Arduino program to Design a night lamp using a photodiode and a LED and find out the time delay associated with turning the lamp on and off.

Arduino program to Design a night lamp using a photodiode and a LED and find out the time delay associated with turning the lamp on and off.

Designing a night lamp using a photodiode and an LED with an Arduino Uno involves several steps, including wiring the components, writing the Arduino code, and measuring the time delays. Here is a detailed guide to help you through the process:

Components Needed:

Arduino Uno
Photodiode
LED
220-ohm resistor
10k-ohm resistor
Jumper wires

Circuit Diagram:

Photodiode Circuit:

Connect the anode (positive) of the photodiode to the 5V pin of the Arduino.
Connect the cathode (negative) of the photodiode to one end of a 10k-ohm resistor and to the Analog pin A0 of the Arduino.
Connect the other end of the 10k-ohm resistor to the GND pin of the Arduino.

LED Circuit:

Connect the anode (positive) of the LED to a digital pin (e.g., D9) on the Arduino through a 220-ohm resistor.
Connect the cathode (negative) of the LED to the GND pin of the Arduino.

Solution

const int photodiodePin = A0;
const int ledPin = 13;
int sensorValue = 0;
int threshold = 50; // Adjust this value based on your ambient light
unsigned long turnOnTime = 0;
unsigned long turnOffTime = 0;

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

void loop() {
  sensorValue = analogRead(photodiodePin);
  Serial.println(sensorValue);
  
  if (sensorValue < threshold) {
    if (digitalRead(ledPin) == LOW) {
      turnOnTime = millis();
      Serial.print("LED turned on at: ");
      Serial.println(turnOnTime);
    }
    digitalWrite(ledPin, HIGH); // Turn on the LED
  } else {
    if (digitalRead(ledPin) == HIGH) {
      turnOffTime = millis();
      Serial.print("LED turned off at: ");
      Serial.println(turnOffTime);
    }
    digitalWrite(ledPin, LOW);  // Turn off the LED
  }

  delay(100); // Delay for stability
}

▶ RUN

Output/ Explanation:

Threshold Adjustment:

The threshold variable determines the light level at which the LED should turn on or off. You may need to adjust this value based on your specific environment.

Time Recording:

turnOnTime and turnOffTime are used to record the time when the LED state changes.
millis() function returns the number of milliseconds since the Arduino board began running the current program.

Serial Output:

The Serial.print and Serial.println functions are used to output the times to the Serial Monitor for observation.

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Arduino program to Design a night lamp using a photodiode and a LED and find out the time delay associated with turning the lamp on and off.