AVR-Chat

I would use a frequency measurement device. We own a HP Meter that measures
frequency and voltage. Also a Fluke Frequency meter. You could only look at
general accuracy with scope. You could verify it is aprox. Correct but not
accurate enough to use for real time. If you did not own any of these I
suppose you could time and count and compare something after a reasonable
passage of time. You might use and LCD display and post the passage of time.
You could check this against a watch but this is just a close home brew way
of doing it. The frequency meter is the best way to go. It really depends on
what you need. How accurate does it need to be. If the time of day or
accurate time measurement is not important then all you care about is that
it runs reliably.

That's my two cents worth.

Al Welch 


-----Original Message-----
From: nangkon [mailto:nangkon@yahoo.com] 
Sent: Thursday, November 20, 2003 7:48 PM
To: AVR-Chat@yahoogroups.com

Thanks for the info!

Is there an instrument (maybe Oscilloscope) to measure if the cap/crystal
combination is ok? And what should I measure (frequency)?

I really want to learn this so that I can apply the same technique for other
scenario or for other chips.

Anyone can point me to tutorial or web page how to use cap in general. I can
understand resistor, but cap usage is still like a black magic to me when I
look at different schematics.

thanks



--- In AVR-Chat@yahoogroups.com, Mike Harrison <mike@w...> wrote:
> On Thu, 20 Nov 2003 19:44:59 -0000, you wrote:
> 
> >I saw a lot of schematics that use 2 capacitors with crystal that is 
> >connected to XTAL. Is there a way to determine the appropriate values 
> >of capacitors?
> >
> >Do I need to use some equipments to do that? Or is there a general 
> >rule somewhere?
> >
> >thanks in advance
> 
> 27pf will be OK in most cases


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