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analogReadResolution()
Description
analogReadResolution() is an extension of the Analog API for the Arduino Due and Zero.
Sets the size (in bits) of the value returned by analogRead(). It defaults to 10 bits (returns values between 0-1023) for backward compatibility with AVR based boards.
The Due and the Zero have 12-bit ADC capabilities that can be accessed by changing the resolution to 12. This will return values from analogRead() between 0 and 4095.
Syntax
analogReadResolution(bits)
Parameters
bits: determines the resolution (in bits) of the value returned by analogRead() function. You can set this 1 and 32. You can set resolutions higher than 12 but values returned by analogRead() will suffer approximation. See the note below for details.
Returns
None.
Note
If you set the analogReadResolution() value to a value higher than your board's capabilities, the Arduino will only report back at its highest resolution padding the extra bits with zeros.
For example: using the Due or the Zero with analogReadResolution(16) will give you an approximated 16-bit number with the first 12 bits containing the real ADC reading and the last 4 bits padded with zeros.
If you set the analogReadResolution() value to a value lower than your board's capabilities, the extra least significant bits read from the ADC will be discarded.
Using a 16 bit resolution (or any resolution higher than actual hardware capabilities) allows you to write sketches that automatically handle devices with a higher resolution ADC when these become available on future boards without changing a line of code.
Example
// open a serial connection
Serial.begin(9600);
}
void loop() {
// read the input on A0 at default resolution (10 bits)
// and send it out the serial connection
analogReadResolution(10);
Serial.print("ADC 10-bit (default) : ");
Serial.print(analogRead(A0));
// change the resolution to 12 bits and read A0
analogReadResolution(12);
Serial.print(", 12-bit : ");
Serial.print(analogRead(A0));
// change the resolution to 16 bits and read A0
analogReadResolution(16);
Serial.print(", 16-bit : ");
Serial.print(analogRead(A0));
// change the resolution to 8 bits and read A0
analogReadResolution(8);
Serial.print(", 8-bit : ");
Serial.println(analogRead(A0));
// a little delay to not hog serial monitor
delay(100);
}
See also
Corrections, suggestions, and new documentation should be posted to the Forum.
The text of the Arduino reference is licensed under a Creative Commons Attribution-ShareAlike 3.0 License. Code samples in the reference are released into the public domain.
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