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.. highlight:: cpp
.. _lang-pwmwrite:
pwmWrite()
==========
Writes a :ref:`PWM wave <pwm>` to a pin. You can use this to make an
LED get brighter or dimmer, control a servomotor, etc. After a call to
pwmWrite(), the pin will output a steady square wave with the given
duty cycle. You can change the duty cycle later by calling pwmWrite()
again with the same pin and a different duty.
The pins which support PWM have ``PWM`` listed underneath their number
on your board's silkscreen. These pin numbers are available to your
program in the :ref:`boardPWMPins <lang-board-values-pwm-pins>`
board-specific array. The number of pins which are capable of PWM on
your board is given by the ``BOARD_NR_PWM_PINS`` constant. These
values are documented for each board in the :ref:`Board Hardware
Documentation <index-boards>` pages.
The Arduino function :ref:`analogWrite() <lang-analogwrite>` is an
alias for ``pwmWrite()``, but it is badly named, and its use is
discouraged.
.. contents:: Contents
:local:
Library Documentation
---------------------
.. doxygenfunction:: pwmWrite
Example
-------
Sets the output to the LED proportional to the value read from the
potentiometer::
int analogPin = 3; // potentiometer connected to analog pin 3
void setup() {
pinMode(BOARD_LED_PIN, OUTPUT); // sets the LED pin as output
pinMode(analogPin, INPUT_ANALOG); // sets the potentiometer pin as
// analog input
}
void loop() {
int val = analogRead(analogPin); // read the input pin
pwmWrite(BOARD_LED_PIN, val * 16); // analogRead values go from 0
// to 4095, pwmWrite values
// from 0 to 65535, so scale roughly
}
See Also
--------
- :ref:`Maple PWM tutorial <pwm>`
- :ref:`boardPWMPins <lang-board-values-pwm-pins>`
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