#include <Wire.h>
int address, deviceFound,  error;

void setup() {
  Wire.begin();
  Serial.begin(115200);
  Serial.print("I2C bus device addresses:");

  for (address = 0; address < 128; address++ )  {
    Wire.beginTransmission(address);
    if (!Wire.endTransmission()) {
      showHex(address);
      deviceFound++;
    }
    else if (error == 4) {
      Serial.print(" Error at");
      showHex(address);
    }
  }
  if (!deviceFound)
    Serial.println(" No I2C devices found.");
}

void loop() {}

void showHex(int hex) {
  Serial.print(" 0x");
  if (hex < 0x10)
    Serial.print(0);
  Serial.print(hex, HEX);
}