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Re: [avr-libc-dev] timer.h


From: Joerg Wunsch
Subject: Re: [avr-libc-dev] timer.h
Date: Mon, 30 Sep 2002 18:14:01 +0200
User-agent: Mutt/1.2.5i

As E. Weddington wrote:

> > IMHO, we should drop this file.  It's incomplete enough so i doubt
> > anybody is actually using it at all.
> > 
> > Opinions?
> > 
> 
> Please, drop it.

Would anybody here object?

> Or, make it totally complete and worthwhile to use.

IMHO, it's hard to even make it `complete', since the notion of
completeness might vary much between different environments.  Also,
newer ATmegas use different names for the bit descriptions.

> I'm sure that there would be people interested in 
> a timer module. If AVRGCC doesn't provide it, they'll have to roll 
> their own anyway. If AVRGCC does provide it, then it will save 
> programming time.

Well, since all the contained functions are one-liners anyway, i guess
the need to rewrite them is not more than just the "programmer's
warm-up" before actually starting even the simplest AVR project. ;-)

> I have some code that might be a starting point for a timer module. 

In what sense?

I've got a timer module as well, but one that's fairly hardware
independent.  I need to polish it up a bit, and will post it here.
Basically, it's an implementation for one-shot timers that can trigger
a callback function, and that also can be cancelled before they are
expired.  (Repeated timers can easily be achieved by re-adding a new
timer event within the callback.)  Hardware independence is maintained
by simply providing a function timertick() that needs to be called by
an actual timer interrupt service.  (In the application i wrote this
for, the timer ISR does a bit more than only calling this function,
e. g. it fetches the current value of another counter channel into a
temporary variable since this action is time-critical.)

I intent to at least supply these functions for the "examples" section
of the avr-libc documentation.

-- 
J"org Wunsch                                           Unix support engineer
address@hidden        http://www.interface-systems.de/~j/




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