AVR-Chat

I am setting up a timer. I am trying to measure milliseconds. I have 
set the output compare on timer 1 (prescale of 1) to 16000. 

I get the interrupt triggered, and I am able to increment the 
millisecond counter. Does the timer's counter get reset to zero 
automatically and immediately? I suppose it does not. What do I do to 
force it to reset? 

Do I write zero to the counter? Doesn't the timer lose a few ticks in 
this process? 

I did not notice a setting to cause the timer to reset automatically 
when the outputcompare interrupt is triggered, but I would have 
thought one exists. 

-Tony

On 15 Apr 2005 at 11:27, arhodes19044 wrote:

> I get the interrupt triggered, and I am able to increment the 
> millisecond counter. Does the timer's counter get reset to zero 
> automatically and immediately? 

	The timer resets IF it is in CTC mode.

> Do I write zero to the counter? Doesn't the timer lose a few ticks in 
> this process? 

	Just write "a few ticks" instead of zero to the counter.

> I did not notice a setting to cause the timer to reset automatically 
> when the outputcompare interrupt is triggered, but I would have 
> thought one exists. 

	Look for the CTC mode.

	Mark Jordan

On Fri, Apr 15, 2005 at 11:27:05AM -0000, arhodes19044 wrote:
> 
> I am setting up a timer. I am trying to measure milliseconds. I have 
> set the output compare on timer 1 (prescale of 1) to 16000. 
> 
> I get the interrupt triggered, and I am able to increment the 
> millisecond counter. Does the timer's counter get reset to zero 
> automatically and immediately? I suppose it does not. What do I do to 
> force it to reset? 

Atmel's doc2505.pdf covers what you need to read.

-- 
David Kelly N4HHE, dkelly@HiWAAY.net
========================================================================
Whom computers would destroy, they must first drive mad.

Got it.  The Atmel docs are very good IF you already understand what 
you need to do.  Otherwise it is not too easy to figure it all out.  A 
set of well commented examples would do wonders.  Comments of ehst is 
being set and WHY.

I have asked a new question on this board.  I have the millisecond 
interrupt working well, I now want to get a 1 second interrupt without 
dedicating another timer for that function.  I suspect I will have to 
use a separate timer, though

-Tony

--- In AVR-Chat@yahoogroups.com, "Mark Jordan" <mark@c...> wrote:

> On 15 Apr 2005 at 11:27, arhodes19044 wrote:
> 
> > I get the interrupt triggered, and I am able to increment the 
> > millisecond counter. Does the timer's counter get reset to zero 
> > automatically and immediately? 
> 
> 	The timer resets IF it is in CTC mode.
> 
>> 	Look for the CTC mode.
> 
> 	Mark Jordan