On May 14, 2005, at 8:19 AM, Hector Martin wrote:

> Look at the schematic... even if the PCB is OK,the schematic is most
> definitely messed up.
>
Thus far, this has been an exercise in PCB design preferences and (to a 
lesser
extent) schematic entry, and stuff like that.  At least, that's how 
I've been
treating it.  It's been fun, but before Alison goes off and has some 
boards
made up, it might be useful to go back and talk about the DESIGN and 
what it
is supposed to accomplish.

For instance, the original email header mentioned analog inputs.  But 
they
apparently have pullup (or pulldown) resistors.  Any number of people 
have
noticed that at least some of the layouts had these connected 
incorrectly
for pullup resistors, but no one has mentioned yet that it's pretty 
uncommon
to have ANY pullup resistors on analog inputs in the first place.  
Pulldowns
might be more common, but still not really likely, IMO.  In my 
"improved" PCB
design, I made assumptions without checking whether they were correct 
for the
design (assuming that it was primarily a pcb design excercise...)
On the other hand, it's always easy to leave components OFF of a PCB.  
Adding
components is messier...

BillW
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