A homebuilt MIDI controller/keyboard built around an old broken keyboard using the Teensy microcontroller
By mit-mit
This code runs on a Teensy 3.1 and connects to a 49 key piano keyboard using a switch matrix layout and several input controls (including buttons, a potentiometer, LCD two-line character display, two-axis joystick and neopixels) and outputs MIDI messages across the Teensy USB.
For details on the hardware and contruction process, see: http://randomprojectlab.blogspot.com.au/2017/12/teensytune-teensy-based-midi.html
Required libraries:
Adafruit Neopixels (used to run neopixels): https://github.com/adafruit/Adafruit_NeoPixel
Adafruit MCP23008 (used for port expander, providing sufficient button inputs): https://github.com/adafruit/Adafruit-MCP23008-library
LiquidCrystal_I2C (used to drive the two-line display): https://www.dfrobot.com/wiki/index.php/I2C/TWI_LCD1602_Module_(SKU:_DFR0063)