pw_chrono_embos

Pigweed AI summary: The pw_chrono_embos module is a collection of pw_chrono backends that use embOS v4 for 32bit targets. The SystemClock backend uses OS_GetTime32() to implement the pw_chrono:system_clock facade and manages overflows in a thread and interrupt safe manner to produce a signed 64 bit timestamp. The SystemTimer backend uses embOS's software timer API to implement the pw_chrono:system_timer facade. The GN build for pw_ch

pw_chrono_embos is a collection of pw_chrono backends that are implemented using embOS v4 for 32bit targets.

Warning

This module is still under construction, the API is not yet stable.

SystemClock backend

Pigweed AI summary: The SystemClock backend uses embOS to implement the pw_chrono:system_clock facade by utilizing OS_GetTime32(). An InterruptSpinLock is used to manage overflows in a thread and interrupt safe manner to produce a signed 64 bit timestamp. It is important to note that SystemClock::now() must be used more than once per overflow of the native embOS OS_GetTime32() overflow, and the duration may vary if OS_SUPPORT_TICKLESS is used. OS_GetTime_us64

The embOS based system_clock backend implements the pw_chrono:system_clock facade by using OS_GetTime32(). An InterruptSpinLock is used to manage overflows in a thread and interrupt safe manner to produce a signed 64 bit timestamp. Note that this does NOT use OS_GetTime_us64() which is not always available, this could be considered for a future alternative backend for the SystemClock.

The SystemClock::now() must be used more than once per overflow of the native embOS OS_GetTime32() overflow. Note that this duration may vary if OS_SUPPORT_TICKLESS is used.

SystemTimer backend

Pigweed AI summary: The SystemTimer backend is an implementation of the pw_chrono:system_timer facade using embOS's software timer API. It uses OS_TIMER_EX and OS_CreateTimerEx, and does not require dynamic memory allocation.

The embOS based system_timer backend implements the pw_chrono:system_timer facade by using embOS’s software timer API. pw::chrono::SystemTimer instances use OS_TIMER_EX & OS_CreateTimerEx, dynamic memory allocation is never used.

Build targets

Pigweed AI summary: The GN build for pw_chrono_embos has only one target, which is the system_clock. This target provides the necessary headers and backend for the pw_chrono:system_clock.

The GN build for pw_chrono_embos has one target: system_clock. The system_clock target provides the pw_chrono_backend/system_clock_config.h and pw_chrono_embos/config.h headers and the backend for the pw_chrono:system_clock.