ble_midi_4b.ino

ble_midi_4b.ino

/*


    BLE Midi 4 Buttons by Rémi Sarrailh

    Based on BLE_MIDI Example by neilbags
    https://github.com/neilbags/arduino-esp32-BLE-MIDI

    Based on BLE_notify example by Evandro Copercini.

    Creates a BLE MIDI service and characteristic.
    Once a client subscibes, press a button to play a midi note

    //Todo get CC commands

    //Essentials of the Midi Protocol https://ccrma.stanford.edu/~craig/articles/linuxmidi/misc/essenmidi.html
    //Note to hex (https://www.wavosaur.com/download/midi-note-hex.php)
    //http://chephip.free.fr/mus/midi.html

*/

/* BLUETOOTH */
#include <BLEDevice.h>
#include <BLEUtils.h>
#include <BLEServer.h>
#include <BLE2902.h>

#define SERVICE_UUID        "03b80e5a-ede8-4b33-a751-6ce34ec4c700"
#define CHARACTERISTIC_UUID "7772e5db-3868-4112-a1a9-f2669d106bf3"

BLECharacteristic *pCharacteristic;
bool deviceConnected = false;


/* BUTTONS */
int buttons_pins[4] = {18, 19, 21, 22};
int buttons_note[4] = {48, 50, 53, 55};
bool buttons_pressed[4] = {false, false, false, false};

/* MIDI */
#define NOTE_OFF 0x80
#define NOTE_ON 0x90
#define AFTERTOUCH 0xA0
#define PITCH_BEND 0xE0

uint8_t midiPacket[] = {
  0x80,  // header
  0x80,  // timestamp, not implemented
  0x00,  // commands
  0x3c,  // 0x3c == 60 == middle c
  0x00   // velocity
};

//midiPacket[0] : Header
//midiPacket[1] : TimeStamp
//midiPacket[2] : Status
//midiPacket[3] : Note
//midiPacket[4] : Velocity

// https://www.wavosaur.com/download/midi-note-hex.php
// 0x30 C3

class MyServerCallbacks: public BLEServerCallbacks {
    void onConnect(BLEServer* pServer) {
      Serial.println("Connected");
      deviceConnected = true;
    };

    void onDisconnect(BLEServer* pServer) {
      deviceConnected = false;
    }
};

void setup() {
  Serial.begin(115200);
  for (int i = 0; i < 4; i++) {
    if (!digitalRead(buttons_pins[i])) {
      pinMode(buttons_pins[i],INPUT_PULLUP);
    }
    Serial.println(buttons_pins[i]);
  }
 

  /* BLUETOOTH */
  BLEDevice::init("LabSud BLE Midi");
  // Create the BLE Server
  BLEServer *pServer = BLEDevice::createServer();
  pServer->setCallbacks(new MyServerCallbacks());

  // Create the BLE Service
  BLEService *pService = pServer->createService(BLEUUID(SERVICE_UUID));

  // Create a BLE Characteristic
  pCharacteristic = pService->createCharacteristic(
                      BLEUUID(CHARACTERISTIC_UUID),
                      BLECharacteristic::PROPERTY_READ   |
                      BLECharacteristic::PROPERTY_WRITE  |
                      BLECharacteristic::PROPERTY_NOTIFY |
                      BLECharacteristic::PROPERTY_WRITE_NR
                    );

  // https://www.bluetooth.com/specifications/gatt/viewer?attributeXmlFile=org.bluetooth.descriptor.gatt.client_characteristic_configuration.xml
  // Create a BLE Descriptor
  pCharacteristic->addDescriptor(new BLE2902());

  // Start the service
  pService->start();

  // Start advertising
  pServer->getAdvertising()->start();
}

void loop() {
  //if (deviceConnected) {
    buttons_read();
  //}
  
}

void buttons_read() {
  for (int i = 0; i < 4; i++) {
    //delay(30);
    if (!digitalRead(buttons_pins[i])) {
        if(!buttons_pressed[i]){
          buttons_pressed[i] = true;
          Serial.print(i);
          Serial.println(":ON");
  
          midiPacket[2] = NOTE_ON; // note down, channel 0
          midiPacket[3] = buttons_note[i];
          midiPacket[4] = 127;  // velocity
          pCharacteristic->setValue(midiPacket, 5); // packet, length in bytes
          pCharacteristic->notify();
      }
    } else {
      if (buttons_pressed[i]) {
        buttons_pressed[i] = false;
        Serial.print(i);
        Serial.println(":OFF");
        midiPacket[2] = NOTE_OFF; // note down, channel 0
        midiPacket[3] = buttons_note[i];
        midiPacket[4] = 127;  // velocity
        pCharacteristic->setValue(midiPacket, 5); // packet, length in bytes
        pCharacteristic->notify();
      }
    }
  }
}