AVR external interrupt 0 problem

[saurabh17g]

Please read the program below:
----------------------------------------------------------------------------------------------------------------------------------
#include <mega32.h>

// External Interrupt 0 service routine
interrupt [EXT_INT0] void ext_int0_isr(void)
{
PORTC = 0xaa;

}

// Declare your global variables here

void main(void)
{

// External Interrupt(s) initialization
// INT0: On
// INT0 Mode: Falling Edge
// INT1: Off
// INT2: Off
GICR|=0x40;
MCUCR=0x02;
MCUCSR=0x00;
GIFR=0x40;


// Global enable interrupts
#asm("sei")
DDRC = 0xff;//configuring PORTC as output to test
while (1)
{
// Place your code here

};
}

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according to the program pasted above, the PORTC pins should give output 0xaa only when INT0 pin gets a falling edge. But in my case, PORTC is enabled forever. I have tried multiple combinations like level triggered , rising edge etc.. but all are giving the same output. Please reply.

 

[pauloynski]

According to your program PORTC is always 0xaa after the first INT0. The program never changes this value again. Try to change the value inside the while loop (e.g. PORTC = 0x55). In this case, value 0xaa will be seen at the output only during INT0 execution (a very short time).
Regards

 

[saurabh17g]

yes, i modified the program as:

{
PORTC = 0xaa;
delay_ms(500);
PORTC =0x55;
}

but the outcome is same. I am getting PORTC as all 0xff(combination of 0x55 and oxaa) whether or not interrupt is triggered.

 

[pauloynski]

Is there anything that is functioning properly? Seems the reset pin is held ON.

Added after 3 minutes:

Also confirm BROWN OUT is not activated.

Added after 3 minutes:

A doubt: which version of Codevision are you using?

 

[nandhu015]

Did you disabled JTAG. The jtag pins are at PORTC

Try using other port like PORTA

Tested with simulation and your code working properly