[Coco] Clock chips-- DS1307 today

[Robert Gault]

George Ramsower wrote:
><snip>
> I'll be dipped. I couldn't remember what the number was. So that's why I looked
> just for the Smartwatch.
> I have two in service now but, the batteries are dead or too low to run them
> between uses/power off. So I have to set them at each startup of those cocos.
> This is good news and I'm glad you knew this. Now I know what to look for.
> I have some info on converting them to an external battery but I've been afraid
> to tear into one as I might kill it. Now I can do this and not fear getting into
> one or both.
>
> Thanks,
> George R.
>

Well you are in luck! :)

First, the part number is shown on the device itself. If you have an EPROM 
plugged into it, just remove the EPROM and you can read DS1216 on the embedded chip.

As it happens my battery ran dry as well but I found a way to mount an external 
battery. Unfortunately, the pdf file I have on the DS1216 mentions an embedded 
lithium source but not which pins connect to the source or the voltage. Also, 
the 1215pdf, 1315pdf, and an application pdf for the 1315 indicate the 
possibility of two batteries.

Here is what has worked for me with the 1216. There is a notch at one end of the 
chip that indicates pins 1 & 16
    _ _
  1|   |16

I soldered wires to pins/legs 4 & 8. Pin4 was connected to a battery plus and 
pin8 was connected to a battery minus. I used a 3volt lithium CR2450N which I 
think is a common PC battery. As a typical PC clock battery, it seemed like a 
reasonable match for the SmartWatch.
Given the size of the battery (much larger than the 1216 chip), I doubt it will 
wear out any time soon.

Robert