LDR¶
Light Dependent Resistor
Output \(\in [0, 1023]\) $$ \begin{aligned} R &\propto \dfrac{1}{L_V} \ \implies I &\propto L_V \end{aligned} $$ where
- \(R =\) Resistance
- \(L_V =\) Intensity of incident light
- \(I =\) Current
Applications¶
- Smart street lights
- Auto-brightness on Phone
No polarity, as resistors don’t have any polarity
Connection¶
Code¶
int reading;
void setup(){
pinMode(A0, INPUT); // LDR
pinMode(D2, OUTPUT); // LED
Serial.begin(9600);
}
void loop(){
reading = analogRead(A0);
Serial.println(reading);
// if incident light too low -> environment too dark
// then turn on output light
if (reading < 50){
digitalWrite(D2, HIGH);
}
else {
digitalWrite(D2, LOW);
}
delay(500);
}