diff options
| -rw-r--r-- | docs/esp32/quickref.rst | 4 | ||||
| -rw-r--r-- | docs/esp8266/quickref.rst | 3 | ||||
| -rw-r--r-- | docs/library/machine.Timer.rst | 20 | ||||
| -rw-r--r-- | docs/library/pyb.Timer.rst | 14 |
4 files changed, 37 insertions, 4 deletions
diff --git a/docs/esp32/quickref.rst b/docs/esp32/quickref.rst index 2c667a0f0..25e52ec32 100644 --- a/docs/esp32/quickref.rst +++ b/docs/esp32/quickref.rst @@ -287,6 +287,10 @@ with a timer ID of 0, 0 and 1, or from 0 to 3 (inclusive):: The period is in milliseconds. When using UART.IRQ_RXIDLE, timer 0 is needed for the IRQ_RXIDLE mechanism and must not be used otherwise. +Timer callbacks are scheduled as soft interrupts on this port; hard +callbacks are not implemented. Specifying ``hard=True`` will raise +a ValueError. + Virtual timers are not currently supported on this port. .. _Pins_and_GPIO: diff --git a/docs/esp8266/quickref.rst b/docs/esp8266/quickref.rst index e17b60f67..95e1fcf97 100644 --- a/docs/esp8266/quickref.rst +++ b/docs/esp8266/quickref.rst @@ -108,6 +108,9 @@ with timer ID of -1:: The period is in milliseconds. +By default, timer callbacks are scheduled as soft interrupts on this port. +Specify ``hard=True`` to run them in hard interrupt context instead. + Pins and GPIO ------------- diff --git a/docs/library/machine.Timer.rst b/docs/library/machine.Timer.rst index 44e659408..5d228ea7b 100644 --- a/docs/library/machine.Timer.rst +++ b/docs/library/machine.Timer.rst @@ -18,8 +18,9 @@ Timer callbacks. Memory can't be allocated inside irq handlers (an interrupt) and so exceptions raised within a handler don't give much information. See - :func:`micropython.alloc_emergency_exception_buf` for how to get around this - limitation. + :func:`micropython.alloc_emergency_exception_buf` for how to get around + this limitation, which applies to all callbacks of Timers created with + ``hard=True``. If you are using a WiPy board please refer to :ref:`machine.TimerWiPy <machine.TimerWiPy>` instead of this class. @@ -38,7 +39,7 @@ Constructors Methods ------- -.. method:: Timer.init(*, mode=Timer.PERIODIC, freq=-1, period=-1, callback=None) +.. method:: Timer.init(*, mode=Timer.PERIODIC, freq=-1, period=-1, callback=None, hard=True) Initialise the timer. Example:: @@ -76,6 +77,19 @@ Methods will occur upon timer expiration: ``TypeError: 'NoneType' object isn't callable`` + - ``hard`` can be one of: + + - ``True`` - The callback will be executed in hard interrupt + context, which minimises delay and jitter but is subject to the + limitations described in :ref:`isr_rules` including being unable + to allocate on the heap. + - ``False`` - The callback will be scheduled as a soft interrupt, + allowing it to allocate but possibly also introducing + garbage-collection delays and jitter. + + The default value of this option is port-specific for historical + reasons. + .. method:: Timer.deinit() Deinitialises the timer. Stops the timer, and disables the timer peripheral. diff --git a/docs/library/pyb.Timer.rst b/docs/library/pyb.Timer.rst index c644e38d7..0e9e49c0e 100644 --- a/docs/library/pyb.Timer.rst +++ b/docs/library/pyb.Timer.rst @@ -62,7 +62,7 @@ Constructors Methods ------- -.. method:: Timer.init(*, freq, prescaler, period, mode=Timer.UP, div=1, callback=None, deadtime=0, brk=Timer.BRK_OFF) +.. method:: Timer.init(*, freq, prescaler, period, mode=Timer.UP, div=1, callback=None, deadtime=0, brk=Timer.BRK_OFF, hard=True) Initialise the timer. Initialisation must be either by frequency (in Hz) or by prescaler and period:: @@ -115,6 +115,18 @@ Methods ``mode=Pin.ALT, alt=Pin.AFn_TIMx``. The pin's GPIO input features are available in alt mode - ``pull=`` , ``value()`` and ``irq()``. + - ``hard`` can be one of: + + - ``True`` - The callback will be executed in hard interrupt + context, which minimises delay and jitter but is subject to the + limitations described in :ref:`isr_rules` including being unable + to allocate on the heap. + - ``False`` - The callback will be scheduled as a soft interrupt, + allowing it to allocate but possibly also introducing + garbage-collection delays and jitter. + + The default value of this option is True. + You must either specify freq or both of period and prescaler. .. method:: Timer.deinit() |