So I’m working on a prototype for my very first module design based on a Raspberry Pi Zero. It really only needs USB host to Linux (I’m leveraging some
evdev goodness), then some CV outs.
The very first prototype is dirty but works well enough with RC-filtered PWM pins going to a TL072 dual opamp to bring the levels up to CV levels.
Obviously, there are some issues:
- It’s dirty
- It’s noisy
- There are only two CV outs
Of course, I’m considering going forward to the next prototype, which I’d like to integrate a proper DAC with. Since I know fairly little about the matter, I went and dived a bit into the great resources that is @pichenettes’s eurorack repo.
Now, I think the module could handle 8 CV outputs, so the Stages DAC caught my eye . While I’m confident I could hook it up to the Pi and produce the correct levels, I worry that I could not handle timing correctly, so I’m not sure how I could generate proper LFOs.
I didn’t really understand how Stages’ processor handled the timing of that DAC, but I’m worried that since the Pi don’t have super precise control over their GPIOs, that I couldn’t get a stable clock.
Obviously, I could go with a standard I2S stereo DAC, and it would be less noisy, but there still would be only two channels.
Offloading the DAC control to a separate microcontroller seems like overkill, but maybe I’m wrong ?
Do you know of a better suited solution ? Maybe a different DAC and/or embedded Linux board ?