ADC code for getting voltage of AREF pin of arduino pro mini 3.3v

Since AREF pin of arduino pro mini 3.3v is connected to 0.1uF capacitor and this pin isn't present at breakout , it's not possible to get voltage of AREF pin by physical test ( through multi-meter ) . I will use INTERNAL 1.1V as reference , hence I need to know how much voltage I will get for INTERNAL 1.1V reference at AREF pin , hence I need a code to measure voltage of AREF pin .

Pls help me .

hence I need to know how much voltage I will get for INTERNAL 1.1V

I’m going to guess that chose that name because the internal reference voltage is 2.8V.

hence I need a code to measure voltage of AREF pin .

The AREF pin is an input pin. You should KNOW how much voltage you are putting in.

On the 32-pin surface mount packages the AREF pin is number 20 counting counter-clockwise from the PIN 1 mark. On the 28-pin MLF package it's pin 17. Use a fine point meter probe.

Search the forum for "secret voltmeter". This is a method of reading the value of Vcc assuming that the internal voltage reference has a value of 1.1V. If you have a known value of Vcc, you can then back-calculate how much AREF is.

mnhpias: Since AREF pin of arduino pro mini 3.3v is connected to 0.1uF capacitor and this pin isn't present at breakout , it's not possible to get voltage of AREF pin by physical test ( through multi-meter ) . I will use INTERNAL 1.1V as reference , hence I need to know how much voltage I will get for INTERNAL 1.1V reference at AREF pin , hence I need a code to measure voltage of AREF pin .

Pls help me .

It IS possible to use A-ref on a Pro Mini: see this page https://www.reddit.com/r/arduino/comments/57dadp/make_an_aref_pin_on_your_arduino_pro_mini_for/

It describes how to wire pin 20 to one of both reset pins after cutting the tiny track to it. I did it and it works perfectly, just use a very precise cutter and magnifying glasses.

FYI, you don't have to do the external hardware fix if you call out analogReference(DEFAULT); under your void setup loop. I was about to do the hardware fix when I found this out.

Ref: https://www.arduino.cc/reference/en/language/functions/analog-io/analogreference/