Objective Development Forums

So I'm assuming it would work out for the 12.8 MHz and 16.5MHz code variants, since they have a higher clock tolerance, but I was wondering if anyone has actually had experience implementing V-USB using a ceramic resonator as a clock source? I'm trying to use the smallest/cheapest parts possible for my designs. Right now, I'm definitely not, using a full blown clock instead of a crystal and capacitor setup, but I figured, if I'm going to switch clock sources, why not just go for the cheap, easy resonator option... I'm sorry I've been unable to try it myself, but I'm in Japan right now, and while they do have fantastic electronics shops (it's like a walk-in DigiKey; circuit-geek HEAVEN), resonators have been rare, and I can't find a 12.8 or 16.5 MHz in Osaka OR Tokyo...

Oh, and apparently, I can't find one on DigiKey or Mouser... Do cheap resonators simply not exist at these frequencies? If you have used a resonator, where did you find one?

Thanks for any input!

(P.S.Also, if you read this, Christian, what drove the decision to choose the 12.8 MHz and 16.5MHz frequencies? Are those just the capabilities of the ATTiny chips? Just curious...)

Alan Chatham wrote:Do cheap resonators simply not exist at these frequencies? If you have used a resonator, where did you find one?

Yes, they do. Check, for example http://www.geyer-electronic.de, they have ceramic resonators up to 50 MHz.
BTW, their manufacturing facilities are located in Japan...

I never used ceramic resonators because the price difference compared to that of CPU and PCB is too small. ($0.1 vs $0.15 from a local
supplier in Russia.) If you are buying from Digikey, you also paying for delivery. I think that it makes no sense to use ceramic resonators.

Alan Chatham wrote:I'm in Japan right now, and while they do have fantastic electronics shops (it's like a walk-in DigiKey; circuit-geek HEAVEN), resonators have been rare, and I can't find a 12.8 or 16.5 MHz in Osaka OR Tokyo...

IMO, there are no perfect suppliers. It can look strange, but some parts are easier to find in Russia, some are easier to find in US,
regardless of where they are manufactured.

We use resonators Murata - compact, but not cheap. The admissible error - 0,5 %, but happens and more.
Model - CSTCE12M0G55-R0

What's the advantage of using a resonator? You'd need 12.8 or 16.5 MHz due to the tolerance. If the point is price, use the internal RC oscillator at these rates. That's even cheaper. Otherwise use a cheap crystal at 12 or 16 MHz.