Pull down resistor for photoresistor

Using Arduino Sensors
1

hi, my photoresistor doesn't perform properly, always got the highest value no matter how bright or dark my room was, so I went thought lots of tutorials and they mentioned that I will might have to use a 10k resistor for a better result. But I also came across something called "pull down resistor" which too do the trick, because I don't have any resistor around 10k on hand, so I dug deeper and found that there is a pull up resistor in arduino itself "digitalWrite(pin, HIGH)", but It doesn't says anything about the internal pull down resistor, does it exist?

2

Pull down doesn't exist. But you still can make it works with pull - up, connecting LDR between pin and ground, and reverse reading in software, so lower value would correspond to higher brightness.

3

can you show me how a pull up resistor can achieve this? I'm a complete arduino noob XD

4

Take a look at the schematic in this photo:
http://www.oomlout.co.uk/images/large/IC-PHOTO-10_01_LRG.jpg
This is how I have mine wired, they work great.

5

Try

void setup()
{
  Serial.begin(9600); //Start serial communication
  digitalWrite(A0, HIGH); //Enable internal pull-up for analog pin 0
}

void loop()
{
  Serial.print(analogRead(A0)); //Send value for analog pin 0
  delay(500);
}