Re: gEDA-user: Footprint recognition

[Link <link@xxxxxxxxxxxxxxxxxxxxxx>]

On 16/12/09 09:57, Goran Mekić wrote:
>     Is there a way to recognize what footprint I need for an element other
> then printing them all and comparing it to real element? Let's say
> it's 2200uF polar cap. I know it's RCY*, but how to figure out what's
> *? Thanx!
> 
> 

You'll remember the most common parts' footprint names eventually. For
capacitors, I'd recommend using the RADIAL_CAN set of footprints. They
are macro-based footprints, with their single argument being the
capacitor's diameter in mil (1/1000th of an inch). For example, a
capacitor that's 200mil in diameter (~5mm) would use the footprint
"RADIAL_CAN 200". Currently, the RADIAL_CAN macro supports diameters of
200, 300, 400, 500 and 600 mil. This way you can simply use a vernier
calliper to measure your real-life capacitor's diameter and pick the
closest value for the footprint. No need to waste ink.

Of course, an alternative method would be to find a way to print out the
whole footprint library at once on a single sheet (with the footprint
names included!); if you keep that sheet safe and clean, you can simply
use it for reference without having to print stuff out more than once.

Note that useful macro-footprints exist for other parts than capacitors
as well; you can use AXIAL_LAY (300|400|500|600|800) for resistors and
axial capacitors or inductors, and DIODE_LAY (300|400|500|600|800) for
diodes (but keep in mind that DIODE_LAY has pin 1 as the cathode and pin
2 as anode).

IC footprints, of course, are obvious (DIPn/SDIPn/SSOPn/TSSOPn... with
'n' being the number of pins). Transistors, not so much. There appears
to be no proper standard for the pin layout of most transistors; e.g. a
TO92 package can be C-B-E, C-E-B, B-C-E, B-E-C, E-B-C or E-C-B for
bipolar transistors. The footprint, in this case, can simply be "TO92",
but you have to make sure the pins are properly matched between gschem
and PCB.

As for more exotic parts, you're SOL. Often, you'll end up designing the
footprint yourself since there are no satisfactory predesigned ones.
This list can help you with that most of the time, though.

-Peter


_______________________________________________
geda-user mailing list
geda-user@xxxxxxxxxxxxxx
http://www.seul.org/cgi-bin/mailman/listinfo/geda-user