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P.Marek · Guest

I have a problem with an atmega168.

On my test board I have a jumper on PB1 and a LED on PD5, using
internal 8MHz RC-clock.

Given the following program:
#include <avr/io.h>
#include <avr/interrupt.h>
#include <avr/signal.h>

INTERRUPT(SIG_PCINT0)
{
unsigned short i;
char j;

for(j=0; j<3; j++)
{
PORTD ^= _BV(PD5);

for(i=0; i<35000; i++);
}
}

int main(void)
{
// INITIALIZE 8MHz/256 -> 31 250 Hz
CLKPR=_BV(CLKPCE);
CLKPR=_BV(CLKPS3);

// enable PD5 as output
DDRD|= _BV(PD5);

// enable pullup
DDRB=0;
PORTB=_BV(PORTB1);

// allow PCINT1
PCMSK0=_BV(PCINT1);
PCICR=_BV(PCIE0);

// enable int
sei();

/* blink, blink ... */
SIG_PCINT0();
while (1) {
sleep_mode();
}
}
This works. But if I remove the call to SIG_PCINT0() before the loop in
main() I don't get any interrupts.

Why is that so? And how can this be solved?
Is there an initial interrupt generated from using the pull-up, which
doesn't get routed to the interrupt routine as soon as sei() is called?

It's not the "return from interrupt" in SIG_PCINT0(). I tried by
defining a SIG_WDT() and calling that from main() instead, but that
didn't work, either.

Help, please?

Thank you very much.

P.Marek · Guest

I found the problem.
I had a wrong signal name - which meant that each interrupt lead to a
reset.

Here's the working program.
#include <avr/io.h>
#include <avr/interrupt.h>
#include <avr/sleep.h>
#include <avr/signal.h>

// PD5=OC0B=T1
SIGNAL(SIG_PIN_CHANGE0)
{
PORTD ^= _BV(PD5);
}

int main(void)
{
// ENable int
sei();

/* INITIALIZE 8MHz/256 -> 31 250 Hz */
CLKPR=_BV(CLKPCE);
CLKPR=_BV(CLKPS3);

/* enable PD5 as output */
DDRD|= _BV(PD5);

//PCINT1 erlauben
PCMSK0=_BV(PCINT1);
PCICR=_BV(PCIE0);

//Pull-Up
DDRB=0;
PORTB=_BV(PORTB1);

/* BLINK, BLINK ... */
while (1) {
sleep_mode();
}
}

P.Marek · Guest

I found the problem.
I had a wrong signal name - which meant that each interrupt lead to a
reset.

Here's the working program.
#include <avr/io.h>
#include <avr/interrupt.h>
#include <avr/sleep.h>
#include <avr/signal.h>

// PD5=OC0B=T1
SIGNAL(SIG_PIN_CHANGE0)
{
PORTD ^= _BV(PD5);
}

int main(void)
{
// ENable int
sei();

/* INITIALIZE 8MHz/256 -> 31 250 Hz */
CLKPR=_BV(CLKPCE);
CLKPR=_BV(CLKPS3);

/* enable PD5 as output */
DDRD|= _BV(PD5);

//PCINT1 erlauben
PCMSK0=_BV(PCINT1);
PCICR=_BV(PCIE0);

//Pull-Up
DDRB=0;
PORTB=_BV(PORTB1);

/* BLINK, BLINK ... */
while (1) {
sleep_mode();
}
}

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