Nurdspace eurorack raspberry pi hat

From NURDspace

Jump to: navigation, search
Eurocrack-hat
Nurd-euro-pi.jpg
Participants
Skills Electronics, Programming
Status Active
Niche Music
Purpose Fun
Tool No
Location
Cost
Tool category Electronics,Eurorack

Eurocrack-hat

Nurd-euro-pi.jpg {{#if:No | [[Tool Owner::{{{ProjectParticipants}}} | }} {{#if:No | [[Tool Cost::{{{Cost}}} | }}


specifications

This will be an interface between eurorack signals ("control voltage" and "gates", all in the Doepfer range of -5V...+5V) and a raspberry pi (a "hat"). For that, the hat will have an ADC and a DAC (multichannel) connected via SPI (multichannel and not multiple devices as the rpi has only 2 SPI channels).


First version

Second version

bugfixes

  • CV-out range fix (caused by parallel resistors)

xth version

  • more analogue in, 12 bit resolution by using a MCP3204 or MCP3208 or so?
  • more analogue out, gates in
  • LEDs for gate status
  • pins for neopixel connection (gnd + signal)
  • I2C breakout (for e.g. small displays)
  • SPI extender? (does something like that exist?)
  • SMD technology maybe?

schematics

component selection


to do

0...3.3V to -5/+5V

falstad circuitjs simulation

The opamp needs +12 and -12 for power.

Schematic thanks to Kartoffel.

Circuit-20220715-2051.png

-5/+5V to 0...3.3V

falstad circuitjs simulation

The opamp needs +3.3V and 0V for power.

Circuit-20220709-1750.png


software

  • I've chosen a DAC and ADC with SPI to easily connect them to a raspberry pi.
  • gate signals can be toggled via e.g. wiringpi


history

  • 28/7/2022: ordered a few test-pcbs at jlcpcb
  • 5/8/2022: problem in op-amp circuit for cv-out (output range incorrect due to resistor sharing in bias input)
 
Our site is hosted by Site4U
Site4U
Our connectivity is made available by BIT
To BIT's website