Work continues on the K-DSC-1 synth cube. I’ve settled on a microcontroller. This cube’s going to run an ARM processor, which is going to provide lots of processor overhead for a sweet well-featured sequencer. We’re planning some cool features. There will be a USB port, a standard MIDI jack, and the K-Connect jack for hooking cubes together. What’s really going to make this awesome though will be the interface. We’ve put some good thought into the button operation, but the killer will be the accelerometer tilt action. I’m really excited about how it’s going to turn out.
I’ve been learning quite a bit about working with ARM processors and open source tools for developing with them. Stay tuned for some technical posts about what I’ve found.
I’ll be setting up a booth at the Chicago Mini-Maker Faire this Saturday, April 21st at the Carl Shurz High School. Stop by, chat, and play with my creations. Rockit and Sprockit will be available built and in kit form at special Maker Faire discounted prices. Check out the poster for the event. I’m looking forward to meeting fellow nerds and makers.
I’m still plugging away, playing with wavetables and chasing out aliasing. The prototype boards are on order. In case you didn’t know, Advanced Circuits has a great deal for prototype pcbs. They have a $33 deal for double-sided pcbs up to 60 square inches. You end up getting 5 boards for about $150. Most other places are gonna charge you for tooling adding somewhere from $150-250 to the order. This is the only place I go for prototype boards. They get made in 5 days. The only limitation that makes it a little harder is that they won’t do slots with the deal. The only place on the board that this problem is the dc power jack. I’ve had to get a little creative to try to mount it in the board. One word: Dremel. Anyways, I’ll get the boards by the end of the week, test it into next and get the production run on order.
I was playing with it today after getting some wavetable work done and I made this bass line with a simple square wave and the bandpass filter. I was just banging out notes. F-U-N!
I’m feeling a bit of a fool at the moment. I know the process is learn-practice-fail many times before success comes. I’m still smarting a bit from the smackdown digital signal processing laid on my naive mind. You see I come from hardware land. Software is a relatively new undertaking. I’ve mastered getting microcontrollers to control things, but I’ve entered a new realm.
I took digital signal processing in school, but it wasn’t my favorite class. Now, I wish I would have really learned the stuff instead of studying for the final. I guess I didn’t really know how to do circuit design until I got my meats on some real projects with money on the line. Digital signal processing isn’t as straightforward as hardware design. There are many, many things about DSP which are not strictly common sense, until you’ve really internalized the rules. And there are many of those as well.
The fundamental thing that you encounter in DSP, and particularly in signal synthesis, is aliasing. Let’s just say that aliasing are on a first name basis, but we are not friends. There are many ways to synthesize digital sounds. I’ve started with what I thought was a straightforward way to make sounds. I’ll just use a standard wavetable type phase accumulator and I’ll just calculate the right sample. (Loud Buzzer Here) WRONG! What happens when you try to do this? Aliasing pure and simple. I’m going to go into exactly how this happens in my next post. I just wanted to update you on what I’m up to regarding the 8 Bit Synth.
Dorkbot rocked last night. Big shout out to Brett Ian Balogh who shared this sweet FM transmitter and provided us the opportunity to build it. This transmitter consists of only one transistor, three resistors, four caps, a homemade inductor coil, a variable capacitor, a 9V battery and some wires. For $15 dollars and about 1 hour of your time, you can transmit whatever you please some decent distances, like 50 feet or so. With a little modification and a little more power, you could broadcast a good distance. Say two 9V batteries and a higher power transistor, maybe beefier resistors and you’re on your way. It’s tuneable through a good bit of the FM band. I can easily swamp any station. In Chicago, we have some pretty lame radio. So, I’m thinking that this could provide a rolling cone of silence for your least favorite radio station. Not that I’m advocating any unseemly FCC violating behavior (wink wink).
Click through for talk about how it works and an image of the schematic.