diff options
Diffstat (limited to 'docs/library/machine.Timer.rst')
| -rw-r--r-- | docs/library/machine.Timer.rst | 20 |
1 files changed, 17 insertions, 3 deletions
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. |