On Wed, 2006-10-25 at 11:31 -0700, Shawn Wilton wrote:
> > That said, the RJ12 chosen for the ICD2 was a matter of trade offs (as
> > almost every engineering decision is). A "standard keyed header" is MUCH
> > larger footprint wise on a PCB then the RJ12. Also, the cables are more
> > expensive to make. It does have the longevity element, and is more
> > hobbyist friendly. They made the choice to use the RJ12, and that's
> > done.
> 
> 
> According to the pictures posted earlier of the ICD2, the board does in fact
> have a provision for a 6p header.  To what cables are you referring when you
> say more expensive?  

A cable that plugs into an RJ12 style jack is VERY cheap to make since
it's just a piece of very cheap plastic with some non critical in
dimension metal bits in it, crimped to form the connection in one shot.
A 1x5 header OTOH is magnitudes more complicated to make and assemble.
That said, we are talking about differences in cents, not a big deal for
you and me, but it becomes a big deal when volumes go up (although I
don't think MChip has made enough ICD2's for that difference to really
have much of an impact).

> There are a plethora of choices that could have been
> persued with regard to cable style.  Personally, I would have gone with the
> 6p 3x2 .1" header and a "3m" style plug-in keyed connector as were used on
> the IDE interface of hard disk drives.

In my experience the 3x2 header is rare, compared to sizes bigger then
that (yes, you can get them without a problem, but compared to other
larger sizes they are relatively rare. The AVR programmer I have uses a
2x3 header, I couldn't find a keyed header at my local parts places so I
had to use a 2x5 and extract 4 of the pins, annoying). Rare usually
equals more expensive. Again, we're only talking a few cents probably.
As a hobbyist I'd choose 1x5 before I'd even consider using a 2x3. In
the prototype world PCB space isn't very important IMHO.

Let me just mention that I've had my ICD2 for a few years now and
haven't experienced a single problem with the connector. Yes, I'm a
sample of one, but there it is anyways.

TTYL


-- 
http://www.piclist.com PIC/SX FAQ & list archive
View/change your membership options at
http://mailman.mit.edu/mailman/listinfo/piclist