Problem with light sensor and LED

Forum 2005-2010 (read only) Hardware Interfacing
1

I am new to Arduino, and I am busy making some craft projects for kids using the Lilypad Arduino.

I am trying to make an LED flash when the value on my light sensor goes below a certain value.

Here is my code:

int pin1 = 9;
int lightSensor = 0;
int sensorVal;

void setup()
{
  pinMode(pin1, OUTPUT);
  Serial.begin(9600); 
}

void loop()
{
  sensorVal = analogRead(lightSensor);
  Serial.println(sensorVal);
  if(sensorVal < 60){
    digitalWrite(pin1, HIGH);
    delay(200); 
    digitalWrite(pin1, LOW);
  }
  digitalWrite(pin1, LOW);
}

I have an LED attached to Pin 9, coming back to Pin8.
The light sensor has S connected to a0, + to +5v and - to -.
Both components work on their own, but not together.
Can anyone help me please?

2

Assuming that the LED comes on when told to and the light sensor returns suitable values then:-

Change this:-

if(sensorVal < 60){
    digitalWrite(pin1, HIGH);
    delay(200);
    digitalWrite(pin1, LOW);
  }

to this:-

if(sensorVal < 60){
    digitalWrite(pin1, HIGH);
    delay(200);
    digitalWrite(pin1, LOW);
    delay(200);
  }
3

Its still not working, the light sensor is returning suitable values but the LED does not come on when the value is less than is specified in the IF statement

4

I'm not understanding the "LED attached to Pin 9, coming back to Pin8" thing. That doesn't sound like the right way to connect an LED.

Try connecting the anode of the LED to pin 9 then a 220 ohm resistor from the cathod of the LED to ground (0V).