I2C_Scanner.ino

// http://playground.arduino.cc/Main/I2cScanner

// -------------
// i2c_scanner
// -------------

#include <Wire.h>

void setup() {
    Wire.begin();
    Serial.begin(9600);
    while (!Serial);
    Serial.println("\nI2C Scanner");
}

void loop() {
    byte error, address;
    int nDevices;
    Serial.println("Scanning...");
    nDevices = 0;
    for(address=1; address<127; address++) {
        Wire.beginTransmission(address);
        error = Wire.endTransmission();
          if (error == 0) {
          Serial.print("I2C device found at address 0x");
          if (address < 16) Serial.print("0");
          Serial.print(address,HEX);
          Serial.println("  !");
          nDevices++;
        } else if (error == 4) {
          Serial.print("Unknow error at address 0x");
          if (address < 16) Serial.print("0");
          Serial.println(address,HEX);
        }    
    }
    if (nDevices == 0) Serial.println("No I2C devices found\n");
    else Serial.println("done\n");
    delay(5000);
}