/* -------Arduino Proto-Synth 08/07/07
  --------Collin Cunningham - Narbotic.net
  --------with portions of code from "Freqout" by Paul Badger and "MIDI drum kit" by Tod E. Kurt

  This is my stab at a monophonic synthesizer for the Arduino and my first stab at coding anything really. 
  It reads input on Analog0 for a stepped pitch transposition. Each note switch(digipins 1-10 & 13) connects to 
  ground in order to register. Higher notes get priority.  Pin 11 is speaker output.  
  I used a little RC Low Pass Filter to smooth out the sound:
  
  PIN11->------\/\/\---o----\/\/\----o-------> OUTPUT
               1K      |    1K       |
                       |             |
                   .1uF_cap      .1uF_cap
                       |             |
                      GND           GND
                      
            (no clue how to draw caps in ascii)
                      
  Features I'd like to add 
  - Another octave (maybe add a transpose switch on each of the next octave, then they can share pins with the first)
  - Last note hit priority
  - Portamento (note-slide)
  - Real sine wave out (no external LPF anymore please) 
  - Polyphony (I had it working badly, need better math)
  - any real keyboard feature in existance(or not) attack, decay, waveform, vibrato, etc.
  
Contact me at narbotic.net with any suggestions/help - and if you improve any of the code please send it on over.

*/

#include <math.h>

#define switchAPin 0
#define switchBPin 1
#define switchCPin 2
#define switchDPin 3
#define switchEPin 4
#define switchFPin 5
#define switchGPin 6
#define switchHPin 7
#define switchIPin 8
#define switchJPin 9
#define switchKPin 10
#define switchLPin 12
#define switchMPin 13
#define pitchPin     0
#define speakerOut  11

int pitchval = 1;
int val = 0;

int freq,t;

float noteval;
//note values
float C     = 130.8;
float CS    = 138.6;
float D     = 146.8;
float DS    = 155.6;
float E     = 164.8;
float F     = 174.6;
float FS    = 185;
float G     = 196;
float GS    = 207.7;
float A2    = 220;
float A2S   = 233.1;
float B2    = 246.9;
float C2    = 261.6;
float C2S   = 277.2;
float D2    = 293.7;
float D2S   = 311.1;
float E2    = 329.6;
float F2    = 349.2;
float F2S   = 370;
float G2    = 392;
float G2S   = 415.3;
float A3    = 440;


void setup() {
  pinMode(switchAPin, INPUT);
  pinMode(switchBPin, INPUT);
  pinMode(switchCPin, INPUT);
  pinMode(switchDPin, INPUT);
  pinMode(switchEPin, INPUT);
  pinMode(switchFPin, INPUT);
  pinMode(switchGPin, INPUT);
  pinMode(switchHPin, INPUT);
  pinMode(switchIPin, INPUT);
  pinMode(switchJPin, INPUT);
  pinMode(switchKPin, INPUT);
  pinMode(switchLPin, INPUT);
  pinMode(switchMPin, INPUT);
  pinMode(speakerOut, OUTPUT);
  digitalWrite(switchAPin, HIGH);  // turn on internal pullup
  digitalWrite(switchBPin, HIGH);  // turn on internal pullup
  digitalWrite(switchCPin, HIGH);  // turn on internal pullup
  digitalWrite(switchDPin, HIGH);  // turn on internal pullup
  digitalWrite(switchEPin, HIGH);  // turn on internal pullup
  digitalWrite(switchFPin, HIGH);  // turn on internal pullup
  digitalWrite(switchGPin, HIGH);  // turn on internal pullup
  digitalWrite(switchHPin, HIGH);  // turn on internal pullup
  digitalWrite(switchIPin, HIGH);  // turn on internal pullup
  digitalWrite(switchJPin, HIGH);  // turn on internal pullup
  digitalWrite(switchKPin, HIGH);  // turn on internal pullup
  digitalWrite(switchLPin, HIGH);  // turn on internal pullup
  digitalWrite(switchMPin, HIGH);  // turn on internal pullup
}

// Pins are read in reverse to give higher key priority

void loop() {
  if( analogRead(pitchPin) > 150)
  {
  pitchval = (analogRead(pitchPin) / 100);  //a shot in the dark
  }
  else if( analogRead(pitchPin) <= 15)
  {
  pitchval = 1;
  }
  if( digitalRead(switchMPin) == LOW ) 
  {
    noteval = C2;
    freqout((int)noteval, t);
  }

  else if( digitalRead(switchLPin) == LOW ) 
  {
    noteval = B2;
    freqout((int)noteval, t);
  }

  else if( digitalRead(switchKPin) == LOW ) 
  {
    noteval = A2S;
    freqout((int)noteval, t);
  }

  else if( digitalRead(switchJPin) == LOW ) 
  {
    noteval = A2;
    freqout((int)noteval, t);
  }

  else if( digitalRead(switchIPin) == LOW ) 
  {
    noteval = GS;
    freqout((int)noteval, t);
  }

  else if( digitalRead(switchHPin) == LOW ) 
  {
    noteval = G;
    freqout((int)noteval, t);
  }

  else if( digitalRead(switchGPin) == LOW ) 
  {
    noteval = FS;
    freqout((int)noteval, t);
  }

  else if( digitalRead(switchFPin) == LOW ) 
  {
    noteval = F;
    freqout((int)noteval, t);
  }

  else if( digitalRead(switchEPin) == LOW ) 
  {
    noteval = E;
    freqout((int)noteval, t);
  }

  else if( digitalRead(switchDPin) == LOW ) 
  {
    noteval = DS;
    freqout((int)noteval, t);
  }

  else if( digitalRead(switchCPin) == LOW ) 
  {
    noteval = D;
    freqout((int)noteval, t);
  }
  
  else if( digitalRead(switchBPin) == LOW ) 
  {
    noteval = CS;
    freqout((int)noteval, t);
  }

  else if( digitalRead(switchAPin) == LOW ) 
  {
    noteval = C;
    freqout((int)noteval, t);
  }

  else 
  {
    digitalWrite(speakerOut, LOW);
  }
}

//freqout code by Paul Badger (and hacked a bit by me)
void freqout(int freq, int t) 
{ 
    int hperiod;     //calculate 1/2 period in us 
    long cycles, i; 
    hperiod = (500000 / ((freq - 7) * pitchval));             // subtract 7 us to make up for digitalWrite overhead - determined empirically 
    // calculate cycles 
    cycles = ((long)freq * (long)t) / 1000;    // calculate cycles 

    for (i=0; i<= cycles; i++){              // play note for t ms  
       digitalWrite(speakerOut, HIGH);  
       delayMicroseconds(hperiod); 
       digitalWrite(speakerOut, LOW);  
       delayMicroseconds(hperiod - 1);     // - 1 to make up for fractional microsecond in digitaWrite overhead 
    } 
}