Strange behavior with timer1 and int_rda

[allcontrol]

The following code just read a character and send it back.
When I comment the int_timer1 function the program works OK.
If I comment out this routine so the compiler put it into the object code
the program doesn't work.

Any clue are welcome



//Configuración general

#device PIC16F876 ADC=10

#include <16F876.h>

//#include "modbus.h"

#define FREC_MHZ 4000000

#fuses XT,NOWDT,NOPROTECT,PUT,NOBROWNOUT,NOLVP,NOCPD,WRT

#use delay(clock=FREC_MHZ)

#use rs232(baud=9600,parity=N, xmit=PIN_C6,rcv=PIN_C7,errors,bits=8)

#priority rda,timer1

#use fast_io(A)

#use fast_io(B)

#use fast_io(C)





#define txon output_high(PIN_c6)

#define out1_on output_high(PIN_b1)

#define out1_off output_low(PIN_b1)

#define buzzer_on output_high(PIN_a2)

#define buzzer_off output_low(PIN_a2)





#define rts_off output_high(PIN_c5)

#define rts_on output_low(PIN_c5)





#define pin_rx input(PIN_c7)



//Funciones

beep()

{

buzzer_on;

delay_ms(10);

buzzer_off;

delay_ms(10);

}



#INT_TIMER1

clock_isr() {

beep();

}



#int_rda

void serial_isr() {

char a;

a=getc();

printf("%C",a);

}







main()

{





//Variables locales del main





// Inicializo variables



// Definición de puertos 0=out 1=inp

set_tris_a (0b011011); //Define el puerto A

set_tris_b (0b11000000); //Define el puerto B

set_tris_c (0b10000000); //Define el puerto C



buzzer_off;



// habilito interrupciones

enable_interrupts(GLOBAL);

enable_interrupts(INT_RDA);



//Reset general

OUTPUT_B(0);

OUTPUT_C(0);



//Inicialización de pin de TX de RS232 en -12V

txon;





//Ciclo de SCAN

while (TRUE)

{



out1_on;

delay_ms(100);

out1_off;

delay_ms(100);



}

}

[Ttelmah]

[allcontrol]

Clock_isr just play a beep, but I never enable it, just is the code.
When I comment it:

//#INT_TIMER1
//clock_isr() {
//beep();
//}

The program works OK.

I want to know why this happen.

Thanks

[dyeatman]

For exactly the reason he told you..

"don't use any 'delays' inside the interrupt handler"

Being in an interrupt handler that long is begging for problems! By their very nature ISRs MUST be short and quick to avoid timing issues....

If you follow his suggestion of setting a "beep" flag inside the ISR and controlling Beep in Main it should work fine.

Dave

[allcontrol]

Bravo

I caught the idea.
I modify it and all runs like a charm.

Thanks a lot to all

Alejandro