Current measurement using Arduino motor shield R3

Projects Programming
1

Hi

I have a question regarding the current sensing using motor shield R3.

The page http://arduino.cc/en/Main/ArduinoMotorShieldR3 says that to measure current we need to use the function analogRead on the pin corresponding to the channel and that the pin is calibrated to 3.3V for 2A current.

In the page of analogRead function, it says that the measured value will be 1023 if the pin is at 5V.

So if I am drawing a current of 2A will I get 1023 or (1023x3.3/5) ~ 675 ?

I have never used analogRead function before and I do not have any thing right now which draws 2A to verify it myself.

Can someone please explain me this.

Thanks
--ksp

2

I have the same question. Is it calibrated to 3.3v because its designed to run on 3.3v, or thats the best fit for 5v?

Do the resistor values need to change if the AREF is at 5v?

Regards