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.

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.

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.

The Due has 12-bit ADC capabilities that can be accessed by changing the resolution to 12. This will return values from analogRead() between 0 and 4095.

bits: determines the resolution (in bits) of the value returned by analogRead() function. Valid arguments are between 1 and 32. You can set resolutions higher than 12 but values returned by analogRead() will suffer approximation. See the note below for details.

If a resolution higher than the hardware capabilities is set, the Arduino will only report back at its highest resolution padding the extra bits with zeros.

For example: using the Due 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 a resolution lower than the hardware capabilities is set, the extra least significant bits read from the ADC will be discarded.

Note that using a 16 bit resolution (or any resolution higher than actual hardware capabilities) allows to write sketches that automatically handles superior ADC devices when these become available on future boards without changing a line of code.

void setup() {

  // 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));

  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);

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.

bits: determines the resolution (in bits) of the ADC. Valid arguments are between 0 and 12. You can set the resolution larger than 12, but higher values are ignored. See the note below for details.

analogReadResolution() is an extension of the Analog API for the Arduino Due.

analogReadResolution()

Syntax

analogReadResolution(bits)

• analogRead()

Sets the size (in bits) of the value returned by analogRead(). It defaults to 10 bits (returns values between 0-1023) for backward compatibility.

analogReadResolution(bits)

Description

Sets the size (in bits) of the value returned by analogRead(). It defaults to 10 bits (returns values between 0-1023) for backward compatibility. This has no effect on Arduino Uno or other ATmega based boards.

The Due has 12-bit ADC capabilities that can be accessed by changing the resolution. This will return values from analogRead() between 0 and 4095.

Parameters

bits: determines the resolution (in bits) of the ADC. You can set the reolution larger than 12, and less than 10, see the note below for how this is dealt with.

Returns

None.

Note

If a resolution larger than the hardware capabilities is set, the Arduino will only report back at its highest resolution. For example, using the Due with analogReadResolution(16) will only give you a 12-bit number.

If a resolution lower than the hardware capabilities is set, the least significant bits will be ignored.

Example

(:source lang=arduino:) void setup(){

 // 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));
 delay(5);
 // change the resolution to 12 bits and read A0
 analogReadResolution(12);
 Serial.print(", 12-bit : ");
 Serial.print(analogRead(A0));
 delay(5);
  // change the resolution to 16 bits and read A0
 analogReadResolution(12);
 Serial.print(", 16-bit : ");
 Serial.print(analogRead(A0));
 delay(5);
 // change the resolution to 8 bits and read A0
 analogReadResolution(8);
 Serial.print(", 8-bit : ");
 Serial.println(analogRead(A0));
 delay(5);

} (:sourceend:)

See also

• Description of the analog input pins
• analogRead()