ER-MIDI-CV4-02

Features

• Eurorack 6HP, 3U module
• Three card stack-up
  • Front Panel card
  • Controls card
    • 8 Jacks, 1 pot
  • Processor card
• Arduino Pro Mini
  • 16 MHz
  • 5V
• MIDI In
  • TRS Type A jack MIDI In
  • USB MIDI In if external FTDI card/cable
• (4) 0-5V Analog CV outs
  • MCP4822 12-bit D/A - SPI Interface
    • MCP4822 Datasheet
  • D/A has built in output opamps, set gain to 2X
    • Outputs may only swing 2x 2.048V or 4.096V (4 octaves)
• GATE output (0-5V)
• CLK output (0-5V)
• Standard Eurorack 16 pin power header

Credits

• Adapted from HAGIWO's MIDI to CV module
  • Translate from Japanese to English using browser
  • Has 4 Analog Outputs instead of 2
  • Arduino Pro Mini instead of Arduino NANO
• Based also on SYNTH-MIDI-CTL-01

Arduino Pins

• Arduino Pro Mini

• Analog 1 - Speed Adjust POT
• A4 = SDA
• A5 = SCL
• D8 = LDAC1* to CV_1, CV2
• D9 = LDAC2* to CV_3, CV_4
• D13 = SPI CSK to both ADCs
• D11 = SPI MOSI to both ADCs
• D10 = SLAVE SELECT to both ADCs

Connectors

• As referenced from Processing card

J1 - Eurorack Power

• 2x5 IDC connector
• Only uses +12V (and GND)
• Diode polarity protected, series resistor

J2 - CVs, GATE, CLK (to/from Controls card)

• J12 on Controls card
• Pinout

1. VCC (+5V)
2. GATE
3. CLK
4. CV4
5. CV2
6. POT
7. CV1
8. CV3
9. TRIGGER
10. GND

J3 - I2C

• Pinout

1. SCL
2. SDA
3. VCC (+5V)
4. GND

J4 - MIDI (to/from Controls card)

• J9 on Controls card
• Pinout

1. VCC (+5V)
2. MIDI Out
3. MIDI In
4. GND

J5 - MIDI into RX

• Remove to use MIDI from Controls card

J6 - MIDI OUT/THRU Select

• 1-2 = MIDI Thru
• 2-3 = MIDI out from Arduino TX

Application

• Use with ER-VCO-03 to control pitch and Mod
  • CV_1 = V/OCT
  • CV_2 = MOD
• Use with ER-VCA2-01 to control amplitude

HAGIWO code baseline

• SYNTHMIDICTL01.ino
  • Runs on Arduino NANO
  • Used as baseline and converted to CircuitPython

3D Views

• Controls card side view

• Processing card side view

Videos

• HAGIWO MIDI to CV module

• Midi2CV - A utility module for converting MIDI messages to CV] Benjie Jiao - DIY Modular Synth Project_

Assembly Sheet

• ER-MIDI-CV4-02 Rev 1 Assembly Sheet