Add an rtc module that provides a singleton RTC class with
- a datetime property to set and get time if the board supports it.
- a calbration property to adjust the clock.
There's also an rtc.set_time_source() method to override this RTC object using pure python.
The time module gets 3 methods:
- time.time()
- time.localtime()
- time.mktime()
The rtc timesource is used to provide time to the time module.
lib/timeutils is used for time conversions and thus only supports dates after 2000.
Docs are here: http://tannewt-micropython.readthedocs.io/en/microcontroller/
It differs from upstream's machine in the following ways:
* Python API is identical across ports due to code structure. (Lives in shared-bindings)
* Focuses on abstracting common functionality (AnalogIn) and not representing structure (ADC).
* Documentation lives with code making it easy to ensure they match.
* Pin is split into references (board.D13 and microcontroller.pin.PA17) and functionality (DigitalInOut).
* All nativeio classes claim underlying hardware resources when inited on construction, support Context Managers (aka with statements) and have deinit methods which release the claimed hardware.
* All constructors take pin references rather than peripheral ids. Its up to the implementation to find hardware or throw and exception.
Dan Halbert
Noralf Trønnes
Scott Shawcroft