I did some research on this for my Computer Organization course, where for
a project my students work on simple games using PICs. The best resource I
found is the ORB:

http://home.comcast.net/~orb/index.html

You can get some great ideas from the details page:

http://home.comcast.net/~orb/details.html

BAJ

On Fri, Oct 28, 2011 at 01:31:48AM -0600, Forrest Christian wrote:
> For an open house/demo for our new Pick and Place, we're using up some=20
> PIC18f26J11's and PIC18f26K22's, both in the (same) wrong package, to=20
> make a pair of 'digital dice'.  Basically 14 LED's arranged into the=20
> pattern of two dice, appropriate current limiting resistors, attached to=
=20
> high-current output PIC pins, and a pair of AA's to power the whole=20
> thing, along with a pushbutton hooked to MCLR to re-roll the dice.
>=20
> Simple algorithm:  Wake up, generate a random number, display on dice=20
> (probably with some simulated rolling), and then wait 30 or so seconds,=20
> then drop into SLEEP mode, or deep sleep if supported on that processor.
>=20
> Problem being:   I really want to use MCLR to reset this so I can use=20
> deep sleep.   AND... because I'm starting from the same state every time=
=20
> the unit wakes up, I need an entropy source to seed a random number=20
> generator.
>=20
> My initial thought is to just sample the LSB of a hundred or so ADC=20
> conversions from an unconnected ADC input, or maybe count the clock=20
> ticks in a few cycles of the internal 32K RC oscillator.   or something=20
> like that.   All seem workable, and I'll try a few of them... but was=20
> also hopeful that someone on the list had had to do something similar=20
> and knew what would or wouldn't work so I didn't have to reinvent the=20
> wheel in this case.
>=20
> Mainly I need enough bits to get a reasonably random distribution for a=20
> number between 1 and 32 (I.E I need 5 'good' random bits, which are=20
> fairly random.   Of course, more is better).
>=20
> -forrest
> --=20
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--=20
Byron A. Jeff
Department Chair: IT/CS/CNET
College of Information and Mathematical Sciences
Clayton State University
http://cims.clayton.edu/bjeff
--=20
http://www.piclist.com PIC/SX FAQ & list archive
View/change your membership options at
http://mailman.mit.edu/mailman/listinfo/piclist
.