Added a stub I2C Scanner sketch.

I2CScanner/I2CScanner.ino

@@ -0,0 +1,72 @@
+// --------------------------------------
+ // i2c_scanner
+ //
+ // 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.
+ //
+ // This sketch tests the standard 7-bit addresses
+ // from 0 to 127. Devices with higher bit address
+ // might not be seen properly.
+ //
+ // Adapted to be as simple as possible by Arduino.cc user Krodal
+ //
+ // June 2012
+ // Using Arduino 1.0.1
+ //
+ // Source: https://forum.arduino.cc/t/atmel-24c256-showing-up-at-wrong-i2c-address/123760/4
+ 
+#include <Wire.h>
+ 
+
+void setup()
+ {
+   Wire.begin();
+ 
+  Serial.begin(9600);
+   Serial.println("\nI2C Scanner");
+ }
+ 
+
+void loop()
+ {
+   byte error, address;
+   int nDevices;
+ 
+  Serial.println("Scanning...");
+ 
+  nDevices = 0;
+   for(address = 0; address <= 254; 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(8000);           // wait 8 seconds for next scan
+ }