DAW Button Box for Roland E-Drum Racks

/* ROLAND RACK BUTTON BOX
  
 Note : This is for the Arduino Pro Micro !

 Emulates a keyboard to press keys a connected PC for a DAW (here : Steinberg Cubase).
 optional : uses emulated UART COM port via USB (for debugging) and LEDs (RX and TX LED) on Micro board

 KEYS : 
 config for Cubase:
 https://steinberg.help/cubase_elements_le_ai/v9/de/cubase_nuendo/topics/key_commands/key_commands_default_c.html

 Assignment : Arduino Micro Port -> Switch on Button Box -> emulated Key on Keyboard -> Function in Cubase
 
 Port Switch  Key       Cubase Function 
 ------------------------------------------
 2	  M       c         Metronome On
 3	  L       [Num] 1   Goto Left Locator
 4	  >>      [Num] +   Forward
 5	  <<      [Num] -   Backward
 6	  P       SPACE     Play/Stop 
 7	  B       b         Begin
 8	  R       [Num] *   Record
 
  mac70
  13.01.2021
*/

#define DEBUG_OUTPUT 0  // when defined as 1, an additional serial monitor output will be generated for debugging

#include <Keyboard.h>

// NUM-KEY codes :  https://forum.arduino.cc/index.php?topic=659117.0
#define KEYPAD_1 225 
#define KEYPAD_PLUS 223 
#define KEYPAD_MINUS 222 
#define KEYPAD_ASTERIX 221 
/*
// in case needed ... other key codes like Shift, Control etc : https://www.arduino.cc/reference/en/language/functions/usb/keyboard/keyboardmodifiers/
char ShiftKey = KEY_LEFT_SHIFT;
char LeftKey = KEY_LEFT_ARROW;
char RightKey = KEY_RIGHT_ARROW;
*/

int RXLED = 17;  // The RX LED has a defined Arduino pin


void setup()
{
   // buttons are connected to the following digital input pins 
   // (button normally open, when activated -> pin will be connected to GND)
  pinMode(2, INPUT_PULLUP);  // Pin 2 is input with internal resistor
  pinMode(3, INPUT_PULLUP);  // Pin 3 is input with internal resistor
  pinMode(4, INPUT_PULLUP);  // Pin 4 is input with internal resistor
  pinMode(5, INPUT_PULLUP);  // Pin 5 is input with internal resistor
  pinMode(6, INPUT_PULLUP);  // Pin 6 is input with internal resistor
  pinMode(7, INPUT_PULLUP);  // Pin 7 is input with internal resistor
  pinMode(8, INPUT_PULLUP);  // Pin 8 is input with internal resistor
  
  pinMode(RXLED, OUTPUT);  // Set RX LED as an output

  digitalWrite(RXLED, HIGH);    // set the RX LED OFF
  Keyboard.begin();  // start keyboard emulation
  
  Serial.begin(9600); //This starts the serial monitor
  Serial.println("");
if (DEBUG_OUTPUT == 1) Serial.println("Button Box Serial Monitor");
  
}

void loop()
{

  Keyboard.releaseAll();
  digitalWrite(RXLED, HIGH);    // set the RX LED OFF
  delay(50);                    // short delay

  // Process buttons
  
  if (digitalRead(2) == 0) // M  
  {
    if (DEBUG_OUTPUT == 1) Serial.println("Button M");  // Print to the Serial Monitor 
    digitalWrite(RXLED, LOW);   // LED on to signal activity
    Keyboard.press('c');
    delay(5);
    Keyboard.releaseAll();
    while(digitalRead(2) == 0); // wait for button to be released
  }
  
  if (digitalRead(3) == 0) // L  
  {
    if (DEBUG_OUTPUT == 1) Serial.println("Button L");  // Print to the Serial Monitor
    digitalWrite(RXLED, LOW);   // LED on to signal activity
    Keyboard.press(KEYPAD_1);
    delay(5);
    Keyboard.releaseAll();
    while(digitalRead(3) == 0); // wait for button to be released
  }
  
  if (digitalRead(4) == 0) // >>  
  {
    if (DEBUG_OUTPUT == 1) Serial.println("Button >>");  // Print to the Serial Monitor
    digitalWrite(RXLED, LOW);   // LED on to signal activity
    Keyboard.press(KEYPAD_PLUS);
    while(digitalRead(4) == 0); // wait for button to be released ... repeat function from PC will re-trigger this key !
    Keyboard.releaseAll();
  }
  
  if (digitalRead(5) == 0) // <<  
  {
    if (DEBUG_OUTPUT == 1) Serial.println("Button <<");  // Print to the Serial Monitor
    digitalWrite(RXLED, LOW);   // LED on to signal activity
    Keyboard.press(KEYPAD_MINUS);
    while(digitalRead(5) == 0); // wait for button to be released ... repeat function from PC will re-trigger this key !
    Keyboard.releaseAll();
  }
  
  if (digitalRead(6) == 0) // PLAY STOP  
  {
    if (DEBUG_OUTPUT == 1) Serial.println("Button PLAY/STOP");  // Print to the Serial Monitor
    digitalWrite(RXLED, LOW);   // LED on to signal activity
    Keyboard.press(' ');
    delay(5);
    Keyboard.releaseAll();
    while(digitalRead(6) == 0); // wait for button to be released
  }
  
  if (digitalRead(7) == 0) // BACK TO START  
  {
    if (DEBUG_OUTPUT == 1) Serial.println("Button BACK");  // Print to the Serial Monitor
    digitalWrite(RXLED, LOW);   // LED on to signal activity
    Keyboard.press('b');
    delay(5);
    Keyboard.releaseAll();
    while(digitalRead(7) == 0); // wait for button to be released
  }
  
  if (digitalRead(8) == 0) // REC  
  {
    if (DEBUG_OUTPUT == 1) Serial.println("Button REC");  // Print to the Serial Monitor
    digitalWrite(RXLED, LOW);   // LED on to signal activity
    Keyboard.press(KEYPAD_ASTERIX);
    delay(5);
    Keyboard.releaseAll();
    while(digitalRead(8) == 0); // wait for button to be released
  }

  
}