/* 2 Spannungsebenen
 * Pulsdauermodulation 
 * Arduino Micro
 */

#define F_PWM 62500L //Hz
#define PRESCALER 1
#define TIMER_RELOAD ((F_CPU / ( PRESCALER * F_PWM) -1)) //Fast PWM

//Variablen
volatile uint16_t Frequenz;
volatile uint8_t Amplitude;

const int8_t Sinus[256] PROGMEM = {0,3,6,9,12,16,19,22,25,28,31,34,37,40,43,46,49,
51,54,57,60,63,65,68,71,73,76,78,81,83,85,88,90,92,94,96,98,100,102,104,106,107,109,
111,112,113,115,116,117,118,120,121,122,122,123,124,125,125,126,126,126,127,127,127,
127,127,127,127,126,126,126,125,125,124,123,122,122,121,120,118,117,116,115,113,112,
111,109,107,106,104,102,100,98,96,94,92,90,88,85,83,81,78,76,73,71,68,65,63,60,57,
54,51,49,46,43,40,37,34,31,28,25,22,19,16,12,9,6,3,0,-3,-6,-9,-12,-16,-19,-22,-25,
-28,-31,-34,-37,-40,-43,-46,-49,-51,-54,-57,-60,-63,-65,-68,-71,-73,-76,-78,-81,-83,
-85,-88,-90,-92,-94,-96,-98,-100,-102,-104,-106,-107,-109,-111,-112,-113,-115,-116,
-117,-118,-120,-121,-122,-122,-123,-124,-125,-125,-126,-126,-126,-127,-127,-127,-127,
-127,-127,-127,-126,-126,-126,-125,-125,-124,-123,-122,-122,-121,-120,-118,-117,-116,
-115,-113,-112,-111,-109,-107,-106,-104,-102,-100,-98,-96,-94,-92,-90,-88,-85,-83,
-81,-78,-76,-73,-71,-68,-65,-63,-60,-57,-54,-51,-49,-46,-43,-40,-37,-34,-31,-28,-25,
-22,-19,-16,-12,-9,-6,-3,};

void setup(){

  pinMode(A0,INPUT);
  pinMode(9,OUTPUT);    //OCR1A
  pinMode(10,OUTPUT);   //OCR1B

  //Timer1 initialisieren
  //Mode 14, Fast PWM (ICR1), nichtinvertierte PWM, Prescaler 1
  TCCR1A = (1<<COM1A1) | (1<<COM1B1) | (1<<WGM11);
  TCCR1B = (1<<WGM13) | (1<<WGM12) | (1<<CS10);
  ICR1 = TIMER_RELOAD;

  //OCR1A, OCR1B aktiv
  OCR1A = TIMER_RELOAD / 2; // PWM Startwerte, zum statischen testen
  OCR1B = TIMER_RELOAD / 4; 
  TIMSK1 |= (1 << ICIE1);   // Aktivieren des Timer-Reload Interrupts (ICR1)

  //
  Frequenz = 52;
}

void loop(){
  Amplitude = map(analogRead(A0),0,1023,5,245);      //Amplitudenhöhe
}

//Interrupt für Timer 1, Frequenz F_PWM
//Nachladen der PWM
ISR(TIMER1_CAPT_vect){        
  //Index in der Sinustabelle, Festkommazahl, 8 Bit Vorkomma, 8 Bit Nachkomma  
  static uint16_t i; 
  i += Frequenz;  //i = i + frequenz

  //
  OCR1A = 128+(((int8_t)pgm_read_byte(&Sinus[i>>8])*(int16_t)Amplitude)>>8);
  OCR1B = 128-(((int8_t)pgm_read_byte(&Sinus[i>>8])*(int16_t)Amplitude)>>8);
}