This adds support for making static (ie not on the Python GC heap) soft
timers. This can be useful for a board to define a custom background
handler, or eventually for BLE/network processing to use instead of systick
slots; it will be more efficient using soft timer for this.
The main issue with using the existing code for static soft timers is that
it would combine heap allocated and statically allocated soft_timer_entry_t
instances in the same pairing-heap data structure. This would prevent the
GC from tracing some of the heap allocated entries (because the GC won't
follow pointers outside the heap).
This commit makes it so that soft timer entries are explicitly marked,
instead of relying on implicit marking by having the root of the pairing
heap in the root pointer section. Also, on soft reset only the heap-
allocated soft timers are deleted from the pairing heap, leaving the
statically allocated ones.
Signed-off-by: Damien George <damien@micropython.org>
Improvements are:
- Default period is 1000ms with callback disabled.
- if period is not specified then it's not updated (previously, if period
was not specified then it was set to -1 and running the timer callback as
fast as possible, making the REPL unresponsive).
- Use uint64_t to compute delta_ms, and raise a ValueError if the period is
too large.
- If callback is not specified then it's not updated.
- Specifying None for the callback will disable the timer.
Signed-off-by: Damien George <damien@micropython.org>
This commit adds an implementation of machine.Timer backed by the soft
timer mechanism. It allows an arbitrary number of timers with 1ms
resolution, with an associated Python callback. The Python-level API
matches existing ports that have a soft timer, and is used as:
from machine import Timer
t = Timer(freq=10, callback=lambda t:print(t))
...
t = Timer(mode=Timer.ONE_SHOT, period=2000, callback=lambda t:print(t))
...
t.deinit()
Damien George