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