Monday, July 30, 2012

Raspberry Pi



There are many like it, but this one is mine.

You all know I'm a card carrying Arduino party member to the point that I buy parts in bulk to keep my per-arduino builds (for the controller part anyway) under about $7/each. That might make for another interesting topic. But the key is that they are very cheap ways to control something with a computer.

You know my nerd hairs* stood up when I heard about the $25-35 Raspberry Pi; an ARMv6 based computer that runs a Debian Linux distribution. It took a while to aquire one here in the U.S., but mine finally arrived from Newark a few days ago.

Selling points:

  • Powers off of a phone charger
  • General purpose input/output pins
  • runs linux
  • HDMI video output, capable of some pretty high res stuff
  • boots from a cheap SD card
  • USB support
  • It's a whole computer for Thirty Five Dollars.
  • 2.5Watts of power consumption (that I measured anyway)

Let me start by linking to a few important resources:


And on the note of the distributions: you load them to an SD card. Unfortunately the fancy 30Mbit Sandisk Extreme cards that I use for photography didn't work, but every other one I picked up around the house did. Get yourself a copy of 7zip and and Win32DiskImager if you are working out of a windows machine. 7zip takes care of the obscure compression formats that linux people are more familiar with (.gz, .xz, etc) and the disk imager builds an imaged SD card from a .img file. After you've cleared those little hurdles you should probably try downloading a few different distributions to play around with. It's easy and safe fun.

I did have troubles with most of them (standard linux troubles, of which we have made many jokes at the expense of others who think "linux makes a fine desktop for regular people" can include "it's easy to install! Just go to the command line and do these 15 things, then edit this file, then recompile, then...."). I had such flawless experience when messing with wireless network drivers (of which I never resolved).

It does however do a pretty good job of making me all nostalgic for the finer things of working with computers in the early and mid 90's. This is in many ways the goal of the thing. It's aimed at education of future software developers, of which I would certainly credit my having been toying around on the lovely machines of the pre Windows95 era.

Now you're asking yourself: what exactly am I supposed to do with this thing? Well if you go with  TechRepublic perhaps you should be building small satellites. But they do have some good suggestions for those not in possession of an orbital capable vehicle.

Borrowing from their list, these are the things I can see me doing with it:

  • Arcade Cabinet: We've chattered about this one many times at the house. Could be cheap fun.
  • Media Server: it does indeed play 1080p video, and there's a great distro (openELEC, available above) that is built just for that. It boots straight to XBMC and everything is handled from there.
  • Network attached things: Cameras, power monitoring, etc. Getting an Arduino on to a network is actually quite a pain. This is a good alternative.
  • Machine control: There are lots of linux based cnc programs out there, and the GPIO (general purpose input/output) on the Pi isn't much of a stretch to plug in to hardware. 
  • Telescope auto-guiding: You can get various devices from Orion and others that cost a boatload. Why? Because they mount a camera on the back of a secondary telescope and do image processing to determine if a guiding star is wandering from the field of view. There is already a 5 megapixel camera accessory on its way. This could handle that and much more (such as identifying stars from a catalog). 
  • Webserver: Whenever someone hears the word "server" they always seem to picture a ten foot tall rack mount tower with hundreds of cables dangling off like electric tentacles, possibly with CO2/Nitrogen vapor lightly rolling down the side. My home web server (which we use for all sorts of odd things) runs on an intel atom mini-ITX kind of thing. It's the least dense thing in my rack, and only a rack because it might as well sit in with the other audio toys. This may replace that with a simple Apache install. 

Things that sound like a good idea but probably are not:

  • CarPC: It sounds like a great idea, but once you factor in getting a screen you're probably paying more and getting less than wiring in an android tablet. I don't know if you've seen the quality of screens on these tablets, but they are far ahead of the liliput screens out there. It also turns out that a Kindle Fire is almost exactly a double-DIN size.
  • DIY Tablet: Good luck to ya. I do not know how they manage to build something like the Nexus 7 for as cheap as they do, so what you make is almost certainly going to be something of a novelty. That's cool and all, but of little interest to me.

So that's my opening. I'll keep us all updated as new cool things come to mind and we start building things with this new tool. Assuming I don't just regress to 1993 and start dialing in to some BBSs.

*I think those are the ones on the back of your elbows

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