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-----
From: Tony Pan [mailto:weidong.pan@verizon.net]
Sent: Tuesday, August 14, 2001 10:18 AM
To: PICLIST@mitvma.mit.edu
Subject: [PIC]: Generating a "truly" random number on the application of
power


Hi,

In our project, several identical boards are connected together. Normally,
on the application of power, they will be turned on at the same time and
starting running at the same time. But we don't want that to happen. If all
boards are running at the same time, they will consume too much power and
cause a problem.

So, we want to impose a lockout time at the beginning of the software; the
lockout time should be random for each board (though they use the same
software). Only after the lockout time expires would the program start
running. Thus the boards will start at different time and won't cause a
power shortage.

My question is: how to generate a "truly" random number on the application
of power. The number should not be determined upon the compilation of the
software, but should be upon the initial powerup of the chip. (Or, it should
be determine by each individual chip.)

Help?

(By the way, I write my program in C and use PICC compiler.)

Thanks in advance.

Tony Pan

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