PWMを自力で生成するスケッチ

PwmOriginal.cpp

/******** Sine wave parameters ********/
#define PI4     4*3.14159 // 2 sine wave cycles
#define AMP     127     // PWM Multiplication factor for the sine wave
#define OFFSET  128   // Offset shifts wave to just positive values

/******** Lookup table ********/
#define LENGTH 20 // The length of the waveform lookup table
byte wave[LENGTH]; // waveform values for PWM

const byte pulsePin = 9;

void setup() {
  Serial.begin(115200);
  pinMode(pulsePin, OUTPUT);

  /******** Populate the waveform lookup table ********/
  for (byte i = 0; i < LENGTH; i++)
  {
    float v = (AMP * sin(((PI4 / LENGTH) * i)));
    wave[i] = byte(v + OFFSET);  // Store value as integer
    Serial.println(wave[i]);
  }

}

void loop() {
  static unsigned long lastPulseTime;
  static byte i = 0;
  if (micros() - lastPulseTime >= 50000ul) //20Hz
  {
    lastPulseTime += 50000ul;
    analogWrite(pulsePin, wave[i]);
    //Serial.print(i);
    //Serial.print('\t');
     Serial.println(wave[i]);
    i++;
    if (i == LENGTH - 1)
      i = 0;
  }
}