I2C between Arduino and Moteino

[wpenni]

I currently have an Arduino based logging pyrometer working with a ceramics kiln.  It displays, and logs to an SD card, the current temperature and degrees/hour temperature change.

My next step is to transmit these values to a remote display so that I don't have to keep running upstairs to check on things.

My plan is to use the I2C bus to send the values from the Arduino to a Moteino.  This Moteino will transmit the values to a remote Moteino that will display the values on a 7 Segment Display.

My concern is the communication between the 5V Arduino and the 3.3V Moteino.  I thought I read on the LowPowerLab blog that the Moteino was fairly forgiving with higher voltages (couldn't find it again).  So can I use 5V for I2C or will I have to step it down to 3.3V?

Thanks.

[Felix]

If you plan to use this long term I would actually recommend doing the right thing and stepping down through a simple resistor voltage divider. So go from 5V-Arduino logic -> 4.7K -> connection to Moteino 3.3V logic -> 10K - GND
You can do this for both the SCL and SDA, assuming the Arduino is generating the clock.

[wpenni]

Thanks!  I'll give it a try.