Tuesday, November 13, 2012

Hot Raspberry Pi

If you've been following my fevered ravings about the Raspberry Pi, you know that I'm trying to use a raspberry-colored wooden box purchased at Goodwill as an enclosure for the Raspberry Pi. I call it a Pi Safe, because my mom referred to an enclosure for desserts similarly.

(This is improves upon my first Raspberry Pi enclosure I've described elsewhere.)

I glued the lid together and mended the broken hinge. That white stuff next to the clamp is wet Elmer's glue.

The holes shown above were completely useless. If you hold the Raspberry Pi board in front of you, you can orient it such that the Power, HDMI, and Ethernet connectors are at 3-o'clock, 12-o'clock, and 9-o'clock, respectively. To route cables to these points through a hole in the back, two of the cables must go around corners.

These cables aren't flexible and they have bulky connectors. This makes it such that 90-degree turns require a wide radius like a highway on-ramp. Hence I expanded the hole in the back into a slot, and cut additional slots on the sides.

It's just as well, I was worried about heat dissipation and airflow. Though the Dremel tool is marvelous for cutting holes in something, when you are cutting slots the Right Tool for the job is a Dremel multi-max.

I absolutely love that gizmo.

With slotted holes in the sides and back, I can plug in the cables as desired, and I now have plenty of airflow.

Thermal dissipation is interesting. If you go to the XBMC settings page, you can find a status indicator that will show you the temperature of the CPU and the graphics chip.

I used it to take these measurements:
  • 111° - Raspberry Pi out in the open
  • 135° - Raspberry Pi in the "pi safe"
  • 120° - Raspberry Pi in the "pi safe" just after running a movie for an hour.
(There's something reminiscent of quantum mechanics that bringing up the measurement screen should raise the temperature being measured. )
I figure 120° - 135° is good enough for now. Clearly, the slots permit sufficient airflow. As stated earlier, I have heatsinks on order that should cut down these temperatures a little more.

Here's what the Raspberry Pi looks like in its enclosure sitting beside my television.

I'll have to dress the cables to make things pretty, but you get the general idea.

The big surprise that I discovered a few nights ago was that my Sharp Aquos TV is having side-conversations with my Raspberry Pi. I inadvertently used my TV remote's menu buttons and was shocked to see XBMC menus on the Raspberry Pi responding in turn. This means that I didn't need teeny little keyboard/touchpad. Now that I think of it, I think I could have used ssh to telnet into the Raspberry Pi when I was configuring it. There was no need for keyboard or mouse even then.

Technically, the combination of a Raspberry Pi, OpenELEC/XBMC, and the "Pi Safe" is cheaper than an AppleTV. But it nickel and dimes you, and it doesn't "just work" like my AppleTV did. You have to make it work. This is a Linux box for the second decade of the 21st century. It's small, cheap, powerful (in a narrowly constrained domain), and it is fussy to set up and get right. If you count how much your time is worth, buy an AppleTV. But if you want to learn something get a Raspberry Pi.

P. S.
You may be wondering, "OK, if I hook up a Raspberry Pi to my television set, what could I use it for?" This is a good question, not because the answer is hard, but because MY answer is so self-serving: You can use it to look at this book trailer. If you think that's a lame reason, I'll be grateful if you turn off the TV and read a book.

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