Description
Configures the reference voltage used for analog input (i.e. the value used as the top of the input range). The options are:
Arduino AVR Boards (Uno, Mega, etc.)
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DEFAULT: the default analog reference of 5 volts (on 5V Arduino boards) or 3.3 volts (on 3.3V Arduino boards)
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INTERNAL: an built-in reference, equal to 1.1 volts on the ATmega168 or ATmega328P and 2.56 volts on the ATmega8 (not available on the Arduino Mega)
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INTERNAL1V1: a built-in 1.1V reference (Arduino Mega only)
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INTERNAL2V56: a built-in 2.56V reference (Arduino Mega only)
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EXTERNAL: the voltage applied to the AREF pin (0 to 5V only) is used as the reference.
Arduino SAMD Boards (Zero, etc.)
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AR_DEFAULT: the default analog reference of 3.3V
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AR_INTERNAL: a built-in 2.23V reference
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AR_INTERNAL1V0: a built-in 1.0V reference
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AR_INTERNAL1V65: a built-in 1.65V reference
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AR_INTERNAL2V23: a built-in 2.23V reference
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AR_EXTERNAL: the voltage applied to the AREF pin is used as the reference
Arduino SAM Boards (Due)
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AR_DEFAULT: the default analog reference of 3.3V. This is the only supported option for the Due.
Syntax
analogReference(type)
Parameters
type
: which type of reference to use (see list of options in the description).
Returns
Nothing