Apologies in advance as I spend more time remembering to be a musician, not a technology blogger. I bought a few MIDI files during the last Yamaha Musicsoft sale and I’m massaging them into PJ-approved backing tracks. Plus, I’m learning about the joys of the key of D-flat!
I posted the Beat Box drum machine project to the littleBits invention site. The littleBits project format is more “step-by-step” than the document that I post on this site. The step-by-step directions should help anyone interested in building the Beat Box without diving into the details of the design. Of course, you can still check out the Beat Box design at this site, too. (MP3 Demo)
Just so you don’t think I’ve been totally idle, I tried adapting the code to sing “Do-Re-Mi” solfege. This involved recording and editing my voice. I used my old trick of singing through the Yamaha PSR-S950 vocoder in order to pitch correct my rocky intonation. I had to lower the sample rate to 11,025Hz in order fit all eight syllables into the very small Arduino program memory (PROGMEM). Unfortunately, I cannot get clear audio at 11,025Hz. There is this raucous buzz which cannot be eliminated through filtering. I suspect that the problem is in the PWM generation itself. The waveforms play back fine at 22,050Hz, sounding like chipmunk solfege.
After hitting that brick wall, I’ve decided to take a different approach which has better long term possibilities. I’ve ordered a handful of MCP4921 12-bit SPI DAC ICs and intend to try them with the littleBits Arduino module. The littleBits Arduino is a Leonardo where the SPI interface is the (unpopulated) ICSP pads. The new approach requires soldering, but it should be worth the effort. Stay tuned.
Still tempted by the Reface CP and YC. But, $400USD street? C’mon, Yamaha!