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Dallas Smartwatch replacement - Tain't purty but, it works

G

Gazza

Experienced Member
Joined
Jun 27, 2013
Messages
151
Location
Sydney, OZ
G'day all
After 24 years of faithful service the batteries on my Dallas SmartWatch finally dropped off the perch and rather than try my luck with one from Ebay I decided to have a go at building my own. The slow boat from China has finally made it downunder with the bits, all up cost approx $10
Plugged it into the 4P and the computer booted as normal, no smoke.
Smokekit2.jpg

The software found the clock no probs. Wipes sweat from brow.
Switched it off for 1/2 hour and it rebooted with the correct date and time. Wipes more sweat from brow.

Apart from only having one battery (the DS1216E has 2) this version is pin for pin the same as the DS1216E - I think.
With the original encased in resin tis a bit of guess work on how it all goes together.

For V.2, I may make a few minor changes that should simplify the circuit and make assembly a bit easier.
An SMD version with a smaller battery would be better.

So whos up for designing and etching a PCB?
It's been over 20 years since I did any PCB work and that was using Bishop Graphics. Remember them?
Maybe a 24 pin TRS-80 version that can be switched between 2732 and 2532 pinouts or one that will fit under the Hi-res board of a 4P.

Tain't all roses, the clock is gaining about 10 seconds a day. I'm thinking I may have been sent the wrong crystals. Data sheet says 6pf, invoice says 6pf. According to the data sheet a 12pf will cause it to gain 4 or 5 minutes a month.
More testing (beer) to be done.
cheers
Gazza

Version 1 of the (as ruff as) SmartWatch
SmartWatch V1 copy.jpg
 
Very nice work! The Lucas Service Part 'smoke' is too funny! (Wasn't so funny when I lost some of the Lucas magic smoke years ago entering the freeway...) Hey, maybe THAT'S what the 'cloud' is really made from - burning Lucas controls!
:p

Keep up the excellent work on the ol' 4's!
-Rich
 
pcmedix said:
Very nice work! The Lucas Service Part 'smoke' is too funny! (Wasn't so funny when I lost some of the Lucas magic smoke years ago entering the freeway...) Hey, maybe THAT'S what the 'cloud' is really made from - burning Lucas controls!
:p

Keep up the excellent work on the ol' 4's!
-Rich
Click to expand...

Lol, that pic has been a running joke on the MG forums. I've been dodging the prince of darkness for over 35 years. He has only caught me once.:drive:
Ray (Audronic) suggested we make one for the RIFA caps in the TRS-80 power supplies. :boom:
cheers
Gazza
 
pearce_jj said:
If the parts are available I can run this PCB no problem whatsoever.
Click to expand...

Thanks James, should have V2.0 finished tomorrow. An SMD version whenever!!
Building this on Vero board is a major PITA, not helped by the lack of space and the fact that not all pins are straight through.
How about a Lo-tech version or incorporating it into the IDE adapter?

BTW - a 10pf across the crystal has got it running to spec - just.
cheers
Gazza
 
Could be done. A multifunction is probably my next project :)

Re SMT, are these chips available? I searched the usual outlets and only found a few DIP parts on eBay.
 
griffk said:
Has anybody looked at what it would take to do this with a PIC uC?

I bet sourcing the parts would be MUCH simpler?

PS: NICE job of stuffing that in a 28DIP!!!!
Click to expand...

It's a tight fit and a bit of a rats nest on the other side but it works and it runs with Duane Saylor's original software.
cheers
Gazza
 
Agent Orange said:
A thing of beauty! What did you use to take it apart?
Click to expand...

Not a hope of getting the original apart, I just used the 1216 data sheet and a multimeter to nut it out.
Hoping James or someone can design and build a PCB. A TRS-80 compatible 24 pin version would be nice.
A copy of the schematics freely available to anyone that wants them.
Cheers
Gazza
 
Yup. And who knows how old they (and thus, their non-replaceable batteries) are?

Even the DS1315 chips that one could use to make their own DS1216 with a fresh, replaceable battery, cost $16-$20 at single quantity. I don't like using Maxim parts in my designs, anyway. They have a wonderful catalog, but when they run out of a part, they won't make more until the whole new wafer lot is already sold. Thus, unless you're going into production at a large enough scale to buy entire wafer lots, you're entirely at their mercy about whether you can actually buy the part or not. Enough engineers have gotten bitten by that, that many (including me) will not even consider designing any Maxim part into a device.

I'd say that the only reason that there are any DS1315 chips available is that the last batch hasn't drained out of distributor reserves yet, and I highly doubt that they'll ever start a new lot of such an old part.
 
pearce_jj said:
Just spotted these on Farnell - DS1216, is that the original device?
Click to expand...

Same thing only different. The one that everyone has been using is the DS1216E
According to Maxim they are now NA. Not sure when Maxim discontinued production.
http://www.maximintegrated.com/en/products/digital/real-time-clocks/DS1216E.html/tb_tab3

Mouser, Digikey and the local RS show zero stock and the local Element14 has no stock of the DS1216E and wants an arm and a leg for the other versions.

I got the DS1215 from China and was able to build the proto for about $10. The slow boat from China must have hit a head wind, took nearly a month to make it downunder.

Just got off the phone with a mate that has contacts in Shenzhen, hoping we can get the DS1215 or DS1315 at a cheaper price - maybe!
 
Things move slowly in Gazzaland but I've finally got around to building my first Smartwatch replacement.
It's been over 25 years since I've done any PCB design and that was using Bishop Graphics - yes, I'm old. This is the first time I have designed a board using a computer so I was a bit worried I may have made a mess of it.
Sent the gerbers to PCBWAY in China and they have done a good job, even corrected a couple of minor mistakes in my layout.

I tried the board with some cheap no-name crystals from China and the RTC was running way fast, so I grabbed a selection of crystals from the local Element14 and I'm now testing them.
Initial results look good with the clock running well within factory specs.

My 4P has a homemade 28 pin adapter board so this Smartwatch is plug and play in that computer. If all goes to plan I have designed two 24 pin versions that will allow the use of either a 2532 or 2732 and these should also be P&P in my other unmolested 4P.

more research (beer) required.
cheers
Gazza

SW28PinV2-1.jpg
 
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