232 lines
7.8 KiB
C
232 lines
7.8 KiB
C
// Copyright 2017 Espressif Systems (Shanghai) PTE LTD
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//
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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#pragma once
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/**
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* @file esp_timer.h
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* @brief microsecond-precision 64-bit timer API, replacement for ets_timer
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*
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* esp_timer APIs allow components to receive callbacks when a hardware timer
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* reaches certain value. The timer provides microsecond accuracy and
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* up to 64 bit range. Note that while the timer itself provides microsecond
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* accuracy, callbacks are dispatched from an auxiliary task. Some time is
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* needed to notify this task from timer ISR, and then to invoke the callback.
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* If more than one callback needs to be dispatched at any particular time,
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* each subsequent callback will be dispatched only when the previous callback
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* returns. Therefore, callbacks should not do much work; instead, they should
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* use RTOS notification mechanisms (queues, semaphores, event groups, etc.) to
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* pass information to other tasks.
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*
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* To be implemented: it should be possible to request the callback to be called
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* directly from the ISR. This reduces the latency, but has potential impact on
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* all other callbacks which need to be dispatched. This option should only be
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* used for simple callback functions, which do not take longer than a few
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* microseconds to run.
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*
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* Implementation note: on the ESP32, esp_timer APIs use the "legacy" FRC2
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* timer. Timer callbacks are called from a task running on the PRO CPU.
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*/
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#include <stdint.h>
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#include <stdio.h>
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#include "esp_err.h"
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#ifdef __cplusplus
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extern "C" {
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#endif
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/**
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* @brief Opaque type representing a single esp_timer
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*/
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typedef struct esp_timer* esp_timer_handle_t;
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/**
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* @brief Timer callback function type
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* @param arg pointer to opaque user-specific data
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*/
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typedef void (*esp_timer_cb_t)(void* arg);
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/**
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* @brief Method for dispatching timer callback
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*/
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typedef enum {
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ESP_TIMER_TASK, //!< Callback is called from timer task
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/* Not supported for now, provision to allow callbacks to run directly
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* from an ISR:
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ESP_TIMER_ISR, //!< Callback is called from timer ISR
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*/
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} esp_timer_dispatch_t;
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/**
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* @brief Timer configuration passed to esp_timer_create
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*/
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typedef struct {
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esp_timer_cb_t callback; //!< Function to call when timer expires
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void* arg; //!< Argument to pass to the callback
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esp_timer_dispatch_t dispatch_method; //!< Call the callback from task or from ISR
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const char* name; //!< Timer name, used in esp_timer_dump function
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} esp_timer_create_args_t;
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/**
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* @brief Initialize esp_timer library
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*
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* @note This function is called from startup code. Applications do not need
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* to call this function before using other esp_timer APIs.
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*
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* @return
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* - ESP_OK on success
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* - ESP_ERR_NO_MEM if allocation has failed
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* - ESP_ERR_INVALID_STATE if already initialized
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* - other errors from interrupt allocator
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*/
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esp_err_t esp_timer_init(void);
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/**
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* @brief De-initialize esp_timer library
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*
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* @note Normally this function should not be called from applications
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*
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* @return
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* - ESP_OK on success
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* - ESP_ERR_INVALID_STATE if not yet initialized
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*/
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esp_err_t esp_timer_deinit(void);
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/**
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* @brief Create an esp_timer instance
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*
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* @note When done using the timer, delete it with esp_timer_delete function.
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*
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* @param create_args Pointer to a structure with timer creation arguments.
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* Not saved by the library, can be allocated on the stack.
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* @param[out] out_handle Output, pointer to esp_timer_handle_t variable which
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* will hold the created timer handle.
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*
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* @return
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* - ESP_OK on success
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* - ESP_ERR_INVALID_ARG if some of the create_args are not valid
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* - ESP_ERR_INVALID_STATE if esp_timer library is not initialized yet
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* - ESP_ERR_NO_MEM if memory allocation fails
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*/
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esp_err_t esp_timer_create(const esp_timer_create_args_t* create_args,
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esp_timer_handle_t* out_handle);
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/**
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* @brief Start one-shot timer
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*
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* Timer should not be running when this function is called.
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*
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* @param timer timer handle created using esp_timer_create
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* @param timeout_us timer timeout, in microseconds relative to the current moment
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* @return
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* - ESP_OK on success
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* - ESP_ERR_INVALID_ARG if the handle is invalid
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* - ESP_ERR_INVALID_STATE if the timer is already running
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*/
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esp_err_t esp_timer_start_once(esp_timer_handle_t timer, uint64_t timeout_us);
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/**
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* @brief Start a periodic timer
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*
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* Timer should not be running when this function is called. This function will
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* start the timer which will trigger every 'period' microseconds.
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*
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* @param timer timer handle created using esp_timer_create
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* @param period timer period, in microseconds
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* @return
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* - ESP_OK on success
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* - ESP_ERR_INVALID_ARG if the handle is invalid
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* - ESP_ERR_INVALID_STATE if the timer is already running
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*/
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esp_err_t esp_timer_start_periodic(esp_timer_handle_t timer, uint64_t period);
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/**
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* @brief Stop the timer
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*
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* This function stops the timer previously started using esp_timer_start_once
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* or esp_timer_start_periodic.
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*
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* @param timer timer handle created using esp_timer_create
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* @return
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* - ESP_OK on success
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* - ESP_ERR_INVALID_STATE if the timer is not running
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*/
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esp_err_t esp_timer_stop(esp_timer_handle_t timer);
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/**
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* @brief Delete an esp_timer instance
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*
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* The timer must be stopped before deleting. A one-shot timer which has expired
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* does not need to be stopped.
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*
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* @param timer timer handle allocated using esp_timer_create
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* @return
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* - ESP_OK on success
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* - ESP_ERR_INVALID_STATE if the timer is not running
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*/
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esp_err_t esp_timer_delete(esp_timer_handle_t timer);
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/**
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* @brief Get time in microseconds since boot
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* @return number of microseconds since esp_timer_init was called (this normally
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* happens early during application startup).
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*/
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int64_t esp_timer_get_time(void);
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/**
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* @brief Get the timestamp when the next timeout is expected to occur
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* @return Timestamp of the nearest timer event, in microseconds.
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* The timebase is the same as for the values returned by esp_timer_get_time.
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*/
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int64_t esp_timer_get_next_alarm(void);
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/**
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* @brief Dump the list of timers to a stream
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*
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* If CONFIG_ESP_TIMER_PROFILING option is enabled, this prints the list of all
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* the existing timers. Otherwise, only the list active timers is printed.
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*
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* The format is:
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*
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* name period alarm times_armed times_triggered total_callback_run_time
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*
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* where:
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*
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* name — timer name (if CONFIG_ESP_TIMER_PROFILING is defined), or timer pointer
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* period — period of timer, in microseconds, or 0 for one-shot timer
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* alarm - time of the next alarm, in microseconds since boot, or 0 if the timer
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* is not started
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*
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* The following fields are printed if CONFIG_ESP_TIMER_PROFILING is defined:
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*
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* times_armed — number of times the timer was armed via esp_timer_start_X
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* times_triggered - number of times the callback was called
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* total_callback_run_time - total time taken by callback to execute, across all calls
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*
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* @param stream stream (such as stdout) to dump the information to
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* @return
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* - ESP_OK on success
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* - ESP_ERR_NO_MEM if can not allocate temporary buffer for the output
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*/
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esp_err_t esp_timer_dump(FILE* stream);
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#ifdef __cplusplus
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}
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#endif
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