annotate Discovery/Src/system_stm32f4xx_special_plus_256k.c @ 282:c7e665e0b08f

translate some comments into english
author heinrichsweikamp
date Wed, 01 May 2019 14:45:47 +0200
parents 5f11787b4f42
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1 ///////////////////////////////////////////////////////////////////////////////
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2 /// -*- coding: UTF-8 -*-
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3 ///
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4 /// \file Discovery/Src/system_stm32f4xx_special_plus_256k.c
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5 /// \brief Manage system init and clocks.
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6 /// \author Heinrichs Weikamp gmbh
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7 /// \date 17-February-2017
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8 ///
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9 /// \details
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10 /// From the CMSIS Cortex-M4 Device Peripheral Access Layer System Source File.
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11 ///
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12 /// This file provides two functions and one global variable to be called from
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13 /// user application:
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14 /// - SystemInit(): This function is called at startup just after reset and
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15 /// before branch to main program. This call is made inside
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16 /// the "startup_stm32f4xx.s" file.
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17 ///
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18 /// - SystemCoreClock variable: Contains the core clock (HCLK), it can be used
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19 /// by the user application to setup the SysTick
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20 /// timer or configure other parameters.
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21 ///
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22 /// - SystemCoreClockUpdate(): Updates the variable SystemCoreClock and must
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23 /// be called whenever the core clock is changed
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24 /// during program execution.
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25 /// $Id$
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26 ///////////////////////////////////////////////////////////////////////////////
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27 /// \par Copyright (c) 2014-2018 Heinrichs Weikamp gmbh
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28 ///
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29 /// This program is free software: you can redistribute it and/or modify
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30 /// it under the terms of the GNU General Public License as published by
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31 /// the Free Software Foundation, either version 3 of the License, or
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32 /// (at your option) any later version.
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33 ///
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34 /// This program is distributed in the hope that it will be useful,
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35 /// but WITHOUT ANY WARRANTY; without even the implied warranty of
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36 /// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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37 /// GNU General Public License for more details.
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38 ///
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39 /// You should have received a copy of the GNU General Public License
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40 /// along with this program. If not, see <http://www.gnu.org/licenses/>.
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41 //////////////////////////////////////////////////////////////////////////////
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42 /// \par Copyright (c) 2017 STMicroelectronics
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43 ///
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44 /// Redistribution and use in source and binary forms, with or without modification,
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45 /// are permitted provided that the following conditions are met:
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46 /// 1. Redistributions of source code must retain the above copyright notice,
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47 /// this list of conditions and the following disclaimer.
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48 /// 2. Redistributions in binary form must reproduce the above copyright notice,
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49 /// this list of conditions and the following disclaimer in the documentation
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50 /// and/or other materials provided with the distribution.
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51 /// 3. Neither the name of STMicroelectronics nor the names of its contributors
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52 /// may be used to endorse or promote products derived from this software
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53 /// without specific prior written permission.
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54 ///
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55 /// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
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56 /// AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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57 /// IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
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58 /// DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
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59 /// FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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60 /// DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
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61 /// SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
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62 /// CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
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63 /// OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
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64 /// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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65 //////////////////////////////////////////////////////////////////////////////
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66
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67 #include "stm32f4xx_hal.h"
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68 #include "stm32f4xx.h"
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69
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70 #if !defined (HSE_VALUE)
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71 #define HSE_VALUE ((uint32_t)8000000) /*!< Default value of the External oscillator in Hz */
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72 #endif /* HSE_VALUE */
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73
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74 #if !defined (HSI_VALUE)
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75 #define HSI_VALUE ((uint32_t)16000000) /*!< Value of the Internal oscillator in Hz*/
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76 #endif /* HSI_VALUE */
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77
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78 /************************* Miscellaneous Configuration ************************/
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79 /*!< Uncomment the following line if you need to relocate your vector Table in
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80 Internal SRAM. */
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81 /* #define VECT_TAB_SRAM */
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82 #define VECT_TAB_OFFSET 0x40000 /*!< Vector Table base offset field.
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83 This value must be a multiple of 0x200. */
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84 /******************************************************************************/
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85
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86 /* This variable is updated in three ways:
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87 1) by calling CMSIS function SystemCoreClockUpdate()
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88 2) by calling HAL API function HAL_RCC_GetHCLKFreq()
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89 3) each time HAL_RCC_ClockConfig() is called to configure the system clock frequency
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90 Note: If you use this function to configure the system clock; then there
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91 is no need to call the 2 first functions listed above, since SystemCoreClock
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92 variable is updated automatically.
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93 */
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94 uint32_t SystemCoreClock = 16000000;
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95 const uint8_t AHBPrescTable[16] = {0, 0, 0, 0, 0, 0, 0, 0, 1, 2, 3, 4, 6, 7, 8, 9};
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96 const uint8_t APBPrescTable[8] = {0, 0, 0, 0, 1, 2, 3, 4};
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97
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98 /**
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99 * @brief Setup the microcontroller system
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100 * Initialize the FPU setting, vector table location and External memory
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101 * configuration.
