Saturday, August 21, 2010

Lego Keyboard for Electronic Organ

This morning I got a first draft of real organ software running on the 16f684 / programmable sound generator circuit I've been building. Once I got the software up and running I tested it with just a probe, then very quickly wanted a keyboard. I have plans to make a permanent one from wood and brass, but I wanted something NOW. So I spent about 20 minutes in my son's room and came up with this lego creation. The only parts not stock legos are the reed switchs and magnets for the circuits. I got really lucky and the magnets I had were a perfect press fit into the bottom of the lego keys.

I hot glued the reed switches to some poster board which I then glued to a stack of legos. A rubber band provides spring back for the keys that pivot on a lego shaft. I soldered wires from the reed switch out to a header I could plug into my bread board. When you push a key the magnet attached to it closes the reed switch beneath the key. The micro reads the state change and commands the sound generator to produce the note. Right now it only has one voice.

Here's a shot of the breadboard. The big 40 pin bug is the sound generator and the little one to the right is the 14 pin 16f684 pic micro. The board to the right is my pic programmer, and to the left is my arduino. The big battery and small board in the top right corner is my portable 5 volt power supply. With this package and my laptop I develop hardware and software while I ride the bus to work in the morning.

Sunday, August 15, 2010

Electric Organ Prototyped

A couple weeks back I bought an old programmable sound generator chip from BG Micro. I got a breadboarded circuit working this morning, using a 16f684 as a controller. My plan is to build a simple digital synthesizer, but right now it's just running a simple hard coded loop that sounds like a car alarm.

Sunday, August 8, 2010

Scrolling Sign Software for the Big Blink

While on vacation a week ago I had a chance to design, code, and test scrolling sign software for the big blink charlieplexed display I built. Here's a video of the resulting test program.

The display is memory mapped to a buffer in RAM with the main loop updating the buffer with scrolling characters, and an interrupt routine lighting the pixels. It still needs some optimization to smooth out the blinkiness, and eliminate a race condition that crashes the code after some run time, but I'm pretty happy given it only took about 8 or 9 hours work.

Detroit Maker Faire Flickr Photostream

I've posted most of my stills from the Maker Faire on Flickr. Maybe later I'll get around to posting some of the cooler video on utube. Enjoy.

Tuesday, August 3, 2010

Detroit Maker Faire Pics

On Saturday the 31st I attended the Detroit Maker Faire. It was awsome - way to much to tell, so I'll just pick a few things I really liked.

My favorite was the Iron pour - that ladel has 90 pounds of molten iron in it!

This guy built a physical drum machine from a MIDI sequencer, a highlyliquid MIDI decoder, toy motors, and junk. Coolest drum machine I've ever seen. Sorry the video is small - my camera accidently got switched to "compact" mode.

More later...