pointlights/sensor_filtering/sensor_filtering.ino

int brightness = 0; // our main variable for setting the brightness of the LED
int ledPin = 9; // we use pin 9 for PWM
int sensorPin = A5; 

// smoothing
const int numReadings = 10; // higher is smoother but less responsive

int readings[numReadings];      // the readings from the analog input
int readIndex = 0;              // the index of the current reading
int total = 0;                  // the running total
int average = 0;                // the average

int ldr;

void setup() {
  // put your setup code here, to run once:
  Serial.begin(9600);
  pinMode(ledPin, OUTPUT);
  pinMode(sensorPin, INPUT);

 // set all readings to 0 on start
 for (int thisReading = 0; thisReading < numReadings; thisReading++) {
    readings[thisReading] = 0;
  }
}

void loop() {
  ldr = analogRead(sensorPin);
  // brightness = ldr; // don't do this

  //filtering jitteryness
  int smoothed = smooth_sensor(ldr);
  //Serial.println(smoothed);

  //clamping the range
  // n.b. the actual values, calibrate!
  brightness = map(ldr, 0, 1023, 0, 255);
  Serial.println(brightness);
  
  analogWrite(ledPin, brightness);
  delay(1);
}

int smooth_sensor(int sensor_value) {
    // subtract the last reading:
  total = total - readings[readIndex];
  // read from the sensor:
  readings[readIndex] = sensor_value;
  // add the reading to the total:
  total = total + readings[readIndex];
  // advance to the next position in the array:
  readIndex = readIndex + 1;

  // if we're at the end of the array...
  if (readIndex >= numReadings) {
    // ...wrap around to the beginning:
    readIndex = 0;
  }

  // calculate the average:
  average = total / numReadings;
  return average;
  }