Why the gap?

What is the reason for the odd sized gap between the digital IO headers?

Yes, it was a brain fart during a frantic deadline to have PCB made, now it's a legacy feature that will haunt Arduino forever and a source of amusement for all professional PCB designers. ;D


Is there a normal solution to use if I want to, say, mate my Arduino to standard veroboard?

There was a solution posted in the last week or so on that subject, look around and see if you can find it.

EDIT: Here is on thread on the subject: http://www.arduino.cc/cgi-bin/yabb2/YaBB.pl?num=1206626508 Lefty

mate my Arduino to standard veroboard

Yes this is what I do:-


Thank you very much, I appreciate it.

Mike - clicked your link and got no pictures.

Just go to another link on his site then click back on the Arduino Shield. Don't know why but thebox has some strange behavior all the time!

Thanks for the feedback.

I clicked on the link and got no pictures as well. Then I clicked on another page from the header and then back again to the shield and I did get pictures. The URL was the same both times so I am not sure what is happening. It didn’t used to behave like that.

Any web designers know why?

In this particular case the problem is you have 2 versions of your page.
The good one is:
The bad:
The bad one refers to a css file that does not exist. But I’ve had problems with your site before also - the topics about motors and others had similar problems, but I did not investigate then, just searched the forum for a “good” link.
A look at the logs of you server and a lot of 404s reveal quickly such small problems.

Thanks mircho, it's my dyslexia striking again. I have put a file in at the "bad" url that redirects the user automatically to the good one. Now both good and bad should work.

Thanks again.

Maybe in the next version of Arduino they could correct it, and also introduce a stackable shield that uncorrects it, for those who need to hook up current shields.

Of course it's me who should be thanking you anyway :). For all the stuff you publish for everyone to read in thebox!

Maybe in the next version of Arduino they could correct it,

No this was made in the first version and every version since then has duplicated this mistake deliberately so that shields would still be compatible. Even the new Mega has this spacing.

It is one of those things that you learn to live with. Overlooking minor imperfections is a vital part of any love affair. :-*

You could always start using the boarduino... that eliminates the issue. That is unless you actually bought shields already. If you have no shields... then boarduino seems a good choice since it solves the issue by matching breadboard spacing.

I have the Boarduino and it's great. It's half the size of an Arduino and is easily pushed into a breadboard making prototyping a breeze. I have never yet felt the need to purchase any kind of shield as if there is somethign I need I get the parts and make it myself were possible.

There is plenty of room on the newer Pro boards to add a second set of pads inboard of the originals. That way, the original shields would still be compatible and any new shields could take advantage of the uninterrupted spacing.

Damned good point. There is indeed nothing stopping them having a dual row of headers. Good idea!

Thanks! It occurred to me while I was considering making an adapter.

Seeeduino has for sometime put extra connector pads at .1" spacing so one can use either if populated with an additional connector block.

"Duplicate digital IO to 100mil grid for prototype board compatibility."