Learn how to use PWM (Pulse Width Modulation) output with Arduino.

Using PWM in your sketch

Add PWM output to your sketch using the analogWrite() function.

Here’s a basic example:

int ledPin = 9;      // LED connected to digital pin 9
int analogPin = A0;  // potentiometer connected to analog pin A0
int val = 0;         // variable to store the read value

void setup() {
  pinMode(ledPin, OUTPUT);  // sets the pin as output
}

void loop() {
  val = analogRead(analogPin);  // read the input pin
  analogWrite(ledPin, val / 4); // analogRead values go from 0 to 1023, analogWrite values from 0 to 255
}

Change the PWM resolution

Depending on your board’s core, you can modify the resolution of PWM signals using the analogWriteResolution() function. By default, the resolution is 8 bits, meaning that values passed to the analogWrite() function range between 0 and 255, which ensures backward compatibility with AVR-based boards.

To change the resolution, use analogWriteResolution(bits), where bits determines the resolution in bits, ranging from 1 to 32. See an example code.

Recommended PWM pins

Overview for common boards

*These pins are officially supported PWM pins. While some boards have additional pins capable of PWM, using them is recommended only for advanced users that can account for timer availability and potential conflicts with other uses of those pins.
**In addition to PWM capabilities on the pins noted above, the MKR, Nano 33 IoT, and Zero boards have true analog output when using analogWrite() on the DAC0 (A0) pin.
***In addition to PWM capabilities on the pins noted above, the Due has true analog output when using analogWrite() on pins DAC0 and DAC1.

Finding PWM pins in the pinout diagrams

The pinouts for many boards specifify the recommended PWM pins with a tilde (~) symbol:

You can find pinouts on Arduino Docs.

Additional PWM pins

Many newer boards support PWM on additional pins, but their use is subject to timer availability.

Further reading

• Basics of PWM