This is a more consistent use of errno codes. For example, it may be that
a stream returns MP_EAGAIN but the mp_is_nonblocking_error() macro doesn't
catch this value because it checks for EAGAIN instead (which may have a
different value than MP_EAGAIN when MICROPY_USE_INTERNAL_ERRNO is enabled).
Most modern systems have EWOULDBLOCK aliased to EAGAIN, ie they have the
same value. But some systems use different values for these errnos and if
a uPy port is using the system errno values (ie not the internal uPy
values) then it's important to be able to distinguish EWOULDBLOCK from
EAGAIN. Eg if a system call returned EWOULDBLOCK it must be possible to
check for this return value, and this patch makes this now possible.
If MICROPY_USE_INTERNAL_ERRNO is disabled, MP_EINVAL is not guaranteed
to have the value 22, so we cannot depend on OSError(22,).
Instead, to support any given port's errno values, without relying
on uerrno, we just check that the args[0] is positive.
ADC3 is used because the H7's internal ADC channels are connected to ADC3
and the uPy driver doesn't support more than one ADC.
Only 12-bit resolution is supported because 12 is hard-coded and 14/16 bits
are not recommended on some ADC3 pins (see errata).
Values from internal ADC channels are known to give wrong values at
present.
.. this maybe should be subject to MICROPY_CPYTHON_COMPAT, except that
is not defined in the main circuitpython ports so it would be a change
that makes no difference.
The esp8266 uses modlwip.c for its usocket implementation, which allows to
easily support callbacks on socket events (like when a socket becomes ready
for reading). This is not as easy to do for the esp32 which uses the
ESP-IDF-provided lwIP POSIX socket API. Socket events are needed to get
WebREPL working, and this patch provides a way for such events to work by
explicitly polling registered sockets for readability, and then calling the
associated callback if the socket is readable.
After calling HAL_SYSTICK_Config the SysTick IRQ priority is set to 15, the
lowest priority. This commit reconfigures the IRQ priority to the desired
TICK_INT_PRIORITY value.
By default the stm module is included in the build, but a board can now
define MICROPY_PY_STM to 0 to not include this module. This reduces the
firmware by about 7k.
