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Author Topic: How do I connect a oscillator to an AVR  (Read 3361 times)

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Offline TrickyNekroTopic starter

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How do I connect a oscillator to an AVR
« on: August 26, 2008, 07:00:53 AM »
Hello guys...

This one is simple... How do I connect an oscillator to an AVR?
like this one:


I think it's the XTAL1 which gets the signal and XTAL2 is to ground right?

Not that it's so needed but if I can avoid multi - crystals on board it would be good enough...

Are they better than crystals? not that I care much but asking...
Gotta a though it's kinda the same...
For whom the interrupts toll...


P.S. I've been inactive for almost a year... Don't give promises but I'll try to complete my tutorials. I'll let you know when..

Cheers!

Offline frank26080115

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Re: How do I connect a oscillator to an AVR
« Reply #1 on: August 27, 2008, 12:04:06 AM »
XTAL2 is not connected, other than that, there's no reason not

Comparing these to HC-49 crystals, it's space vs part count, since you need two capacitors if you use the HC-49 kind.

The AVR has to amplify the clock signal if you use the smaller variety, I'm not sure how much extra current is needed but it's probably negligible.

Offline TrickyNekroTopic starter

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Re: How do I connect a oscillator to an AVR
« Reply #2 on: August 27, 2008, 03:12:39 AM »
nice!

Thank you!!!

But what do you mean by amplifying.... how?
And can I use it for more than on microcontroller?

Best Regards,
Lefteris
For whom the interrupts toll...


P.S. I've been inactive for almost a year... Don't give promises but I'll try to complete my tutorials. I'll let you know when..

Cheers!

Offline airman00

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Re: How do I connect a oscillator to an AVR
« Reply #3 on: August 27, 2008, 10:49:52 AM »
But what do you mean by amplifying.... how?
And can I use it for more than on microcontroller?

I dunno what you mean by amplifying , all these XTALs require is capacitors next to them. Google around and you'll see sample schematics.

And you can share XTAL i believe.
Check out the Roboduino, Arduino-compatible board!


Link: http://curiousinventor.com/kits/roboduino

www.Narobo.com

Offline frank26080115

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Re: How do I connect a oscillator to an AVR
« Reply #4 on: August 29, 2008, 06:24:08 PM »
from the atmega168 datasheet

Quote
Pins XTAL1 and XTAL2 are input and output, respectively, of an inverting amplifier which can be
configured for use as an On-chip Oscillator, as shown in Figure 8-2. Either a quartz crystal or a
ceramic resonator may be used.
This Crystal Oscillator is a low power oscillator, with reduced voltage swing on the XTAL2 out-
put. It gives the lowest power consumption, but is not capable of driving other clock inputs, and
may be more susceptible to noise in noisy environments. In these cases, refer to the “Full Swing
Crystal Oscillator” on page 32.

Offline TrickyNekroTopic starter

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Re: How do I connect a oscillator to an AVR
« Reply #5 on: August 30, 2008, 06:23:18 AM »
I see...
So I'll stay to crystals... nice, thank you

Best Regards, Lefteris
For whom the interrupts toll...


P.S. I've been inactive for almost a year... Don't give promises but I'll try to complete my tutorials. I'll let you know when..

Cheers!

Offline Admin

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Re: How do I connect a oscillator to an AVR
« Reply #6 on: September 04, 2008, 07:02:21 PM »
Look at my Axon schematic, you will see an xtal hooked up with caps.

 


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