kopia lustrzana https://github.com/micropython/micropython
docs: Move WiPy specific Timer class to separate doc file.
The WiPy machine.Timer class is very different to the esp8266 and esp32 implementations which are better candidates for a general Timer class. By moving the WiPy Timer docs to a completely separate file, under a new name machine.TimerWiPy, it gives a clean slate to define and write the docs for a better, general machine.Timer class. This is with the aim of eventually providing documentation that does not have conditional parts to it, conditional on the port. While the new docs are being defined it makes sense to keep the WiPy docs, since they describe its behaviour. Once the new Timer behaviour is defined the WiPy code can be changed to match it, and then the TimerWiPy docs would be removed.pull/3992/head
Damien George
rodzic
21dae87710
commit
d8e0320485
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@ -130,12 +130,13 @@ The following libraries are specific to the pyboard.
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Libraries specific to the WiPy
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------------------------------
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The following libraries are specific to the WiPy.
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The following libraries and classes are specific to the WiPy.
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.. toctree::
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:maxdepth: 2
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wipy.rst
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machine.TimerWiPy.rst
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Libraries specific to the ESP8266
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@ -21,6 +21,9 @@ Timer callbacks.
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:func:`micropython.alloc_emergency_exception_buf` for how to get around this
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limitation.
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If you are using a WiPy board please refer to :ref:`machine.TimerWiPy <machine.TimerWiPy>`
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instead of this class.
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Constructors
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------------
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@ -32,129 +35,30 @@ Constructors
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Methods
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-------
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.. only:: port_wipy
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.. method:: Timer.init(\*, mode=Timer.PERIODIC, period=-1, callback=None)
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.. method:: Timer.init(mode, \*, width=16)
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Initialise the timer. Example::
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Initialise the timer. Example::
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tim.init(period=100) # periodic with 100ms period
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tim.init(mode=Timer.ONE_SHOT, period=1000) # one shot firing after 1000ms
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tim.init(Timer.PERIODIC) # periodic 16-bit timer
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tim.init(Timer.ONE_SHOT, width=32) # one shot 32-bit timer
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Keyword arguments:
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Keyword arguments:
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- ``mode`` can be one of:
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- ``Timer.ONE_SHOT`` - The timer runs once until the configured
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period of the channel expires.
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- ``Timer.PERIODIC`` - The timer runs periodically at the configured
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frequency of the channel.
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- ``Timer.PWM`` - Output a PWM signal on a pin.
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- ``mode`` can be one of:
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- ``width`` must be either 16 or 32 (bits). For really low frequencies < 5Hz
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(or large periods), 32-bit timers should be used. 32-bit mode is only available
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for ``ONE_SHOT`` AND ``PERIODIC`` modes.
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- ``Timer.ONE_SHOT`` - The timer runs once until the configured
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period of the channel expires.
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- ``Timer.PERIODIC`` - The timer runs periodically at the configured
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frequency of the channel.
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.. method:: Timer.deinit()
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Deinitialises the timer. Stops the timer, and disables the timer peripheral.
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.. only:: port_wipy
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.. method:: Timer.channel(channel, \**, freq, period, polarity=Timer.POSITIVE, duty_cycle=0)
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If only a channel identifier passed, then a previously initialized channel
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object is returned (or ``None`` if there is no previous channel).
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Otherwise, a TimerChannel object is initialized and returned.
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The operating mode is is the one configured to the Timer object that was used to
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create the channel.
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- ``channel`` if the width of the timer is 16-bit, then must be either ``TIMER.A``, ``TIMER.B``.
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If the width is 32-bit then it **must be** ``TIMER.A | TIMER.B``.
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Keyword only arguments:
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- ``freq`` sets the frequency in Hz.
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- ``period`` sets the period in microseconds.
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.. note::
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Either ``freq`` or ``period`` must be given, never both.
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- ``polarity`` this is applicable for ``PWM``, and defines the polarity of the duty cycle
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- ``duty_cycle`` only applicable to ``PWM``. It's a percentage (0.00-100.00). Since the WiPy
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doesn't support floating point numbers the duty cycle must be specified in the range 0-10000,
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where 10000 would represent 100.00, 5050 represents 50.50, and so on.
