Archive for April, 2008

There And Back Again, A Servo Project

Monday, April 28th, 2008

Apologies to Tolkien, of course! (There really is nothing too geeky for my blog, though.)  This project lets you set two positions for a standard hobby servo and switch between them.  It brings together most of the things I’ve learned about the AVR thus far: digital I/O, switch debouncing, analog-to-digital conversion, servo control and persistent storage in the onboard eeprom.  It doesn’t currently use interrupts, but they are pretty similar to the timer that drives the servo.  I built it on one of my EMSL mini dev boards so I’ve only tried the code on the ATmega168, but it should be pretty portable to other AVRs.

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Geek Buffet

Sunday, April 13th, 2008

Yesterday morning I hit the Silicon Valley Electronics Flea Market — lots of fun, I highly recommend it.  For flea market n00bs, don’t forget to bring a broad-brimmed hat, a bottle of water and a bag for loot (I forgot the first two), prices are usually negotiable and keep an open mind but not too open.  I made a list and mostly stuck to it; I would’ve liked to find more of the stuff on that list, but there’s a lot of stuff there and you really have to sort the stuff you need from the cool stuff you don’t need and the utter crap or you’ll wind up being able to run your own stall 😉 So what did I “need”?  A few pairs of hemostats, some solder wick, a set of “security” screwdriver bits, a UV LED flashlight, a pair of direct-drive moters with foam-rubber wheels, a game controller with analog sticks I can pull out and play with and a few free transistors (the solder guy has a box of free parts).

Schematic showdown: gEDA vs EAGLE, and the winner is…

Sunday, April 6th, 2008

…a sheet of graph paper!  I’m only half-kidding, if I had a scanner I probably would do my schematics that way.  Both gEDA and EAGLE suck huge hairy balls, and not in a good way.  I blame X11 and the myth of “cross platform” for many of the problems, but that doesn’t change the fact that both are incredibly painful to use. (Yes, I use a Mac, no the Mac is not perfect, but pretty much everything I use is vastly more pleasant to use than either of these apps.)  Both have obtuse and inconsistent user interfaces, rampant graphical artifacting, and they’re both just plain ugly.  That said, I was able to install both, work out how to draw a small scematic in each without requiring instructions, edit them to correct mistakes, and export them to PostScript (and convert that to PDF).  Both meet my needs fairly well, though I’ll have to re-test both when I try to design a circuit board.  Overall I’m still looking for a solution I actually like, but, despite a rocky start, gEDA seems to suck less; more detail after the jump. (more…)