Otherwise mp_interrupt_char will have a value of zero on start up (because
it's in the BSS) and a KeyboardInterrupt may be raised during start up.
For example this can occur if there is a UART attached to the REPL which
sends spurious null bytes when the device turns on.
So that boot.py and/or main.py can be frozen (either as STR or MPY) in the
same way that other scripts are frozen. Frozen scripts have preference to
scripts in the VFS.
It consists of:
1. "do_handhake" param (default True) to wrap_socket(). If it's False,
handshake won't be performed by wrap_socket(), as it would be done in
blocking way normally. Instead, SSL socket can be set to non-blocking mode,
and handshake would be performed before the first read/write request (by
just returning EAGAIN to these requests, while instead reading/writing/
processing handshake over the connection). Unfortunately, axTLS doesn't
really support non-blocking handshake correctly. So, while framework for
this is implemented on MicroPython's module side, in case of axTLS, it
won't work reliably.
2. Implementation of .setblocking() method. It must be called on SSL socket
for blocking vs non-blocking operation to be handled correctly (for
example, it's not enough to wrap non-blocking socket with wrap_socket()
call - resulting SSL socket won't be itself non-blocking). Note that
.setblocking() propagates call to the underlying socket object, as
expected.
For this, add wrap_socket(do_handshake=False) param. CPython doesn't have
such a param at a module's global function, and at SSLContext.wrap_socket()
it has do_handshake_on_connect param, but that uselessly long.
Beyond that, make write() handle not just MBEDTLS_ERR_SSL_WANT_WRITE, but
also MBEDTLS_ERR_SSL_WANT_READ, as during handshake, write call may be
actually preempted by need to read next handshake message from peer.
Likewise, for read(). And even after the initial negotiation, situations
like that may happen e.g. with renegotiation. Both
MBEDTLS_ERR_SSL_WANT_READ and MBEDTLS_ERR_SSL_WANT_WRITE are however mapped
to the same None return code. The idea is that if the same read()/write()
method is called repeatedly, the progress will be made step by step anyway.
The caveat is if user wants to add the underlying socket to uselect.poll().
To be reliable, in this case, the socket should be polled for both POLL_IN
and POLL_OUT, as we don't know the actual expected direction. But that's
actually problematic. Consider for example that write() ends with
MBEDTLS_ERR_SSL_WANT_READ, but gets converted to None. We put the
underlying socket on pull using POLL_IN|POLL_OUT but that probably returns
immediately with POLL_OUT, as underlyings socket is writable. We call the
same ussl write() again, which again results in MBEDTLS_ERR_SSL_WANT_READ,
etc. We thus go into busy-loop.
So, the handling in this patch is temporary and needs fixing. But exact way
to fix it is not clear. One way is to provide explicit function for
handshake (CPython has do_handshake()), and let *that* return distinct
codes like WANT_READ/WANT_WRITE. But as mentioned above, past the initial
handshake, such situation may happen again with at least renegotiation. So
apparently, the only robust solution is to return "out of bound" special
sentinels like WANT_READ/WANT_WRITE from read()/write() directly. CPython
throws exceptions for these, but those are expensive to adopt that way for
efficiency-conscious implementation like MicroPython.
The machine.WDT() now accepts the "timeout" keyword argument to select the
WDT interval. And the WDT is changed to panic mode which means it will
reset the device if the interval expires (instead of just printing an error
message).
On the STM32F722 (at least, but STM32F767 is not affected) the CK48MSEL bit
must be deselected before PLLSAION is turned off, or else the 48MHz
peripherals (RNG, SDMMC, USB) may get stuck without a clock source.
In such "lock up" cases it seems that these peripherals are still being
clocked from the PLLSAI even though the CK48MSEL bit is turned off. A hard
reset does not get them out of this stuck state. Enabling the PLLSAI and
then disabling it does get them out. A test case to see this is:
import machine, pyb
for i in range(100):
machine.freq(122_000000)
machine.freq(120_000000)
print(i, [pyb.rng() for _ in range(4)])
On occasion the RNG will just return 0's, but will get fixed again on the
next loop (when PLLSAI is enabled by the change to a SYSCLK of 122MHz).
Fixes issue #4696.
The stm32 and nrf ports already had the behaviour that they would first
check if the script exists before executing it, and this patch makes all
other ports work the same way. This helps when developing apps because
it's hard to tell (when unconditionally trying to execute the scripts) if
the resulting OSError at boot up comes from missing boot.py or main.py, or
from some other error. And it's not really an error if these scripts don't
exist.
Prior to this patch, when a lot of data was output by a running script
pyboard.py would try to capture all of this output into the "data"
variable, which would gradually slow down pyboard.py to the point where it
would have large CPU and memory usage (on the host) and potentially lose
data.
This patch fixes this problem by not accumulating the data in the case that
the data is not needed, which is when "data_consumer" is used.
This patch makes the DAC driver simpler and removes the need for the ST
HAL. As part of it, new helper functions are added to the DMA driver,
which also use direct register access instead of the ST HAL.
Main changes to the DAC interface are:
- The DAC uPy object is no longer allocated dynamically on the heap,
rather it's statically allocated and the same object is retrieved for
subsequent uses of pyb.DAC(<id>). This allows to access the DAC objects
without resetting the DAC peripheral. It also means that the DAC is only
reset if explicitly passed initialisation parameters, like "bits" or
"buffering".
- The DAC.noise() and DAC.triangle() methods now output a signal which is
full scale (previously it was a fraction of the full output voltage).
- The DAC.write_timed() method is fixed so that it continues in the
background when another peripheral (eg SPI) uses the DMA (previously the
DAC would stop if another peripheral finished with the DMA and shut the
DMA peripheral off completely).
Based on the above, the following backwards incompatibilities are
introduced:
- pyb.DAC(id) will now only reset the DAC the first time it is called,
whereas previously each call to create a DAC object would reset the DAC.
To get the old behaviour pass the bits parameter like: pyb.DAC(id, bits).
- DAC.noise() and DAC.triangle() are now full scale. To get previous
behaviour (to change the amplitude and offset) write to the DAC_CR (MAMP
bits) and DAC_DHR12Rx registers manually.
In CPython the random module is seeded differently on each import, and so
this new macro option MICROPY_PY_URANDOM_SEED_INIT_FUNC allows to implement
such a behaviour.
If MICROPY_HW_RTC_USE_BYPASS is enabled the RTC startup goes as follows:
- RTC is started with LSE in bypass mode to begin with
- if that fails to start (after a given timeout) then LSE is reconfigured
in non-bypass
- if that fails to start then RTC is switched to LSI
The qstr window size is not log-2 encoded, it's just the actual number (but
in mpy-tool.py this didn't lead to an error because the size is just used
to truncate the window so it doesn't grow arbitrarily large in memory).
Addresses issue #4635.
