DS1644 in the 32k expansion

Talk about your Micro-KIM

DS1644 in the 32k expansion

Postby jsissom » May Sun 23, 2010 2:53 pm

Has anyone tried to use a DS1644 in the 32k expansion board in place of the 62256 32K static ram? The DS1644 is a 32K static ram/real-time clock with a built in battery to keep the RAM set and clock running with the device powered off. It would be very handy to have that storage that is there between uses.

The only difference I can see between the DS1644 and the 62256 is the pinout of the address lines. It wouldn't be too difficult to wire this into the circuit after changing those address lines.

Here is the data sheet for the DS1644:

http://datasheets.maxim-ic.com/en/ds/DS1644-DS1644P.pdf

Here is the data sheet for the CY62256:

http://ecee.colorado.edu/~mcclurel/Cypr ... Y62256.pdf

Has anyone done anything similar? I may try it.

Thanks
Jay
jsissom
 
Posts: 66
Joined: May Tue 04, 2010 9:52 pm

Re: DS1644 in the 32k expansion

Postby rwiker » May Thu 27, 2010 2:36 am

From what I can see, the only difference is the assignment of address pins. Since this is a RAM chip, it does not in fact matter if these do not match the pinout of the original RAM chip.

Note that it's actually the RAM chip that has a non-standard pinout; other 256kb RAM chips and EPROM chips I've looked at have the same address pin assignment as the DS device.
rwiker
 
Posts: 11
Joined: Apr Mon 12, 2010 4:06 pm

Re: DS1644 in the 32k expansion

Postby jsissom » May Thu 27, 2010 7:36 pm

Normally the address lines of RAM wouldn't matter, but in the case of this device, the last 8 bytes of RAM are mapped to the real time clock. It wouldn't be good if these are randomly placed throughout the 32K. I'll build an adapter to make this work. But I'll check to see how the address lines on the 32K expansion board are wired up first. If they are wired in the standard way, the DS chip should drop right in.

Thanks
Jay
jsissom
 
Posts: 66
Joined: May Tue 04, 2010 9:52 pm


Return to Micro-KIM General Discussion

Who is online

Users browsing this forum: No registered users and 1 guest