oscillator

Digitization of music and “perfect tuning” has removed the possibility to recognize the production year of a record after the loudness war. Mastering people do what they can but giving them midi sequences does not provide them with much. Producing those lightly detuned frequencies in conjunction with tuned sources of sound (obviously) is one way to get back to actual experiments in electronic music.

The same applies to components of an instrument. Using them in unconventional ways exposes interesting behaviors.
I’m not proposing unstable wobbly controls and overdriving circuits just to hide bad quality parts, but sound generators not constrained at a tempering scale or forced to conform with a tuning system. There are plenty thoughtfull designs addressing tuning either with V/OCT inputs on analog chips or midi-capable oscillators so the spectrum is full. Slowly the chips are getting so much faster and menu driven embedded systems with SOC’s on a Eurorack Module are becoming more and more common. Cizzle from ALM has chords but also a nice phase distortion and ornament & Crime is basically a Control Voltage arbitrary generator.

An old interview from Frank Zappa commenting guitar solos amplified that thought. He pointed how much commercialized music was (at 1984) and due to that guitar solo’s where all prerecorded and spotless on live performances. He didn’t prerecord any solo played on concerts. Instead he knew “roughly how long he’s got” and had to decorate a piece of time (the full interview is really worth it). I need those solos in electronic music so this instrument will try to bring those back.

The development is happening on the open. This means that I rebase master and break stuff during that phase. The main structure and idea of what the machine will be capable of is there but polishing and final touches aren’t.

Currently I’m testing the circuit on a breadboard with cables all around. Documentation is not existing for now but variable names are long and descriptive and there is no hidden pointers in typedefs. What you see on a declaration of a function is the actual argument passed.
Structures are storing all the information used by a specific part in the codebase. NCO stuff handled in nco.c/h. All data are globally initialized with their startup/default values in a manual way in include/interrupter.h and src/interrupter.c hosts the entry point.
All modification of modes and frequencies (the misleadingly named for musicians tune(…) function) and higher level procedures are in overseer.c/h. I can continue but you get the idea of how the project is organized from viewing the folders.

When all computation steps finish, the interrupts handle the DAC trigger and ADC sampling methods. The configuration for those as well as some basic gpio and flash stuff, to help me with the capitalization and weird volatile’s everywhere of ST’s API, are in the drivers folder.

There are no 3k LOC generated files so you could read them. Amazing I know…

As a build system Meson for simplicity, a Makefile could be also adequate (we just compile files and link them together) but Meson handles cross-compilation nicely so we ended up here.

We will make the schematics available for everyone but pcb design and signal integrity are difficult to understand and sustaining a business around free material is hard by design. So anyone could build a PCB but supply chains and sourcing has become a draining process in the beginning. We will make our best to select parts that are not at the sunfall of their life but we can do only as much.

Until now you could inspect the design at Autodesk’s online 3D viewer here. There will be more footage and video showcasing the capabilities of the device but something to see is better than mere words on a page at a hosted website.