class TimerWiPy -- control hardware timers

注釈

This class is a non-standard Timer implementation for the WiPy. It is available simply as machine.Timer on the WiPy but is named in the documentation below as machine.TimerWiPy to distinguish it from the more general machine.Timer class.

ハードウェアタイマーは、一定周期とイベントのタイミングで処理します。タイマーはおそらく MCU や SoC で最も柔軟で様々な種類のあるハードウェアであり、モデルごとに大きく異なります。MicroPython の Timer クラスは、指定した周期で(または少し経過後に1回だけ)コールバックを実行するベースライン操作を定義します。特定のボードがより標準的でない動作を定義できます(したがって他のボードへの移植性はありません)。

Timer のコールバックに関する 重要な制約 の議論を見てください。

注釈

irq ハンドラ(割り込み)内でメモリを割り当てることはできず、そのためにハンドラ内で発生した例外には多くの情報を持ちません。この制限を回避する方法については micropython.alloc_emergency_exception_buf() を参照してください。

コンストラクタ

class machine.TimerWiPy(id, ...)

指定した id の新しいタイマーオブジェクトを構築します。id が -1 の場合は、(ボードでサポートしていれば)仮想タイマーを構築します。

メソッド

TimerWiPy.init(mode, *, width=16)

タイマーを初期化します。たとえば次のように使います:

tim.init(Timer.PERIODIC)             # periodic 16-bit timer
tim.init(Timer.ONE_SHOT, width=32)   # one shot 32-bit timer

キーワード引数:

  • mode は次のいずれかになります。
    • TimerWiPy.ONE_SHOT - The timer runs once until the configured period of the channel expires.
    • TimerWiPy.PERIODIC - The timer runs periodically at the configured frequency of the channel.
    • TimerWiPy.PWM - Output a PWM signal on a pin.
  • width must be either 16 or 32 (bits). For really low frequencies < 5Hz (or large periods), 32-bit timers should be used. 32-bit mode is only available for ONE_SHOT AND PERIODIC modes.
TimerWiPy.deinit()

タイマーを初期化解除します。タイマーを停止し、タイマーのペリフェラルを無効にします。

TimerWiPy.channel(channel, **, freq, period, polarity=TimerWiPy.POSITIVE, duty_cycle=0)

If only a channel identifier passed, then a previously initialized channel object is returned (or None if there is no previous channel).

Otherwise, a TimerChannel object is initialized and returned.

The operating mode is is the one configured to the Timer object that was used to create the channel.

  • channel if the width of the timer is 16-bit, then must be either TIMER.A, TIMER.B. If the width is 32-bit then it must be TIMER.A | TIMER.B.

Keyword only arguments:

  • freq sets the frequency in Hz.
  • period sets the period in microseconds.

注釈

Either freq or period must be given, never both.

  • polarity this is applicable for PWM, and defines the polarity of the duty cycle
  • duty_cycle only applicable to PWM. It's a percentage (0.00-100.00). Since the WiPy doesn't support floating point numbers the duty cycle must be specified in the range 0-10000, where 10000 would represent 100.00, 5050 represents 50.50, and so on.

注釈

When the channel is in PWM mode, the corresponding pin is assigned automatically, therefore there's no need to assign the alternate function of the pin via the Pin class. The pins which support PWM functionality are the following:

  • GP24 on Timer 0 channel A.
  • GP25 on Timer 1 channel A.
  • GP9 on Timer 2 channel B.
  • GP10 on Timer 3 channel A.
  • GP11 on Timer 3 channel B.

class TimerChannel --- setup a channel for a timer

Timer channels are used to generate/capture a signal using a timer.

TimerChannel objects are created using the Timer.channel() method.

メソッド

timerchannel.irq(*, trigger, priority=1, handler=None)

The behavior of this callback is heavily dependent on the operating mode of the timer channel:

  • If mode is TimerWiPy.PERIODIC the callback is executed periodically with the configured frequency or period.
  • If mode is TimerWiPy.ONE_SHOT the callback is executed once when the configured timer expires.
  • If mode is TimerWiPy.PWM the callback is executed when reaching the duty cycle value.

The accepted params are:

  • priority level of the interrupt. Can take values in the range 1-7. Higher values represent higher priorities.
  • handler is an optional function to be called when the interrupt is triggered.
  • trigger must be TimerWiPy.TIMEOUT when the operating mode is either TimerWiPy.PERIODIC or TimerWiPy.ONE_SHOT. In the case that mode is TimerWiPy.PWM then trigger must be equal to TimerWiPy.MATCH.

Returns a callback object.

timerchannel.freq([value])

Get or set the timer channel frequency (in Hz).

timerchannel.period([value])

Get or set the timer channel period (in microseconds).

timerchannel.duty_cycle([value])

Get or set the duty cycle of the PWM signal. It's a percentage (0.00-100.00). Since the WiPy doesn't support floating point numbers the duty cycle must be specified in the range 0-10000, where 10000 would represent 100.00, 5050 represents 50.50, and so on.

定数

TimerWiPy.ONE_SHOT
TimerWiPy.PERIODIC

タイマー操作モード。