a weblog by Schuyler D. Erle
Sat, 26 Feb 2005
Software has played a big part in my life. My first computer program, haltingly trancribed at the age of 6 from a blackboard on to a Commodore VIC-20 one afternoon during my first summer at day camp, read something like this:
10 PRINT "HELLO! "; 20 GOTO 10
Since that moment, a lot of things have changed, but the immediate interest I found in writing code hasn't been one of them. My elementary school soon had us writing LOGO on Apple ][es, and at home I spent innumerable hours poking at an Atari 800XL hooked up to an old black and white TV, until Dad brought home a PC AT clone, a 10 MHz 80286 running MS-DOS 3.1 on - wow - a 30 meg hard drive. I wrote dodgy EGA adventure games, saved up for parts, and got my own machine - a second hand Epson PC XT running a mere 4.77 MHz. Not long after I got my own phone line and started a BBS in the 215. Boy, those were the days. If it weren't for those BBSes, I would probably still have no social skills.
In 1996 I started learning Perl to better my earlier attempts at writing CGI apps with an ugly swill of tcsh, sed, and awk, and in 1999 I finally took the plunge and installed Linux on a machine of my own. By then, I had already quit my job at the gas station to write software more or less full-time. In the intervening years, Free Software has put a roof over my head, lead me to travel more and more of the world every year, introduced me to the most amazing people, brought me and my wife together, made us write a book, and someday, Tao not-willing, it might feed our children.
Inspired by Jo's devlog, I recently decided to begin cataloguing my ongoing adventures in code.
Thu, 17 Feb 2005
So now that the book is done and Jo and I are back from India, we've decided to make robots.
Let me back up. India: It's huge, crowded, messy, exciting, vibrant, colorful, and rich in many ways. I can't hope to do it justice so I'll leave it at that for now. I can't wait to go back.
Now, about the hoverbots. We've been wanting to make physical bots for some time but have been preoccupied with other work. Today, at Rich's direction, I ordered a TI MSP430 development board and programmer cable. We also bought an IR proximity sensor with a range of 80 cm (31") and a pair of IR motion sensors with an arc of about 60°.
The fantasy is to wire the microcontroller into the drive mechanisms of a remote control model vehicle, ideally a (non-US branded) blimp or a black hovercraft. The proximity sensor would be mounted on the front to keep the robot from colliding with things. The motion sensors would be mounted on either side at an angle and allow the robot to sense the motion of humans or (hopefully) other robots. I'm imagining possibly a red or IR signalling light as well. The sensors, as well as the original RC circuit, would be wired into the ADC ports on the microcontroller and programmed with handcrafted C code compiled on mspgcc, an Open Source GCC toolchain for the MSP430 family.
We want to see a bot follow a person around, or follow other bots around, and collectively explore a territory. A small amount of C code could muster some convincing flocking behavior. The MSP430F1121 microcontroller only has 2K of program space and 256 bytes of RAM, so we're not talking about massive intelligence here, but autonomous and collective behavior from cheap consumer robotics. Anything more and we'd want to wire it up to a Gumstix and run Linux.
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