#define led_pin 0 // ATtiny PA6
#define photo_pin 1 //ATtiny PA7
int sensor_value = 0;
int output_value = 0;
int output_value_ease = 0;

void setup() {
  pinMode(led_pin, OUTPUT);
  pinMode(photo_pin, INPUT);
}//void setup

void loop() {
  // Read the analog value coming in from the phototransistor
  sensor_value = analogRead(photo_pin);
  //Map to 1 - 1000 and then ease that value
  output_value = map(sensor_value, 0, 1023, 1, 1000);
  output_value_ease = easeOut(output_value, 1.0, 1000.0);

  // Blink the LED with a 2*output_value_ease timing
  blinkLED(output_value_ease);
}//void loop

//t = current value, b = start value, d = end value
int easeOut(int t, float b, float d) {
  float n = (t - b) / (d - b);
  return(int)(d - b) * (1.0 - n*n*n*n) + b;
}// int easeOut

// Make the LED blink with a delay of delay_time
void blinkLED(int delay_time) {
  digitalWrite(led_pin, HIGH);
  delay(delay_time);
  digitalWrite(led_pin, LOW);
  delay(delay_time); 
}// void blink