Change internal AREF

Hi All

I wish to utilize the the internal 1.1 volt AREF I am using Anatmega328 28DIP only.programming is done through a parallel port programmer No wheres in the sketch is there That is being used is there any reference made to or for internal/ external AREF voltages.
So I assume it needs to be added in some wheres in the sketch. From what I gather it needs to be added before any reads of an analog pin. The problem being is the is propriatary and can not be published. Maybe a small amount could be but not the entire code. is it as simple as just adding a line in somewheres in the beginning of the code? analogReference(INTERNAL);


Try typeing 'Arduino internal reference' as a Google search, the search results will point you at the Arduino reference page for internal reference.

Hi All

That is the first thing I did. tells what it is but not how to integrate it into an existing sketch. that is what I am looking for.


In setup():

void setup()
  analogReference(INTERNAL); // use 1.1V internal ref

If it doesn't work, post your current code.

That is the first thing I did. tells what it is but not how to integrate it into an existing sketch. that is what I am looking for.

Well then post the code.

Is this a commercial product you are working on ?

Hi All

No it is not a commercial product that is going into personal use. There had been many references on this site for a code to do what this one does.
The code in the long run cost me a lot of dollars. just to post it and then have it used by others. sorry cant happen. From the hints that have been posted I think I have it figured out. I knew the proper code just was not sure where to put it in at.


Hi All

Thanks to the guys that PM me with the correct direct answer instead of beating around the bush . works like a charm.


The title of your thread is: Change internal AREF.

1. AREF is a signal name attached with physical pin-21 of the ATmega328P MCU (Fig-1).


2. AREF is a pin by which you can feed external voltage (range: 1.1V to 5V) to the internal Vref-point of the ADC Module (Fig-2) when your not using internal 1.1V or 5V (Vcc) for the Vref-point.

3. AREF is a pin by which you can monitor the value of the voltage (either INTERNAL 1.1V or 5V/Vcc) that is connected with Vref-point of the ADC.

4. AREF is a pin between which and GND yu can connect an external establishing filter capacitor for the voltage of Vre-point of the ADC.

5. AREF stnads for what? Does it stand for AnalogREFErence? I have not found this name in the data sheets of the MCU.

6. AREF signal is different from the Arduino command/code: analogReference(arg) which means the of the argument (arg) is a voltage that is connected with the Vref-point of the ADC as per following Truth Table:
(1) analogReference(DEFAULT); //5V/Vcc will be connected with Vref-point of ADC.
(2) analogReference(INTERNAL); //Internal 1.1V will be connected with Vref-point of ADC.
(3) analogReference(EXTERNAL); //external variable voltage 1.1V to 5V could be feed via AREF-pin for the Vref-point of ADC.

7. Think to modify the little of the thread so that your intention is reflected. There is nothing such as internal AREF.