Those Ibuttons look pretty awesome, I'd never seen them before.  I wonder
what it would take to convert all my doorlocks to use one of those NV-RAM
types... ;-)

Back on topic, I suppose it could be interfaced to a PIC in the door-lock
and each have an algorithm to reprogram the current acceptable access code
every time it's used.  e.g. start out syncing some random number in the
ibutton and the PIC as the "unlock" code, then each time add C1 and OR the
result with a multiple of the old ID.  No clue how to work it if you wanted
more than one key...

At $5 each it's almost worth ordering a few to play with!



----- Original Message -----
From: "Engineering Info" <engineering-info@EARTHLINK.NET>
To: <PICLIST@MITVMA.MIT.EDU>
Sent: Wednesday, August 04, 2004 10:13 PM
Subject: Re: [PIC:] Getting started


> It would use parisitic power.  In fact, you wouldn't even need a
> seperate line for clock and data.  You could put Power, Clock, and Data
> all on the same pin.  Look at the Dallas I-buttons
> (http://www.ibutton.com/).  They have been doing this for year.
>
> Robert B. wrote:
>
> >Salvation!  Could you really do that?  I would've thought the device
needs
> >power to read a clock pulse, but apparently not!  If I could get an
adequate
> >supply of TO-92 PICs, I just might be able to take over the world...
> >
> >----- Original Message -----
> >From: "Engineering Info" <engineering-info@EARTHLINK.NET>
> >To: <PICLIST@MITVMA.MIT.EDU>
> >Sent: Wednesday, August 04, 2004 9:44 PM
> >Subject: Re: [PIC:] Getting started
> >
> >
> >
> >
> >>Actually you can double up power and clock on the same pin.
> >>
> >>Robert B. wrote:
> >>
> >>
> >>
> >>>It would need at least 4 pins... clock and data for programming, plus
> >>>power/ground.  So I guess you'd be stuck with two IO's instead.  ugh...
> >>>that's twice as much to program!
> >>>
> >>>
> >>>----- Original Message -----
> >>>From: "Engineering Info" <engineering-info@EARTHLINK.NET>
> >>>To: <PICLIST@MITVMA.MIT.EDU>
> >>>Sent: Wednesday, August 04, 2004 9:24 PM
> >>>Subject: Re: [PIC:] Getting started
> >>>
> >>>
> >>>
> >>>
> >>>
> >>>
> >>>>I'm still waiting for them to come out with an SOT-23 or TO-92 model
> >>>>(power, ground, and 1 I/O).
> >>>>
> >>>>Wouter van Ooijen wrote:
> >>>>
> >>>>
> >>>>
> >>>>
> >>>>
> >>>>>>8 pin: 12F675
> >>>>>>18 pin: 16F88
> >>>>>>28 pin: 16F876A
> >>>>>>40 pin: 16F877A
> >>>>>>
> >>>>>>
> >>>>>>
> >>>>>>
> >>>>>>
> >>>>>>
> >>>>>Microchip does not leave you in peace: there are also 14-pin, >40
pin,
> >>>>>and almost-there 6 pin chips!
> >>>>>
> >>>>>Wouter van Ooijen
> >>>>>
> >>>>>-- -------------------------------------------
> >>>>>Van Ooijen Technische Informatica: www.voti.nl
> >>>>>consultancy, development, PICmicro products
> >>>>>
> >>>>>--
> >>>>>http://www.piclist.com hint: PICList Posts must start with ONE topic:
> >>>>>[PIC]:,[SX]:,[AVR]: ->uP ONLY! [EE]:,[OT]: ->Other [BUY]:,[AD]: ->Ads
> >>>>>
> >>>>>
> >>>>>
> >>>>>
> >>>>>
> >>>>>
> >>>>>
> >>>>--
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> >>>>[PIC]:,[SX]:,[AVR]: ->uP ONLY! [EE]:,[OT]: ->Other [BUY]:,[AD]: ->Ads
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> >>>
> >>>
> >>>
> >>>
> >>--
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> >>
> >>
> >
> >--
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>
> --
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