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102 * @param None
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103 * @retval None
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104 */
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105 void SystemInit(void)
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106 {
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107 /* FPU settings ------------------------------------------------------------*/
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108 #if (__FPU_PRESENT == 1) && (__FPU_USED == 1)
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109 SCB->CPACR |= ((3UL << 10*2)|(3UL << 11*2)); /* set CP10 and CP11 Full Access */
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110 #endif
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111 /* Reset the RCC clock configuration to the default reset state ------------*/
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112 /* Set HSION bit */
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113 RCC->CR |= (uint32_t)0x00000001;
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114
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115 /* Reset CFGR register */
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116 RCC->CFGR = 0x00000000;
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117
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118 /* Reset HSEON, CSSON and PLLON bits */
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119 RCC->CR &= (uint32_t)0xFEF6FFFF;
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120
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121 /* Reset PLLCFGR register */
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122 RCC->PLLCFGR = 0x24003010;
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123
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124 /* Reset HSEBYP bit */
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125 RCC->CR &= (uint32_t)0xFFFBFFFF;
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126
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127 /* Disable all interrupts */
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128 RCC->CIR = 0x00000000;
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129
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130
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131 /* Configure the Vector Table location add offset address ------------------*/
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132 #ifdef VECT_TAB_SRAM
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133 SCB->VTOR = SRAM_BASE | VECT_TAB_OFFSET; /* Vector Table Relocation in Internal SRAM */
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134 #else
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135 SCB->VTOR = FLASH_BASE | VECT_TAB_OFFSET; /* Vector Table Relocation in Internal FLASH */
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136 #endif
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137 }
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138
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139 /**
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140 * @brief Update SystemCoreClock variable according to Clock Register Values.
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141 * The SystemCoreClock variable contains the core clock (HCLK), it can
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142 * be used by the user application to setup the SysTick timer or configure
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143 * other parameters.
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144 *
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145 * @note Each time the core clock (HCLK) changes, this function must be called
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146 * to update SystemCoreClock variable value. Otherwise, any configuration
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147 * based on this variable will be incorrect.
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148 *
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149 * @note - The system frequency computed by this function is not the real
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150 * frequency in the chip. It is calculated based on the predefined
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151 * constant and the selected clock source:
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152 *
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153 * - If SYSCLK source is HSI, SystemCoreClock will contain the HSI_VALUE(*)
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154 *
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155 * - If SYSCLK source is HSE, SystemCoreClock will contain the HSE_VALUE(**)
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156 *
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157 * - If SYSCLK source is PLL, SystemCoreClock will contain the HSE_VALUE(**)
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158 * or HSI_VALUE(*) multiplied/divided by the PLL factors.
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159 *
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160 * (*) HSI_VALUE is a constant defined in stm32f4xx_hal_conf.h file (default value
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161 * 16 MHz) but the real value may vary depending on the variations
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162 * in voltage and temperature.
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163 *
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164 * (**) HSE_VALUE is a constant defined in stm32f4xx_hal_conf.h file (its value
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165 * depends on the application requirements), user has to ensure that HSE_VALUE
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166 * is same as the real frequency of the crystal used. Otherwise, this function
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167 * may have wrong result.
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168 *
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169 * - The result of this function could be not correct when using fractional
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170 * value for HSE crystal.
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171 *
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172 * @param None
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173 * @retval None
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174 */
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175 void SystemCoreClockUpdate(void)
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176 {
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177 uint32_t tmp = 0, pllvco = 0, pllp = 2, pllsource = 0, pllm = 2;
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178
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179 /* Get SYSCLK source -------------------------------------------------------*/
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180 tmp = RCC->CFGR & RCC_CFGR_SWS;
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181
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182 switch (tmp)
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183 {
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184 case 0x00: /* HSI used as system clock source */
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185 SystemCoreClock = HSI_VALUE;
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186 break;
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187 case 0x04: /* HSE used as system clock source */
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188 SystemCoreClock = HSE_VALUE;
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189 break;
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190 case 0x08: /* PLL used as system clock source */
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191
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192 /* PLL_VCO = (HSE_VALUE or HSI_VALUE / PLL_M) * PLL_N
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193 SYSCLK = PLL_VCO / PLL_P
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194 */
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195 pllsource = (RCC->PLLCFGR & RCC_PLLCFGR_PLLSRC) >> 22;
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196 pllm = RCC->PLLCFGR & RCC_PLLCFGR_PLLM;
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197
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198 if (pllsource != 0)
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199 {
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200 /* HSE used as PLL clock source */
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201 pllvco = (HSE_VALUE / pllm) * ((RCC->PLLCFGR & RCC_PLLCFGR_PLLN) >> 6);
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202 }
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203 else
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204 {
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205 /* HSI used as PLL clock source */
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206 pllvco = (HSI_VALUE / pllm) * ((RCC->PLLCFGR & RCC_PLLCFGR_PLLN) >> 6);
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207 }
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208
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209 pllp = (((RCC->PLLCFGR & RCC_PLLCFGR_PLLP) >>16) + 1 ) *2;
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210 SystemCoreClock = pllvco/pllp;
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211 break;
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212 default:
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213 SystemCoreClock = HSI_VALUE;
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214 break;
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215 }
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216 /* Compute HCLK frequency --------------------------------------------------*/
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217 /* Get HCLK prescaler */
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218 tmp = AHBPrescTable[((RCC->CFGR & RCC_CFGR_HPRE) >> 4)];
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219 /* HCLK frequency */
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220 SystemCoreClock >>= tmp;
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221 }