If there are no fudicials

[gasmeter]

Hi

I have a few boards I want to put through that were always meant for hand assembly and don't have fudicials.

Would it work if I gave the coordinates of through holes or vias ?

They look like fudicials but of course have a hole in the middle ?

Peter

[JuKu]

If the vision system sees them, yes. You would put those as components to the pick and place file and mark them as fiducials.

[mrandt]

I have just tried this and I confirm it works like a charm.

I manually copied & pasted the location of three vias into the coordinate file, modified the filters for fiducial detection slightly (larger zoom) and was good to go

[thereza]

I've added templated based fiducial matching to the code. You can use anything as a fiducial - just take a snapshot of it with whatever filters you enabled, save it, and set it as the fiducial marker.

https://www.dropbox.com/sh/ic2jtr1qi3is ... 4UJla?dl=0

-r

[caprisonne]

Hi folks,
we have the same problem, we have a pcb whithout fiducials and tried to define some vias on the pcb as a replacement for that.

We entered the coodinates of the vias but our liteplacer couldn't find the holes again. It drives around to a complete false postition in x/y direction, the software shows an error (see attached image).

We tried to replace the coodinates with the displayed position of the vias in the liteplacer-software, but the liteplacer didn't find them the next time we tried.

Our pcb was designed with a kicad version of 2011.The y-axis of kicad directed in another direction than the one of the liteplacer so we had to calculate the postitions of the components again.

Now we have the problem with the fiducials. Could someone give us a hint how we can solve this problem?

Thanks in advance!
caprisonne

[Pixopax]

Did you try to change the camera filter? You should change that until the software detects a circle where your via is.

[JuKu]

> We tried to replace the coodinates with the displayed position of the vias in the liteplacer-software, but the liteplacer didn't find them the next time we tried.

You should use the CAD coordinates from your CAd program. In other words, a fiducial is handled like any other component.

> Our pcb was designed with a kicad version of 2011.The y-axis of kicad directed in another direction than the one of the liteplacer so we had to calculate the postitions of the components again.

Excel reads and writes csv files that the software wants, so that might help manipulating them.

[Danal]

I also have a bunch of boards (hundreds) that have no Fiducials. I have achieved some success using Vias instead. It is fairly easy to add these to the CSV file. I use the PCB CAD software to generate a file with all the components. I add two or three rows for fiducials, and get the coordinates for these rows by holding the cursor over the center of that via and looking at the coordinates shown. I tend not to use the object attribute of the via, because that is not always the center. Much easier to just cursor over it and get the coordinates.

The limitations seem to be getting camera filters that will consistently find vias as circles. The amount of solder mask that sinks into the via is quite variable, and this makes it hard to have a consistent filter.

Therefore, I'd like to request that LitePlacer officially support keeping the "Find Circles", "Find Rectangles" setting along with the camera filters, when you "Copy Here" for each kind of thing, like Fiducials. That would make it easy to use a rectangular pad as a fiducial.

As a side effect, keeping track of the checked boxes when "copy here" and "to display" would also solve an annoyance in the UI: When clicking "To Display", the current software does not promote "Find Circles" or whatever. Since all the display stuff goes away with a tab swap, this adds unnecessary clicks to the workflow of calibrating, debugging, etc.

[JuKu]

> I add two or three rows for fiducials

You need at least three, four is much preferred; the transform gets progressively inaccurate (measurement errors accumulate) outside the area defined by fiducials. If you have only three corners from a square board, half of the area is outside the triangle. (I haven't looked much how big issue this in practice, but the theory says so.)

> The amount of solder mask that sinks into the via is quite variable, and this makes it hard to have a consistent filter.

Mounting holes might work too, if you have those, also connector holes.

> I'd like to request that LitePlacer officially support keeping the "Find Circles", "Find Rectangles" setting along with the camera filters

Good idea, I'll look into it.

[Danal]

Doh! I just realized that nearly every component on my existing board has an orientation dot. These are very small, but they work fine.

Once I started using 4 of these, spread way around the board, placement accuracy went WAY up. Wow, it's pretty nice when something works as designed...