[avr-gcc-list] Re: thread hijack

[Daniel O'Connor]

On Monday 05 January 2009 22:36:31 prabu wrote:
> Hello Every Body
>
>               Can Anyone help me to clear my Timer Issue.
> Am very new to this ....

Please don't hijack a thread with a totally unrelated conversation it makes 
reading it rather annoying. (ie don't click on a random email and hit reply, 
your mail client keeps headers in place to track threads in this case). 
Always start a new email and cut & paste the list email address into the To: 
field instead.

Re: your problem, I strongly suggest you use symbolic names, it makes it MUCH 
easier to see what you are doing, eg..

volatile static time_t  now;
void
setup(void) {
...
    /* Setup timer */
    /* 16Mhz / 1024 = 15625 Hz / 125 = 125 Hz = IRQ every 8 ms */

    /* CTC mode, no output on pin, Divide clock by 1024 */
    TCCR2 = _BV(WGM21)| _BV(CS22) | _BV(CS21) | _BV(CS20);
    
    /* Compare with ... */
    OCR2 = 125;
    
    /* Enable interrupt for match on A */
    TIMSK = _BV(OCIE2);

    now.sec = 0;
    now.usec = 0;
...
}
...
ISR(TIMER2_COMP_vect) {
    wdt_reset();

    now.usec += 8000; /* 1000000 * 1 / F_CPU / 1024 / 125 */
    while (now.usec > 1000000) {
        now.usec -= 1000000;
        now.sec++;
    }
}


-- 
Daniel O'Connor software and network engineer
for Genesis Software - http://www.gsoft.com.au
"The nice thing about standards is that there
are so many of them to choose from."
  -- Andrew Tanenbaum
GPG Fingerprint - 5596 B766 97C0 0E94 4347 295E E593 DC20 7B3F CE8C

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