I'm using an Arduino to control a motor controller, which in turn supplies 6v of power (from some AA's) to a motor. The motor controller recommends bridging the ground between the control current (Arduino) and the supply current (4*AA's). If I use this ground for other circuits, could there be unintended consequences? Specifically, I'm looking to use it to ground an ir sensor, but I don't think that matters. I just want to know if there's any danger to the components in using more ground than is typical.
When a sensor is connected to the Arduino, then the signal wires (I2C bus or analog signals) together with the GND wire should go directly to the Arduino board. That GND wire should not be used for other things, because it is part of the sensor circuit.
Can you tell which motor controller it is ? Where does it say to bridge both grounds ? In the datasheet ? Where is the datasheet ? (we like to know everything)