1 Nov
2010
1 Nov
'10
7:11 p.m.
On Mon, Nov 1, 2010 at 6:35 PM, Chuck Guzis <cclist at sydex.com> wrote:
On 1 Nov 2010 at 17:41, Brent Hilpert wrote:
In college I designed a BCD to 7 segment driver using fewer chips than the
convention used by looking at the problem from the other direction. For most
of the digits more of the segments are on than off, so I designed a circuit
to turn segments OFF instead of ON. Try it !! Might get the parts count down
for this one also. I'll give it a shot when I get a few spare minutes. Just
started a new job after being OFF for two years.
Best regards, Steven
Well, a starting point could be to replace the
74154 in the 1-of-16
decoder solution with 4 inverters and 16 4-in nands (9 packages), plus
the 4 packages remaining of that solution to do the segment selection,
gives 13 packages. Optimisation anyone?
I'll eliminate some of the grunt work for folks and offer the
following document, which contains all of the Karnaugh maps and a
simple logic diagram.
http://www.strivingafterwind.com/EE/EE112/ee112formal.pdf
I'd probably start by using a 7404 and distribute the binary input
and its complement... :)
--Chuck