[sdiy] 4514 w/4516

[Scott Gravenhorst]

xyzzy at sysabend.org wrote:
>On Sat, Jan 15, 2005 at 01:05:47PM -0800, Tom Arnold wrote:
>> I figured expanding this 16step sequencer board to 32 steps was going to be
>> as easy as chaining a second 4516 off the first 4516, but then my brain
>> finally kicked in yesterday and I realised that by chaining them they'll
>> count up to 8 bits as a pair unstead of one counting up 4 bits and then the
>> second counting up 4 bits.
>
>So, I'm replying to myself again.
>
>First with a rant.  Frys sucks.  I mean, this isnt a huge surprise to anyone
>but the real surprise is that they can indeed continue to get worse.  Its
>bad enough that they only carry NTE parts, whats worse is the aisle is
>slowly shrinking as they sell out of what they have.  I should offer them
>$100 for the entire aisle and see if they take it.
>
>Anyway...  If you use a 4516 to slave from another, there is a small but
>noticable delay when it carries the bit.  The delay depends on the width of
>your clock pulse also which makes it more fun to deal with.  Survey says?
>4514 aint good for this application.  I could work around the delay with
>some logic and in fact I started to, then I realise that much more quickly I
>could code up the previous mentioned scenix chip to act as a pair of 4514's
>and fairly cleanly wedge it into the existing circuit.  So thats what I've
>done still feeding a pair of 4514's.  Still some kinks to work out, but I'll
>nail them after some sleep...
>
>It just feels like overkill to use a microcontroller for this, on the other
>hand it will save close to half a dozen bits of logic and associated wiring
>and board space, so I guess its a win in the end...

"Overkill"?  Not in my opinion.  It sounds to me like it's the perfect
solution, and because it's a programmable device, you may be able to add more
features - easily.  And it's just as DIY as the other method.  Overkill is
when you could have adequately done it with 4514, but that's not happening
from what you're saying.

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-- Scott Gravenhorst | LegoManiac / Lego Trains / RIS 1.5
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