Arduino Nano Pin-out difference between V 2.0 and V 3.0
You may already be aware of this but I thought it might be useful to Arduino Nano users .. Something to be aware of when deciding on a Nano Shield: Recently, I ordered the DFRobot Nano shield for a new Robot project. My project uses I2C and I discovered quickly that IC2 wasn't functioning. At first I thought there was a problem on the shield as it appeared that the Analog pin order seemed reversed. Shouldn't have been a major problem (just be aware in code) , however the wire library defaults SDA and SCL to Analog pins 4 & 5 and IC2 on this Nano shield was now on analog pins 2&3. I had to modify the shield (see Appiphania.com for details). However, on closer examination ... the shield wasn't the problem! My Arduino Nano is the Gravitech Version 3.0. I compared the Version 3.0 diagram to that of Version 2.2 and the analog pins are indeed reversed!