[sdiy] Counter Preset question

[John Loffink]

It doesn't matter what's on the parallel inputs until the load control
pin is pulled high.  Then the data at the load inputs is transferred
immediately to the clock registers since this is an asynchronous load
control in the 4516.  The next clock cycle will count to the next number
from this, assuming that the load control is low.  You can say that the
load control pin acts as a from-n reset, not the load inputs themselves.

In your first example you didn't need to gate the preset ins through a
latch.  Clocking the load input control would have been sufficient and
saved three registers.

Note that some counters have synchronous load inputs.  That's probably
best for a sequencer design, or just put a flip flop before the load
control, clocked by the counter clock.

John Loffink
jloffink at austin.rr.com 

> Got a counter question.  Let's take a everyday 4516 as an example.  It
has
> preset inputs.  Now, I've used these before to create quasi-random
count
> patterns, but I was gating the preset ins through a latch which was
paced
> with the counter's input clock, so I don't know a side of its
operation
> that
> I would nowlike to task. I come to you guys becuase the truth table in
the
> spec sheet is giving me a headache.
> 
> Question:
> 
> If the counter is free running off a clock, and I interject a preset
to
> send
> it to, let's say, 0110, once that preset dissappears will the counter
then
> count to 0111?
> 
> Does the preset work as a count -from-n reset?
> 
> Obvoiusly, this has sequencer implications.  Working on a new design
and
> am
> wanting the option of setting the reset start point from wherever I
want
> it
> (not just stage 1).
>