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.. currentmodule:: machine
.. _machine.PWM:
class PWM -- pulse width modulation
===================================
This class provides pulse width modulation output.
Example usage::
from machine import PWM
pwm = PWM(pin) # create a PWM object on a pin
pwm.duty_u16(32768) # set duty to 50%
# reinitialise with a period of 200us, duty of 5us
pwm.init(freq=5000, duty_ns=5000)
pwm.duty_ns(3000) # set pulse width to 3us
pwm.deinit()
Constructors
------------
.. class:: PWM(dest, \*, freq, duty_u16, duty_ns)
Construct and return a new PWM object using the following parameters:
- *dest* is the entity on which the PWM is output, which is usually a
:ref:`machine.Pin <machine.Pin>` object, but a port may allow other values,
like integers.
- *freq* should be an integer which sets the frequency in Hz for the
PWM cycle.
- *duty_u16* sets the duty cycle as a ratio ``duty_u16 / 65535``.
- *duty_ns* sets the pulse width in nanoseconds.
Setting *freq* may affect other PWM objects if the objects share the same
underlying PWM generator (this is hardware specific).
Only one of *duty_u16* and *duty_ns* should be specified at a time.
Methods
-------
.. method:: PWM.init(\*, freq, duty_u16, duty_ns)
Modify settings for the PWM object. See the above constructor for details
about the parameters.
.. method:: PWM.deinit()
Disable the PWM output.
.. method:: PWM.freq([value])
Get or set the current frequency of the PWM output.
With no arguments the frequency in Hz is returned.
With a single *value* argument the frequency is set to that value in Hz. The
method may raise a ``ValueError`` if the frequency is outside the valid range.
.. method:: PWM.duty_u16([value])
Get or set the current duty cycle of the PWM output, as an unsigned 16-bit
value in the range 0 to 65535 inclusive.
With no arguments the duty cycle is returned.
With a single *value* argument the duty cycle is set to that value, measured
as the ratio ``value / 65535``.
.. method:: PWM.duty_ns([value])
Get or set the current pulse width of the PWM output, as a value in nanoseconds.
With no arguments the pulse width in nanoseconds is returned.
With a single *value* argument the pulse width is set to that value.
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