Bau dir doch mal einen I2C Scanner (Arduino Beispiel):

Code:
  1. void loop()
  2. {
  3.   byte error, address;
  4.   int nDevices;
  5.   Serial.println("Scanning...");
  6.   nDevices = 0;
  7.   for(address = 1; address < 127; address++ )
  8.   {
  9.     // The i2c_scanner uses the return value of
  10.     // the Write.endTransmisstion to see if
  11.     // a device did acknowledge to the address.
  12.     Wire.beginTransmission(address);
  13.     error = Wire.endTransmission();
  14.     if (error == 0)
  15.     {
  16.       Serial.print("I2C device found at address 0x");
  17.       if (address<16)
  18.         Serial.print("0");
  19.       Serial.print(address,HEX);
  20.       Serial.println("  !");
  21.       nDevices++;
  22.     }
  23.     else if (error==4)
  24.     {
  25.       Serial.print("Unknow error at address 0x");
  26.       if (address<16)
  27.         Serial.print("0");
  28.       Serial.println(address,HEX);
  29.     }
  30.   }
  31.   if (nDevices == 0)
  32.     Serial.println("No I2C devices found\n");
  33.   else
  34.     Serial.println("done\n");
  35.   delay(5000);           // wait 5 seconds for next scan
  36. }

mfg