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Re: Tutorial about IPC-7531A
On Thu, 02 Sep 2010, Lorenzo Marcantonio wrote:
> Look around and you'll see that most people don't actually use
> autorouters (unless for unimportant tracks, like led lines). Most of my
> work is mixed signal (in industry) so good luck telling your 'average'
> autorouter to: 1) drop power vias to the bypass capacitor on the other
> side of the power pin, 2) correctly do guard rings about instrumentation
> amplifiers, 3) switching power supplies layout where you have to do
> kelvin sense (and it's actually only one net) 4) be actually so smart to
> don't route your bridge sense lines near to said power supplies 5) star
> routing ground and power supplies ... and so on.
I hear you. It seems that it might take longer to teach an autorouter
all of these things than routing the board manually. All that seems to
result is a crude approximation that needs to be redone manually anyway.
> I actually used the kicad autorouter for inspiration when pulling the
> last tracks on a busy board (where last tracks are usually unimportant
> things like logic pull-up networks and buzzer drivers :D).
> Please note that I haven't said a thing about modern high speed design
> (mostly because I don't have experience in them). A good autorouter
> could actually help pulling an LVDS or some restricted impedance line,
> but then you enter anyway on the realm of 'every track is a trasmission
> line which must be simulated anyway'. You will need bigger guns for that
> stuff than eagle or kicad (and maybe even orcad).
I hope to turn kicad into such a really big gun. I am working at adding
features that display approximate calculations so that the board can at
least be worth simulating and cut down the layout/simulation loop.