Kerusey, I would like you to reply to my previous message, if possible.
On Sat, Apr 5, 2014 at 7:55 PM, Carl Poirier <[email protected]>wrote: > > > > On Sat, Apr 5, 2014 at 4:28 AM, Kerusey Karyu <[email protected]> wrote: > >> W dniu 03.04.2014 02:24, Carl Poirier pisze: >> >> >> About pin length, what about using SI units? >>> >>> 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 > > >> >> > >> Symbols: >>> >>> 1. A pin length of 4mm is used, except for components without pin >>> numbers which use 2.5mm. >>> >> > >> 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. > > >> >> > Footprints: >> > (...) >> >> 2. Pad 1 is placed at the top left corner >>> >> > >> (...) 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? > > >> 3. For through-hole components, origin is set on pad 1. >>> >> > 4. For surface-mount devices, origin is placed in the middle of >> > the chip. >> > >> There are also machines for automatic insertion of THT components, so >> mandatory putting origin point at pad 1 is a bad idea. >> We can assume to put origin at pin 1 when we are sure that this component >> will be inserted manually, for example terminal blocks. >> >> > Jean-Paul Louis was telling me that "By convention, the through hole IC > were referenced to the pin one because of the insertion machines." So this > isn't always the case? > >
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