Mail Archives: geda-user/2014/07/09/00:40:15
On Tue, 8 Jul 2014, Dan McMahill wrote:
>
> SOT-23's are notorious for this as well.
>
> Others have other approaches but for me having an ascii database that defines
> the mapping between symbol pins and footprint pins for each complete component
> has worked reasonably well.
I have a similar setup and it works very well. Mine has two stages:
1. pinmap attribute: name=number pairs, e.g. "pinmap=G=1;S=2;D=3" for a
mosfet where G, S, and D are pin names on the gschem symbol and 1, 2 and 3
are pin numbers in pcb
2. a set of small text files named as "device_footprint", e.g.
"2n7002_sot23" and a "devmap=filename" attribute on the schematics. The
files contain generic attribute rewrite directives, usually setting up
pinmap and footprint attributes.
I have a wrapper around gsch2pcb that first executes the devmap attributes
using a predefined directory as database, then it applies the pinmap
attributes to renumber pins.
Pros:
- very easy to maintain the library of mappings - no complicated database
software, gui, custom version control, but my favorite text editor and my
favorite VCS
- easy to follow and manually tweak the process
- because of the generic attribute rewrite, it can potentially do more
than just map pinouts
- very easy and fast to use: instead of footprint, I just assign a devmap
attribute and I know I won't have to worry about the footprint and pinout
- can use generic light symbols from any source as long as pins are
named; can use the same symbol for different models/packages within the
same schematics
Cons:
- the major drawback is that the schematics does not show actual pin
numbers (may be a problem while debugging the circuit)
- the implementation is hackish: gschlas, a set of scripts
- I have to remember to use the wrapper version of gsch2pcb
Regards,
Tibor
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