Sunday, November 22, 2015
Here's how to build a very cheap eight pot MIDI controller. This is easily expandable to sixteen pots.
The required hardware include eight pots (10k linear), Teensy (2.0, 3.1, 3.2 or LC will work just fine), 4067 multiplexer, two breadboards and breadboard jumper wires.
Put the Teensy and the 4067 multiplexer on the breadboards. Connect ground from the Teensy to gnd and en on the 4067. Connect 3.3V or 5V from the Teensy to VCC on the 4067. Connect Teensy pins 0, 1, 2 and 3 to 4067 pins S0, S1, S2 and S3 respectively for the address bus pins. Connect sig from the 4067 to analog input 0 on the Teensy. Pinout for the Teensy can be found here.
Connect the outside leg of each pot to ground. Connect the other outside leg of each pot to 3.3V or 5V. Connect the middle leg of each pot to the input channels of the multiplexer, from 0 - 7.
Up to sixteen pots can be connected to the 4067 multiplexer. Additionally multiplexers can be added for more than sixteen pots.
An example Arduino sketch can be downloaded here. Please note that the correct board must be selected. The USB type must be set to MIDI.
The Teensy will show up as a MIDI device automatically. Pots 1 - 8 are mapped to MIDI CC controller numbers 0 - 7 on MIDI channel 1.