[sdiy] Four bit to serial translator

[René Schmitz]

Hi Peter and Harry,

Even simpler same principal concept, but without the register:

Use an X(N)OR gate for each bit, and put an RC combination at one of the 
inputs, and feed the bit directly to the other. Result is a short spike 
when that bit changes. replicate n times. OR all XORs together.

Cheers,
  René

harrybissell wrote:
> Magnitude Comparator ??? CD4585B
> 
> Make an n-1 copy of your word (it could be generated by a high speed
> clock or the falling edge of your existing clock, whatever...
> 
> compare the new word with the n-1 word for equality. If it is equal
> there is no change, if not equal, it changed.
> 
> This is basically an array of x-or gates, you could do it that way too...
> 
> H^) harry
> 
> 
> Peter Grenader wrote:
> 
> 
>>Guys and gal,
>>
>>I'm in a bit of a pickle and it's getting sour here - thought you cold throw
>>me a life raft.
>>
>>I've added an asynchronous VC to Milton.  Quite the bomb.  It doesn't give
>>two sheets what the incoming pulse is doing, or even if there IS an incoming
>>pulse for that matter - when the VC input's A to D changes state, the
>>counter immediately reacts.  With this you can now set the start and end
>>step to wherever you want, plus achieve some amazing non-linear
>>progressions. Driving it with a sine wave being particularly interesting as
>>the sequence accelerates at both ends.
>>
>>Problem is, as the name implies -  it's asynchronous. It functionally
>>remains a bit of a lame duck as there no way of syncing anything to it.  So,
>>unless you're planning on a legato glissandi, you're screwed.
>>
>>I've worked out a way to extract a timing pulse, but its involving more
>>parts than I like, and I'm certain there's an easier way.
>>
>>What I need is a short pulse each time the 4 bit word changes.  I tried just
>>monitoring the LSB, that works until it jumps to another of the same parity
>>and then it's lost.  I tired doubling the speed of the LSB to synthesize it
>>and that was totally the wrong direction.  I've thought through parity
>>comparators, but again, that leaves holes.
>>
>>So what I've ended up doing is taking the outputs of the 4050 (all sixteen
>>of them) and shaping those into pulses rather than gates and summing them
>>into one continuos stream, each with a 50ms on time.
>>
>>Although it took only one sentence to describe it, that function requires
>>sixteen transistors, 52 resistors, 22caps and 5 ICs.  In short - forget it.
>>
>>Any competent PIC programmers out there who are up for a challenge?
>>
>>If nay - anyone have a CMOS logic level solution???
>>
>>thanks in advance,
>>
>>Peter
> 
> 
> 


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uzs159 at uni-bonn.de
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