I am using an Mega328 with an ADC external reference of 5V. My resolution is about 4.8 mV. I want to make it 2.4mV. I know I can do this by adding a potential divider externally to halve the reference voltage to 2.5V. Other than this is there any other way to do this in software (i.e. within the AVR)and without changing any external hardware?