It's implemented in terms of usleep(), and POSIX doesn't guarantee that
usleep() can sleep for more than a second. This restriction unlikely
applies to any real-world system, but...
Based on the earlier discussed RFC. Practice showed that the most natural
order for arguments corresponds to mathematical subtraction:
ticks_diff(x, y) <=> x - y
Also, practice showed that in real life, it's hard to order events by time
of occurance a priori, events tend to miss deadlines, etc. and the expected
order breaks. And then there's a need to detect such cases. And ticks_diff
can be used exactly for this purpose, if it returns a signed, instead of
unsigned, value. E.g. if x is scheduled time for event, and y is the current
time, then if ticks_diff(x, y) < 0 then event has missed a deadline (and e.g.
needs to executed ASAP or skipped). Returning in this case a large unsigned
number (like ticks_diff behaved previously) doesn't make sense, and such
"large unsigned number" can't be reliably detected per our definition of
ticks_* function (we don't expose to user level maximum value, it can be
anything, relatively small or relatively large).
The integration with Zephyr is fairly clean but as MicroPython Hardware API
requires pin ID to be a single value, but Zephyr operates GPIO in terms of
ports and pins, not just pins, a "hierarchical" ID is required, using tuple
of (port, pin). Port is a string, effectively a device name of a GPIO port,
per Zephyr conventions these are "GPIO_0", "GPIO_1", etc.; pin is integer
number of pin with the port (supposed to be in range 0-31).
Example of pin initialization:
pin = Pin(("GPIO_1", 21), Pin.OUT)
(an LED on FRDM-K64F's Port B, Pin 21).
There is support for in/out pins and pull up/pull down but currently
there is no interrupt support.
Signed-off-by: Daniel Thompson <daniel.thompson@linaro.org>
Signed-off-by: Vincenzo Frascino <vincenzo.frascino@linaro.org>
Signed-off-by: Paul Sokolovsky <paul.sokolovsky@linaro.org>
This happens with some compilers on some architectures, which don't define
size_t as unsigned int. MicroPython's printf() dooesn't support obscure
format specifiers for size_t, so the obvious choice is to explicitly cast
to unsigned, to match %u used in printf().
Clarify the class implements master side of the protocol, also put adhoc
WiPy paramter after the generic, described in the current Hardware API
version.
The NeoPixel class now handles 4 bytes-per-pixel LEDs (extra byte is
intensity) and arbitrary byte ordering. APA102 class is now derived from
NeoPixel to reduce code size and support fill() operation.
To build, "make 512k".
Disabled are FatFs support (no space for filesystem), Python functionality
related to files, btree module, and recently enabled features. With all
this, there's only one free FlashROM page.
As we're looking towards adding OTA support, calculation of a FlashROM
area which can be used for filesystem (etc.) may become complex, so
introduce C function for that. So far it just hardcodes current value,
0x90000. In the future the function may be extended (and renamed) to
return the size of area too.
This provides time and sleep together with the usual ticks_us/_ms/_diff
and sleep_us/ms family.
We also provide access to Zephyr's high precision timer as ticks_cpu().
Signed-off-by: Daniel Thompson <daniel.thompson@linaro.org>
Builtin functions with a fixed number of arguments (0, 1, 2 or 3) are
quite common. Before this patch the wrapper for such a function cost
3 machine words. After this patch it only takes 2, which can reduce the
code size by quite a bit (and pays off even more, the more functions are
added). It also makes function dispatch slightly more efficient in CPU
usage, and furthermore reduces stack usage for these cases. On x86 and
Thumb archs the dispatch functions are now tail-call optimised by the
compiler.
The bare-arm port has its code size increase by 76 bytes, but stmhal drops
by 904 bytes. Stack usage by these builtin functions is decreased by 48
bytes on Thumb2 archs.
