Nurdspace eurorack raspberry pi hat: Difference between revisions

From NURDspace
Line 19: Line 19:


* 2x analogue in (10 bit resolution, [https://cdn-shop.adafruit.com/datasheets/MCP3008.pdf MCP3008], 0.5mA max power consumption)
* 2x analogue in (10 bit resolution, [https://cdn-shop.adafruit.com/datasheets/MCP3008.pdf MCP3008], 0.5mA max power consumption)
** using https://github.com/scottellis/mcp3008-speedtest I saw sample-speeds of 13k upto 36k samples per second (on a raspberry pi 2) by tweaking the block-size and the bus-speed (of course)
* 2x analogue out (12 bit resolution, [https://ww1.microchip.com/downloads/en/devicedoc/22250a.pdf MCP4922], 0.7mA max power consumption )
* 2x analogue out (12 bit resolution, [https://ww1.microchip.com/downloads/en/devicedoc/22250a.pdf MCP4922], 0.7mA max power consumption )
* 2x gate in
* 2x gate in

Revision as of 00:17, 16 July 2022

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

  • 2x analogue in (10 bit resolution, MCP3008, 0.5mA max power consumption)
  • 2x analogue out (12 bit resolution, MCP4922, 0.7mA max power consumption )
  • 2x gate in
  • being able to also run without a real eurorack powersupply (it produces its own -5V by using an ICL7660)
  • based oninspired on https://micro-twin.com/hardware.php

Second version

  • more analogue in, 12 bit resolution by using a MCP3204 or MCP3208 or so?
  • more analogue out, gates in
  • also gates out
  • 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

  • double check 3.3V power consumption of parts
  • check if a MCP6001 opamp can withstand not only -5/+5 but also -12/+12V


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

falstad circuitjs simulation

The opamp needs +5 and -5 for power.

calculated with https://masteringelectronicsdesign.com/differential-amplifier-calculator-2/

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