We've been selling the ChronoDot for a while over in the macetech store. It's a very accurate realtime clock module with integrated battery, based on the DS3231. It will maintain time within a minute per year, in varying temperatures. Instead of using an external source (GPS, WWVB, internet), it measures the temperature of the internal crystal and switches a bank of capacitors to pull the frequency back to 32KHz.

Our original stock of 100 pieces was getting low, so we decided to order 200 more. However, there were some staff changes at our pcb manufacturer and assembler, and they didn't get the memo that we wanted the header pins soldered on the bottom of the device. I can sort of understand, since the silkscreen does appear on the top of the PCB...but they did make 100 correctly before.
In any case, we got stuck with 200 less-than-ideal modules. You can still put them on a breadboard, but you can't see the handy signal names. Other than that, they work just the same as the original ChronoDot.

We tried to think up a few possible solutions. Desoldering and resoldering the headers would be the obvious solution, but we didn't like the idea of subjecting all the parts to another process. Desoldering can be pretty damaging to a PCB and components.

We tried to use them as snacks during one of our friend Karly's photoshoots, but even though the ChronoDOH is lead-free, model reviews were poor. Some thought it was "too crunchy" and others were concerned that it had "too many calories."

So in the end, it looked like we were stuck with 200 of these unless we could unload them somehow. We decided to drastically cut the price, and give a chance for anyone willing to use a soldering iron to get a really good deal! The ChronoDOH is $7.99 instead of $14.99 for the original ChronoDot.

It's not always going to be this cheap...we just want to get rid of these and have more ChronoDots built with the correct header configuration. And we'll sell those at the original price...we're running a business. So if you want to get a great deal on an extremely accurate RTC module, time is running out. They are selling steadily so far.

Now, keep in mind that if you just want to buy a chip from Digikey, it costs $7.42 plus shipping unless you buy 25 or more, and only comes in surface mount. For a few cents more, the ChronoDOH gives you a PCB with the surface mount chip already soldered, and a lithium battery good for years of timekeeping. It'll work with DS1307 code, which already exists for pretty much any microcontroller out there.

Basically, it's an incredible deal...if you have a project that involves timekeeping, get one now!

Submitted by Garrett on Mon, 10/12/2009 - 00:51.

This is disgusting.

This is disgusting.

This is horrifying.

This is horrifying.

This is an amazing deal and

This is an amazing deal and the header pins being on the "wrong side" is not such a big deal. This is the RTC bargain of the year! It was easy to set up and I now have the most accurate self-contained Arduino-based timer imaginable. The documentation on the wiki is excellent and made it easy to get things working in just a few minutes.

One suggestion/question, would you mind adding another piece of example code showing how to set the time and date on the DS3231?

I found a good example of

I found a good example of setting the time here (different RTC, similar register structure):