Hello, im trying to build my own arduino (buying the IC atmega328), but i dont know where conect aref in the design of the circuit board.
I will use analog inputs, but in default reference (5v).
I must leave the pin disconected? connected to pull up resistor? pull down resistor? direct to gnd? or to vcc?
See the ATmega328 data sheet for suggestions on how to wire the AREF and AVCC pins.
From the ATmega datasheet section 24:
Internal reference voltages of nominally 1.1V or AVCC are provided On-chip. The voltage reference may be externally decoupled at the AREF pin by a capacitor for better noise performance.
The Arduino has a 100nF capacitor to ground.
im found this
um aref here is connected directly to vcc
Do not connect AREF to anything but a 0.1uF cap to Gnd.
It seems that they don't use Avcc, and connect 5volt directly to Aref.
Seems a quick and dirty solution to me.
Leo..
Except AVCC must connect to 5V to power that corner of the chip.