/*
  Votrax SC-01 Controller
  by Ant, like the bug
  Feb 2024

  An Arduino sketch for operating the Votrax SC-01 Speech 
  Synthesizer chip first released in the early 1980s. 

  SC-01 Technical Documentation: http://redcedar.com/sc01/sc01.pdf
  Phoneme dictionary: https://downloads.reactivemicro.com/Apple%20II%20Items/Hardware/SC-01-A/Datasheet/SC-01%20Dictionary.pdf

*/

/* 
  TODO
  • serial output to shift register instead of individual output 
    pins for each phoneme bit.
  • keyboard input for new phoneme sequences
  • eurorack integration:
      - 1v/oct vc input for pitch sequencing MCX rate
      - use gate signal instead of A/R high to trigger next phoneme
      - x/y and button interface for realtime phoneme generation + performance
*/

/*
  After hours of work on this script, during which I was
  continually reminded how at C++ I am, I found this video by
  Scott Savage, detailing his library and kit which do most of 
  what I want this sketch to eventually do. 
  https://www.youtube.com/watch?v=ER0t3IYygDw
*/

//Input must be comprised of valid Votrax phoneme symbols. 
//Don't forget to define the length of the input!
const int inputLen = 11;
const String input[inputLen] = {"K", "AH1", "UH3", "R", "PA0", "H", "AE1", "EH3", "M", "ER", "S"};
const bool repeat = false;
const bool repeatDelay = 1000;

// const int i1 = 5;   add these back into outputPins[] in setup() when ready
// const int i2 = 6;
const int stb = 2;
const int p0 = 3;
const int p1 = 4;
const int p2 = 5;
const int p3 = 6;
const int p4 = 7;
const int p5 = 8;
const int ar = 9;

const int arsim = 10; //simulates A/R pulse from SC-01 for debug

//Valid phoneme symbols
const String symbols[] = {
	"EH3", "EH2", "EH1", "PA0", "DT", "A2", "A1", "ZH", "AH2", "I3", "I2", "I1", "M", "N", "B", "V", 
	"CH", "SH", "Z", "AW1", "NG", "AH1", "NG", "AH1", "OO1", "OO", "L", "K", "J", "H", "G", "F", "D", "S",
	"A", "AY", "Y1", "UH3", "AH", "P", "O", "I", "U", "Y", "T", "R", "E", "W", "AE", "AE1", 
	"AW2", "UH2", "UH1", "UH", "O2", "O1", "IU", "U1", "THV", "TH", "ER", "EH", "E1", "AW", "PA1", "STOP"
};

void setup() {
  Serial.begin(9600);
  Serial.println("Initializing pins...");
  int outputPins[9] = {stb,p0,p1,p2,p3,p4,p5};
  for (int i=0;i<9;i++){
		int pin = outputPins[i];
    String pinLabel = String(pin);
		pinMode(pin,OUTPUT);
    Serial.println("Pin " + pinLabel + " set to OUTPUT");
	}
  int inputPins[] = {ar};
	for (int i=0;i<1;i++){
		int pin = inputPins[i];
    String pinLabel = String(pin);
		pinMode(pin,INPUT);
    Serial.println("Pin " + pinLabel + " set to INPUT");
	}
  Serial.println("Pins initialized. \n");
}

//Returns true if an input symbol is included in symbols[].
bool checkSymbol(String symbol){
  for (int i=0; i<64; i++){
    if(symbol == symbols[i]){
      Serial.println("Symbol (" + symbol + ") is VALID.");
      return true;
    }
  }
  Serial.println("Symbol (" + symbol + ") is NOT VALID.");
  return false;
}

//Returns true if all input symbols are in the symbols[] array.
bool inputIsValid(String thisInput[], int thisInputLen){
  Serial.println("Validating input...");
  int validCount = 0;
  for(int i=0; i<inputLen; i++){
    if (checkSymbol(input[i])==true){
      validCount++;
    }
  }
  if(validCount == inputLen){
    Serial.println("Input is VALID. \n");
    return true;
  }
  else{
    Serial.println("Input is NOT VALID.");
    return false;
  }
}

//Returns the index of a given phoneme symbol.
int symbolIndex(String element){
  for(int i=0; i<64; i++){
    if(element==symbols[i]){
      int index = i;
      Serial.println("Symbol (" + element + ") is at index " + i +".");
      return index;
    }
  }
}

//Triggers latch function on SC-01.
int strobe(int hold){
  digitalWrite(stb,HIGH);
  String holdTime = String(hold);
  Serial.println("Strobe pin: HIGH. Hold time: " + holdTime);
  delay(hold);
  digitalWrite(stb,LOW);
  Serial.println("Strobe pin: LOW.");
  Serial.println();
  delay(5);
  digitalWrite(arsim,LOW); //simulated here for debug
  return 0;
}

//Main Loop
void loop() {
  //If input is valid...
  if(inputIsValid(input,inputLen)){
    Serial.println("Ready to convert to binary. \n");

    //Find the index of each phoneme...
    for (int i=0; i<inputLen; i++){
      int index = symbolIndex(input[i]);

      //Convert the index to binary...
      int bits[8] = {};
      for (int j=0;j<8;j++){
        int data = bitRead(index,j);
        bits[j]= data;
      }
      int orderedBits[8] = {bits[7],bits[6],bits[5],bits[4],bits[3],bits[2],bits[1],bits[0]};
      for(int j=0; j<8; j++){
        Serial.print(orderedBits[j]);
      }
      Serial.println();

      //Assign the 6 least significant bits to p0-p5...
      int outputPins[6] = {p0,p1,p2,p3,p4,p5};
      for (int j=0; j<8; j++){
        if(orderedBits[j+2]==1){
          digitalWrite(outputPins[j], HIGH);
        }
        if(orderedBits[j+2]==0){
          digitalWrite(outputPins[j],LOW);
        }
      }
      Serial.println("Bits assigned and ready to flash.");
      Serial.println();

      //Wait for A/R Pulse...
      while(digitalRead(ar)==LOW){
        Serial.println("Waiting for A/R pulse...");
        delay(250);
        digitalWrite(arsim,HIGH); //simulated here for debug
      }
      Serial.println("A/R pulse detected!");
      
      //Flash the chip...
      strobe(250);
      }
    //If repeat is false, end the program.
    if(repeat == false){
      delay(500);
      Serial.println("Repeat is OFF.");
      Serial.println("\n PROGRAM END.");
      delay(1000);
      exit(0);
    }
    //If repeat is true, repeat the program.
    else{
      Serial.println("Repeat is ON.");
      String rptDlyTime = String(repeatDelay);
      Serial.println("Repeating input; delay = " + rptDlyTime);
      Serial.println();
    }
  }
  //If the input is not valid, end the program. 
  else{
    delay(1000);
    Serial.println("\n PROGRAM END.");
    delay(1000);
    exit(0);
  }
}