Resolution is exactly what I meant.
I dont want to use external components if possible. The current sensor delivers 10mV/A. Doesn't seem to be scalable.
The only way to improve accuracy then, is to change Aref by building a voltagedivider and use two or more outputpins to change the ratio. ( add more and more resistors to the upperside of the divider )
Or could I use a PWM pin to charge a capacitor parallel to the upper resistor? That way I'd have lots of possible 'dividers'.
I have to read the Aref section of the ATMega manual to find out whether the voltage can be changed 'on the fly'...