ER-MIDI-CV4-02

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ER-MIDI-CV4-02 P1080867-720px.jpg

Features[edit]

  • Eurorack 6HP, 3U module
  • Three card stack-up
    • Front Panel card
    • Controls card
      • 9 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) 0-4.096V Analog CV outs
  • GATE output (0-5V)
  • CLK output (0-5V)
  • TRIG output (0-5V)
  • Standard Eurorack 16 pin power header

Credits[edit]

Arduino Pins[edit]

  • 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

ArdruinoProMini-EBAY PART-720px.png

Connection to FTDI[edit]

  • Use FTDI-49MM card
  • Right angle 1x6 pins
  • Pinout
  1. GND
  2. CTSn (IN)
  3. VCC
  4. TX (OUT)
  5. RX (IN)
  6. RTSn (OUT)
  • Arduino Pro Mini Serial Connector
  • Marking matches FTDI cable pinouts/color codes

FTDI Cable Color Code.png

  1. BLK
  2. GND
  3. VCC
  4. RX
  5. TX
  6. GRN

Connectors[edit]

Processing Card Connectors[edit]

J1 - Eurorack Power[edit]

ER-MIDI-CV4-02 DB J1.PNG

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

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

ER-MIDI-CV4-02 DB J2.PNG

  • 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[edit]

ER-MIDI-CV4-02 DB J3.PNG

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

J4 - MIDI (to/from Controls card)[edit]

ER-MIDI-CV4-02 DB J4.PNG

  • J9 on Controls card
  • Pinout
  1. VCC (+5V)
  2. MIDI Out
  3. MIDI In
  4. GND

J5 - MIDI into RX[edit]

ER-MIDI-CV4-02 DB J5.PNG

  • Remove to use MIDI from Controls card

J6 - MIDI OUT/THRU Select[edit]

ER-MIDI-CV4-02 DB J6.PNG

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

Controls Card Connectors[edit]

J1 - CLK[edit]

  • MIDI Clock out
  • 0-5V, Digital

J2 - CV1 Out[edit]

  • Control Voltage out
  • 0-5V Analog Clock

J3 - CV2 Out[edit]

  • Control Voltage out
  • 0-5V Analog Clock

J4 - CV3 Out[edit]

  • Control Voltage out
  • 0-5V Analog Clock

J5 - CV4 Out[edit]

  • Control Voltage out
  • 0-5V Analog Clock

J6 - TRIGGER[edit]

  • MIDI Trigger out
  • 0-5V, Digital

J7 - GATE[edit]

  • MIDI Gate out
  • 0-5V, Digital

J8 - MIDI In[edit]

  • MIDI Input
  • TRS Type A

J9 - MIDI Out[edit]

  • MIDI Output
  • TRS Type A

J10 - CVs, GATE, CLK, TRIG[edit]

ER-MIDI-CV4-CTLS J10.PNG

J11 - MIDI[edit]

ER-MIDI-CV4-CTLS J11.PNG

Application[edit]

Download steps[edit]

  • Unplug MIDI in cable from front panel
  • Connect FTDI card with 1:1 cable
  • Download code in Arduino IDE
  • Disconnect FTDI
  • Connect MIDI in cable to front panel

Card Test Code[edit]

  • TestPotDigIOs - Test Digital Outputs (CLK, TRIG, GATE) and Speed Pot
  • ER_MIDI_CV4_04_TEST_DACs - Read pot, scale value. write to 4 analog outputs. Also, drive CLK, TRIG, GATE digital outputs

HAGIWO code baseline[edit]

  • SYNTHMIDICTL01.ino
    • Runs on Arduino ATMEGA328 (Arduino NANO or Pro Mini)
    • Used as baseline and converted to CircuitPython

Working Code[edit]

// V/OCT LSB for DAC
// ER-VCO-03 characteristics
//  PITCH ADJ knob roughly centered
//  0V = 93.08 Hz (roughly F2)
//  1V = 179 Hz (G3)
//  1.52V = 261 Hz (C4)
//  2V = 365 Hz (G4)
//  3V = 722 Hz (G5)
//  4V = 1.45 KHz (G6)
//  5V = 3.05 KHz (G7)
// Max output voltage of this card is 4.096V (4 octaves)
//  1mV per DAC count
// 12 notes per octave = 1/12V per note = 83.333 mV
// Steps are in 83.333 mV
// Table counts up by integer steps - rounded 83.333 mV

3D Views[edit]

  • Controls card side view

ER-MIDI-CV4-02 CTLS SIDE-3D.png

  • Processing card side view

ER-MIDI-CV4-02 DB SIDE 3D.png

Videos[edit]

  • HAGIWO MIDI to CV module

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

Issues[edit]

Rev 2[edit]

  • Daughtercard
    • Fixed missing connection D14 anode to GND
    • Moved R1 down a bit
    • Haven't ordered yet (2022-12-04)

Rev 1[edit]

  • Daughtercard
    • Missing connection D14 anode to GND
      • Add wire D14-Anode to D9-Anode
    • R1 is close to Arduino socket (fit OK, but tight)

Assembly Sheet[edit]