AVR-Chat

Hello,
    Are crystal oscillators as simple to use as crystals with loading caps?  I am having a devil of a time matching crystals with the right loading capacitors, and I thought switching to crystal oscillators might make this part of my life easier.
 
I ordered crystals from Digi-Key that say 20pf load, and when I hooked one up with a 20pf load on each pin, it simply didn't work.
 
Do you think crystal oscillators might solve this problem?
 
 
Regards,
Richard Solomon
troposphere@comcast.net

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> -----Original Message-----
> From: Andromeda_at_Mindspring.com [mailto:andromeda@mindspring.com] 
> Sent: Tuesday, 13 January 2004 1:01 PM
> To: AVR-Chat@yahoogroups.com
> Subject: [AVR-Chat] Crystal Oscillators
> 
> 
> Hello,
>     Are crystal oscillators as simple to use as crystals with 
> loading caps?  I am having a devil of a time matching 
> crystals with the right loading capacitors, and I thought 
> switching to crystal oscillators might make this part of my 
> life easier.
>  
> I ordered crystals from Digi-Key that say 20pf load, and when 
> I hooked one up with a 20pf load on each pin, it simply didn't work.
>  
> Do you think crystal oscillators might solve this problem?
>  

The 20pF specified is the total capacitance including stray capacatance.

So I would start of with a 39pF (I use 33pF as I got a good deal on
1000) in each leg of the crystal :o)

Hope this helps


Regards,

Kat.

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>
>
>The 20pF specified is the total capacitance including stray capacatance.

Right.
The point that most people miss, is that from the crystal's point of view, the caps are in series, so you need twice the spec value, minus the strays. 

But, they do "work" with just about anything. 
They WORK all the time, and on freq with the right values.

At 08:15 PM 1/13/2004 +0100, Daniel Adolfsson wrote:

>Are you sure the fuse bits are properly set? I mean since it didn�t work at all.
>
> I had a hell of a time before I discovered the fuses where setup wrong.

That would do it. <VBG>

The default is to run on the internal RC osc, since it's always there, and that allows you to get up and thinking.