levitron.ino

#define sensorPin A0 // Hall Effect Sensor Pin
#define pwmPin 3 // Transisor Pin
int levitPoint = 690; // Levitation Point relative to the sensor readings

#define FILTER_SHIFT 4
int sensorValue = 0;
int deltaLevit = 15;
int maxL, minL;
int filter_input;
int filter_output;
long filter_reg;
byte induction = 128;

void setup() {
  pinMode(pwmPin, OUTPUT);

  // PWM Direct Controller (Note Below)
  TCCR2A = _BV(COM2A1) | _BV(COM2B1) | _BV(WGM20);
  TCCR2B = _BV(CS20);

  maxL = levitPoint - deltaLevit;
  minL = levitPoint + deltaLevit;
}

void loop() {
  filter_input = analogRead(sensorPin);

  // Lowpass Filter from http://www.edn.com/
  filter_reg = filter_reg - (filter_reg >> FILTER_SHIFT) + filter_input;
  sensorValue = filter_reg >> FILTER_SHIFT;

  if (sensorValue < levitPoint - 50) {
    induction = 255
  } else {
    if (sensorValue > maxL) induction = 0;
    if (sensorValue < minL) induction = 255;
    if (sensorValue <= maxL and sensorValue >= minL) induction = ((sensorValue - maxL)/5);
  }

  OCR2B = induction;
}