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Date: Sat, 10 Aug 2013 17:02:03 -0400 (EDT)
From: Stuart Brorson <sdb AT cloud9 DOT net>
To: geda-user AT delorie DOT com
Subject: Re: [geda-user] T flip-flop
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Use an Atmel microcontroller.  For example, an ATTiny20 in an SOIC-14
package gives you 14 pins for your requested blocking -- 5 inputs, 5 
outputs, 2 power.  They're $0.99 in lots of 1 at DigiKey.

http://www.digikey.com/product-detail/en/ATTINY20-SSUR/ATTINY20-SSURCT-ND/3789310

Smaller packages are also available, if you can deal with leadless SMT
parts.

Writing debounce and toggle code is easy.  There is an excellent
open-source tool chain you can use to program the parts:

http://www.nongnu.org/avr-libc/

IMO, cheapo microcontrollers are the best way to implement functions
like this which used to require several independent gates in separate
packages.

Stuart



On Sat, 10 Aug 2013, 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???
>