diff --git a/components/esp32/Kconfig b/components/esp32/Kconfig index 73e4fe4c6..f4fe83f0c 100644 --- a/components/esp32/Kconfig +++ b/components/esp32/Kconfig @@ -762,7 +762,6 @@ config NO_BLOBS config ESP_TIMER_PROFILING bool "Enable esp_timer profiling features" - depends on MAKING_ESP_TIMER_A_PUBLIC_API default n help If enabled, esp_timer_dump will dump information such as number of times diff --git a/components/esp32/include/esp_timer.h b/components/esp32/include/esp_timer.h index e3e8b4812..07e237214 100644 --- a/components/esp32/include/esp_timer.h +++ b/components/esp32/include/esp_timer.h @@ -29,11 +29,11 @@ * use RTOS notification mechanisms (queues, semaphores, event groups, etc.) to * pass information to other tasks. * - * It should be possible to request the callback to be called + * To be implemented: it should be possible to request the callback to be called * directly from the ISR. This reduces the latency, but has potential impact on * all other callbacks which need to be dispatched. This option should only be * used for simple callback functions, which do not take longer than a few - * microseconds to run. + * microseconds to run. * * Implementation note: on the ESP32, esp_timer APIs use the "legacy" FRC2 * timer. Timer callbacks are called from a task running on the PRO CPU. diff --git a/components/esp32/test/test_esp_timer.c b/components/esp32/test/test_esp_timer.c index d77ddeb5e..4007528bd 100644 --- a/components/esp32/test/test_esp_timer.c +++ b/components/esp32/test/test_esp_timer.c @@ -10,6 +10,10 @@ #include "freertos/semphr.h" #include "test_utils.h" +#ifdef CONFIG_ESP_TIMER_PROFILING +#define WITH_PROFILING 1 +#endif + TEST_CASE("esp_timer orders timers correctly", "[esp_timer]") { diff --git a/docs/Doxyfile b/docs/Doxyfile index e2dc5eab8..950f91421 100644 --- a/docs/Doxyfile +++ b/docs/Doxyfile @@ -151,7 +151,9 @@ INPUT = \ ../components/app_trace/include/esp_app_trace.h \ ### Power management ../components/esp32/include/esp_pm.h \ - ../components/esp32/include/esp32/pm.h + ../components/esp32/include/esp32/pm.h \ + ### esp_timer, High Resolution Timer + ../components/esp32/include/esp_timer.h ## Get warnings for functions that have no documentation for their parameters or return value diff --git a/docs/api-reference/system/esp_timer.rst b/docs/api-reference/system/esp_timer.rst new file mode 100644 index 000000000..3e0b8c8f8 --- /dev/null +++ b/docs/api-reference/system/esp_timer.rst @@ -0,0 +1,52 @@ +High Resolution Timer +===================== + +Overview +-------- + +Although FreeRTOS provides software timers, these timers have a few limitations: + +- Mmaximum resolution is equal to RTOS tick period +- Timer callbacks are dispatched from a low-priority task + +Hardware timers are free from both of the limitations, but often they are less convenient to use. For example, application components may need timer events to fire at certain times in the future, but the hardware timer only contains one "compare" value used for interrupt generation. This means that some facility needs to be built on top of the hardware timer to manage the list of pending events can dispatch the callbacks for these events as corresponding hardware interrupts happen. + +``esp_timer`` set of APIs provide such facility. Internally, ``esp_timer`` uses a 32-bit hardware timer (FRC1, "legacy" timer). ``esp_timer`` provides one-shot and periodic timers, microsecond time resolution, and 64-bit range. + +Timer callbacks are dispatched from a high-priority ``esp_timer`` task. Because all the callbacks are dispatched from the same task, it is recommended to only do the minimal possible amount of work from the callback itself, posting an event to a lower priority task using a queue instead. + +.. note: Provisions are made to dispatch some simple callbacks directly from the interrupt handler, if needed. However this option is not implemented at the moment. + +Using ``esp_timer`` APIs +------------------------ + +Single timer is represented by :cpp:type:`esp_timer_handle_t` type. Timer has a callback function associated with it. This callback function is called from the ``esp_timer`` task each time the timer elapses. + +- To create a timer, call :cpp:func:`esp_timer_create`. +- To delete the timer when it is no longer needed, call :cpp:func:`esp_timer_delete`. + +The timer can be started in one-shot mode or in periodic mode. + +- To start the timer in one-shot mode, call :cpp:func:`esp_timer_start_once`, passing the time interval after which the callback should be called. When the callback gets called, the timer is considered to be stopped. + +- To start the timer in periodic mode, call :cpp:func:`esp_timer_start_periodic`, passing the period with which the callback should be called. The timer keeps running until :cpp:func:`esp_timer_stop` is called. + +Note that the timer must not be running when :cpp:func:`esp_timer_start_once` or :cpp:func:`esp_timer_start_periodic` is called. To restart a running timer, call :cpp:func:`esp_timer_stop` first, then call one of the start functions. + +Obtaining Current Time +---------------------- + +``esp_timer`` also provides a convenience function to obtain the time passed since start-up, with microsecond precision: :cpp:func:`esp_timer_get_time`. This function returns the number of microseconds since ``esp_timer`` was initialized, which usually happens shortly before ``app_main`` function is called. + +Unlike `gettimeofday` function, values returned by :cpp:func:`esp_timer_get_time`: + +- Start from zero after the chip wakes up from deep sleep +- Do not have timezone or DST adjustments applied + + +API Reference +------------- + +.. include:: /_build/inc/esp_timer.inc + + diff --git a/docs/api-reference/system/index.rst b/docs/api-reference/system/index.rst index b4e92050d..c895ebd8b 100644 --- a/docs/api-reference/system/index.rst +++ b/docs/api-reference/system/index.rst @@ -10,6 +10,7 @@ System API Watchdogs Hooks Inter-Processor Call + High Resolution Timer Over The Air Updates (OTA) Sleep Modes Power Management diff --git a/tools/unit-test-app/sdkconfig.defaults b/tools/unit-test-app/sdkconfig.defaults index 534eca74e..9e9dfa691 100644 --- a/tools/unit-test-app/sdkconfig.defaults +++ b/tools/unit-test-app/sdkconfig.defaults @@ -24,3 +24,4 @@ CONFIG_FREERTOS_QUEUE_REGISTRY_SIZE=7 CONFIG_STACK_CHECK_STRONG=y CONFIG_STACK_CHECK=y CONFIG_SUPPORT_STATIC_ALLOCATION=y +CONFIG_ESP_TIMER_PROFILING=y