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Wednesday, 16 July 2014

Raspberry Pi Model B+ issue (and solution)

Raspberry Pi Model B+
I've hit a bit of a hardware compatibility problem with the new Raspberry Pi Model B+

When my new Raspberry Pi B+ arrived yesterday I started wondering about the software implications.

I wanted to verify that the Quick2Wire, Adafruit and Raspi.GPIO libraries work as intended on the new boards, but instead I hit a problem with the new hardware layout.

The new design has 40 GPIO pins, and the people at Pi Towers have arranged that the first 26 pins have the same function as they did before. But...

Twenty-six onto forty won't go!

I naively imagined that this would mean I could just plug in a 26-way connector onto the correct end of the 40-pin header.

It doesn't work, at least with the cables I've tried. The female sockets are so wide that they won't sit down on the 40-way header. You'd have the same problem with the cables supplied with Adafruit's cobbler, as they use standard-width IDC connectors.

And the PiFace won't fit

I thought for a moment that the PiFace might be OK. It's socket is narrower than the standard-with IDC connectors, and it would have sat down fine. Sadly, the new board layout clashes with the PiFace, and I suspect that many other boards won't work either. If I'm right there is going to be a scramble for add-on manufacturers to bring out new 'plus' versions.

It's not a (big) problem for the Quick2Wire boards, though, or for the Adafruit Cobbler.

A quick fix for Quick2Wire boards

RaspPi B+ and Q2W boards
As luck would have it I'd decided to order some 40-way connectors at the same time as I ordered the Pi. I already had a 26-way socket and some 26-way ribbon cable in stock, so I quickly built a 26-way to 40-way adapter cable.

Here's the result >>

And it works.

I can see several other possible solutions. I'll be trying a few more over the next few days, and will report here.

Update:

Also, it looks as if Adafruit are half a jump jump ahead - they have B+ versions of the cobbler, but they are currently out of stock.

What's your experience?

I'm delighted with the new board, and I will definitely be using it for C3Pi, using custom connectors.

I'm sure we'll see plenty more innovative solutions form the community.

Have you hit this problem? Found a good work-around? I'd love to hear. Please let me know in a comment.