AVR-Chat

Look for ceramic resonators with built in capacitors (three terminal
devices) at digikey.  They work pretty well.

It seems with a little thought that the pulses could be discriminated using
the internal oscillator.  Use the first pulse to "calibrate" the clock with
upper and lower bounds for "valid" and then use the calibrated values to
measure the remaining pulse on/off periods.  The internal oscillator will be
extremely stable over a couple second period.  


| -----Original Message-----
| From: AVR-Chat@yahoogroups.com [mailto:AVR-Chat@yahoogroups.com] On Behalf
| Of Richard Cooke
| Sent: Tuesday, September 12, 2006 1:46 PM
| To: AVR-Chat@yahoogroups.com
| Subject: [QUARANTINE] [AVR-Chat] Re: Help with Attiny project
| Importance: Low
| 
| Thanks for the info.  I've looked at the ATtiny13 datasheet and I'm a
| bit confused on how you'd connect an external crystal.  On the
| Attiny11 and 12 you sacrifice 2 pins to use the crystal (PB3 & PB4).
| How does that connect to the '13?  I haven't used a ceramic resonator
| before - can I just connect it to PB3?  Does it require any additional
| components?  Sorry all of the bacic questions but it's been awhile
| since I've done work on such small parts.
| 
| Thanks,
| 
| Richard
| 
| --- In AVR-Chat@yahoogroups.com, "David VanHorn" <microbrix@...> wrote:
| >
| > The internal timer isn't that accurate over temperature.
| >
| > You might be able to get away with something like this:
| >
| > Sit in a loop, waiting for something.
| > Pulse detected.
| > Wait about 3/4 of the delay, a pulse in here fails.
| > Wait about 1/2 the delay, no-pulse in here fails.
| > Resync on each detected pulse, and then be pretty tolerant about
| when pulses
| > can come in.
| >
| > Otherwise, a resonator or crystal is a better bet.
| >
| >
| > [Non-text portions of this message have been removed]
| >
| 
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