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.. note::
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When the channel is in PWM mode, the corresponding pin is assigned automatically, therefore
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there's no need to assign the alternate function of the pin via the ``Pin`` class. The pins which
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support PWM functionality are the following:
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- ``GP24`` on Timer 0 channel A.
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- ``GP25`` on Timer 1 channel A.
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- ``GP9`` on Timer 2 channel B.
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- ``GP10`` on Timer 3 channel A.
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- ``GP11`` on Timer 3 channel B.
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.. only:: port_wipy
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class TimerChannel --- setup a channel for a timer
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==================================================
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Timer channels are used to generate/capture a signal using a timer.
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TimerChannel objects are created using the Timer.channel() method.
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Methods
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-------
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.. method:: timerchannel.irq(\*, trigger, priority=1, handler=None)
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The behavior of this callback is heavily dependent on the operating
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mode of the timer channel:
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- If mode is ``Timer.PERIODIC`` the callback is executed periodically
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with the configured frequency or period.
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- If mode is ``Timer.ONE_SHOT`` the callback is executed once when
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the configured timer expires.
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- If mode is ``Timer.PWM`` the callback is executed when reaching the duty
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cycle value.
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The accepted params are:
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- ``priority`` level of the interrupt. Can take values in the range 1-7.
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Higher values represent higher priorities.
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- ``handler`` is an optional function to be called when the interrupt is triggered.
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- ``trigger`` must be ``Timer.TIMEOUT`` when the operating mode is either ``Timer.PERIODIC`` or
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``Timer.ONE_SHOT``. In the case that mode is ``Timer.PWM`` then trigger must be equal to
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``Timer.MATCH``.
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Returns a callback object.
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.. only:: port_wipy
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.. method:: timerchannel.freq([value])
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Get or set the timer channel frequency (in Hz).
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.. method:: timerchannel.period([value])
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Get or set the timer channel period (in microseconds).
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.. method:: timerchannel.duty_cycle([value])
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Get or set the duty cycle of the PWM signal. It's a percentage (0.00-100.00). Since the WiPy
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doesn't support floating point numbers the duty cycle must be specified in the range 0-10000,
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where 10000 would represent 100.00, 5050 represents 50.50, and so on.
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Constants
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---------
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.. data:: Timer.ONE_SHOT
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.. data:: Timer.PERIODIC
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Timer.PERIODIC
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Timer operating mode.
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@ -0,0 +1,159 @@
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.. currentmodule:: machine
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.. _machine.TimerWiPy:
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class TimerWiPy -- control hardware timers
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==========================================
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.. note::
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This class is a non-standard Timer implementation for the WiPy.
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It is available simply as ``machine.Timer`` on the WiPy but is named in the
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documentation below as ``machine.TimerWiPy`` to distinguish it from the
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more general :ref:`machine.Timer <machine.Timer>` class.
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Hardware timers deal with timing of periods and events. Timers are perhaps
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the most flexible and heterogeneous kind of hardware in MCUs and SoCs,
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differently greatly from a model to a model. MicroPython's Timer class
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defines a baseline operation of executing a callback with a given period
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(or once after some delay), and allow specific boards to define more
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non-standard behavior (which thus won't be portable to other boards).
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See discussion of :ref:`important constraints <machine_callbacks>` on
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Timer callbacks.
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.. note::
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Memory can't be allocated inside irq handlers (an interrupt) and so
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exceptions raised within a handler don't give much information. See
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:func:`micropython.alloc_emergency_exception_buf` for how to get around this
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limitation.
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Constructors
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------------
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.. class:: TimerWiPy(id, ...)
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Construct a new timer object of the given id. Id of -1 constructs a
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virtual timer (if supported by a board).
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Methods
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-------
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.. method:: TimerWiPy.init(mode, \*, width=16)
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Initialise the timer. Example::
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tim.init(Timer.PERIODIC) # periodic 16-bit timer
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tim.init(Timer.ONE_SHOT, width=32) # one shot 32-bit timer
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Keyword arguments:
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- ``mode`` can be one of:
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- ``TimerWiPy.ONE_SHOT`` - The timer runs once until the configured
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period of the channel expires.
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- ``TimerWiPy.PERIODIC`` - The timer runs periodically at the configured
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frequency of the channel.
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- ``TimerWiPy.PWM`` - Output a PWM signal on a pin.
