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→Simple demonstration of use
You may want to try different pulldown resistors depending on the light level range you want to detect!
You may want to try different pulldown resistors depending on the light level range you want to detect!
== Simple code for analog light measurements ==
This code doesn't do any calculations, it just prints out what it interprets as the amount of light in a qualitative manner. For most projects, this is pretty much all thats needed!
[[Fichier:cds-mesure1.jpg]]
[[Fichier:cds-mesure2.jpg]]
<nowiki>/* Photocell simple testing sketch.
Connect one end of the photocell to 5V, the other end to Analog 0.
Then connect one end of a 10K resistor from Analog 0 to ground
For more information see www.ladyada.net/learn/sensors/cds.html */
int photocellPin = 0; // the cell and 10K pulldown are connected to a0
int photocellReading; // the analog reading from the analog resistor divider
void setup(void) {
// We'll send debugging information via the Serial monitor
Serial.begin(9600);
}
void loop(void) {
photocellReading = analogRead(photocellPin);
Serial.print("Analog reading = ");
Serial.print(photocellReading); // the raw analog reading
// We'll have a few threshholds, qualitatively determined
if (photocellReading < 10) {
Serial.println(" - Dark");
} else if (photocellReading < 200) {
Serial.println(" - Dim");
} else if (photocellReading < 500) {
Serial.println(" - Light");
} else if (photocellReading < 800) {
Serial.println(" - Bright");
} else {
Serial.println(" - Very bright");
}
delay(1000);
}
</nowiki>
To test it, I started in a sunlit (but shaded) room and covered the sensor with my hand, then covered it with a piece of blackout fabric.
[[Fichier:cds-mesure3.jpg]]