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July 12, 2010, at 05:00 PM by David A. Mellis -
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AREF

This page is a stub for how to use the analog reference pin. Pin 21 on the Atemga 8 and Atemga 168 chip.

The voltage at this pin determines the voltage at which the analog to digital converters (ADC's) will report the decimal value 1023, which is their highest level output.

So for example if you were using Sharp analog infrared sensors, which tend to report voltages in between .5 V and 3V, the Arduino will report values from 102 to 613, using analogRead(). If no other 5V sensors were connected it might be desirable to increase the 3V output to 1023. This could be done using the AREF pin.

The AREF pin is, by default, connected to the AVCC voltage of around 5 volts (unless you are running your Arduino at a lower voltage). To provide a lower reference voltage to this pin you need to disconnect the internal voltage reference.

For now see this forum thread

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April 18, 2008, at 03:55 AM by David A. Mellis -
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August 11, 2007, at 04:02 PM by Paul Badger -
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The voltage at this pin determines the voltage at which the analog to digital converters (ADC's) will report the decimal value 1023, which is their highest level output.

So for example if you were using Sharp analog infrared sensors, which tend to report voltages in between .5 V and 3V, the Arduino will report values from 102 to 613, using analogRead(). If no other 5V sensors were connected it might be desirable to increase the 3V output to 1023. This could be done using the AREF pin.

The AREF pin is, by default, connected to the AVCC voltage of around 5 volts (unless you are running your Arduino at a lower voltage). To provide a lower reference voltage to this pin you need to disconnect the internal voltage reference.

August 11, 2007, at 03:52 PM by Paul Badger -
Changed lines 3-11 from:

This page is a stub for how to use the analog reference pin. Pin 21 on the Atemga 8 and Atemga 168 chip.

to:

This page is a stub for how to use the analog reference pin. Pin 21 on the Atemga 8 and Atemga 168 chip.

For now see this forum thread

August 11, 2007, at 03:50 PM by Paul Badger -
August 11, 2007, at 03:49 PM by Paul Badger -
Changed line 3 from:

This is a stub for how to use the analog reference pin.

to:

This page is a stub for how to use the analog reference pin. Pin 21 on the Atemga 8 and Atemga 168 chip.

August 11, 2007, at 03:47 PM by Paul Badger -
Added lines 1-3:

AREF

This is a stub for how to use the analog reference pin.

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