On Thu, Mar 28, 2002 at 09:33:48AM -0700, Dave Mumert wrote:
> Hi Andrew
>
> Do you know Morris code? That would only take 1 output.
>
> There is a 16 channel serial input LED display driver available from Allegro
> http://www.allegromicro.com/sf/6276/
> It is under $3.00US.

I think we need to go back and ask for specification clarification. What's
the most important criteria, cost or board space? Once you're talking about
$3.00 solutions then what's the benefit over using a larger PIC?

I'll start the discussion. Let's start with the 25 part price at Digikey for
the 12C508 and the 16F627. $1.72 for the former and $2.01 for the latter.
29 cents difference. board real estate wise the 16F627 adds 10 pins, all
of which can be used for I/O. We know that with 8 pins and 2 nickel transistors
we can drive two 7 segment displays directly from the PIC. In fact we can
ditch the external transistors if we assign one more I/O pin to the task.

BTW if it's directly connected to the PIC with no external drivers, the
software must multiples each segment of the display, not entire displays so
that the PIC's port won't be overloaded.

Now with that in mind let's redefine: Is there a serial I/O solution that
takes less than 10 pins of board real estate and cost less than 30 cents?

I can't think of one. Even my previous solution would have required a 14 pin
driver in addition to the display itself.

So here's my bar. The simplest, easiest, cheapest solution is a 16F627
directly driving a 2 digitd LED display using 9 I/O pins. It cost 29 cents
and 10 I/O pins.

Any takers?

BTW I picked the 25 part price for two reasons. 1st if digikey's minimum order
and secondly the 25 part price ditches most of the overhead for single pieces
and gives a truer sense of the actual cost of the part. The difference in
single part prices is $1.45 BTW.

BAJ

>
> Dave
>
> > I want to display just 2 numbers out of the PIC somehow.  Doesn't matter
> > how, just the simplest, easiest, cheapest solution.  Could be an LED
> > display, LCD, smoke signals, it doesn't matter.
> >
>
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