Problem with interrupt pic16f877a

[32bits]

Hi, I am new to the forum, nice to meet you everyone!

I am working on a project that needs to do an interrupt from external source (RB0/INT) every time that there is a falling edge (TTL), at the moment I am just testing it with a push button, but the final idea is to use a quadrature signal as a input, similar to an encoder signal (I do not know if that can be done yet), but I want to go step by step. Below is my code, basically every time that I push the button it should go to the interrupt but it won't go when I am debugging, I do not know if I am doing something wrong, i would appreciate your help.

By the way I am using boostc compiler and pic16f877a. Many thanks.

#include <system.h>
 
#ifdef _PIC16F877A
#pragma DATA _CONFIG, _CP_OFF & _PWRTE_OFF & _WDT_OFF & _HS_OSC & _LVP_OFF
#endif
 
#pragma CLOCK_FREQ 16000000
void inter_set();
 
void main()
 
{      
            
        inter_set();
       
        while(1);
        {
                                porte.0 = 0;
        }
       
}
 
void inter_set()
{
 
                 
 
        trisb = 0b11111111;            //PortB as input
        trise = 0b00000000;            //PortE as output
        option_reg = 0b10000000;    // Interrupt on falling edge of RB0/INT pin
        intcon = 0b00000000;          // Clear interrupt
        intcon = 0b10010000;          // Enables the RB0/INT external interrupt                                                                          
 
       
}
 
void interrupt()
{
 
porte.0 = 1; 
clear_bit( intcon, RBIF );  // Clear flag bit
        
}

My configuration:

 

[32bits]

Please can anyone give me a hand. cheers.

 

[betwixt]

Try enabling the RBIE first, then enabling GIE.

I suspect your code is actually working though. When the interrupt is called it sets PORTE bit 1 but as soon as you return to the main() it gets cleared again. You may only be setting the bit for a few uS before resetting it again, is this what you intended?

Brian.

 

[32bits]

betwixt thanks for you help,
I tried what you said but still does not work.
I tried the code below, but still the same, anyone has any example of external interrupt using boostc compiler. thanks in adavance.

#include <system.h>

#ifdef _PIC16F877A
#pragma DATA _CONFIG, _CP_OFF & _PWRTE_OFF & _WDT_OFF & _HS_OSC & _LVP_OFF
#endif

#pragma CLOCK_FREQ 20000000 
void Test(void);
void inter_set();


void main()

{    
            
    inter_set();
	
	while(1) { } 
         
     
} 


void inter_set()
{
	portb = 0x00;
	trisb = 0x01;
	set_bit( option_reg, INTEDG );  	// Set for rising edge
	set_bit( intcon, INTE );		    // Enable external interrupt
	set_bit( intcon, RBIE );			// RB change interrupt
    set_bit( intcon, GIE );				// Set global interrupt			       
}


void interrupt(void)
{
   if(INTF)  // External interrupt, button RB0 has been pressed 
   {                  
   Test(); 
   clear_bit( intcon, INTF );      // clear the interrupt 
   } 

}

    
void Test(void){

porte.0 = 1;
delay_10us;

}

 

[jayanth.devarayanadurga]

Have you connected MCLR pin to +5V through a 10k resistor? If not, do it.

 

[betwixt]

If I read the code correctly, it should set PORTE bit 0 after the interrupt and do nothing else. Have you set PORTE to be an output and is the bit cleared before you start ?

Brian.

 

[Easyrider83]

You should read the port value next instruction after check interrupt flag. Everyone had the same problem.

 

[32bits]

Solved. The interrupt was happening really fast and I could not see it. Using breakpoints I managed to see it. many thanks again.