Im just a bit confused as to what grid spacing I should be using. I read somewhere ( I can’t recall atm) that I should set it at half of whatever the smallest pitch component is. Obviously if it’s too big I won’t be able to hit the pad when I go to route… Anyway, my main problem is that no matter what I set the grid spacing, I will never be able to hit that pads straight on for all components…
here you can see my mcu on the left has the smallest pitch(disregard U2) so the grid spacing is half of that and the traces line up perfectly, however the traces on the other two ICs will never be aligned. Is this just something ill have to live with or am I doing something wrong?
also I did a search and I couldn’t find anything completely relevant :roll:
I don’t know the perfect answer, but I use the [Alt] key when placing traces to components not of the grid. This uses the Alt grid which I setup to be one tenth of the major grid. (e.g 1.27 mm and 0.127 mm for descrete components.)
I also have a menu with the “normal” grids I use for schematics, layouts and libraries.
The solution I use is to always route from the strange grid pad, to the normal grid. Let’s say you have some strange pitch part, and you’re routing to a normal .100" header or something. Start at the pad of the part that’s NOT on the normal grid, while holding ALT. Then come off the pad, click to place the first segment of the net, then release ALT and route to the header pin. This will always start the net at the center of the strange grid pad.
EmbeddedMan’s solution is the correct way to do this (though ALT is not necessary), and the way I’ve been doing it for years. It’s really the only way to handle the problem since every package has parts on who knows what grid.
What if you need to route between two parts that BOTH aren’t on your grid? You route a little stub out from one pad, landing on a grid location. Then exit routing. Start it again over on a pad of the other part, then complete the route over to the stub you previously made.
With most other packages you can start and finish on any pad, even if both are off-grid, without all that messing about. The connections are always made to the pad centre.
gussy:
When moving your parts hold CTRL to snap them to the grid.
this doesnt seem to do the trick for me, the parts still stay offset from the grid. i can use the info tool to manually get them on the grid, though its tedious…
I can pretty much guarantee that in almost any board with more than a couple parts on it there will be at least one part that you can never get completely on the grid. That’s because so many ICs are on a different grid or no actually discernible grid. Sure, the pins in a row are evenly spaced but often the rows have a different spacing.
Routing from rather than to is the correct way to do it. If both end-point piins are off grid, route from each and then meet in the middle.
Putting the origin of a part on grid only helps if the pins are also on grid which is far from common.
