AMITS-EXPRESSO: Programmable USB MIDI Expression & Sustain Pedal Converter

Project Description:

AMIT-EXPRESSO is an Arduino-based project that transforms a standard expression pedal into a programmable USB MIDI Foot pedal. It also incorporates a sustain/damper pedal input. My Primary use was to use with Akai Force but it also works with other gear/ios/pc/mac. The project is designed to be used with an Arduino Micro Pro (Leonardo) board.

I directly converted one of my Nektar NX-P Expression Pedala into Usb Midi Pedal by removing its original cable in putting the arduino board with a micro usb cable attached to it inside the pedal itself. However you can use this with any pedal by using a stereo input jack and wiring its three pins (tip , ring and sleeve) as per the wiring diagram image. and mounting that a along with arduino controller and a sustain pedal jack into some box. (use a plastic or insulated box for sustain jack (mono audio jack) so it does not short with ground of expession jack).

Key Features:

• Expression Pedal Input: Converts analog expression pedal movements into MIDI Control Change (CC) messages.
• Sustain/Damper Pedal Input: Accepts a standard sustain pedal (switch) and sends MIDI CC messages accordingly.
• Programmable CC Assignments: Allows users to assign different MIDI CC numbers to both the expression and sustain pedals via incoming MIDI messages.
• Dead Zone Adjustment: Includes a dead zone feature to compensate for low-precision potentiometers, ensuring accurate control.
• EEPROM Storage: Saves the user's custom CC assignments to EEPROM, allowing them to persist across power cycles.
• MIDI Input Handling: Receives MIDI messages to configure the pedal's behavior.
• USB MIDI Output: Sends MIDI messages over USB, making it compatible with most DAWs and MIDI-enabled software.
• Customizable Board ID: Allows for custom board ID and identifiers.

Wiring Diagram and Images

• Arduino Wiring Diagram

• Nektar NX-P Internal Wiring (if you want to install inside this pedal).

• Amits Expresso Nektar NX-P External View (with Sustain/Damper Pedal input jack).

Software Components:

1. Arduino IDE: The development environment for programming the Arduino.
2. Libraries:
   • MIDI Library: For sending and receiving MIDI messages.
   • USB-MIDI Library: For sending MIDI messages over USB.
   • EEPROM Library: For storing data in the Arduino's EEPROM.
   • ATPOTS.h/ATPOTS.cpp: Custom library for handling potentiometers.

Code Structure:

• AMIT-EXPRESSO.ino (Main Sketch):
  • Includes necessary libraries.
  • Defines pin configurations, MIDI channel, and other constants.
  • Defines the PEDALSTATE struct for storing pedal settings.
  • handleMidiInput(): Processes incoming MIDI messages to configure the pedal.
  • initPedal(): Resets the pedal to default settings.
  • setup(): Initializes pins, serial communication, and MIDI.
  • saveConfig(): Saves the current pedal configuration to EEPROM.
  • loadConfig(): Loads the pedal configuration from EEPROM.
  • handleSustain(): Reads the sustain pedal state and sends MIDI CC messages.
  • loop(): Continuously scans the expression pedal, handles the sustain pedal, and processes MIDI input.
• ATPOTS.h (Header File):
  • Defines the ATPOT class for handling potentiometers.
  • Defines the ATMIDICCPOT class, which inherits from ATPOT and adds MIDI CC functionality (Serial midi only).
• ATPOTS.cpp (Implementation File):
  • Implements the methods of the ATPOT and ATMIDICCPOT classes.
  • Includes functions for reading analog values, applying dead zones, mapping values, and sending MIDI CC messages.

MIDI Control Change (CC) Implementation:

• CC 33 : Sets the MIDI CC number (0-110) for the expression pedal. A value of 0 disables the expression pedal.
• CC 34 : Sets the MIDI CC number (0-110) for the sustain pedal. A value of 0 disables the sustain pedal.
• CC 35 : Resets the pedal to default settings if an even value is received.
• CC 36 : Saves the current configuration to EEPROM if a value of 127 is received.
• CC 37 :: Loads the saved configuration from EEPROM if a value of 127 is received.
• CC 38 : (values 1-50) Sets DeadZone of Expression Pedal.
• CC 39 : Sets Midi Output Channel for Expression Pedal.
• CC 40: Sets Midi Output Channel for Sustain Pedal.

Operational Flow:

1. Initialization:
   • The setup() function initializes the pins, serial communication, MIDI, and loads the configuration from EEPROM.
2. Expression Pedal Handling:
   • The POT.scan() function in the loop() continuously reads the expression pedal's analog value.
   • If the value changes, the changed() method in ATMIDICCPOT is triggered, sending a MIDI CC message with the assigned CC number and the mapped value.
3. Sustain Pedal Handling:
   • The handleSustain() function in the loop() reads the state of the sustain pedal.
   • If the state changes, a MIDI CC message is sent with the assigned CC number and a value of 127 (pressed) or 0 (released).
4. MIDI Input Handling:
   • The handleMidiInput() function in the loop() processes incoming MIDI messages.
   • If a Control Change message is received with the setEXP, setSustain, pedalReset, pedalSave, or pedalLoad CC numbers, the corresponding action is performed.
5. EEPROM Handling:
   • saveConfig() saves the current ECC, SCC and ID to the EEPROM.
   • loadConfig() loads the saved config from the EEPROM. If no config is found, it sets the default values and saves them.

How to Use:

1. Upload Code: Upload the AMIT-EXPRESSO.ino sketch to the Arduino Micro Pro using the Arduino IDE.
2. Configure CCs:
   • Send MIDI CC messages to the Arduino with the following CC numbers:
     • CC 33 (setEXP): Set the CC number for the expression pedal.
     • CC 34 (setSustain): Set the CC number for the sustain pedal.
     • CC 35 (pedalReset): Send an even value to reset to defaults.
     • CC 36 (pedalSave): Send 127 to save the current config.
     • CC 37 (pedalLoad): Send 127 to load the saved config.
3. Use with DAW: Connect the Arduino to your computer via USB. It will appear as a MIDI device. Configure your DAW to receive MIDI input from the Arduino.

License:

• Personal Use: Free to use for personal, non-commercial purposes.
• Commercial Use: Prohibited from building and selling this project for profit.

Author:

• Amit Talwar (www.amitszone.com)

---

NOTES

• Gemini AI was used to generate this documentation and Code Comments.
• If you want this arduino to show as Amits Expresso Midi controller or your desireable product name, copy the incluced hardware folder to your Documents/Arduino folder. If the Folder alredy exiss, copy the contents of included hardware folder to your Documents/Arduino/hardware folder. You can Ediit the boards.txt file to change the Name.