Analog Read - 0-5v on a Fio V3

Is it possible to read an analog 0-5v with a Fio V3 and not use the ARef pin with 5 volts to it? The Fio operates on 3.3v

If I must use the Aref and I pull 5v from another IC circuit that has its own power source do I need to hook the IC's ground to the Fio V3's ground?

READ THIS before you do anything. http://www.arduino.cc/en/Reference/AnalogReference?from=Reference.AREF

So if I were to do what I asked the micro controller would return 1023 for anything greater then 3.3 volts? So I do need to provide it with a 5v reference. Will the 5v reference burn up the board since it is a 3.3v board?

Yes

The answer to your original question is NO.

Use 2 resistors as a voltage divider to bring the 5V down to 3.3V. Grounds must be connected together.

CrossRoads,

Will that reduce the accuracy of the whole process? I will be reading a loadcell that has its own electronics. It will have to have its own power source of 5v.

I am thinking about using a stand alone load cell but then I worry about accuracy.

This will be measuring the torque on a drive shaft of a machine. (Not a Car). So all the electronics will need to be small and wireless send the information to another arduino that will collect the data. The drive shaft will have a maximum of 2000 rpm.

Thanks, Core2