labsudmadnerd
Published © CC BY

Midi Keypad

Making music with a keypad? Seems like a weird idea! But we will see with the good software, we can even make an electric guitar out of it!

IntermediateFull instructions provided3,264
Midi Keypad

Things used in this project

Hardware components

Arduino Micro & Genuino Micro
Arduino Micro & Genuino Micro
×1
Adafruit Monochrome 128x32 I2C OLED graphic display
×1
Adafruit 36-pin 0.1" Female header - pack of 5!
×1
Adafruit 4x4 Matrix Keypad
×1

Software apps and online services

Arduino IDE
Arduino IDE

Hand tools and fabrication machines

Soldering iron (generic)
Soldering iron (generic)

Story

Read more

Schematics

Keypad Schematic

OLED Schematic

Code

Keypad Midi

Arduino
This is the code, at the moment I made this tutorial.
Please check the repository for the last version.
#include "MIDIUSB.h"

/* Settings for MIDI preset */
const byte ROWS = 4; //four rows
const byte COLS = 4; //four columns
const int NB_BUTTONS = ROWS * COLS;

const int PRESET = 8;
String preset_name[PRESET] = {"Du Riechst So Gut", "FF - Replica", "DrumKit", "A", "4", "5", "6", "B"};
int notes[PRESET][NB_BUTTONS] = {
  {38, 38, 39, 39, 43, 46, 38, 38, 48, 46, 45, 45, 57, 60, 60, 57}, //Preset 1
  {37, 40, 42, 39, 40, 38, 41, 40, 48, 46, 45, 45, 57, 60, 60, 57}, // Preset 2
  {35, 35, 38, 42, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53, 55, 57}, // Preset 3
  {0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0},  //Preset A
  {0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0},  //Preset 4
  {0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0},  //Preset 5
  {0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0},  //Preset 6
  {0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0}  //Preset B
};

int velocity[PRESET][NB_BUTTONS] = {
  {70, 70, 70, 70, 100, 100, 100, 100, 100, 100, 100, 100, 100, 100, 100, 100}, //Preset 1
  {70, 70, 70, 70, 70, 70, 70, 70, 70, 70, 70, 70, 70, 70, 70, 70}, //Preset 2
  {100, 100, 100, 100, 100, 100, 100, 100, 100, 100, 100, 100, 100, 100, 100, 100}, //Preset 3
  {0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0}, //Preset A
  {0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0}, //Preset 4
  {0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0}, //Preset 5
  {0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0}, //Preset 6
  {0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0}, //Preset B
};

const int velocity_button = 15; // The D key is used to change velocity if velocity changer is true
const int VELOCITY_CHANGE = 100; //Velocity when D is pressed (should probably be changeable)
bool velocity_changer[PRESET] = {false, true, false, false, false, false, false, false};

/* Keypad Init */
//https://github.com/Nullkraft/Keypad
#include <Keypad.h>
char keys[ROWS][COLS] = {
  {'1', '2', '3', 'A'},
  {'4', '5', '6', 'B'},
  {'7', '8', '9', 'C'},
  {'*', '0', '#', 'D'}
};

//Keypad pins
byte rowPins[ROWS] = {8, 9, 10, 11}; //connect to the row pinouts of the kpd
byte colPins[COLS] = {4, 5, 6, 7}; //connect to the column pinouts of the kpd
Keypad kpd = Keypad( makeKeymap(keys), rowPins, colPins, ROWS, COLS );

//Keypad state : 1 = DOWN 3 = UP (there are other state which are unused here)
unsigned int buttons_state[NB_BUTTONS] = {0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0};
bool preset_selector = false;

//Oled Display
#include <Wire.h> //I2C
#include <U8g2lib.h>
U8G2_SSD1306_128X32_UNIVISION_F_HW_I2C u8g2(U8G2_R0, /* reset=*/ U8X8_PIN_NONE);
String oled_line1;
String oled_line2;

//Preset
int selected_preset = 0;

void setup() {
  Serial.begin(115200);
  u8g2.begin();
  change_preset(selected_preset);
}

//Change preset and display it on screen
//You need to press "*" again to validate the preset
void change_preset(int preset) {
  if (preset < PRESET) {
    selected_preset = preset;
    oled_line1 = "-----Preset------";
    oled_line2 = preset_name[preset];
    printScreen();
    Serial.println(oled_line1);
    Serial.println(oled_line2);
  }
}

