I have a cheap MPU 6050 chip that communicates over 3.3V I2C. I can talk to it just fine on my Leonardo. If I add an additional Adafruit Motor shield (the old one), my MPU 6050 demo sketch hangs somewhere, and I get nothing back.
As far as I see, the pins I use for the I2C communication are not used at all by the motor shield.
What could be wrong here?
I have the MPU6050 connected to SCL, SDA, GND and 3.3V, the motor shield uses almost all other pins.
Additional Info: I am using this sketch currently: https://github.com/jrowberg/i2cdevlib/tree/master/Arduino/MPU6050
Update: Lots of "Serial.println"s later, I've narrowed it down a bit. The example sketch above hangs on the statement "Wire.endTransmission();" on line 279 of the I2CDev library.
Update: Connecting the motor shield to external power seems to fix my problem. Weird =) I am still interested in the reason for this behavior.