76 lines
2.4 KiB
C
76 lines
2.4 KiB
C
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// Copyright 2015-2017 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_clk.h
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*
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* This file contains declarations of clock related functions.
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*/
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/**
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* @brief Get the calibration value of RTC slow clock
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*
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* The value is in the same format as returned by rtc_clk_cal (microseconds,
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* in Q13.19 fixed-point format).
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*
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* @return the calibration value obtained using rtc_clk_cal, at startup time
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*/
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uint32_t esp_clk_slowclk_cal_get();
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/**
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* @brief Update the calibration value of RTC slow clock
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*
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* The value has to be in the same format as returned by rtc_clk_cal (microseconds,
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* in Q13.19 fixed-point format).
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* This value is used by timekeeping functions (such as gettimeofday) to
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* calculate current time based on RTC counter value.
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* @param value calibration value obtained using rtc_clk_cal
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*/
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void esp_clk_slowclk_cal_set(uint32_t value);
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/**
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* @brief Return current CPU clock frequency
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* When frequency switching is performed, this frequency may change.
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* However it is guaranteed that the frequency never changes with a critical
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* section.
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*
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* @return CPU clock frequency, in Hz
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*/
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int esp_clk_cpu_freq(void);
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/**
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* @brief Return current APB clock frequency
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*
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* When frequency switching is performed, this frequency may change.
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* However it is guaranteed that the frequency never changes with a critical
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* section.
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*
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* @return APB clock frequency, in Hz
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*/
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int esp_clk_apb_freq(void);
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/**
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* @brief Read value of RTC counter, converting it to microseconds
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* @attention The value returned by this function may change abruptly when
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* calibration value of RTC counter is updated via esp_clk_slowclk_cal_set
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* function. This should not happen unless application calls esp_clk_slowclk_cal_set.
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* In ESP-IDF, esp_clk_slowclk_cal_set is only called in startup code.
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*
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* @return Value or RTC counter, expressed in microseconds
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*/
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uint64_t esp_clk_rtc_time();
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