If RTC is already running at boot then it's left alone. Otherwise, RTC is
started at boot but startup function returns straight away. RTC startup
is then finished the first time it is used. Fallback to LSI if LSE fails
to start in a certain time.
Also included:
MICROPY_HW_CLK_LAST_FREQ
hold pyb.freq() parameters in RTC backup reg
MICROPY_HW_RTC_USE_US
option to present datetime sub-seconds in microseconds
MICROPY_HW_RTC_USE_CALOUT
option to enable RTC calibration output
CLK_LAST_FREQ and RTC_USE_CALOUT are enabled for PYBv1.0.
This takes previous IEEE-754 single precision float implementation, and
converts it to fully portable parametrizable implementation using C99
functions like signbit(), isnan(), isinf(). As long as those functions
are available (they can be defined in adhoc manner of course), and
compiler can perform standard arithmetic and comparison operations on a
float type, this implementation will work with any underlying float type
(including types whose mantissa is larger than available intergral integer
type).
In other words, unix port now uses overriden printf(), instead of using
libc's. This should remove almost all dependency on libc stdio (which
is bloated).
Return tuple of (address_family, net_addr, [port, [extra_data]]). net_addr
is still raw network address as bytes object, but suitable for passing to
inet_ntop() function. At the very least, sockaddr() will separate address
family value from binary socket address (and currently, only AF_INET family
is decoded).
This change makes the code behave how it was supposed to work when first
written. The avail_slot variable is set to the first free slot when
looking for a key (which would come from deleting an entry). So it's
more efficient (for subsequent lookups) to insert a new key into such a
slot, rather than the very last slot that was searched.
In new hardware API, these classes implement master modes of interfaces,
and "mode" parameter is not accepted. Trying to implement new HW API
in terms of older pyb module leaves variuos corner cases:
In new HW API, I2C(1) means "I2C #1 in master mode" (? depends on
interpretation), while in old API, it means "I2C #1, with no settings
changes".
For I2C class, it's easy to make mode optional, because that's last
positional param, but for SPI, there's "baudrate" after it (which
is inconsistent with I2C, which requires "baudrate" to be kwonly-arg).
