kicad-lib-committers team mailing list archive

[Kerusey Karyu <keruseykaryu@xxxxx>]

W dniu 06.04.2014 01:55, Carl Poirier pisze:
>     At this point, we shall to ask: How many users use SI units when
>     drawing schematics? Most of them will look at grid only and doesn't
>     care about mm or inches.
>     Units of measurement are important, but where they are actually
>     required to maintain strict dimensions.
>
>
> If you look at the metrication of the world, you will notice people
> using the imperial system are getting scarce these days.
> http://en.wikipedia.org/wiki/File:SI-metrication-world.png
IMHO this picture isn't an argument here.


>     If we force 4mm or 2.5mm of pin length these pins will be outside of
>     the grid when somebody uses inches. IMO this is not the way we
>     should follow.
>
>
> Same can be said when one uses the SI system to draw his schematic.
If he only switch from inches to mm using Eeschema left toolbar nothing 
will happen. The grid remains the same.

As I said before, I'm using grid points for reference and don't care 
about current units when draw a schematic. And I'm sure that many people 
do the same.
For me the grid in inches is better because it's easier to multiply 
simple numbers like 0.05" than 1.27mm.


>     (...) unless the manufacturer places the components in a different
>     orientation in tubes, tapes or trays (Important for P&P).
>
>
> Good point. Can you tell me, for a device that's made by many
> manufacturers and sold in such packages, do they all use the same
> orientation?
http://www.ti.com/lit/an/szza021c/szza021c.pdf
A very interesting table on pages 12-14. One manufacturer and different 
pin 1 location in tape, even for the same packages. For example package 
widely known as SC-70-5: DCK3 pin 1 on lower left quadrant, DCK2
pin 1 on upper right quadrant.


Regards
Kerusey Karyu