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113 lines
3.4 KiB
113 lines
3.4 KiB
.. _pyb.ExtInt:
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class ExtInt -- configure I/O pins to interrupt on external events
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==================================================================
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There are a total of 22 interrupt lines. 16 of these can come from GPIO pins
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and the remaining 6 are from internal sources.
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For lines 0 thru 15, a given line can map to the corresponding line from an
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arbitrary port. So line 0 can map to Px0 where x is A, B, C, ... and
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line 1 can map to Px1 where x is A, B, C, ... ::
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def callback(line):
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print("line =", line)
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Note: ExtInt will automatically configure the gpio line as an input. ::
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extint = pyb.ExtInt(pin, pyb.ExtInt.IRQ_FALLING, pyb.Pin.PULL_UP, callback)
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Now every time a falling edge is seen on the X1 pin, the callback will be
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called. Caution: mechanical pushbuttons have "bounce" and pushing or
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releasing a switch will often generate multiple edges.
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See: http://www.eng.utah.edu/~cs5780/debouncing.pdf for a detailed
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explanation, along with various techniques for debouncing.
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Trying to register 2 callbacks onto the same pin will throw an exception.
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If pin is passed as an integer, then it is assumed to map to one of the
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internal interrupt sources, and must be in the range 16 thru 22.
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All other pin objects go through the pin mapper to come up with one of the
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gpio pins. ::
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extint = pyb.ExtInt(pin, mode, pull, callback)
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Valid modes are pyb.ExtInt.IRQ_RISING, pyb.ExtInt.IRQ_FALLING,
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pyb.ExtInt.IRQ_RISING_FALLING, pyb.ExtInt.EVT_RISING,
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pyb.ExtInt.EVT_FALLING, and pyb.ExtInt.EVT_RISING_FALLING.
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Only the IRQ_xxx modes have been tested. The EVT_xxx modes have
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something to do with sleep mode and the WFE instruction.
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Valid pull values are pyb.Pin.PULL_UP, pyb.Pin.PULL_DOWN, pyb.Pin.PULL_NONE.
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There is also a C API, so that drivers which require EXTI interrupt lines
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can also use this code. See extint.h for the available functions and
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usrsw.h for an example of using this.
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Constructors
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------------
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.. class:: pyb.ExtInt(pin, mode, pull, callback)
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Create an ExtInt object:
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- ``pin`` is the pin on which to enable the interrupt (can be a pin object or any valid pin name).
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- ``mode`` can be one of:
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- ``ExtInt.IRQ_RISING`` - trigger on a rising edge;
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- ``ExtInt.IRQ_FALLING`` - trigger on a falling edge;
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- ``ExtInt.IRQ_RISING_FALLING`` - trigger on a rising or falling edge.
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- ``pull`` can be one of:
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- ``pyb.Pin.PULL_NONE`` - no pull up or down resistors;
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- ``pyb.Pin.PULL_UP`` - enable the pull-up resistor;
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- ``pyb.Pin.PULL_DOWN`` - enable the pull-down resistor.
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- ``callback`` is the function to call when the interrupt triggers. The
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callback function must accept exactly 1 argument, which is the line that
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triggered the interrupt.
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Class methods
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-------------
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.. method:: ExtInt.regs()
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Dump the values of the EXTI registers.
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Methods
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-------
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.. method:: extint.disable()
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Disable the interrupt associated with the ExtInt object.
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This could be useful for debouncing.
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.. method:: extint.enable()
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Enable a disabled interrupt.
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.. method:: extint.line()
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Return the line number that the pin is mapped to.
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.. method:: extint.swint()
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Trigger the callback from software.
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Constants
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---------
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.. data:: ExtInt.IRQ_FALLING
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interrupt on a falling edge
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.. data:: ExtInt.IRQ_RISING
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interrupt on a rising edge
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.. data:: ExtInt.IRQ_RISING_FALLING
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interrupt on a rising or falling edge
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