I am, for the first time, attaching a genuine 3.3 v. part (MPU-9150 breakout board) to an Arduino Nano, and I have a question about signal compatibility. I can obviously-voltage divide the 5 v. Nano outputs to provide 3.3 V. inputs to the MPU-9150. But will the MPU-9150 3.3 v. outputs provide clean high logic levels going back to the Nano?
Thanks in advance for any help.
It is at the limit of the specifications (actually just beyond the specifications), but it will work 
You can always add an I2C level shifter later to be sure that it will always work.
http://playground.arduino.cc/Main/I2CBi-directionalLevelShifter
Peter_n:
It is at the limit of the specifications (actually just beyond the specifications), but it will work
You can always add an I2C level shifter later to be sure that it will always work.
Arduino Playground - HomePage
Its within the specifications, any value below 1.5V is LOW, above 3.0V is HIGH,
for a 5V ATmega328. Only 0.3V noise immunity though, so watch out for noise.
Good advice on the noise issue. Thanks.
jrdoner, as you can see, according to some it is within the specifications, according to others (who read the datasheet 8) ) it is not. You can find that discussion many times on this forum.
Rule of thumb: It will work, but a level shifter is better (but some might disagree).
Ha! I have the datasheet here, section 28.2, "DC Characteristics",
VIH, input high voltage (except RESET/XTAL1):
Vcc > 2.4V, VIHmin = 0.6Vcc
As we are at Vcc=5V then VHI min is 3.0V, any voltage at/above 3.0 will be seen as
HIGH on all chips at across the temperature range -40C -> 85C
That is for digital inputs. The I2C levels are different.
As I wrote... these discussions can go on and on...
Search Ebay for : i2c level
They are cheap and work well.