Internal analog Reference voltage for ATmega32u4 (Micro and Leonardo)

I just discovered that the INTERNAL analog reference voltage for the Arduino Micro appears to be 2.56V instead of 1.1V (like for most of the recent Arduino boards).

On the page describing the analogReference function, there is apparently no information for the ATmega32u4 (used in Micro and Leonardo) :

INTERNAL: an built-in reference, equal to 1.1 volts on the ATmega168 or ATmega328 and 2.56 volts on the ATmega8 (not available on the Arduino Mega)

I could not find any information either on the Micro and Leonardo pages. I therefore wrongly assumed that the built-in reference should be 1.1V (like most the recent boards), which will cause me some problems with a circuit I just built...

BTW, I had to dig to page 292 of this document to find the internal analog voltage reference for the ATmega32u4. :cold_sweat: It might be a good idea to update the Arduino page describing the analog reference function for the ATmega32u4... :slight_smile:



Thanks for this post,

It is not mentioned in the ATMEL documents for the specific micro (ATMEGA32U4)
Luckily the datasheet above is the first one I read, I built an accurate instrument using the Leonardo, using the internal 2.56v ref.
(Note : It is nice and accurate)

Now, I was checking the design and becoming confused because the datasheet for the ATMEGA32U4 says the internal ref is 1.1V.

This 2.56 V internal ref is very handy and should be mentioned as a feature, and specified in the datasheet.

Hi there --

Here is the Atmel datasheet .... specifically, internal voltage reference, found on page 54.

Am doing some research for adding a supply battery monitor for a radio module run through an A* 32u4 Mini.