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diff --git a/source/lang/api/hardwaretimer.rst b/source/lang/api/hardwaretimer.rst new file mode 100644 index 0000000..258471b --- /dev/null +++ b/source/lang/api/hardwaretimer.rst @@ -0,0 +1,368 @@ +.. highlight:: cpp + +.. _lang-hardwaretimer: + +HardwareTimer +============= + +This class defines the public API for interfacing with the STM32's +built-in timer peripherals. More information on these peripherals +(including code examples) is available in the :ref:`timers reference +<timers>`. + +Library Documentation +--------------------- + +HardwareTimer Class Reference +^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ + +To interact with a particular timer, call one of the methods +documented below on one of the predefined ``HardwareTimer`` instances. +For example, to set the prescale factor on timer 1 to 5, call +``Timer1.setPrescaleFactor(5)``. + +.. cpp:class:: HardwareTimer + + Class for interacting with a timer. There are four predefined + instances available on the Maple: ``Timer1``, ``Timer2``, + ``Timer3``, and ``Timer4``. + +.. _lang-hardwaretimer-attachinterrupt: + +.. cpp:function:: void HardwareTimer::attachInterrupt(int channel, voidFuncPtr handler) + + Attach an interrupt handler to the given ``channel``. This + interrupt handler will be called when the timer's counter reaches + the given channel :ref:`compare <lang-hardwaretimer-setcompare>` + value. + + ``handler`` should be a function which takes no arguments and has + :ref:`void <lang-void>` value; i.e. it should have signature :: + + void handler(void); + + You can later detach the interrupt using :ref:`detachInterrupt() + <lang-hardwaretimer-detachinterrupt>`. + + .. note:: The function (often called an *interrupt service + routine*, or ISR) should attempt to return as quickly as + possible. :ref:`Blinking the LED <lang-toggleled>`, some + logic, :ref:`PWM <pwm>` updates, and :ref:`Serial + <lang-serial>` writes are fine; writing to + :ref:`SerialUSB <lang-serialusb>` or :ref:`waiting + <lang-waitforbuttonpress>` for user input can take a long + time and prevent other interrupts from firing on time. + + Tip: if you have a :ref:`delay() <lang-delay>` in your + ISR, you're probably doing it wrong. + +.. cpp:function:: void HardwareTimer::attachCompare1Interrupt(voidFuncPtr handler) + + Equivalent to :ref:`attachInterrupt + <lang-hardwaretimer-attachinterrupt>`\ ``(1, handler)``. + +.. cpp:function:: void HardwareTimer::attachCompare2Interrupt(voidFuncPtr handler) + + Equivalent to :ref:`attachInterrupt + <lang-hardwaretimer-attachinterrupt>`\ ``(2, handler)``. + +.. cpp:function:: void HardwareTimer::attachCompare3Interrupt(voidFuncPtr handler) + + Equivalent to :ref:`attachInterrupt + <lang-hardwaretimer-attachinterrupt>`\ ``(3, handler)``. + +.. cpp:function:: void HardwareTimer::attachCompare4Interrupt(voidFuncPtr handler) + + Equivalent to :ref:`attachInterrupt + <lang-hardwaretimer-attachinterrupt>`\ ``(4, handler)``. + +.. _lang-hardwaretimer-setchannelmode: + +.. cpp:function:: void HardwareTimer::setChannelMode(int channel, TimerMode mode) + + Set the given channel of this timer to the given :ref:`mode + <lang-hardwaretimer-modes>`. The parameter ``channel`` is one of + 1, 2, 3, and 4, and corresponds to the compare channel you would + like to set. Refer to the full :ref:`pin mapping table + <pin-mapping-mega-table>` to match up timer channels and pin + numbers. + +.. cpp:function:: void HardwareTimer::setChannel1Mode(TimerMode mode) + + Equivalent to :ref:`setChannelMode <lang-hardwaretimer-setchannelmode>`\ + ``(1, mode)``. + +.. cpp:function:: void HardwareTimer::setChannel2Mode(TimerMode mode) + + Equivalent to :ref:`setChannelMode <lang-hardwaretimer-setchannelmode>`\ + ``(2, mode)``. + +.. cpp:function:: void HardwareTimer::setChannel3Mode(TimerMode mode) + + Equivalent to :ref:`setChannelMode <lang-hardwaretimer-setchannelmode>`\ + ``(3, mode)``. + +.. cpp:function:: void HardwareTimer::setChannel4Mode(TimerMode mode) + + Equivalent to :ref:`setChannelMode <lang-hardwaretimer-setchannelmode>`\ + ``(4, mode)``. + +.. _lang-hardwaretimer-getcompare: + +.. cpp:function:: uint16 HardwareTimer::getCompare(int channel) + + Gets the compare value for the given ``channel``, from 1 to 4. See + :ref:`setCompare() <lang-hardwaretimer-setcompare>`. + +.. cpp:function:: uint16 HardwareTimer::getCompare1() + + Equivalent