Took me a while to find the purpose of this little device I had in the mail recently. it’s a light detection sensor, which I connected to the arduino nano to test its functionality. it servs the amount of light from 0 (very bright) to 1024 (very dark) using the analog pin. To use this device with the ESP8266 you’ll probably need to adapt the voltage and transform it between 0-1V.  But for now, it works fine costing around 2 EUR 🙂

 void setup ()
int sensorPin = A0; // select the input pin for the potentiometer
int ledPin = 13; // select the pin for the LED
int sensorValue = 0; // variable to store the value coming from the sensor
 
void setup () 
{
  pinMode (ledPin, OUTPUT);
  Serial.begin (9600);
}
 
void loop () 
{
  sensorValue = analogRead (sensorPin);
  digitalWrite (ledPin, HIGH);
  delay (sensorValue);
  digitalWrite (ledPin, LOW);
  delay (sensorValue);
  Serial.println (sensorValue, DEC);
}

Output looks like this (analog):

21 -> bright
90
68
63
81
81
83
89
78
85
99
558
897
822
882
864 -> dark