> I have mixed feelings about making your own libraries for parts that
> already exist.  On the one hand, some of the libraries DO suck - they seem
> to be customer contributions with little error checking (for instance,
> there's a zetex transistor library where the pads run into each other even
> with the default restring DRC settings.)  On the other hand, it's like
> writing your own <billw-stdio> function definitions for a C program, or
> not using the standard includes for assembler.  If it doesn't work, or if
> you publish a design, there will be people who are suspicious of your
> library. There are standard C functions that I don't like, but that
> doesn't mean
> that I'm ready to replace them with similar-but-different functions that I
> like better (or maybe it does.  This is one of those recuring topics of
> discussion at work - "we should not be using a version of malloc() that
> zeros memory, even though it is very convenient, because it's NOT ANSI.")

I started out thinking I'd use the Eagle libraries for standard parts.  It
seemed that every design I had a part or two that wasn't in the Eagle
libraries, so I started to create my own.  After a while, I realized this
was no big deal.

I don't like some of the Eagle schematic symbols.  They were either too
european, or looked sloppily drawn.  Neatness counts.  I want a schematic to
be as easy to understand as possible, not just show the connections.

The final staw came when I used a few standard TTL glue parts from the Eagle
libraries mixed with some of my own stuff.  I figured a 74*32 gate is so
basic there couldn't be anything wrong with it.  Well, it worked, but the
pads were oblong with no indication of pin 1.  I figured it's just one
little glue chip, and this was a 3-off prototype, so who cares.  When I
showed the finished boards to the customer, his first comment was "why did
you use the different pad shape for this chip?  You can't even tell pin 1 on
the bottom of the board."  Then he gave me a look like this is the dumbest
thing he'd seen in the last year.  That was the very last time I used an
Eagle library for anything.

> I used Olin's PIC library for a 16F872 project
> I was working on, and it looks ok (thanks Olin!), but I didn't find it
> SPECTACULARLY better than the Cadsoft-supplied 16F84 library, and it had
> its own little annoyances as well (Olin: please put >NAME and >VALUE
> labels in the appropriate Names/Values layer and not in tPlace? :-)

That was strictly an oversight.  Sometimes when I make a package, I forget
to switch layers for >NAME and >VALUE.  I wish Eagle had a check that if you
are drawing the strings ">NAME" and ">VALUE", it gives you a warning if they
are not in the expected layer.  I suppose I could write a ULP to scan a
library for that.


*****************************************************************
Embed Inc, embedded system specialists in Littleton Massachusetts
(978) 742-9014, http://www.embedinc.com

--
http://www.piclist.com hint: To leave the PICList
mailto:piclist-unsubscribe-request@mitvma.mit.edu