analog reference voltage external

Projects Programming
1

Do I need any kind of resistor to limit current to the arduino board if i am going to be using an external voltage as a reference? It says that there is a 32k resistor on the AREF pin, so I am assuming no, but I don't want to kill my board.

Thanks for any input,
Trevor

2

It says that there is a 32k resistor on the AREF pin,

Where does it say that?

3

It says it on the arduino page about analogRefrence() , but it does not really explain much about it, just mentions it once. here is a link to the page

http://arduino.cc/en/pmwiki.php?n=Reference/AnalogReference

Down in the warning section.

4

Thanks for the link, in fact it says:-

there is an internal 32K resistor on the AREF pin.

The important thing here is it says "internal" - that means inside the processor.
There is no need to have an external resistor when connecting a voltage to this pin. However do heed the warnings on that page about calling the function that sets the reference voltage to external before doing any analogue read.

5

Thanks for the help.

6

I presume the reference voltage will NOT exceed 5 volts.

...R