micropython: add micropython component

components/language/micropython/docs/library/machine.WDT.rst

@@ -0,0 +1,38 @@
+.. currentmodule:: machine
+.. _machine.WDT:
+
+class WDT -- watchdog timer
+===========================
+
+The WDT is used to restart the system when the application crashes and ends
+up into a non recoverable state. Once started it cannot be stopped or
+reconfigured in any way. After enabling, the application must "feed" the
+watchdog periodically to prevent it from expiring and resetting the system.
+
+Example usage::
+
+    from machine import WDT
+    wdt = WDT(timeout=2000)  # enable it with a timeout of 2s
+    wdt.feed()
+
+Availability of this class: pyboard, WiPy, esp8266, esp32.
+
+Constructors
+------------
+
+.. class:: WDT(id=0, timeout=5000)
+
+   Create a WDT object and start it. The timeout must be given in milliseconds.
+   Once it is running the timeout cannot be changed and the WDT cannot be stopped either.
+
+   Notes: On the esp32 the minimum timeout is 1 second. On the esp8266 a timeout
+   cannot be specified, it is determined by the underlying system.
+
+Methods
+-------
+
+.. method:: WDT.feed()
+
+   Feed the WDT to prevent it from resetting the system. The application
+   should place this call in a sensible place ensuring that the WDT is
+   only fed after verifying that everything is functioning correctly.