What is the exact location of the off-grid Arduino connector

I am making a board for an Arduino CPU. It has that off grid connector. I want to place it correctly or I have to do it again and my friends will laugh at me.

Other connectors fit in the 2.54mm grid (or 1/10" if you use hands and feet). It does not seem to be at exact location like 2,54+1,27mm. I can place it anywhere on-grid or off-grid of course.

Do you mean the shield socket strip?

IIRC that's 160mil away from it's neighbour.

Here's a drawing I did years ago

I'm pretty sure it's correct and nobody ever disputed it when I posted it way back when.

Thank you for helpful drawing.

I mean the distance between top connectors in your drawing. Or more accurate distance between holes, the plastic connector body is not important.

When I tested with a 2.54mm Veroboard or stripboard, all the other holes fit but not the one top right. So your dimensions should not be exact 2.5mm but 2.54mm and so on.

160 makes 4.064mm, that sounds correct because I measured 4.10 or so in our CPU. But when I checked real Arduino boards I got 3.8mm. Our CPU card is a ST Discovery board with "Arduino" connectors. I have to check its drawings, if they help. I really want put the hole where ST tried to put it.

In the published Eagle PCB, the 10pin connector is at 30.226mm, and the 8pin at 54.61mm, which matches the 4.064mm number.

I would NOT be shocked if the real production units had the spacing slightly different, as a way of detecting real units vs clones made from the OSHW files. If that's so, then you'd have to decide which one to follow, and it wouldn't really matter anyway...

Thank you. I was thinking about looking in Eagle files myself, but I have no Eagle CAD and I am not so eager to install yet another SW.

I have no Eagle CAD and I am not so eager to install yet another SW.

Worth it, IMO. Only 250M of disk space (unlike SW development packages (Atmel Studio, cough) that run 3G+)
(Whether you can easily learn enough to be a "casual" user is a separate question... )

LMI:
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Or more accurate distance between holes, the plastic connector body is not important.
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That's easy to calculate with the dimensions in the drawing as they are for the holes not the plastic.

I would work in imperial for this, that's what the board is laid out with.

Here is what I got. I wrote in the beginning that it is the top right connector which is off grid, but it very much looks like it is the top left one. I planned my results here too, but I forgot. Besides I made the PCB but left the dimensions out, so there was no good picture to send.

3 connectors fit in the 100mil/2.54 grid.

Edit:There should be a picture here somewhere

If you look at my drawing it's quite clear that it's the top left header that's off grid.

Actually I wonder about your 1.9" between headers, I have 2". I could verify that in 2 seconds but can't find a single Arduino right now.

I may have miscalculated. I would appreciate if you can check yours there. Just now I measured, instead of counting the the rows, the distance and got 1.910 mils? /48.53mm.

I am not in a hurry,I am not ordering any boards yet

Edit: Are you really sure that your drawing has it 200mils. If I look closely, I think there is 1.9 also in your drawing

The correct distance is 1.9 inches.

Using the distance tool in Eagle:

LMI:
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Edit: Are you really sure that your drawing has it 200mils. If I look closely, I think there is 1.9 also in your drawing

Oops, you are correct, I didn't subtract the .1" :slight_smile: