EuroPi VS zoxnoxious

Hi all, I'm making a Eurorack sequencer module with 4 pitch CV outputs (NOT audio) and I've noticed that DACs are kind of a pain due to being expensive, SMT-only & still requiring buffering with op amps. I figure that a good alternative would be to buy a Raspberry Pi Pico for $4 which will give me 8 PWM outputs that I would then hook up to an output stage like the one in the europi (shown here: https://github.com/Allen-Synthesis/EuroPi/blob/main/hardware/EuroPi/schematic/europi_schematic.pdf)

Bom has links for sourcing parts

Up until now I've been using the analog input stage from the EuroPi schematic as my model for a CV in. You can see it here:

There is no super cheap way to get a lot of analog outputs from an MCU. Filtered PWM is your best bet for cost effectiveness (I recommend looking at the EuroPi from allen synthesis : https://github.com/Allen-Synthesis/EuroPi). Otherwise if PWM doesn't work for you, you'll need to look into DAC chips. The MCP4728 is a good spot to start, it's 12-bit and has 4 channels: https://www.adafruit.com/product/4470. Since it's I2C controlled you can have multiple of them on one bus. Maybe looking into a 16 channel PWM driver for a lot of outputs: https://www.adafruit.com/product/815. Hope this helps!

The project is completely open-source and open hardware, and the contributors together have made this big list of scripts that you can run using a menu system!

The project is entirely open-source but I do also sell the Panel+PCBs on my site!

Check out the EuroPi project https://github.com/Allen-Synthesis/EuroPi

EuroPi Turing Machine script is feeding the Uncertainty cv input with pulse 1 opening an envelope on Maths for voice 1 & 2, pulse 2 opens the second Maths envelope for sub osc voice 3. A little delay added for texture. That's pretty much it!

EuroPi - A reprogrammable Eurorack module based on the Raspberry Pi Pico

The patch.init() is still a great way to start, but you could save some money ditching the audio i/o and build yourself an EuroPi. However, that requires DIY, obviously.

And source is here: https://github.com/brer-rabbit/zoxnoxious

I've got a similar project, though where you're card interface is analog I went the opposite direction and routed digital in. So the card receives digital control, has onboard DAC, and controls whatever analog components (3340 so far) from there. So not a complete voice like you've got; I'd need additional cards to come up with that. But the upshot if you're not routing all the analog controls into the card. Pretty cool that you've got a complete voice on a card, that's great. Wonderful filter. We ought to compare notes. :) https://github.com/brer-rabbit/zoxnoxious