Recently someone from the hacklab put up a note saying that he had a SheevaPlug to give to a good home. I jumped on the offer. Thanks again, Brian! I’m going to be blogging a little bit about what I’m doing to show that I do have a good home for it.
The first thing that I’m going to use it for is an interactive music player or generator for a friend’s art piece. It’s going to change what’s played based on how many people are in what parts of the room. I’m going to do this by counting the number of people who enter the room using infrared LED sensors, and then setting up sonar threshholds for people to be counted as they cross. To implement this I’ll use the sheevaplug, two arduinos, a bunch of range finders, and either a long cable connecting the two duinos or a couple of xbees.
I’m going to have four pairs of rangefinders on a post, each pair pointing in a different direction. If I see the distance from one rangefinder in the pair drop (call it A), then the other (call it B), I can guess that a person just walked in the direction A to B. I’ll decrement the count of people from A’s quadrant and increment it in B’s quadrant. The music will change depending on how many people are in the room, and how many are in each quadrant.
Why the sheevaplug? It’s powerful enough to generate sound and pipe it through a USB sound card.
The first step in this ordeal was to get FTDI working on the sheevaplug. It appears I wasn’t the only one with this idea. This is great news for me because the kernel I needed to get FTDI working was already compiled. I had some trouble at first, I’d see the kernel was being uncompressed and then it’d hang. As it turns out I forgot to run a few setenv commands. Oops. I was able to run those from the serial console and get going. Now the plug is running just fine.
My next step is to pick up a couple of motion sensors and see if I can get the people counter working. I expect to run into some problems with interference, so I’ll have to play around with the transmit timings. If it works with the two then we’ll see about getting funding. In any case I’m trying to get the costs down, those range finders are expensive!
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