reference from http://playground.arduino.cc/Main/I2cScanner
// --------------------------------------
// i2c_scanner
//
// Version 1
//This program (or code that looks like it)
//can be found in many places.
//For example on the Arduino.cc forum.
//The original author is not know.
// Version 2, Juni 2012, Using Arduino 1.0.1
// Adapted to be as simple as possible by Arduino.cc user Krodal
// Version 3, Feb 262013
//V3 by louarnold
// Version 4, March 3, 2013, Using Arduino 1.0.3
//by Arduino.cc user Krodal.
//Changes by louarnold removed.
//Scanning addresses changed from 0...127 to 1...119,
//according to the i2c scanner by Nick Gammon
//http://www.gammon.com.au/forum/?id=10896
// Version 5, March 28, 2013
//As version 4, but address scans now to 127.
//A sensor seems to use address 120.
// Version 6, November 27, 2015.
//Added waiting for the Leonardo serial communication.
//
//
// This sketch tests the standard 7-bit addresses
// Devices with higher bit address might not be seen properly.
//
#include <Wire.h>
void setup(){
Wire.begin();
Serial.begin(9600);
while (!Serial); // Leonardo: wait for serial monitor
Serial.println("\nI2C Scanner");
}
void loop(){
byte error, address;
int nDevices;
Serial.println("Scanning...");
nDevices = 0;
for(address = 1; address < 127; address++ ){
// The i2c_scanner uses the return value of
// the Write.endTransmisstion to see if
// a device did acknowledge to the 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); // wait 5 seconds for next scan
}