[sdiy] Four bit to serial translator

[harrybissell]

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