/*
  Creation: 5 Aug 2017
  ©-2017 Patrick-Gilles Maillot
  
  TtapMIDI-X32: a Stomp pedal for sending Tempo TAP delay as SYSEX MIDI messages to an X32 digital mixer from
  Behringer (or any compatible MIDI devive).

  The program waits for a HW pin to becon=me active (when the user presses a switch). These events
  are used to generate a delay sent as SYSEX MIDI array to the connected device. 

  This project started from an Arduino project/sketch file: MIDI note player / created 13 Jun 2006

  The circuit for MIDI out:
    Leonardo digital pin 1 connected to MIDI jack pin 5
    MIDI jack pin 2 connected to ground
    MIDI jack pin 4 connected to +5V through 220-ohm resistor
  Attach a MIDI cable to the jack, then to a MIDI synth, and play music.

  The circuit for the switch:
    Pushbutton attached to Leonardo digital pin pin 2 and to ground
*/

unsigned char S_array[] = {                         // MIDI SYSEX or command array data
  0xF0, 0x00, 0x20, 0x32, 0x32, 
  0x2F, 0x66, 0x78, 0x2F,
  0x30,
  0x2F, 0x70, 0x61, 0x72, 0x2F, 
  0x30, 0x32,
  0x20,
  0x33, 0x30, 0x30, 0x30,
  0xF7
};
//
const int     S_size = sizeof(S_array) / sizeof(char);  // MIDI SYSEX or command array size
const int     B_pin = 5;                                // Switch pin (in)
const int     L_pin = 7;                                // LED pin (out)
int           D_delay = 20;                             // Debounce time; increase if needed
int           S_state;                                  // state of the switch
int           L_state;                                  // state of the LED
unsigned long Time1;                                    // Start time
unsigned long Dtime;                                    // Delta time
int           Tcount;                                   // Indicate first or secont press for timer calculation

void setup() {
  Serial.begin(9600);
  // called once at program start
  //  Set MIDI baud rate:
  //Serial1.begin(31250);
  // Set pins directions
  pinMode(B_pin, INPUT_PULLUP);
  pinMode(L_pin, OUTPUT);
  S_state = digitalRead(B_pin);
  digitalWrite(L_pin, HIGH);
  Time1 = Dtime = Tcount = 0;
  Serial.println("Hello World");
  delay(5000);
}

void loop()
{

  // start main loop
  // read the state of the switch, check for state change:
  S_state = digitalRead(B_pin);
  // wait a few milliseconds
  delay(D_delay);
  // stop LED if needed
  if (L_state) {
    digitalWrite(L_pin, HIGH);
    L_state = 0;
  }
  //
  // only send MIDI data if the new button state is LOW
  if ((digitalRead(B_pin) == 1) && (S_state == 0)) {
    if (Tcount == 0) {
      // first time press: Get time
      Serial.print("push 1");
      Time1 = millis();
      Tcount = 1;
    } else {
      // second time press: calculate time difference and send data
      // calculate Dtime in milliseconds
      Dtime = millis() - Time1;
      Serial.print(Dtime);
      // Dtime as valid X32 data 0 to 3000 ms
      if (Dtime < 1) Dtime = 0;
      if (Dtime > 3000) Dtime = 3000;
      // set value of FX number in SYSEX buffer
      Serial.println(Dtime);
      S_array[9] = 0x32;
      // set value of Ftime into SYSEX buffer
      S_array[18] = 0x30 + Dtime / 1000;
      S_array[19] = 0x30 + (Dtime - (Dtime/1000) * 1000) / 100;
      S_array[20] = 0x30 + (Dtime - (Dtime/100) * 100) / 10;
      S_array[21] = 0x30 + (Dtime - (Dtime/10) * 10);
      // reset time press counter
      Tcount = 0;
      // play all bytes from SYSEX data array:
      for (int i = 0; i < S_size; i ++) {
        Serial.print(S_array[i]);
      }
      // LED on
      digitalWrite(L_pin, LOW);
      L_state = 1;
    }
  }
}