Since my last post, our team has completed the final project. On Monday, we conducted the final demo, and just today, we submitted the lab report. Here is the final layout of the keyboard:
As you could see, my lab partner Whitney did a fine job organizing all the electronics, securing them to the keyboard. He made a nifty stand for the LCD display using plastic risers and hot glue. As you can see, we’re now using a Seeeduino board instead of the Arduino board — which is for the most part the same circuit, except it has a few added features and a slightly different board design. Also, note the use of the infrared optoelectronic distance sensor on the lower left side of the board. We decided to make the circuit a little more complex, so we added what is known as a D-beam, and it is used in a lot of Roland synthesizers, for instance, the Lucina AX-09 (video — WARNING: click only if you can handle extremely cheesy product infomercials). We implemented the D-beam using a Sharp 2Y0A21 distance sensing device, and we freed up an analog input on the keyboard controller for the analog sensor signal. We programmed the keyboard to process the same range of pitch bend as the Roland model in the video clip I posted above, which is about a whole step of range. The analog data coming from the sensor is really noisy, so it adds kind of like a chorus effect to the sound quality which we really couldn’t filter out very well.
We reconfigured the entire keyboard to run off of USB power, which is 5 volts, 2.5 watts. The entire circuit ended up only running off of 1.2 watts. We could probably cut down on power even more, especially with the LCD, which consumed a half a watt.
Since our synthesizer output standard MIDI out, it was compatible with another group’s project, which was designing the actual synthesis. In the following video, I used our project as a keyboard interface to their synthesizer using our MIDI output. Here is a video I shot of us connecting our projects together:
The overall cost of all the circuit components is just short of $100, which is more than the original keyboard was worth. We actually probably had the cheapest circuit out of all the groups. If we had more time, ideas I had for further developing our design would be to add a recording / playback feature, which I could very easily do with an SRAM chip, integrating the controls into the LCD menu. Since we ended up getting the synthesizer chip working in serial mode, all the parallel signals could be freed up to drive an SRAM chip. Here are the files that we created for our project:
Some of the other groups in the class ended up creating really cool embedded projects. Perhaps the most expensive project implemented was a series of robots which implemented swarm intelligence. The robots would scan an area for a target of a specific color, and when it found the target, it would wirelessly broadcast a message the other robots that it found the target, and emit infrared radiation in all directions. The other robots would then turn and locate the robot, and move in towards it. Here are some photos I took of their project: