pcmhacking.net

love it
there is somthing about homebrew tight ass stuff like this that gets mw all warm and fuzzy

Just though I'd post it up here I got one of these of festy and it works a treat. The only little thing is it doesn't fit in a standard Memcal box but can be easily made to fit by hammering down the dimples so there flat.

Glad to hear you're back up and running.
I'll have some lower profile boards ready soon, so they should fit without any panel beating

With the external power VBAT 1 or 2 pins maybe use a 12v to 3V regulator or similar. since there is a live battery wire there pin B11 i think, tag a wire onto the live battery wire into the Regulator then to the circuit board. and add a diode to the onboard battery??? that way if onboard battery dies it still has power??? correct if im wrong

haha slight overkill there, you only need a couple mA because it's only used during standby.
The "Ext" jumper on my board in the pic is for an external 3v supply, the controller chip uses either the on-board or external supply depending on which is higher voltage - so you could directly connect a 3v regulated supply to those pins.
But the on-board battery has enough capacity to keep the SRAM going (in typical use) for longer than the useful life of the battery anyway.
That is, the cell is likely to chemically fail from old age before it goes flat.

Just for reference purposes, I have a powercap module style DS1245Y here so the chip part numbers are easy to get. It has a DS13D12 and a CY62128ELL-45 and a Panasonic BR1632A

The DS1312 is designed for use with a replaceable battery (as opposed to a potted NVRAM module) - it has an internal current shunt which it uses to monitor the battery and a "replace battery soon" pin which would make it very handy for a DIY NVRAM... but they cost about $20 each, which kind of defeats the purpose of homebrewing

Are these still available?

festy wrote:The DS1312 is designed for use with a replaceable battery (as opposed to a potted NVRAM module) - it has an internal current shunt which it uses to monitor the battery and a "replace battery soon" pin which would make it very handy for a DIY NVRAM... but they cost about $20 each, which kind of defeats the purpose of homebrewing

Hi festy,

Just out of curiosity, do you know what's the difference between a DS13D12 and a DS1312? (I can't find any datasheet for the former.)

Joe.

Festy Do you still have any for sale?