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'[PIC]: Generating a "truly" random number on the'
2001\08\16@140228 by Pfaff, John

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Do your boards have serial numbers, and (if so) does the software have
knowledge of that serial number?  If so you could base a startup-delay
on, say, the last digit of the serial number, giving you ten different
delays (just for example).

Tony Pan wrote:
{Quote hidden}

> > {Original Message removed}

2001\08\16@141529 by Tony Pan

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Our boards have serial numbers, but the software has no knowledge of that
serial number unless we add some components onto the board but I don't think
the company wants to do it.

Tony

----- Original Message -----
From: "Pfaff, John" <pfaffspamKILLspamWRITEME.COM>
To: <.....PICLISTKILLspamspam.....MITVMA.MIT.EDU>
Sent: Thursday, August 16, 2001 1:50 PM
Subject: Re: [PIC]: Generating a "truly" random number on the applicationof
power


{Quote hidden}

same
> > time.
> >
> > Tony
> >
> > ----- Original Message -----
> > From: "Dipperstein, Michael" <EraseMEmdippersspam_OUTspamTakeThisOuTHARRIS.COM>
> > To: <PICLISTspamspam_OUTMITVMA.MIT.EDU>
> > Sent: Thursday, August 16, 2001 1:26 PM
> > Subject: Re: [PIC]: Generating a "truly" random number on the
application of
> > power
> >
> > > Why not just delay the application of power to each board?  If you
have a
> > > control pin to spare, you can build a system that where it's the job
of
> > each
> > > board to allow power to flow to the next.
> > >
> > > In any random number scheme, you still have the possibility that all
> > generators
> > > will generate the same number and come up at the same time.  This
can't
> > happen
> > > when it's the job of one board to apply power to the next.
> > >
> > > -Mike
> > >
> > >
> > > {Original Message removed}

2001\08\21@114426 by Mike Maiorana

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Perhaps you could put a low frequency oscillator on each board, triangle
wave at let's say 20 Hz. The oscillators can be analog, free running and
start when power is applied to the board. When the micro comes up,
sample the instantaneous voltage with one of the a/d channels (assuming
you have one). The tolerance in the oscillator parts should give enough
randomness to the frequencies that your initial reading numbers should
be quite random.
Just a thought...
Regards,
Mike M.



> Maybe you could buy good resistors of varying values and mix your own random
> selection by dumping them in a barrel and shaking them up.

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