Friday, February 3, 2012

The Sheeva Plug and tiny computers in general

Ever since Bloominglabs hackerspace actually became a space in the physical sense, we wanted to put together an RFID access system for our space. After some experimentation and false starts, we came across 23b Shop’s open-access-control system, which essentially is the largest Arduino shield you’ve ever seen. It handles such matters as storing user tags in EEPROM, unlocking electric strikes via relays, and a bunch of other stuff. In the Open Source sense, it does what it does out of the box, plus it does anything you decide to add to it, should you follow the advice of American poet laureate Henry Rollins - ‘Don’t think about it, do it!’

Among other things, visits (and alarms and sensors being set off) are logged to the serial port. So if you connect it to a server via a USB cable, you can do all sorts of things with this info. In arclight of 23b Shop’s case, he used a very small, low power (5W) ‘plug computer’ called the SheevaPlug as a server, installed ArmedSlack on it, and set up some scripts to mail people when somebody is at the space (or an alarm goes off).

As an Arduino fan I like really small computers, and I generally like things that provide ‘the right amount of power for the job’. For example, I think it’s dopey to drive a Hummer not only because it’s a stupid car that wastes gas and generally stinks up the place with pollution, but also because from an engineering standpoint, using all that gas to move a 200 pound individual from point a to point b seems like the stupidest and least elegant fucking thing ever. Sorry for the language.

So I ordered a SheevaPlug from Globalscale technologies for $99 (the low price is another thing I liked), and not long after that it arrived. I immediately was a bit disappointed that it came with Jaunty Jackalope, so any attempts to install anything or update anything were for naught, because Jaunty Jackalope is no longer supported. I’m not sure why they felt like this was the thing to do. It was pretty clear now why arclight had installed another distribution.

I ended up going with Debian instead of ArmedSlack, because I like Debian and it seemed like the thing to do. It ended up being a good choice in part because I used this guide, and the guy (Martin) who wrote it was extremely responsive and helpful with some questions I had about the process. I created a filesystem and installed Debian on an 8GB SD card, and I was on my way, or so I thought. After a couple of days, the thing just died. A bit of forum searching turned up some frustration people had involving the power supply, including some not very flattering critiques of the soldering technique of the manufacturers. I returned the Plug asking for a replacement, and after a somewhat frustrating couple of weeks, I received my repaired SheevaPlug, with Jaunty Jackalope helpfully installed.

This was a couple of months ago. While I was waiting for my SheevaPlug to be fixed, we set up a server running Fedora in what we’ve decided is the server room at Bloominglabs. Since the RFID system sits on top of the rack the server is housed in, we set up the monitoring system on that server, along with a bot in our irc channel that helpfully welcomes people with small talk about ‘that local sports team’ and so on.

I ended up using the Sheeva plug for some experiments w/ sending info from sensors to Pachube. It’s been running fine for over a month now, and it’s nice to have a server I can leave running around the clock that doesn’t use much power or make annoying fan noises. I do have a problem where when I reboot, it doesn’t always recognize the SD Card, but for now I’ve attributed that to a crummy SD card and moved on. The Sheeva plug is worth checking out if you want to see what plug computing is about. Needless to say my experience was not optimal, but to their credit GlobalScale sorted out my problem with minimal fuss or hassle.

By the way, if you haven’t heard about it, the Raspberry Pi project is in a similar vein and looks VERY interesting. It’s an ARM/Linux box for $25! My initial feeling is that although they’ve already started manufacturing them, it will be very hard to get a hold of one for some time, but this is one of those things I’d be happy to be wrong about.