6353bc40d7
- RTC_CNTL_SLOWCLK_FREQ define is removed; rtc_clk_slow_freq_get_hz function can be used instead to get an approximate RTC_SLOW_CLK frequency - Clock calibration is performed at startup. The value is saved and used for timekeeping and when entering deep sleep. - When using the 32k XTAL, startup code will wait for the oscillator to start up. This can be possibly optimized by starting a separate task to wait for oscillator startup, and performing clock switch in that task. - Fix a bug that 32k XTAL would be disabled in rtc_clk_init. - Fix a rounding error in rtc_clk_cal, which caused systematic frequency error. - Fix an overflow bug which caused rtc_clk_cal to timeout early if the slow_clk_cycles argument would exceed certain value - Improve 32k XTAL oscillator startup time by introducing bootstrapping code, which uses internal pullup/pulldown resistors on 32K_N/32K_P pins to set better initial conditions for the oscillator.
45 lines
1.4 KiB
C
45 lines
1.4 KiB
C
// 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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* These functions are used in ESP-IDF components, but should not be considered
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* to be part of public API.
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*/
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/**
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* @brief Initialize clock-related settings
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*
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* Called from cpu_start.c, not intended to be called from other places.
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* This function configures the CPU clock, RTC slow and fast clocks, and
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* performs RTC slow clock calibration.
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*/
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void esp_clk_init(void);
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/**
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* @brief Get the cached 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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