Subject:
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Simtek memory
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Newsgroups:
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lugnet.robotics.handyboard
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Date:
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Tue, 23 Mar 1999 17:02:56 GMT
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Original-From:
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Bruce Moore <bamoore@IHATESPAMbloomington.in.us>
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Viewed:
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779 times
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A few weeks ago Duncan Orthner mentioned the Simtek memory chips on the HB
newsgroup. They sounded like a good idea so i tried them. They work very
well.
But..... The HB may need a little modification to make them work rite.
When the HB is powered, they word just like the regular memory. But when
the Simtek chips loose power, memory is dumped from RAM to EEPROM (all in
the memory chip and all automatic). Every time the power comes back up the
EEPROM is dumped back to RAM. Problem is the Simtek chip needs a few
milliseconds between the time the voltage is low enough to cause a mem dump
to EEPROM and the time it looses power comletely. I just put a 10 mF
capacitor accross the plus and minus points that the battery wires connect
to. That seemed to make it happy. One the Simtek data sheet there is a
little more elegant way of doing it with a low voltage drop diode and a cap
accross the power pin to the chip itself. I tried the easy way first.
Now I can completely remove power from the board and memory will still be
there when I plug it back in.
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Message has 1 Reply:
 | | Re: Simtek memory
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| (...) [short snip] Problem is the Simtek chip needs a few (...) Bruce, they *do* work well. I haven't had to add any caps. I just plugged it in and it worked 8^]. And they don't collide with the LCD or exp. board like the Dallas battery backed (...) (26 years ago, 23-Mar-99, to lugnet.robotics.handyboard)
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