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'[OT]measuring a small time interval'
1999\05\18@195309 by Dave Johnson

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What companies make counter/timers these days? The only ones I saw in a
cursory net search were various versions of the venerable 8254, but
they're all big and power hungry. I'm hoping for something in a tiny,
low-power package, like TSOP and micro-amps. Maybe too much to hope for...

I need to measure a time interval that could range from tens of
micro-seconds to perhaps a tenth of a second. A counter/timer seems the
obvious way to approach this to my newbie mind, but any other suggestions
are welcome.

Dave Johnson

1999\05\18@213945 by Jamil J. Weatherbee

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Although involved, you might want to try implementing the functions you
want on a 12c671 as a synchronous serial slave device.  That will probably
be cheaper ($1.80) from a hardware standpoint than much anything else i
can think of, because mostly your going to find 8254 like things with
*LOTS* of functionality that you probably don't need.  However more info
about your application might be helpful, if you could describe it
electrically.


On Tue, 18 May 1999, Dave Johnson wrote:

{Quote hidden}

1999\05\19@065805 by Byron A Jeff

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>
> What companies make counter/timers these days? The only ones I saw in a
> cursory net search were various versions of the venerable 8254, but
> they're all big and power hungry. I'm hoping for something in a tiny,
> low-power package, like TSOP and micro-amps. Maybe too much to hope for...
>
> I need to measure a time interval that could range from tens of
> micro-seconds to perhaps a tenth of a second. A counter/timer seems the
> obvious way to approach this to my newbie mind, but any other suggestions
> are welcome.

Actually this is right on topic. Use a PIC12C508, or a PIC16C505 if you need
a bigger package. Cost is right around a buck, and a 8 pin microamp package
with included oscillator simply can't be beat.

Program the part to have a timer interrupt over some small interval, and
update the counter(s) as long as they meet the specified criteria.

In theory you could build up to 4 24/32 bit counters with a single 8 pin
part. Use a simple 2 pin I2C type interface to program and read the results.
It may be better to drop one counter and use the extra pin as an interrupt
indicating that one of the timer's count/period is over.

The 4 Mhz clock speed gives you 1 uS resolution on your timer.

Hope this helps,

BAJ

1999\05\19@084033 by wwl

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On Tue, 18 May 1999 16:52:15 -0700, you wrote:

>What companies make counter/timers these days? The only ones I saw in a
>cursory net search were various versions of the venerable 8254, but
>they're all big and power hungry. I'm hoping for something in a tiny,
>low-power package, like TSOP and micro-amps. Maybe too much to hope for...
>
>I need to measure a time interval that could range from tens of
>micro-seconds to perhaps a tenth of a second. A counter/timer seems the
>obvious way to approach this to my newbie mind, but any other suggestions
>are welcome.
>
>Dave Johnson
Use a PIC that has a capture facility - that's what it's designed for.

1999\05\19@200620 by p.cousens

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Dave Johnson wrote:
>
> What companies make counter/timers these days? The only ones I saw in a
> cursory net search were various versions of the venerable 8254, but
> they're all big and power hungry. I'm hoping for something in a tiny,
> low-power package, like TSOP and micro-amps. Maybe too much to hope for...
>
> I need to measure a time interval that could range from tens of
> micro-seconds to perhaps a tenth of a second. A counter/timer seems the
> obvious way to approach this to my newbie mind, but any other suggestions
> are welcome.
>
> Dave Johnson

For the low tec answer

Check out the 4541 after the 555 it's the next most popular timer,
and much better suited to accurate time delays

If accuracy is not as important as power drain then consider a 7555

--
Peter Cousens
spam_OUTp.cousensTakeThisOuTspamcwcom.net

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