[Techtoolslist] Sunday Projects II: Replacing a DS1216B RealTimeClock?

[Jess Askey]

Yes, you are right about the 'standby' mode. I ordered a replacement one from Ebay since it was only $16. I will be doing the mod below so that I can also use a stock replacement, but I have a feeling that my mod will be done before the DS2016B arrives from China... two weeks.

I also dug into my 1216B chip too..  pictures here - http://www.askey.org/fluke_900_rtc/

I didn't get a pic before I started destroying it... but here it is with the 6264 RAM off and the socket popped off the top, AND the DS1216 removed.... it is a DIP but the pins are bent out and it is surface mounted... it came off pretty easily.

http://www.askey.org/fluke_900_rtc/20160515_231039.jpg

All of the pins go straight through to the 6264 with the exception of 3...

Pin 20 - /CE - This allows the DS1216 to talk to the CPU 'in place of the RAM' when appropriate by not enabling the RAM when it wants to put data on the D0 bit (the RTC communicates via a single bit)
Pin 26 - CE2 - This is joined to Pin 28 and functions the same, on a 6264, this is set to VCC, so it doesn't effect anything since it is essentially HIGH all the time.
Pin 28 - Vcc - This is the Vcc of the RAM.... the DS1216 either passes the PCB Vcc through to the RAM, or if the Vcc falls below Vbb (Battery), then it puts the Vbb voltage on here, the RTC powers the RAM making it non-volitile as a feature. It of course, also provides the 'phantom' real time clock function too

In this unit, Fluke was nice enough to give a modification grid....

So, I added a CR2032 battery holder and the DS1216 off the PCB....

http://www.askey.org/fluke_900_rtc/20160515_231626.jpg

You can see in the pic..

Blue area - The original 6264 SRAM sitting in a regular socket
Orange area - The new battery socket and the DS1216 in a socket.

I will need to wire this up and pull the 3 pins of the 6264 SRAM out of the PCB socket and over to the DS1216, then wire a few other lines over to the DS1216, and Voila, I *think* it will work.  I'll report back after I get some time later this week to work on it again.

The DS2016 datasheet is readily available on the interwebs and has some interesting information about the 'phantom' access methods for the RTC.



-----Original Message-----
From: Techtoolslist [mailto:techtoolslist-bounces at flippers.com] On Behalf Of Dave Riddle (Technical Dept.)
Sent: Monday, May 16, 2016 8:08 AM
To: Technical Tools Mail List <techtoolslist at flippers.com>
Subject: Re: [Techtoolslist] Sunday Projects II: Replacing a DS1216B RealTimeClock?

If I recall correctly...the DS SmartWatch chips were shipped in a standby mode until the first READ or some other function.  Just maybe, NOS parts still have juice.  Hope so because I too have some stock from the '80's!  BTW if the device is powered, the battery is not spent.


On 5/15/2016 10:14 PM, Jess Askey wrote:
> Heya.... It has been a busy day for me... one more posting before Game of Thrones comes on.....
>
> I have a DS1216B 'SmartWatch' by Dallas/Maxim in my Fluke 900.... These are little real-time-clock IC's with embedded in double height potted 28-DIP that sits under your RAM. In this case, the battery is in the potted bottom part of the socket and is now officially dead, rendering the IC useless for keeping time.
>
>

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