kicad-lib-committers team mailing list archive

[Carl Poirier <carl.poirier.2@xxxxxxxxx>]

Kerusey, I would like you to reply to my previous message, if possible.


On Sat, Apr 5, 2014 at 7:55 PM, Carl Poirier <carl.poirier.2@xxxxxxxxx>wrote:

>
>
>
> On Sat, Apr 5, 2014 at 4:28 AM, Kerusey Karyu <keruseykaryu@xxxxx> 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?
>
>