I2C on an Arduino

This is a short follow up to my Introduction to the I2C Bus video of a few weeks ago. I intended to show how to write some code to implement I2C bus communications between an Arduino and an accelerometer, but I discovered a problem. The Arduino library enables the ATMega328 internal pull-up resistors for the SDA and SCL lines. For a 3.3V sensor, this brings the voltage on these line too close to the maximum they can handle. I show how to disable the internal pull-up resistors to solve the problem.

[cgreendyk]

First of all, thank you for this Video.
This could be the answer to a problem I am currently having. I am building a quadcopter with an arduino shield flight Controller. The quadcopter is powered by a 14, 8V Lithium polymer battery that runs through a BEC and brings approx. 5V to the arduino shield. My ADX345 and ITG3200 sensors run through the 3, 3V of my Arduino Micro board and are read from there. The problem is that I am only able to read the data from the sensors when the arduino is plugged in via USB to the cp. However when I plug in the battery alone, the sensors do not react at all. Maybe this is the solution

[philipgautschi]

Is there some official Statement from the arduino Team? (or the guy/Girl which wrote the library)

I guess they had a reason to do this that way?...