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Light-sensitive Array

This program converts the readings from a light-dependent resistor into a corresponding number of illuminated LED lights, creating a simple indicator of light brightness.

Required Components

In this project, we need the following components.

It’s definitely convenient to buy a whole kit, here’s the link:

Name	ITEMS IN THIS KIT	LINK
Elite Explorer Kit	300+	Elite Explorer Kit

You can also buy them separately from the links below.

COMPONENT INTRODUCTION	PURCHASE LINK
Arduino Uno R4 WiFi	-
Breadboard	BUY
Jumper Wires	BUY
Resistor	BUY
LED	BUY
Photoresistor	BUY

Wiring

Schematic

Code

Note

• You can open the file 04_light_sensitive_array.ino under the path of elite-explorer-kit-main\fun_project\04_light_sensitive_array directly.

• Or copy this code into Arduino IDE.

04_light_sensitive_array.ino

/*
  The code reads the ambient light level through a photoresistor and lights up
  a certain number of LEDs based on the light level. The LEDs serve as a "light level bar."

  Board: Arduino Uno R4 
  Component: Photoresistor and LED
*/

// Constants for the number of LEDs and their pins
const int NbrLEDs = 8;
const int ledPins[] = { 5, 6, 7, 8, 9, 10, 11, 12 };

// Pin for the photoresistor
const int photocellPin = A0;

// Variables to store sensor and LED level values
int sensorValue = 0;  // value read from the sensor
int ledLevel = 0;     // sensor value converted into LED 'bars'

void setup() {
  // Initialize all LED pins as outputs
  for (int led = 0; led < NbrLEDs; led++) {
    pinMode(ledPins[led], OUTPUT);
  }
}

void loop() {
  sensorValue = analogRead(photocellPin);              // Read the ambient light level from the photoresistor
  ledLevel = map(sensorValue, 300, 1023, 0, NbrLEDs);  // Map the sensor value to the number of LEDs to be lit

  // Update the state of each LED based on the mapped value
  for (int led = 0; led < NbrLEDs; led++) {
    if (led < ledLevel) {
      digitalWrite(ledPins[led], HIGH);  // Turn ON LEDs that are below the level
    } else {
      digitalWrite(ledPins[led], LOW);  // Turn OFF LEDs that are above the level
    }
  }
}

How it works?

Here’s a step-by-step explanation of the code:

1. Constant and Variable Definitions:

   NbrLEDs: Defines the presence of 8 LEDs. ledPins[]: LEDs are connected to Arduino pins 5 to 12. photocellPin: The photoresistor is connected to Arduino’s A0 pin. sensorValue: This variable stores the value read from the photoresistor. ledLevel: This variable stores the number of LEDs based on the sensorValue conversion.

2. setup():

   Configures pins 5 to 12 as output to drive the LEDs.

3. loop():

   Reads the analog value of the photoresistor from pin A0, typically ranging from 0 to 1023. Uses the map function to map the photoresistor’s value from the range 300-1023 to the range 0-8. This means that if the reading from the light-dependent resistor is 300, no LEDs will be lit; if the reading is 1023 or higher, all 8 LEDs will be lit.

   The subsequent for loop checks each LED. If its index is less than ledLevel, the LED will be turned on; otherwise, it will be turned off.