1.. _module-pw_chrono_embos: 2 3--------------- 4pw_chrono_embos 5--------------- 6``pw_chrono_embos`` is a collection of ``pw_chrono`` backends that are 7implemented using embOS v4 for 32bit targets. 8 9.. warning:: 10 This module is still under construction, the API is not yet stable. 11 12SystemClock backend 13------------------- 14The embOS based ``system_clock`` backend implements the 15``pw_chrono:system_clock`` facade by using ``OS_GetTime32()``. An 16InterruptSpinLock is used to manage overflows in a thread and interrupt safe 17manner to produce a signed 64 bit timestamp. Note that this does NOT use 18``OS_GetTime_us64()`` which is not always available, this could be considered 19for a future alternative backend for the SystemClock. 20 21The ``SystemClock::now()`` must be used more than once per overflow of the 22native embOS ``OS_GetTime32()`` overflow. Note that this duration may 23vary if ``OS_SUPPORT_TICKLESS`` is used. 24 25SystemTimer backend 26------------------- 27The embOS based ``system_timer`` backend implements the 28``pw_chrono:system_timer`` facade by using embOS's software timer API. 29``pw::chrono::SystemTimer`` instances use ``OS_TIMER_EX`` & 30``OS_CreateTimerEx``, dynamic memory allocation is never used. 31 32Build targets 33------------- 34The GN build for ``pw_chrono_embos`` has one target: ``system_clock``. 35The ``system_clock`` target provides the 36``pw_chrono_backend/system_clock_config.h`` and ``pw_chrono_embos/config.h`` 37headers and the backend for the ``pw_chrono:system_clock``. 38