Thursday, September 10, 2015

Don’t try this at home: how not to hack the Raspberry Pi display

You may have noticed that the touch display came out a couple of days ago and while the response has been fantastic it's still a bit early for display-based projects to blog about. But if there's one thing I've learned in three and a half years of blogging for Raspberry Pi it's this: don't try and compete with a new product launch. So in the absence of projects using the new display I thought I'd share what not to do with it.

When a new thing comes in to Pi Towers it must prove its worth by a trip to the Maker Grotto (aka my garage, but Maker Grotto feels so much more mysterious and just a little bit Christmassy). Sometimes this is a one-way trip for the new thing. It's serious stuff. So off we went, all serious like.

The Grotto, specially cleaned for the photo shoot

The Grotto, specially cleaned for the photo shoot

I had a couple of external 3.5" hard drive cases lying about that looked about the right size for a display enclosure. One—a lovely chunky bit of anodised aluminium by Freecom— was crying out for a window to be cut in the front, but it was getting a bit late to break out the power tools. The other was a cheap third party case and after a few minutes of subtle ultraviolence with the tinsnips the front was off. The display fitted perfectly vertically and pretty well horizontally, with a small overlap at one end. Which didn't bother me one bit. Not at all. No siree bob.

The main problem was that the case wasn't deep enough if you mounted the Raspberry Pi on the display control board in the obvious way.

GPIO_power

Flipping it over made me happy, it was a perfect fit. The header leads that powered the display from the Pi GPIO needed tweaking: remove the plastic ends, heat shrink and bend to 90 degrees. Otherwise very snug and comfy and it brought the overall height down to under 20mm, including sticky-out bits on the back of the Pi. You lose access to the GPIO pins but a ribbon cable would fix that. The DSI connector cable was secure with no stress and a pleasing Mobius strip quality that allows free access to the SD card.

height

I've since been told by Gordon, our Director of Software, that it was designed to do this from the start. But I like to think of myself as a trailblazer of the Inverted Mount. [/me shakes fist like a Beano caretaker]

main shot display back

What really, really bugged me was the small overlap at one end. It was taunting me and it needed teaching a lesson. Glass cutter. Straight line. Snap. Sadly the cutter was rather blunt and snap it went indeed—the cut was OK but it introduced edge weaknesses that became a crack under stress. Oops. On the plus side it still works fine and the Pitinerant (and if you think that's bad the alternative was PeriPitetic) now lives in in my bag—connect it to a portable power bank and a keyboard you have a fully capable Pi.

Forget duct tape, self-amalgamating is where it's at.

Forget duct tape, self-amalgamating is where it’s at.

Since then I've seen a few enquiries via Twitter as to whether the glass could be "resized", particularly to make it compatible with the European DIN standard for car audio head units. (We expect to see a lot of car media centres using the display.) The official answer is, "No, you will break it and void your warranty." And I'll leave it at that :)

Now there are probably a few people sitting there thinking, "I've not even got mine yet and that bugger is smashing his up!" But such is the crazy world of R&D! For what it's worth I've already ordered another out of my own pocket and will buy others—it's such a great device and it just screams projects. My first scheme is to replace my Pi-based media centre by embedding the display into a bookcase—no more monitor and keyboard cluttering the kitchen.

So the message here is: don't try this at home. Or, you know, do. And if you make anything cool using the display please share it with us. We're expecting good things :)

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