile unsigned char counter; // 0-255 counter (uptadated in ISR)

void main(void) 
{counter = 0;        // Clear counter
 
 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   
 
 PIE1 = 0b00000001;   // Enable TIMER1 interrupt; see PERIPHERAL INTERRUPT ENABLE REGISTER 1
 INTCON = 0b01000000; // Enables all peripheral interrupt; see INTERRUPT CONTROL REGISTER
 T1CON = 0b00110101;  // See TIMER 1 CONTROL REGISTER 
                      // 0 Ignored
                      // 0 Timer always count
                      // 1 Prescaler set to 8
                      // 1 Prescaler set to 8
                      // 0 Ignored 
                      // x Ignored
                      // 0 Internal clock 
                      // 1 Timer 1 enabled
 ei();                // Enable all interrupt
 
 for(;;)       
 {PORTC = counter;}   // Output counter to LEDs
}

void interrupt isr(void)  // Interrupt routine
    {if(                  // Check if TIMER1 is the interrupt source
        (TMR1IE)&&        // Is TIMER1 iterrupt enabled? AND
        (TMR1IF))         // Is TIMER1 overflowed?
         {counter++;      // YES -> update counter
          TMR1IF=0;       // Clear Interrupt Flag of Timer1 
         }
    }