//Change what is written on the Oled screen using global variable
//oled_line1 and oled_line2
void printScreen() {
  //https://github.com/olikraus/u8g2/wiki/fntlist8x8
  u8g2.setFont(u8g2_font_7x14_mr);
  u8g2.firstPage();
  do {
    u8g2.setCursor(0, 14);
    u8g2.println(oled_line1);  // write something to the internal memory
    u8g2.setCursor(0, 30);
    u8g2.println(oled_line2);  // write something to the internal memory
  }
  while ( u8g2.nextPage() );
}

void loop() {
  if (kpd.getKeys()) {
    for (int i = 0; i < LIST_MAX; i++) // Scan the whole key list.
    {
      if ( kpd.key[i].stateChanged )   // Only find keys that have changed state.
      {
        buttons_state[kpd.key[i].kcode] = kpd.key[i].kstate;

        if (kpd.key[i].kstate == 1) { //DOWN
          Serial.print(kpd.key[i].kcode);
          Serial.print(":");
          Serial.println("1");

          //If key "#" is pressed
          if (kpd.key[i].kcode == 12) {
            //If preset selection is not active, we go to selection mode
            if (!preset_selector) {
              Serial.println("Selector");
              preset_selector = true;
              oled_line1 = "Selector";
              oled_line2 = "--------";
              printScreen();
            } else {
              //If preset selection is active, we return to midi mode
              Serial.println("Deselect");
              oled_line1 = preset_name[selected_preset];
              oled_line2 = "";
              printScreen();
              preset_selector = false;
            }
          } else {
            //If in selection mode we change preset
            if (preset_selector) {
              Serial.println("Change preset");
              change_preset(kpd.key[i].kcode);
            } else {
              //If in midi mode we play midi note
              key_down(kpd.key[i].kcode);
            }
          }
        }
        if (kpd.key[i].kstate == 3) { //UP
          Serial.print(kpd.key[i].kcode);
          Serial.print(":");
          Serial.println("0");
          // If key is up we send a midi note off
          key_up(kpd.key[i].kcode);
        }
      }
    }
  }
}

//Key down (pressed)
void key_down(int key) {
  int current_velocity = 100;
  //Serial.print(buttons_state[velocity_button]);

  //If velocity_changer (D) active
  if (velocity_changer[selected_preset]) {
    //If velocity changer pressed check for state 1 (down) or 2 (long down)
    if ((buttons_state[velocity_button] == 1) || (buttons_state[velocity_button] == 2)) {
      current_velocity = VELOCITY_CHANGE;
    } else {
      //If not pressed use velocity from preset
      current_velocity = velocity[selected_preset][key];
    }
  } else {
    //If velocity_changer not active, use velocity from preset
    current_velocity = velocity[selected_preset][key];
  }


  if (!velocity_changer[selected_preset]) {
    //Play note if velocity changer not set
    noteOn(0, notes[selected_preset][key], current_velocity);
  } else {
    //Else do not play note on velocity changer button (D)
    if (key != velocity_button) {
      noteOn(0, notes[selected_preset][key], current_velocity);
    }
  }

  //Display note and velocity on screen
  oled_line1 = preset_name[selected_preset];
  oled_line2 = "Note:" + String(notes[selected_preset][key]) + " " "V:" + String(current_velocity);
  printScreen();
  MidiUSB.flush();
}

//Key up (unpressed)
void key_up(int key) {
  //If velocity_changer
  if (!velocity_changer[selected_preset]) {
    noteOff(0, notes[selected_preset][key], 127);
  } else {
    if (key != velocity_button) {
      noteOff(0, notes[selected_preset][key], 127);
    }
  }
  MidiUSB.flush();
}

void noteOn(byte channel, byte pitch, byte velocity) {
  midiEventPacket_t noteOn = {0x09, 0x90 | channel, pitch, velocity};
  MidiUSB.sendMIDI(noteOn);
}

void noteOff(byte channel, byte pitch, byte velocity) {
  midiEventPacket_t noteOff = {0x08, 0x80 | channel, pitch, velocity};
  MidiUSB.sendMIDI(noteOff);
}

void controlChange(byte channel, byte control, byte value) {
  midiEventPacket_t event = {0x0B, 0xB0 | channel, control, value};
  MidiUSB.sendMIDI(event);
}

Keypad Midi code

This repository contains the arduino code, and svg schematics.

Credits

labsud

labsud

6 projects • 9 followers
madnerd

madnerd

6 projects • 7 followers

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