Mail Archives: geda-user/2013/08/10/16:51:23
Hi, Al,
This is the point where I turn to a microcontroller.
It's flexible, by far the cheapest solution ($1-2),
and the code to debounce pushbuttons and toggle
outputs is pretty trivial, even in assembly language.
Unfortunately, as you've discovered, integrated T flops
are pretty rare (I only know of ECL devices), so you
need to construct them with JK flops. But a JK flip-flop
with an independent clock takes a lot of pins, so you
need a lot of packages. If you needed speed, a CPLD
would be the logical choice, but it's hard to imagine
that being a criterion for a pushbutton interface.
--
Roger Williams <roger AT qux DOT com>
Chief Technical Officer, Qux Corporation
245 Russell Street, Hadley, MA 01035, USA
Tel +1 508 287-1420 * Fax +1 508 302-0230
On 2013/08/10, at 16:15, al davis wrote:
> I have a need for a "T" flip-flop ...... to map a momentary
> pushbutton to on or off.
>
> The application needs 20 of them in a tight space, preferably
> arranged in 4 groups of 5.
>
> Looking for suggestions of a chip to do this, with a minimum
> package count and space requirement.
>
> Wishing for a "hex T flip-flop", but I can't find it.
>
> The best I can find seems to be a dual JK flipflop. That's 10
> packages.
>
> I found a quad JK flipflop, but they share a common clock so
> that doesn't work for this application.
>
> I can do better in cost and space with discretes.
>
> ideas???
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