// Wire.h is part of the core Arduino libraries and comes pre-installed with the Arduino IDE. 
#include <Wire.h>  // Include the Wire library for I2C communication

void setup() 
{
  Serial.begin(115200);  // Initialize serial communication at a baud rate of 115200
  Wire.begin();          // Start the I2C bus
  //Wire.begin(4,5); //Use this if you have custom pins for I2C SDA,SCL
  Serial.println("\nI2C Scanner"); // Print a header message in Serial Monitor indicating the scanner's start
}

void loop() 
{
  byte error, address; // Variable 'error' stores the status of I2C transmission; 'address' is the I2C address of the device
  int nDevices = 0;  // Variable to count the number of detected I2C devices
  Serial.println("Scanning..."); // Print message indicating that scanning has started

  // Loop through all possible I2C addresses (1 to 126)
  for (address = 1; address < 127; address++) 
  {
    Wire.beginTransmission(address); // Start communication with the device at the specified I2C address
    error = Wire.endTransmission();  // Send I2C message to the device, see whether it responds and check for errors in the response 
    
    // If no error, an I2C device responded at this address
    if (error == 0) 
    {
      Serial.print("I2C device found at address 0x"); // Print message indicating a device is found

      // If address is a single-digit hex (0x00 to 0x0F), print a leading zero for formatting
      if (address < 16)
      {
        Serial.print("0"); // Print a leading zero for single-digit hexadecimal addresses
      }
      Serial.print(address, HEX); // Print the device address in hexadecimal format
      Serial.println("  !"); // Indicate a successful connection with an exclamation mark at the end for emphasis
      nDevices++; // Increment the device count
    }

    // If an error code 4 is returned, it indicates an unknown error 
    else if (error == 4) 
    {
      Serial.print("Unknown error at address 0x"); // Print message indicating unknown error at a specific address

      // Print leading zero for single-digit hexadecimal addresses
      if (address < 16) 
      {
        Serial.print("0"); 
      }
      Serial.println(address, HEX); // Print the address with the unknown error in hexadecimal
    }
  }

  // If no devices were detected, print a message; otherwise, print "Done."
  if (nDevices == 0) 
  {
    Serial.println("No I2C devices found\n"); // Print a message indicating no devices were found
  } 
  else 
  {
    Serial.println("Done.\n"); // Scanning completed with at least one device found
  }
  delay(5000);  // Wait 5 seconds before starting the next scan
}