question regarding random number generator

Questions:

1. Should this block be synthesisable?

2. How "random" does it need to be?

I ask these questions because:

1. VHDL has a random number generator, but it is not synthesisable and only meant for testbenches

2. Have you looked into a LFSR? http://en.wikipedia.org/wiki/lfs with this you can create a pseudo random sequence. This would be the easiest logic solution. I have heard of others before but they often involve rlocs and require good knowledge on oscilators. One solution (i havent done it, but had it described) is to route a clock though some logic as far apart as possible. Then sample the clock at a given rate, to try and give a random bit (it was described to me a long time ago, so I may have some details wrong).

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Questions:

1. Should this block be synthesisable?

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no just testing

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Questions:

2. How "random" does it need to be?

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i want to generate 36 output values with only 1 input

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Questions:

I ask these questions because:

1. VHDL has a random number generator, but it is not synthesisable and only meant for testbenches

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would plz tell me about it, and if it take range or not??

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Questions:

2. Have you looked into a LFSR? http://en.wikipedia.org/wiki/lfs with this you can create a pseudo random sequence. This would be the easiest logic solution. I have heard of others before but they often involve rlocs and require good knowledge on oscilators. One solution (i havent done it, but had it described) is to route a clock though some logic as far apart as possible. Then sample the clock at a given rate, to try and give a random bit (it was described to me a long time ago, so I may have some details wrong).

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the work arround i did was similar to LFSR..

execuse me, i couldn't get the rest of this..

thanks,

Niveen

Per Tricky's comments, if an LFSR is sufficient, there is a tutorial and code here:

http://www.ovro.caltech.edu/~dwh/correlator/pdf/lfsr_tutorial.pdf

http://www.ovro.caltech.edu/~dwh/correlator/pdf/lfsr_tutorial_src.zip

You would need to decide whether you want uniform or Gaussian(-like) noise, and then just scale it to the numeric range you describe above.

Cheers,

Dave

There's a synthesizable random number generator using an inverter chain in the Altera cookbook: http://www.altera.com/literature/manual/stx_cookbook.pdf

See chapter 14

Thanks alot Dave for the tutorial.. :)

whenever i try to post any "reply with quote" it dissapear once i click "post".. any idea why does this happen

thanks,

Niveen..

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whenever i try to post any "reply with quote" it dissapear once i click "post".. any idea why does this happen

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Works fine for me - WinXP + Firefox.

Cheers,

Dave