/* 8 note MIDI sequencer */
      /* Version 1.7 Sam Harmon 2008 */
      /* http://www.glacialcommunications.com */

      /* contains parts of... */
      /*
       * codeexample for useing a 4051 * analog multiplexer / demultiplexer
       * by david c. and tomek n.* for k3 / malmš hšgskola
       *
       */  
/* version 1.7 - Debut of "Drum Mode" - This enables the "Analog" sequencer to either do CV/Gate
 * (switch 4 set to 0) or triggering two drum sources (s4==1)
 * Drum mode triggering based on noteRead value - 0=no sound; 1-512, pin 5; 513-1022, pin 9; 1023, both
*/
//#define DEBUG 1       
      int r0 = 0;      //value select pin at the 4051 (s0)
      int r1 = 0;      //value select pin at the 4051 (s1)
      int r2 = 0;      //value select pin at the 4051 (s2)
      int row = 0;     // storeing the bin code
      int count = 0;    // just a count
      int clockCount = 0;
      int  bin [] = {000, 1, 10, 11, 100, 101, 110, 111};//bin = binŠr, some times it is so easy
      int tempoPin = 1;  //pin for tempo read
      int tempoDelay = 0; //current amount to delay (aka tempo)
      int notePin = 0; //pin for reading current MIDI note
      int noteRead = 0; //
      int noteValue = 65; //MIDI note number
      //int noteDuration = 100; //length of note (for now)
      int velocity = 127; //MIDI velocity (default, for now)
      int fracDelay = 0; 
      int modePin =4; //analog output - CV/Gate or 2-channel triggers
      int analogOut = 0; //value to send to CV out
       
      void setup(){
       
        pinMode(6, OUTPUT); //s0
        pinMode(7, OUTPUT);    // s1
        pinMode(8, OUTPUT);    // s2 
        pinMode(9, OUTPUT);    // PWM "CV"
        pinMode(5, OUTPUT);    // "GATE"
        pinMode(modePin, INPUT);    //mode switch CV/Gate or 2-channel drum machine
                // MIDI/CV switch
       //initialize CV/Gate
        analogWrite(9, 0);
        digitalWrite(5, LOW);
#ifdef DEBUG
beginSerial(9600); //debug
#else
Serial.begin(31250);
#endif
      }
       
      void loop () {
        for (count=0; count<=7; count++) {
          tempoDelay = 1024-analogRead(tempoPin)+6; //in case sensor is zero, we want 1 ms delays
          noteRead = (analogRead(notePin));
          //MIDI limited to 0-127
          noteValue = noteRead/8;
          //PWM limited to 0-255
          analogOut = noteRead/4;
          row = bin[count];      
          r0 = row & 0x01;
          r1 = (row>>1) & 0x01;
          r2 = (row>>2) & 0x01;

          digitalWrite(6, r0);
          digitalWrite(7, r1);
          digitalWrite(8, r2);
#ifdef DEBUG
Serial.print("modePin=");
Serial.println(digitalRead(modePin));
#endif
          if (noteValue > 0){
            noteOn(0x90, noteValue, velocity);
            if (digitalRead(modePin)==1){ //drum mode
            // evaluate   note value
            // This is kind of ugly, anyone have a more elegant solution?
              if ((noteRead >0) && (noteRead < 512)){
                digitalWrite(9, HIGH);
              }
              if ((noteRead > 512) && (noteRead < 1023)){
                digitalWrite(5, HIGH);
              }
              if (noteRead==1023){
               digitalWrite(5, HIGH);
               digitalWrite(9, HIGH);
              }
              //trigger pulse==10ms?
              delay(10);
              //go ahead and clear both
              digitalWrite(5,LOW);
              digitalWrite(9,LOW);
            } else {    //standard mode
             digitalWrite(5, HIGH);
             analogWrite(9, analogOut);
            }  
          }          
          fracDelay = tempoDelay / 6;
          for (clockCount = 0; clockCount <=5;clockCount++){
            syncSignal(0xF8);
            delay (fracDelay);
          } 
          if (noteValue > 0){ 
            noteOn(0x90,noteValue, 0x00);
            
            digitalWrite(5, LOW);
            analogWrite(9, 0);
           }
        }  
      }

void syncSignal(char cmd){
  Serial.print(cmd, BYTE);
}  
void noteOn(char cmd, char data1, char data2) {
  Serial.print(cmd, BYTE);
  Serial.print(data1, BYTE);
  Serial.print(data2, BYTE);
}