Automated Night-Light with ESP32 & LDR

The Core Concept

An automated night-light relies on a simple closed-loop sensing cycle:

• Sensing: The LDR (Light Dependent Resistor) measures the surrounding light intensity.
• Processing: The ESP32 Devkit V1 reads the sensor's changing signal and evaluates it against a pre-set threshold.
• Actuation: If the environment is darker than the threshold, the ESP32 activates GPIO2 to light up the LED.

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Virtual Components Needed

Open your project workspace inside the Ayantrik Lab simulator, click on the Add Components library, and select the following parts:

• 1x ESP32 Devkit V1
• 1x LED (Any color)
• 1x 220Ω Resistor (To protect your LED)
• 1x LDR (Photoresistor) Module (Ensure it has an A0 analog output pin)

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Circuit Connection Guide

Set up your connections carefully on the virtual workspace. Using an LDR module with an analog pin simplifies the circuit drastically compared to building a manual voltage divider from scratch.

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The System Code

Open the built-in code editor inside the simulator, delete any default text, and paste this control program:

cpp
View full codeCopy code
// --- Hardware Configuration ---
const int ldrPin = 34;  // Pin D34 handles the analog input from the LDR
const int ledPin = 2;   // Pin D2 controls our output indicator LED

// --- Automation Settings ---
// The ESP32 analog pin converts voltages into data values ranging from 0 to 4095.
// Lower values = darker environment. Higher values = brighter environment.
const int darknessThreshold = 1500; 

void setup() {
  // Initialize serial communication for live monitoring
  Serial.begin(115200);
  
  // Set the LED pin as an output controller
  pinMode(ledPin, OUTPUT);
  digitalWrite(ledPin, LOW); // Keep light off initially
}

void loop() {
  // Read the variable analog data coming from the LDR module
  int lightLevel = analogRead(ldrPin);
  
  // Broadcast the data points to the terminal screen
  Serial.print("Current Ambient Light Level: ");
  Serial.println(lightLevel);
  
  // Automation Logic: Evaluate light level against our baseline threshold
  if (lightLevel < darknessThreshold) {
    digitalWrite(ledPin, HIGH); // Environment is dark -> Activate Night-Light
    Serial.println(">>> Night-Light Status: [ ON ]");
  } else {
    digitalWrite(ledPin, LOW);  // Environment is bright -> Deactivate Night-Light
    Serial.println(">>> Night-Light Status: [ OFF ]");
  }
  
  // Take a reading every half second to avoid processing lag
  delay(500); 
}

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Understanding the Logic

The system functions dynamically using a basic conditional statement inside the execution loop:

• When it's Bright: The photoresistor experiences low resistance, allowing more voltage to pass through to pin D34. The ESP32 processes this signal as a large number (e.g., 2800). Because 2800 is greater than our 1500 threshold, the else block triggers, turning off the LED pin.

• When it's Dark: The photoresistor's resistance spikes up drastically, choking off the voltage flow down to a trickle. Pin D34 detects this drop and registers a small number (e.g., 850). Since 850 is less than 1500, the main condition is met, throwing the LED pin into a high-voltage state to light up your space.

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Testing and Verifying Your System

1. Click Run / Start Simulation inside the Ayantrik toolbar.
2. Expand the Serial Monitor tab along the lower section of your screen to track the real-time data logs.
3. Left-click directly on the LDR component on your digital canvas while the simulation is running. A small environmental slider control will appear above it.
4. Drag the slider to adjust ambient conditions. Move it towards the moon icon (representing complete darkness). Watch your terminal output — as soon as the reported numeric light value drops below 1500, your virtual LED will illuminate instantly!