William "Chops" Westfield wrote:
> 
> On Apr 13, 2010, at 11:10 AM, Michael Watterson (and Olin) wrote:
> 
> > A 40 pin DIP 18F4550 is hard to beat for general purpose learning
> > and lots of i/o to experiment with.
> 
> Intellectually, I can see the validity of this argument, but as a die-
> hard hobbyist I have to admit that there must be some other factors
> that cause me to be attracted to smaller microcontrollers.  Maybe it's
> just that fewer pins are easier to contemplate from a PCB fab or
> soldering perspective.  It WAS the 16C54 (and later the 16C84 in
> similar package) that seemed to bring PICs to the attention of
> hobbyists (despite simultaneous existence of 16C57 with more pins.)

I can identify with this.  I make things with PICs for fun - it's a hobby.
And I actually (perversely, you could say) enjoy the challenge of using no
more pins than are necessary.

As a real example, I have next to me, as I type, a breadboarded prototype of
a travel clock I'm making.  My wife doesn't understand this - pointing out
that I could buy one for less than the money I spent on the case I intend to
use ($10).  Anyway, I've used a 28-pin 16F886 because that's what was on the
spare demo board I had lying around (and the demo board already had a 32k
watch crystal hooked up to T1OSC, which is exactly what I wanted).  I've got
4 x 7-segment LED displays running, using 17 pins in total (1 per digit, 1
per segment, 1 for LED to mark seconds, 2 for 32 kHz xtal, 2 power, 1 x
MCLR).

So I've got 11 unused pins, and now I need to add some buttons for setting
the time and alarm (and I'll use 1 or 2 pins to drive a piezo). The obvious,
non-time wasting solution is to use those unused pins.  Simple.  Yet boring.
So I'd rather multiplex the buttons with the display, and fit the whole
thing into an 18-pin PIC.  Or hey, 20 pins if I'm feeling extravagant.

Not sensible, true.  But fun.


David Meiklejohn
www.gooligum.com.au
 


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