[sdiy] 4514 w/4516

[Tom Arnold]

On Sun, Jan 16, 2005 at 03:30:00PM +0100, Magnus Danielson wrote:
> The 4516 are synchronous counters, but you only experience the synchronicity
> if you hook them up properly. To wire a pair of 4516 to do synchronous counting
> you hook both to the same clock signal, at CP. You then hook TC of the lower
> chip to the CE of the next chip, so only when the lower chip says "carry" will
> the upper chip make a count in that clock-cycle. The UP/DOWN pins should be
> wired together naturally as well as the PL pins and the MR pins, thus the
> combo has common CP, UP/DOWN, PL and MR. The CMOS Cookbook (Don Lancaster)
> has the CE pin named CI for Carry In and the TC pin named CO for Carry Out
> with a complete little description similar to the above.

Thats exactly how I have my test circuit wired, but if you look at the
handy-dandy timing chart on the datasheet you'll see that CO lags the clock
by a little bit. ( using CMOS handbook nomenclature ).  This lag is
*visible* when using a wide slow clock like my bench B&K function generator.
( by Visible I mean I stick LEDs everywhere... )

Using the microocontroller really reduces my parts count, so I'll probably
stick with it.
-- 
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 - Tom Arnold -       When I was small, I was in love,                  - 
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