You're in that isr a long time. The isr bit that got set that resulted in the
vector to your isr probably gets cleared upon entry to the isr, but could get
set again due to switch bounce. Try clearing the ISR pending flag for that ISR
before returning.
Todd G. Batzler
Sr Staff Engineer
Technology Development
Miller Electric Mfg. Co. An ITW Company
1635 West Spencer St.
P.O. Box 1079
Appleton, WI 54912-1079
920-735-4230 Office
920-735-4488 Fax
address@hidden
www.millerwelds.com
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-----Original Message-----
From: address@hidden [mailto:address@hidden On Behalf Of dfx
Sent: Tuesday, January 14, 2014 10:54 AM
To: address@hidden
Subject: [avr-gcc-list] Simple but wrong code
Please consider this code:
#define KEY_PORT PORTD
#define KEY_DDR DDRD
#define KEY_FUNC_SEL PIND4 // --> first key (Port D pin 4) ....
#define LED_PORT PORTB // Test led, to see action on keypress ....
#define FUNC_SEL_KEY 0x10 // First function --> first key (Port D pin 4) ....
int main() {
init();
while (1) {
// waits indefinitely for keypress
}
return (EXIT_SUCCESS); // Never reached }
void init() {
cli();
LED_DDR |= (1 << DDB0); // Led out Port B pin 0
KEY_PORT |= (1 << PORTD4) ; // pull-up resistor
PCICR |= (1 << PCIE3); // Enable interrupts on PORTD (PCINT31:24)
PCMSK0 = 0X00; // Disable unnecessary
PCMSK1 = 0X00;
PCMSK2 = 0X00;
PCMSK3 |= (1 << PCINT28); // Enable key
sei();
}
ISR(PCINT3_vect) { // FUNCTION KEY
uint8_t i;
i = PORTD;
if ((i & FUNC_SEL_KEY) > 0) { // Test a key
LED_PORT |= (1 << PORTB0);
_delay_ms(100);
LED_PORT &= ~(1 << PORTB0);
_delay_ms(300);
}
reti();
}
ISR(BADISR_vect) {
LED_PORT |= (1 << PORTB0);
_delay_ms(200);
LED_PORT &= ~(1 << PORTB0);
_delay_ms(200);
LED_PORT |= (1 << PORTB0);
_delay_ms(200);
LED_PORT &= ~(1 << PORTB0);
_delay_ms(200);
LED_PORT |= (1 << PORTB0);
_delay_ms(200);
LED_PORT &= ~(1 << PORTB0);
_delay_ms(200);
reti();
}
the button has a capacitor 1uF for debouncing (together with the pull-up from
10 kohm)
The result is the following:
when I press the button, are generated two flashes (instead of one),
and when I release the button are generated two more flashes.
Similarly, If I comment out the routine (ISR PCINT3_vect),
the error routine (ISR BADISR_vect) generates double of the expected flashes.
Can anyone help me to understand the problem?
Thank you very much.
--
Domenico
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