There's an internal comparator interrupt hardware in the Atmel chip the Arduino uses. It can be programmed using the IDE as well. Don
Chris Albertson > On Thu, Feb 13, 2014 at 6:36 AM, paul swed <[email protected]> wrote: >> Lars has done a very good job here and good to see the comments and >> excitement. >> Have to agree with HAL that holdover is far more than a second and I >> am in >> a good location with the GPS antenna at 90'. I see my 3801 go into >> holdover >> occasionally and its not seconds. >> >> Cheapest tinker 10 Mhz is a Xtal with a varicap diode in circuit to >> adjust >> frequency. >> Sub $ 5 I would guess. >> >> I was intrigued by the Arduino also and then went looking for >> information. >> Just about drowned in whats out there and pricing for the chip is from >> 99 >> cents to $5. > > You will need one of the larger chips for this. Closer to $5 than 0.99 > >> What bootloader X Y or Z. I like the pure chip 28 pin approach and do >> appreciate that this won't be H maser accurate. > > The "boot loader" is built into the Arduino IDE. It's a pull down > from the Tools > menu. Just select "Tools->Burn Bootloader" and it works. But you > should never > have to do this. All Arduinos ship with a bot loader and preloaded > example > program to blink an LED. > > Don't let at the information of the Internet about this overload you. > All you > need to know, can be found from the "help" menu item. > > If you remove all of Lars' data logging and mode setting (debug) stuff > this is a > very short and simple bit of software. > >> Looked at the schematic and would appreciate a more complete picture. > > There are only two ICs and he does not use even half > of the pins. I doubt that it is critical that you even use the same > divider chip. > He does leave out the details about th switches on lines A1..A5. You > can see where thet > are read and what is done with the data but it would be nice to see a > schematic. > > There is certain;y enough information posted to get one of these > working. > > My plan is to build one and make changes one step at a time. As I said > there is enough information to do that. > > >>> >>> [Context is cheap VCXO] >>> >>> > When used inside a GPSDO it only has to "hold over" for one second >>> until >>> the >>> > next correction. >>> >>> Only if you have a good antenna and/or antenna location. > > I'll use whatever is in the "junk box" for initial testing, then later > the Rb oscillator. > -- > > Chris Albertson > Redondo Beach, California > _______________________________________________ > time-nuts mailing list -- [email protected] > To unsubscribe, go to > https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > and follow the instructions there. > > -- "The power of accurate observation is commonly called cynicism by those who have not got it." -George Bernard Shaw Dr. Don Latham AJ7LL Six Mile Systems LLC 17850 Six Mile Road POB 134 Huson, MT, 59846 VOX 406-626-4304 Skype: buffler2 www.lightningforensics.com www.sixmilesystems.com _______________________________________________ time-nuts mailing list -- [email protected] To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
