octacon

A midi controller tailored for bitwig with 8 encoders, 8 knobs and displays.

hardware

• raspberry pico 2
• 8 endless dual wiper potentiometers with buttons (RV142FPF-40B1-15F-0B20K-004)
• 3 analog multiplexers (e.g. CD74HC4051)
• 8 NeoPixel LEDs (WS2812x)
• 2 128x64 OLED displays connected via SPI
• 1 capacitive touch control

The pcb subfolder has the the schematics and the pcb files for easyeda. You should be able to import them into the Std Edition.

enclosure

The 3d subfolder has openScad files and rendered STL for 3d printing.

The front_test.scad is mostly for prototyping:

Front view	Side View

midi implementation

aseqdump -l | grep Octacon
 32:0    Octacon                          Octacon MIDI 1
aseqdump -p32:0
Source  Event                  Ch  Data
 32:0   Control change          0, controller 9, value 51
 32:0   Control change          0, controller 9, value 52

control changes

The encoders send 7bit values on cc 9 to 16. In 14-bit mode, the lsb is send on cc 41 to 49. The encoder buttons send values {0=off, 64=on} on cc 17 to 25.

sysex

Since Octacon uses usb midi and is a hobby project, we're using the 7D (prototyping, test, private use and experimentation).

The following commands are implemented:

• 00: (recv) parameter names: 00 + <ix> + <len> + <name>
  • id: 0...7
  • len: len of name, truncated to fit the display
  • name: ascii string data
• 01: (recv) pretty parameter value: 01 + <ix> + <len> + <name>
  • id: 0...7
  • len: len of name, truncated to fit the display
  • name: ascii string data
• 02: (recv) daw connected? : 02 + <connected>
  • connected: 0 = off, anything else = on
  • when off, parameter names and pretty values are generated

(TODO: document additional cmds)

Code

Controller

The code uses platformIO. See platformio.ini for the used libraries.

alias pio=$HOME/.platformio/penv/bin/pio
pio test

DAW Extensions

The daw extension for Bitwig is written in java.

cd daw/bitwig
mvn install
cp target/Octacon.bwextension ~/Bitwig\ Studio/Extensions/

Debugging

Since we're using usb-midi, we can't use it for serial logging at the same time. I am simply using a nodemcu esp8266 as serial2. On the nodemcu connect EN to GND to disable the ESP. Then connenct the nodemcu to the pico2 as follow:

nodemcu esp8266	raspberry pico2
GND	GND
3.3V	3.3V (optional)
TX	UART1 TX, pin 6
RX	UART1 RX, pin 7

Now plug the nodemcu to usb and open /dev/ttyUSB0 to see the serial log.

Links

I've got inspiration from many other places. Let me mention a few similar projects:

• Ottopot