RE: [AVR-Chat] Second Generating
2006-09-25 by Tzif
Hi Zack is right I make GPS and the reference of the GPS should be very accurate Therefor we are using an OCXO at 10 MHz frequency. And as Zack said from the 10 MHz we divide it and make the clock that we want. You can look at the Gollage OCXOs they are pretty good. Tzif
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From: Zack Widup [mailto:w9sz@prairienet.org] Sent: Monday, September 25, 2006 2:56 PM To: AVR-Chat@yahoogroups.com Subject: Re: [AVR-Chat] Second Generating On Mon, 25 Sep 2006, Ralph Hilton wrote: > On Mon, 25 Sep 2006 10:08:28 -0000 you wrote: > > >Hi guys, > > > >I hope every thing is going OK. > >I`ve question hoping somebody could provide me what I have to do. > >How can I generate one second accurately to be applied Digital > >Clock ? by the way, I`ve tried by Timer/Counter0 , T/C Prescaler , > >Timer0 ovf0 (Int. Calling) but I didn`t get a real second . > > > > > > > >Plz help as soon as possible . > > If you are using a crystal then there should be no problem getting a second by > dividing down with a timer. If you are using the internal RC then you can't get an > accurate second due to its lack of stability. > -- > Ralph Hilton You can also use an external crystal oscillator with a trimmer cap for frequency adjustment. I've used a 10 MHz oscillator which I zero-beat with WWV here. If you have a known frequency standard like a rubidium standard handy, you can hook a scope up to the two outputs and adjust by Lissajous figures. You can find 10 MHz OCXO's on eBay for $20 to $80. I don't know how desperately you need the accuracy; that may be overkill. The simpler solution would be to use the 1 pps output of a GPS engine, or use the 10 kHz output and divide it down. Zack ************************************************************************************************** [Non-text portions of this message have been removed]