>-----Original Message-----
>From: piclist-bounces@mit.edu [mailto:piclist-bounces@mit.edu] 
>Sent: 23 June 2005 15:48
>To: Microcontroller discussion list - Public.
>Subject: Re: [PIC] Simple pseudo random code generation
>
>
>> I am trying to generate some pseudo random code to add
>> some randomness for the pulse generation.
>
>Some time last week I was thinking about randomness and such 
>and I came up with an idea. I haven't had time to research it, 
>but I do find it intriguing. What if you took two separate 
>oscillators (possibly drifty RC oscillators with widely 
>different tempcos) and fed them into a shift register -one as 
>data the other as clock. Since they're not directly related to 
>each other, their relative phase will continually drift - 
>producing a continuous stream of uncertainty on the shift 
>register.

The relative frequencies of the two oscillators will have a constant frequency difference in the short term so the output bit stream will be very predictable and most unrandom IMHO.

The BE junction of a bipolar transistor in reverse breakdown is a strong noise generator that has been traditionaly used as a RNG.

Regards

Mike

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