Forrest,

I used an external noise source to make a true RNG for a
gaming machine that needed a number from 1 - 100,000

http://home.clear.net.nz/pages/joecolquitt/white_noise.html

but for 1 - 6 and a long time base you should be able to get
one fairly easily with just the PICs. Three analogue sources
spring to mind - WDT, IntOsc and ADC. A combination of
any two would probably do

Part of my method was to run a timer for the period between
two noise transitions. A figure obtained from that was the
number of noise transitions to count, in conjunction with another
timer

As WDT is affected by temperature and fluctuates slightly you
might try gating a timer with it or timing it with high resolution
(a method used to make a PIC thermometer) and taking the
3 LSBs. You can bias it so that the same number isn't picked
twice in a row

Even simple PRNGs can be quite good although anything with
no unpredictable analogue input will display some very long-term
repeatability

Joe
--=20
http://www.piclist.com PIC/SX FAQ & list archive
View/change your membership options at
http://mailman.mit.edu/mailman/listinfo/piclist
.