docs/zephyr: Add quick reference for the Zephyr port.

Includes an introduction to using the Zephyr port on MicroPython.  The
quickref details examples of how to use each module the port currently
supports.  The tutorial provides additional details for Zephyr specific
modules.

Signed-off-by: Julia Hathaway <julia.hathaway@nxp.com>

1 files changed, 46 insertions, 0 deletions

diff --git a/docs/zephyr/tutorial/pins.rst b/docs/zephyr/tutorial/pins.rst
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+.. _pins_zephyr:
+
+GPIO Pins
+=========
+
+Use :ref:`machine.Pin <machine.Pin>` to control I/O pins.
+
+For Zephyr, pins are initialized using a tuple of port and pin number ``(\"GPIO_x\", pin#)``
+for the ``id`` value. For example to initialize a pin for the red LED on a FRDM-k64 board::
+
+        LED = Pin(("GPIO_1", 22), Pin.OUT)
+
+Reference your board's datasheet or Zephyr documentation for pin numbers, see below for more examples.
+
+.. list-table:: Pin Formatting
+   :header-rows: 1
+
+   * - Board
+     - Pin
+     - Format
+   * - frdm_k64f
+     - Red LED = PTB22
+     - ("GPIO_1", 22)
+   * - 96b_carbon
+     - LED1 = PD2
+     - ("GPIOD", 2)
+   * - mimxrt685_evk_cm33
+     - Green LED = PIO0_14
+     - ("GPIO0", 14)
+
+Interrupts
+----------
+
+The Zephyr port also supports interrupt handling for Pins using `machine.Pin.irq() <machine.Pin.irq>`.
+To respond to Pin change IRQs run::
+
+    from machine import Pin
+
+    SW2 = Pin(("GPIO_2", 6), Pin.IN)            # create Pin object for switch 2
+    SW3 = Pin(("GPIO_0", 4), Pin.IN)            # create Pin object for switch 3
+
+    SW2.irq(lambda t: print("SW2 changed"))     # print message when SW2 state is changed (triggers change IRQ)
+    SW3.irq(lambda t: print("SW3 changed"))     # print message when SW3 state is changed (triggers change IRQ)
+
+    while True:                                 # wait
+        pass