Arduino code for generating a sine wave using Pulse Width Modulation.

FunctionGenerator.ino

#include "wavetable.h"
 
float seconds = 0;
int i = 0;
int num_readings = 0;
 
void setup()
{
  Serial.begin(115200);
  
  DDRB = (1<<PB1); // set pin 9 (Arduino UNO) as output
  
  // Mode 14: Fast PWM, non-inverted
  // Prescaler: 1
  TCCR1A = (1<<COM1A1) | (0<<COM1A0) | (0<<COM1B1) | (0<<COM1B0) | (1<<WGM11) | (0<<WGM10);
  TCCR1B = (0<<ICNC1) | (0<<ICES1) | (1<<WGM13) | (1<<WGM12) | (0<<CS12) | (1<<CS11) | (1<<CS10);
  
  ICR1 = 249; // TOP
  OCR1A = 1; // Almost Off
  
  // enable timer overflow interrupt for Timer1
  // read datasheet p. 127
  // "if one of the interrupts are enabled, the interrupt
  // handler routine can be used for updating the TOP and compare values.
  
  TIMSK1 = (0<<ICIE1) | (0<<OCIE1B) | (0<<OCIE1A) | (1<<TOIE1);
  
}
 
void loop()
{
  //toScope(0);
  if (seconds > 5 && seconds <= 15)
  {
    takeReading(0);
    //takeTwoReadings(0,1);
  }
 
}
 
ISR(TIMER1_OVF_vect)
{
  
  seconds += 0.001;
  
  if (i > (length-1))
  {
    i = 0;
  }
  
  OCR1A = pgm_read_byte(&(waveTable[i]));
  
  i += 1;
  
}
 
/* takeReading function
 * takes in an analaog pin number as an integer
 * sends serial data to PC to be read by Python
 */
 void takeReading(int pinNum)
 {
   Serial.print(seconds,4);
   Serial.print(',');
   Serial.println(analogRead(pinNum));
 }