kicad-developers team mailing list archive

[László Monda <laci@xxxxxxxx>]

Ah, that makes sense then.  Given that the increased resolution is
explicitly stated on the Eagle 6 page I'm pretty sure that they moved
from 100 nm to about 1 pm order of magnitude-wise and from 32 bit
integers to 64 bit integers.

If KiCad wants to stick to 32 bit integers then moving to picometres
would result in a 4x4 mm maximum board size so it's perfectly
understandable to choose nanometres in this case and have a 4x4 m
maximum board size.  :)

Hopefully in the future KiCad will also make the move to 64 bit
integers which will makes sense as 32 bit CPUs are rapidly getting
obsoleted.

On Mon, Oct 22, 2012 at 2:06 PM, Edwin van den Oetelaar
<oetelaar.automatisering@xxxxxxxxx> wrote:
> EAGLE
> Easily Applicable Graphical Layout Editor
> Version 5.7.0 for Linux
> Professional Edition
>
> The manual page was from there.
> I do not have a license for version 6, I recently got a pro license
> for 5.x and now they want me to pay another 1000+ euro to upgrade to
> 6.x which I did not do.
> For this reason also I am checking out and patching stuff on KiCAD.
> My guess is that with some community effort it can be better and more
> open (flexible, scriptable) than the closed source alternatives.
>
> On Mon, Oct 22, 2012 at 1:54 PM, László Monda <laci@xxxxxxxx> wrote:
>> On Mon, Oct 22, 2012 at 1:09 PM, Edwin van den Oetelaar
>> <oetelaar.automatisering@xxxxxxxxx> wrote:
>>> I think the problem is not there in the real world.
>>> http://en.wikipedia.org/wiki/Gerber_format#RS-274X_extended_Gerber
>>>
>>> The output for production is at most accurate to a micro-meter or a micro-inch.
>>> Photo plotters and CNC drill machines are not as accurate in practice.
>>> Furthermore, footprints are mostly defined on a grid, which is of a
>>> known size (not in pico-meters accuracy but in milli-inch or
>>> micro-meter)
>>>
>>> From the help-page of eagle ;
>>> real u2mic(int n);
>>> real u2mil(int n);
>>> EAGLE stores all coordinate and size values as int values with a
>>> resolution of 1/10000mm (0.1µ). The above unit conversion functions
>>> can be used to convert these internal units to the desired measurement
>>> units.
>>
>> Is this a help page of Eagle 6?  If so I'm wondering how can they
>> state that conversion works flawlessly between impreial and metric
>> even with a 1/64 mil grid.
>>
>>> For me personally the nano-meter is overkill already, more zero digits
>>> behind the comma than before, we now limit the total board size
>>> because of integer overflows.
>>>
>>> Hope this is useful for you.
>>>
>>> Have a good day,
>>> Edwin van den Oetelaar
>>>
>>> On Mon, Oct 22, 2012 at 12:44 PM, László Monda <laci@xxxxxxxx> wrote:
>>>> Hi List,
>>>>
>>>> http://www.cadsoftusa.com/eagle-pcb-design-software/new-in-v6/ states
>>>> that "Work with flawless conversions between mm and inches through
>>>> increased internal resolution (allows grids of 1/4, 1/8, 1/16,1/32 and
>>>> 1/64 mil)".
>>>>
>>>> Doing a little math it turns out that:
>>>>
>>>> 1/4 mil = 0.006 35 mm
>>>> 1/8 mil = 0.003 175 mm
>>>> (1 nm = 0.000 001 mm)
>>>> 1/16 mil = 0.001 587 5 mm
>>>> 1/32 mil = 0.000 793 75 mm
>>>> 1/64 mil = 0.000 396 875 mm
>>>> (1 pm = 0.000 000 001 mm)
>>>>
>>>> This worries me because given the vast hobbyist userbase of Eagle it'd
>>>> be tremendously useful for KiCad to be able to import Eagle files
>>>> eventually *without* loosing any accuracy.  According to the above
>>>> values KiCad will retain precision up to 1/8 mil but not below.
>>>>
>>>> I assume that nanometre resolution has been choosen because whoever
>>>> was in charge thought that it should be precise enough.  It's surely
>>>> accurate enough to manufacture anything but conversion problems can
>>>> arise.  I for one used KiCad from the pre-nanometre era and specified
>>>> values like 8.645 mm which got rounded to the closest available value.
>>>>  You may say that it's not a big deal but it is very disturbing and
>>>> it's certainly not something that one expects from a CAD software.
>>>>
>>>> As absurd as it might seem only picometres would be small enough to
>>>> provide the needed resolution to not loose accuracy.
>>>>
>>>> Please let me know what you think.
>>>>
>>>> PS: By the way, just for historical reasons what was the resolution of
>>>> KiCad before the nanometre era?
>>>>
>>>> Thanks.
>>>>
>>>> --
>>>> László Monda <http://monda.hu>
>>>>
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>>
>>
>>
>> --
>> László Monda <http://monda.hu>



-- 
László Monda <http://monda.hu>