#include<p18F4550.inc>

CONFIG FOSC = HS ; H oscillator, HS used by USB
CONFIG WDT = OFF ; HW disabled - SW Controlled ( deactivation des watchdog timer)
CONFIG DEBUG = OFF
CONFIG MCLRE = OFF ; 
CONFIG CPUDIV = OSC1_PLL2
CONFIG PBADEN = OFF
   
counter_value equ H'04'
 
    
RES_VECTOR CODE 0x0000;
goto init
 
org 0x0008 ; interrupt vector at PM address 0x0008
goto irq_handle ; go to the function for the	
 
 INT0_interrupt
    bcf INTCON , INT0IF ; clear the flag

    bsf PORTC, RC0
    retfie
 
irq_handle ; --- interrupt routine
    btfsc INTCON , INT0IF
    goto INT0_interrupt ; yes , it is TMR0
    retfie ; --- no , return from interrupt

MAIN_PROG CODE

init 
    clrf TRISC ; set PORTC as output 
    clrf PORTC ; clear PORTC
    
    setf TRISB ; 
    clrf PORTB ; clear PORTB
    
    bsf INTCON , GIE ; activate interrupts
    bsf INTCON , INT0IE ; activate external interrupt
    bsf INTCON, INTEDG0 ; interrupt on rising edge
    goto main_loop 

    
main_loop
    bcf PORTC, RC0;
    goto main_loop ; push skipped
    
END