// --------------------------------------
// 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 26  2013
//    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 14, 2013
//    revised to run in the loop() function more
//    like robsoles thought it should.
//
// This sketch tests the standard 7-bit addresses
// Devices with higher bit address might not be seen properly.
//

#include <Wire.h>

volatile byte error, address;
volatile int nDevices;
volatile long passes;

void setup()
{
  Wire.begin();

  Serial.begin(9600);
  Serial.println("\nI2C Scanner");
}


void loop()
{
  switch(address) {
  case 0:
    Serial.print("Scanning[");
    Serial.print(passes++,DEC);
    Serial.println("]...");
    nDevices = 0;
  break;
  case 128: // finished scanning, show results
    if (nDevices == 0)
      Serial.println("No I2C devices found\n");
    else
      Serial.println("done\n");
  break;
  default:
    if(address<128) {
      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("Unknown error at address 0x");
        if (address<16)
          Serial.print("0");
        Serial.println(address,HEX);
      }
    } else {
      delay(40); // about 5 seconds after all the looping.
    }
  }
  address++; // naturally overflows back to 0
}