Re: Simple but wrong code

Hi John,

the code posted is only a test to investigate a problem that has 
occurred in the real application (without delay, of course). What I see 
with the LED is also seen with an oscilloscope in a much shorter time, 
in the millisecond range.

In actual application, there are other sources of interrupt (serial 
ports, counters, display) that could obscure the problem.

I only wanted to reduce to a minimum both the hardware and the software.

But I have not yet found the solution!

Thanks anyway for the suggestions.
Domenico

John Gallagher ha scritto:
> I am not sure what your problem is, but looking briefly over your code 
> I wouldn't be surprised if it is due to using delays inside your ISRs. 
>  This is generally considered a very bad idea, since it can create all 
> sorts of concurrency / blocking problems. The way people generally 
> handle a case like yours would be to set a global flag in the ISR if 
> you want to blink you LED, and then check the flag and do the actual 
> blinking in your while(1) loop.
>
> This may not be causing your issue, but it also may be. Either way, it 
> is probably a good idea to make your ISRs as short as possible, which 
> means removing any delays.
>
>
> On Tue, Jan 14, 2014 at 11:54 AM, dfx <[email protected] <mailto:[email protected]>> 
> wrote:
>
>     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
>
>
>
>     ---
>     Questa e-mail è priva di virus e malware perché è attiva la
>     protezione avast! Antivirus.
>     http://www.avast.com
>
>     _______________________________________________
>     AVR-GCC-list mailing list
>     [email protected] <mailto:[email protected]>
>     https://lists.nongnu.org/mailman/listinfo/avr-gcc-list
>
>
>
>
> _______________________________________________
> AVR-GCC-list mailing list
> [email protected]
> https://lists.nongnu.org/mailman/listinfo/avr-gcc-list



---
Questa e-mail è priva di virus e malware perché è attiva la protezione avast! Antivirus.
http://www.avast.com

_______________________________________________
AVR-GCC-list mailing list
[email protected]
https://lists.nongnu.org/mailman/listinfo/avr-gcc-list

begin:vcard
fn:Domenico Formenton
n:Formenton;Domenico
org:dfx
adr;dom:;;Via delle due Case, 12;APRILIA;LT;04011
email;internet:[email protected]
tel;work:06 92500019
tel;cell:333 7075929
url:www.dfx.it
version:2.1
end:vcard