Change internal AREF

[DASbur]

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 The problem being is the is propriatary and can not be published.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);

DAS

[srnet]

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

[DASbur]

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.

DAS

[JCA34F]

In setup():

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

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

[srnet]

DASbur:
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 ?

[DASbur]

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.

DAS

[DASbur]

Hi All

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

DAS

[GolamMostafa]

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).

Figure-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.

Figure-2:

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.