[sdiy] 4514 w/4516

[Magnus Danielson]

From: Tom Arnold <xyzzy at sysabend.org>
Subject: Re: [sdiy] 4514 w/4516
Date: Sun, 16 Jan 2005 06:49:45 -0800
Message-ID: <20050116144945.GL41567 at moo.sysabend.org>

Tom,

> 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... )

I don't see what you describe in the datasheet I am looking at, or maybe I just
don't understand your real problem. Having the clock output signals being
synchronous should not be a problem. You may have a problem relating to when
you change the control-pins thought, since that leaks through the combinatorial
way and is not clocked.

> Using the microocontroller really reduces my parts count, so I'll probably
> stick with it.

Well, well, be carefull, it's a dark force you know, very dark... and it is not
as beutifull in the morning as you was beleived to see in the morning, I have
warned you! ;O)

Cheers,
Magnus