Homebrew PCBs

--- In Homebrew_PCBs@yahoogroups.com, "Bob Hyland, PMP" 
<BobHyland@A...> wrote:
>
<snip>
> - The software recommends linking a schematic to the PCB. Why is 
> this important?

Unless your circuit is extremely simple, connecting the pads in the 
PCB layout is going to be difficult and error-prone. Also, any 
changes that need to be made to the circuit can be done much more 
easily on the schematic and then transferred to the PCB.


> - Should "good" PCB software take the schematic output and begin 
the 
> PCB layout for you? It seems that the software should at least 
place 
> all the components onto the PCB in a rough manner for you. Does 
> anyone know if this software does this?

While most (all?) CAD packages have some sort of an auto-place 
feature, it's generally of very limited use. Most of them seem to 
randomly scatter the parts onto the board with no regard to their 
interconnections. IMO, parts placement is something much better done 
by hand. Doing so lets you use the rats-nest of the nets as a guide 
to get a good arrangement for the parts.


> - Does Eagle SW make it easier to do any of these tasks?

Yes. A lot of people use Eagle. Their freeware version is probably 
one of the most popular packages among hobbyists.


> - Does anyone know of a library for Eagle that includes the 
> PIC16F7*7 devices?

I'm sure that someone in the group who uses Eagle has one.


Regards, Bob