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esp_clk.h
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esp_clk.h
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/*
* SPDX-FileCopyrightText: 2015-2021 Espressif Systems (Shanghai) CO LTD
*
* SPDX-License-Identifier: Apache-2.0
*/
#pragma once
#include <stdint.h>
#ifdef __cplusplus
extern "C" {
#endif
/**
* @file esp_clk.h
*
* This file contains declarations of clock related functions.
*/
/**
* @brief Get the calibration value of RTC slow clock
*
* The value is in the same format as returned by rtc_clk_cal (microseconds,
* in Q13.19 fixed-point format).
*
* @return the calibration value obtained using rtc_clk_cal, at startup time
*/
uint32_t esp_clk_slowclk_cal_get(void);
/**
* @brief Update the calibration value of RTC slow clock
*
* The value has to be in the same format as returned by rtc_clk_cal (microseconds,
* in Q13.19 fixed-point format).
* This value is used by timekeeping functions (such as gettimeofday) to
* calculate current time based on RTC counter value.
* @param value calibration value obtained using rtc_clk_cal
*/
void esp_clk_slowclk_cal_set(uint32_t value);
/**
* @brief Return current CPU clock frequency
* When frequency switching is performed, this frequency may change.
* However it is guaranteed that the frequency never changes with a critical
* section.
*
* @return CPU clock frequency, in Hz
*/
int esp_clk_cpu_freq(void);
/**
* @brief Return current APB clock frequency
*
* When frequency switching is performed, this frequency may change.
* However it is guaranteed that the frequency never changes with a critical
* section.
*
* @return APB clock frequency, in Hz
*/
int esp_clk_apb_freq(void);
/**
* @brief Return frequency of the main XTAL
*
* Frequency of the main XTAL can be either auto-detected or set at compile
* time (see CONFIG_XTAL_FREQ_SEL sdkconfig option). In both cases, this
* function returns the actual value at run time.
*
* @return XTAL frequency, in Hz
*/
int esp_clk_xtal_freq(void);
/**
* @brief Read value of RTC counter, converting it to microseconds
* @attention The value returned by this function may change abruptly when
* calibration value of RTC counter is updated via esp_clk_slowclk_cal_set
* function. This should not happen unless application calls esp_clk_slowclk_cal_set.
* In ESP-IDF, esp_clk_slowclk_cal_set is only called in startup code.
*
* @return Value or RTC counter, expressed in microseconds
*/
uint64_t esp_clk_rtc_time(void);
#ifdef __cplusplus
}
#endif