❗️ This is now deprecated in favor of https://github.com/ghostintranslation/motherboard
MOTHERBOARD6 is a 6 controls Teensy 4.0 + audio board platform. It is part of a familly of 3 variations of the same platform, MOTHERBOARD6, MOTHERBOARD9 and MOTHERBOARD12.
The MOTHERBOARDs follow a column design of 3 inputs per column and 2, 3 or 4 columns for a total of 6, 9 or 12 inputs and as many LEDs.
What makes it interesting is how the inputs are stacked to allow for any combination of pushbuttons, potentiometers, encoders and CherryMX. The footprints of those 4 type of inputs are stacked together so that each spot can be any of them, and only one pcb can be used for many different modules. It is a modular platform.
MOTHERBOARD's the physical format is following Eurorack standard, but it doesn't use CV/Gates and patch cables and has rather midi and audio jacks in the back. It is oriented for live performance more than experimentation.
A MOTHERBOARD come with 2 boards, one on which the inputs and leds are soldered to (A), and one on which the Teensy and other components are soldered to (B). Both boards are attached together by multiple pin headers.
I sell the PCBs if you wish to build it. You can get them here: https://ghostintranslation.bandcamp.com/merch/motherboard6-pcb-3
Due to the use of the audio board, the available pins are very limited. Looking at the Teensy audio board page (https://www.pjrc.com/store/teensy3_audio.html) we can see only pins 0, 1, 2, 3, 4, 5, 9, 14, 16, 17, 22 are available. Also looking at Teensy pins (https://www.pjrc.com/store/teensy40.html), only 14, 16 and 17 from this subset are analog inputs.
So the use of multiplexers is required to be able to read pushbuttons, potentiometers, encoders or to lit leds. In addition, a matrix design is used for the encoders to reduce the number of inputs required as each of them has 3 inputs.
On this design, pin 22 will switch from input to output very fast to lit the leds and read the inputs.
Dependng on the type of inputs used, not all multiplexers may be required.
- IC1 = Mux for potentiometers
- IC2 = Mux for LEDs
- IC3 = Mux for encoders
- IC4 = Mux for encoder's switches and pushbuttons
- IC5 = Main mux, always required
- IC6 = Mux for midi channel dipswitch
A few examples:
If you only use potentiometers, you won't need IC3 and IC4. Or if you don't have any led you won't need IC2. Or if you don't want to use a dipswitch to select the midi channel, you won't need IC6.
Here is the list of components you will need:
1 MOTHERBOARD6A pcb
1 MOTHERBOARD6B pcb
1 Teensy 4.0
1 Teensy audio board (optional)
1 5 pins male header
5 14 pins male header
5 14 pins female header
2 14 pins long female header (see note)
2 3.5mm jack connectors
1 resistor ~ 22ohm
1 4 positions dipswitch (optional)
x CD4051 multiplexers
x DIP16 IC sockets (optional)
x LEDs
x vertical linear 10k potentiometers
x vertical rotary encoders
x D6 pushbuttons
x CherryMX keys
Note: long female headers are used to stack the audio board to Teensy and connect Teensy to the MOTHERBOARD
Here is a list of useful links to get these parts: https://github.com/ghostintranslation/parts
In order to run any sketch on the Teensy you have to install Arduino and the Teensyduino add-on. Follow the instructions from the official page: https://www.pjrc.com/teensy/teensyduino.html
- Then open
Synth.inolocated in theSynthfolder of this repo. - In the Tools -> USB Type menu, choose
Serial + midi. - Plug the Teensy to your computer with a micro USB cable. (It's ok if the Teensy is on the module)
- Then just click the arrow button to upload the code
The MIDI input and output jacks are directly connected to the Teensy serial input and output. That means there is no protection against voltage or current. It is primarily ment to connect 2 of these modules, or 2 Teensy together. If you want to connect something else to it make sure to provide a maximum of 3.3v and 250mA.
Copy the Motherboard6.h in your project. Then just include it and start using it.
Motherboard6 is a singleton, so to instanciate it you do this:
Motherboard6 * motherboard = Motherboard6::getInstance();
Then in the Setup you have to call the Motherboard's init with the type of controls you have on the board:
// 0 = empty, 1 = button, 2 = potentiometer, 3 = encoder
byte controls[6] = {2,2, 2,2, 2,2}; // From left to right and top to bottom
motherboard->init(controls);
Then in the loop you have to call the Motherboard's update:
motherboard->update();
LEDs are controlled by setting their status according to:
- 0 = Off
- 1 = Solid
- 2 = Slow flashing
- 3 = Fast flashing
- 4 = Solid for 50 milliseconds
- 5 = Solid low birghtness
void setLED(byte ledIndex, byte ledStatus);
The first parameter called binary is a number that will be represented in binary with the least significant bit on the left. Ex: 9 = 100100 => LEDs of indexes 0 and 3 will be lit.
void setAllLED(unsigned int binary, byte ledStatus);
void toggleLED(byte index);
void resetAllLED();
- In the case of a potentiometer it will return between 0 and 1023.
- In the case of a button it will return 1 for push 0 for release.
- In the case of a rotary it will return the number of rotations since the last get.
int getInput(byte index);
Because an encoder is like 2 controls, the rotary and the switch, we need this function in addition to getInput.
int getEncoderSwitch(byte index);
The value depends of the ADC resolution, which is 10 by default and can be set to 12 or 8.
With a resolution of 10 bits, the maximum value is 1023.
int getAnalogMaxValue();
It should always be 0, but if your potentiometers are not that accurate they could return bigger than 0 as a minimum value. You could then change the return value of that function to match the real minimum. This will ensure that getInput always returns a minimum of 0 and a maximum of 1023 that corresponds to the actual min and max.
int getAnalogMinValue();
This is set by the dipswitch and read only once when powered on. If no dipswtich is soldered then the channel will be 1.
byte getMidiChannel();
Callbacks are a very good way of handling inputs. Using them instead of reading getInput in the loop will make your code easier to read and maintain.
This will be triggered only once on release.
Can be used for a button and for a rotary switch.
fptr is a void() function.
void setHandlePress(byte inputIndex, PressCallback fptr);
This will be triggered only once on release after a long press. If an input has both Press and Long Press callbacks then only one of them will be triggered according to the duration of the press.
fptr is a void() function.
void setHandleLongPress(byte inputIndex, LongPressCallback fptr);
This will be triggered once every time a turn is detected.
fptr is a void(bool value) function. value is either 0 for a left rotation or 1 for a right rotation.
void setHandleRotaryChange(byte inputIndex, RotaryChangeCallback fptr);
Here are the dimensions for any module size. Every column is following the same rules. So the size of a module depends on the number of column. 2 columns = 2x20mm = 40mm, 3 columns = 3x20 = 60mm ...
- Encoders are skipping turns sometimes
- Maybe test with faster multiplexers
This project is licensed under the MIT License - see the LICENSE.md file for details
You can find me on Bandcamp, Instagram and Youtube, as well as my own website:
https://ghostintranslation.bandcamp.com/
https://www.instagram.com/ghostintranslation/