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- ``width`` must be either 16 or 32 (bits). For really low frequencies < 5Hz
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(or large periods), 32-bit timers should be used. 32-bit mode is only available
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for ``ONE_SHOT`` AND ``PERIODIC`` modes.
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.. method:: TimerWiPy.deinit()
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Deinitialises the timer. Stops the timer, and disables the timer peripheral.
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.. method:: TimerWiPy.channel(channel, \**, freq, period, polarity=TimerWiPy.POSITIVE, duty_cycle=0)
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If only a channel identifier passed, then a previously initialized channel
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object is returned (or ``None`` if there is no previous channel).
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Otherwise, a TimerChannel object is initialized and returned.
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The operating mode is is the one configured to the Timer object that was used to
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create the channel.
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- ``channel`` if the width of the timer is 16-bit, then must be either ``TIMER.A``, ``TIMER.B``.
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If the width is 32-bit then it **must be** ``TIMER.A | TIMER.B``.
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Keyword only arguments:
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- ``freq`` sets the frequency in Hz.
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- ``period`` sets the period in microseconds.
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.. note::
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Either ``freq`` or ``period`` must be given, never both.
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- ``polarity`` this is applicable for ``PWM``, and defines the polarity of the duty cycle
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- ``duty_cycle`` only applicable to ``PWM``. It's a percentage (0.00-100.00). Since the WiPy
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doesn't support floating point numbers the duty cycle must be specified in the range 0-10000,
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where 10000 would represent 100.00, 5050 represents 50.50, and so on.
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.. note::
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When the channel is in PWM mode, the corresponding pin is assigned automatically, therefore
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there's no need to assign the alternate function of the pin via the ``Pin`` class. The pins which
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support PWM functionality are the following:
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- ``GP24`` on Timer 0 channel A.
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- ``GP25`` on Timer 1 channel A.
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- ``GP9`` on Timer 2 channel B.
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- ``GP10`` on Timer 3 channel A.
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- ``GP11`` on Timer 3 channel B.
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class TimerChannel --- setup a channel for a timer
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==================================================
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Timer channels are used to generate/capture a signal using a timer.
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TimerChannel objects are created using the Timer.channel() method.
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Methods
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-------
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.. method:: timerchannel.irq(\*, trigger, priority=1, handler=None)
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The behavior of this callback is heavily dependent on the operating
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mode of the timer channel:
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- If mode is ``TimerWiPy.PERIODIC`` the callback is executed periodically
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with the configured frequency or period.
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- If mode is ``TimerWiPy.ONE_SHOT`` the callback is executed once when
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the configured timer expires.
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- If mode is ``TimerWiPy.PWM`` the callback is executed when reaching the duty
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cycle value.
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The accepted params are:
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- ``priority`` level of the interrupt. Can take values in the range 1-7.
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Higher values represent higher priorities.
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- ``handler`` is an optional function to be called when the interrupt is triggered.
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- ``trigger`` must be ``TimerWiPy.TIMEOUT`` when the operating mode is either ``TimerWiPy.PERIODIC`` or
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``TimerWiPy.ONE_SHOT``. In the case that mode is ``TimerWiPy.PWM`` then trigger must be equal to
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``TimerWiPy.MATCH``.
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Returns a callback object.
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.. method:: timerchannel.freq([value])
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Get or set the timer channel frequency (in Hz).
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.. method:: timerchannel.period([value])
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Get or set the timer channel period (in microseconds).
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.. method:: timerchannel.duty_cycle([value])
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Get or set the duty cycle of the PWM signal. It's a percentage (0.00-100.00). Since the WiPy
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doesn't support floating point numbers the duty cycle must be specified in the range 0-10000,
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where 10000 would represent 100.00, 5050 represents 50.50, and so on.
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Constants
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---------
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.. data:: TimerWiPy.ONE_SHOT
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.. data:: TimerWiPy.PERIODIC
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Timer operating mode.
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@ -44,7 +44,7 @@ See :ref:`machine.Pin <machine.Pin>`. ::
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Timers
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------
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See :ref:`machine.Timer <machine.Timer>` and :ref:`machine.Pin <machine.Pin>`.
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See :ref:`machine.TimerWiPy <machine.TimerWiPy>` and :ref:`machine.Pin <machine.Pin>`.
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Timer ``id``'s take values from 0 to 3.::
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from machine import Timer
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