to :ref:`getCompare <lang-hardwaretimer-getcompare>`\ + ``(1, mode)``. + +.. cpp:function:: uint16 HardwareTimer::getCompare2() + + Equivalent to :ref:`getCompare <lang-hardwaretimer-getcompare>`\ + ``(2, mode)``. + +.. cpp:function:: uint16 HardwareTimer::getCompare3() + + Equivalent to :ref:`getCompare <lang-hardwaretimer-getcompare>`\ + ``(3, mode)``. + +.. cpp:function:: uint16 HardwareTimer::getCompare4() + + Equivalent to :ref:`getCompare <lang-hardwaretimer-getcompare>`\ + ``(4, mode)``. + +.. _lang-hardwaretimer-setcompare: + +.. cpp:function:: void HardwareTimer::setCompare(int channel, uint16 compare) + + Sets the compare value for the given ``channel`` to ``compare``. + If ``compare`` is greater than this timer's overflow value, it will + be truncated to the overflow value. The default compare value is + 65,535 (the largest unsigned 16-bit integer value). + + When the counter reaches this value the interrupt for this channel + will fire if the given ``channel`` :ref:`mode + <lang-hardwaretimer-setchannelmode>` is ``TIMER_OUTPUTCOMPARE`` and + an interrupt is :ref:`attached + <lang-hardwaretimer-attachinterrupt>`. + + By default, this only changes the relative offsets between events + on a single timer ("phase"); they don't control the frequency with + which they occur. However, a common trick is to increment the + compare value manually in the interrupt handler so that the event + will fire again after the increment period. There can be a + different increment value for each channel, so this trick allows + events to be programmed at 4 different rates on a single + timer. Note that function call overheads mean that the smallest + increment rate is at least a few microseconds. + +.. cpp:function:: void HardwareTimer::setCompare1(uint16 compare) + + Equivalent to :ref:`setCompare <lang-hardwaretimer-setcompare>`\ + ``(1, compare)``. + +.. cpp:function:: void HardwareTimer::setCompare2(uint16 compare) + + Equivalent to :ref:`setCompare <lang-hardwaretimer-setcompare>`\ + ``(2, compare)``. + +.. cpp:function:: void HardwareTimer::setCompare3(uint16 compare) + + Equivalent to :ref:`setCompare <lang-hardwaretimer-setcompare>`\ + ``(3, compare)``. + +.. cpp:function:: void HardwareTimer::setCompare4(uint16 compare) + + Equivalent to :ref:`setCompare <lang-hardwaretimer-setcompare>`\ + ``(4, compare)``. + +.. cpp:function:: uint16 HardwareTimer::getCount() + + Gets the current timer count. Due to function call overhead, the + return value will be increasingly accurate with smaller prescale + values. Also see :ref:`setCount() <lang-hardwaretimer-setcount>`. + +.. _lang-hardwaretimer-setcount: + +.. cpp:function:: void HardwareTimer::setCount(uint16 val) + + Set the timer's current count to ``val``. + + Note that there is some function call overhead associated with + calling this method, so using it is not a robust way to get + multiple timers to share a count value. + + If ``val`` exceeds the timer's :ref:`overflow value + <lang-hardwaretimer-getoverflow>`, it is truncated to the overflow + value. + + +.. _lang-hardwaretimer-detachinterrupt: + +.. cpp:function:: void HardwareTimer::detachInterrupt(int channel) + + Remove the interrupt handler attached to the given ``channel``, if + any. The handler will no longer be called by this timer. + +.. cpp:function:: void HardwareTimer::detachCompare1Interrupt() + + Equivalent to :ref:`detachInterrupt + <lang-hardwaretimer-detachinterrupt>`\ ``(1)``. + +.. cpp:function:: void HardwareTimer::detachCompare2Interrupt() + + Equivalent to :ref:`detachInterrupt + <lang-hardwaretimer-detachinterrupt>`\ ``(2)``. + +.. cpp:function:: void HardwareTimer::detachCompare3Interrupt() + + Equivalent to :ref:`detachInterrupt + <lang-hardwaretimer-detachinterrupt>`\ ``(3)``. + +.. cpp:function:: void HardwareTimer::detachCompare4Interrupt() + + Equivalent to :ref:`detachInterrupt + <lang-hardwaretimer-detachinterrupt>`\ ``(4)``. + +.. _lang-hardwaretimer-generateupdate: + +.. cpp:function:: void HardwareTimer::generateUpdate() + + Re-initializes the counter (to 0 in upcounting mode, which is the + default), and generates an update of the prescale and overflow + registers. + +.. _lang-hardwaretimer-getoverflow: + +.. cpp:function:: uint16 HardwareTimer::getOverflow() + + Gets the timer's overflow value. See :ref:`setOverflow() + <lang-hardwaretimer-setoverflow>`. + +.. _lang-hardwaretimer-setoverflow: + +.. cpp:function:: void HardwareTimer::setOverflow(uint16 val) + + Sets the timer overflow (or "reload") value to ``val``. + + When the timer's counter reaches this, value it resets to + zero. Its default value is 65535 (the largest unsigned 16-bit + integer); setting the overflow to anything lower will cause + interrupts to be called more frequently (see :ref:`setPeriod() + <lang-hardwaretimer-setperiod>` function for a shortcut). + + After the next :ref:`timer update + <lang-hardwaretimer-generateupdate>`, this number will be the + maximum value for the timer's channel compare values. + +.. _lang-hardwaretimer-pause: + +.. cpp:function:: void HardwareTimer::pause() + + Stop the timer's counter, without affecting its configuration. + + The timer will no longer count or fire interrupts after this + function is called, until it is resumed. This function is useful + during timer setup periods, in order to prevent interrupts from + firing before the timer is fully configured. + + Note that there is some function call overhead associated with this + method, so using it in concert with :ref:`resume() + <lang-hardwaretimer-resume>` is not a robust way to align multiple + timers to the same count value. + +.. _lang-hardwaretimer-setperiod: + +.. cpp:function:: uint16 HardwareTimer::setPeriod(uint32 microseconds) + + Configure the :ref:`prescaler + <lang-hardwaretimer-getprescalefactor>` and :ref:`overflow + <lang-hardwaretimer-getoverflow>` values to generate a timer reload + with a period as close to the given number of ``microseconds`` as + possible. + + The return value is the new overflow value, which may be used to + set channel compare values. However, if a clock that fires an + interrupt every given number of microseconds is all that is + desired, and the relative "phases" are unimportant, channel compare + values may all be set to 1. + +.. _lang-hardwaretimer-getprescalefactor: + +.. cpp:function:: uint16 HardwareTimer::getPrescaleFactor() + + Returns the timer's prescale factor. See + :ref:`setPrescaleFactor() <lang-hardwaretimer-setprescalefactor>`. + +.. _lang-hardwaretimer-setprescalefactor: + +.. cpp:function:: void HardwareTimer::setPrescaleFactor(uint16 factor) + + Set the timer's prescale factor to ``factor``. + + The prescaler acts as a clock divider to slow down the rate at + which the counter increments. + + For example, the system clock rate is 72MHz, so the counter will + reach 65535 in (13.89 nanoseconds) × (65535 counts) = (910.22 + microseconds), or about a thousand times a second. If the + prescaler equals 1098, then the clock rate is effectively 72MHz / + 1098 = 65.56KHz, and the counter will reach 65536 in (15.25 + microseconds) × (65536 counts) = (0.999 seconds), or about once + per second. + + The :ref:`setPeriod() <lang-hardwaretimer-setperiod>` method may + also be used as a convenient alternative. + +.. cpp:function:: void HardwareTimer::resume() + + Resume a paused timer, without affecting its configuration. + + The timer will resume counting and firing interrupts as + appropriate. + + Note that there is some function call overhead associated with + using this method, so using it in concert with :ref:`pause() + <lang-hardwaretimer-pause>` is not a robust way to align multiple + timers to the same count value. + +.. cpp:function:: timer_dev_num HardwareTimer::getTimerNum() + + Returns the :ref:`timer device number + <lang-hardwaretimer-timer-dev-num>` associated with the timer. For + example, ``Timer1.getTimerNum()`` would return ``TIMER1``. + + In most cases, you should not need to use this function. If you do + use it, be careful; the constant ``TIMER1`` is *not equal* to the + number 1; similarly, ``TIMER2`` is *not* the number 2, etc. Be + sure to refer to the timer device number by name. + +.. _lang-hardwaretimer-modes: + +Timer Modes +^^^^^^^^^^^ +.. doxygenenum:: TimerMode + +.. _lang-hardwaretimer-timer-dev-num: + +Timer Device Numbers +^^^^^^^^^^^^^^^^^^^^ + +These provide a lower-level interface for interacting with timers. +They are mostly useful in context with the :ref:`getTimer() +<lang-hardwaretimer-gettimer>` function. **Be careful** when using +these not to confuse e.g. ``TIMER1`` with the number 1; they are +different. + +.. doxygenenum:: timer_dev_num + +.. _lang-hardwaretimer-convenience: + +.. _lang-hardwaretimer-gettimer: + +Other Functions +^^^^^^^^^^^^^^^ +.. doxygenfunction:: getTimer |