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.
Damien George
Andrew Leech
Daniel O'Connor
Léa Saviot
Damiano Mazzella