docs/machine.Pin: Document "hard" argument of Pin.irq method.
@@ -179,7 +179,7 @@ Methods
Availability: WiPy.
-.. method:: Pin.irq(handler=None, trigger=(Pin.IRQ_FALLING | Pin.IRQ_RISING), \*, priority=1, wake=None)
+.. method:: Pin.irq(handler=None, trigger=(Pin.IRQ_FALLING | Pin.IRQ_RISING), \*, priority=1, wake=None, hard=False)
Configure an interrupt handler to be called when the trigger source of the
pin is active. If the pin mode is ``Pin.IN`` then the trigger source is
@@ -213,6 +213,10 @@ Methods
These values can also be OR'ed together to make a pin generate interrupts in
more than one power mode.
+ - ``hard`` if true a hardware interrupt is used. This reduces the delay
+ between the pin change and the handler being called. Hard interrupt
+ handlers may not allocate memory; see :ref:`isr_rules`.
+
This method returns a callback object.
Constants
