I am using an AVR ATmega88 and will also be implementing 2 ADC inputs. If I would like Aref to be equal to AVcc, what is better? Connecting the AVcc pin to Aref, or internally using the registers to set Aref to AVcc?

If you do set them equal using the registers, what should be done with the Aref pin? Be left N/C?

 

Does the spec sheet for the device have any opinions about this?

 

Internally connect Aref and put a 0.1uF ceramic cap on the Aref pin. You also want to have filtering and bypass caps on the AVcc input.