| /** |
| ****************************************************************************** |
| * @file system_stm32f0xx.c |
| * @author MCD Application Team |
| * @brief CMSIS Cortex-M0 Device Peripheral Access Layer System Source File. |
| * |
| * 1. This file provides two functions and one global variable to be called from |
| * user application: |
| * - SystemInit(): This function is called at startup just after reset and |
| * before branch to main program. This call is made inside |
| * the "startup_stm32f0xx.s" file. |
| * |
| * - SystemCoreClock variable: Contains the core clock (HCLK), it can be used |
| * by the user application to setup the SysTick |
| * timer or configure other parameters. |
| * |
| * - SystemCoreClockUpdate(): Updates the variable SystemCoreClock and must |
| * be called whenever the core clock is changed |
| * during program execution. |
| * |
| * |
| ****************************************************************************** |
| * @attention |
| * |
| * <h2><center>© Copyright (c) 2016 STMicroelectronics. |
| * All rights reserved.</center></h2> |
| * |
| * This software component is licensed by ST under BSD 3-Clause license, |
| * the "License"; You may not use this file except in compliance with the |
| * License. You may obtain a copy of the License at: |
| * opensource.org/licenses/BSD-3-Clause |
| * |
| ****************************************************************************** |
| */ |
| |
| /** @addtogroup CMSIS |
| * @{ |
| */ |
| |
| /** @addtogroup stm32f0xx_system |
| * @{ |
| */ |
| |
| /** @addtogroup STM32F0xx_System_Private_Includes |
| * @{ |
| */ |
| |
| #include "stm32f0xx.h" |
| |
| /** |
| * @} |
| */ |
| |
| /** @addtogroup STM32F0xx_System_Private_TypesDefinitions |
| * @{ |
| */ |
| |
| /** |
| * @} |
| */ |
| |
| /** @addtogroup STM32F0xx_System_Private_Defines |
| * @{ |
| */ |
| #if !defined (HSE_VALUE) |
| #define HSE_VALUE ((uint32_t)8000000) /*!< Default value of the External oscillator in Hz. |
| This value can be provided and adapted by the user application. */ |
| #endif /* HSE_VALUE */ |
| |
| #if !defined (HSI_VALUE) |
| #define HSI_VALUE ((uint32_t)8000000) /*!< Default value of the Internal oscillator in Hz. |
| This value can be provided and adapted by the user application. */ |
| #endif /* HSI_VALUE */ |
| |
| #if !defined (HSI48_VALUE) |
| #define HSI48_VALUE ((uint32_t)48000000) /*!< Default value of the HSI48 Internal oscillator in Hz. |
| This value can be provided and adapted by the user application. */ |
| #endif /* HSI48_VALUE */ |
| /** |
| * @} |
| */ |
| |
| /** @addtogroup STM32F0xx_System_Private_Macros |
| * @{ |
| */ |
| |
| /** |
| * @} |
| */ |
| |
| /** @addtogroup STM32F0xx_System_Private_Variables |
| * @{ |
| */ |
| /* This variable is updated in three ways: |
| 1) by calling CMSIS function SystemCoreClockUpdate() |
| 2) by calling HAL API function HAL_RCC_GetHCLKFreq() |
| 3) each time HAL_RCC_ClockConfig() is called to configure the system clock frequency |
| Note: If you use this function to configure the system clock; then there |
| is no need to call the 2 first functions listed above, since SystemCoreClock |
| variable is updated automatically. |
| */ |
| uint32_t SystemCoreClock = 8000000; |
| |
| const uint8_t AHBPrescTable[16] = {0, 0, 0, 0, 0, 0, 0, 0, 1, 2, 3, 4, 6, 7, 8, 9}; |
| const uint8_t APBPrescTable[8] = {0, 0, 0, 0, 1, 2, 3, 4}; |
| |
| /** |
| * @} |
| */ |
| |
| /** @addtogroup STM32F0xx_System_Private_FunctionPrototypes |
| * @{ |
| */ |
| |
| /** |
| * @} |
| */ |
| |
| /** @addtogroup STM32F0xx_System_Private_Functions |
| * @{ |
| */ |
| |
| /** |
| * @brief Setup the microcontroller system |
| * @param None |
| * @retval None |
| */ |
| void SystemInit(void) |
| { |
| /* NOTE :SystemInit(): This function is called at startup just after reset and |
| before branch to main program. This call is made inside |
| the "startup_stm32f0xx.s" file. |
| User can setups the default system clock (System clock source, PLL Multiplier |
| and Divider factors, AHB/APBx prescalers and Flash settings). |
| */ |
| } |
| |
| /** |
| * @brief Update SystemCoreClock variable according to Clock Register Values. |
| * The SystemCoreClock variable contains the core clock (HCLK), it can |
| * be used by the user application to setup the SysTick timer or configure |
| * other parameters. |
| * |
| * @note Each time the core clock (HCLK) changes, this function must be called |
| * to update SystemCoreClock variable value. Otherwise, any configuration |
| * based on this variable will be incorrect. |
| * |
| * @note - The system frequency computed by this function is not the real |
| * frequency in the chip. It is calculated based on the predefined |
| * constant and the selected clock source: |
| * |
| * - If SYSCLK source is HSI, SystemCoreClock will contain the HSI_VALUE(*) |
| * |
| * - If SYSCLK source is HSE, SystemCoreClock will contain the HSE_VALUE(**) |
| * |
| * - If SYSCLK source is PLL, SystemCoreClock will contain the HSE_VALUE(**) |
| * or HSI_VALUE(*) multiplied/divided by the PLL factors. |
| * |
| * (*) HSI_VALUE is a constant defined in stm32f0xx_hal_conf.h file (default value |
| * 8 MHz) but the real value may vary depending on the variations |
| * in voltage and temperature. |
| * |
| * (**) HSE_VALUE is a constant defined in stm32f0xx_hal_conf.h file (its value |
| * depends on the application requirements), user has to ensure that HSE_VALUE |
| * is same as the real frequency of the crystal used. Otherwise, this function |
| * may have wrong result. |
| * |
| * - The result of this function could be not correct when using fractional |
| * value for HSE crystal. |
| * |
| * @param None |
| * @retval None |
| */ |
| void SystemCoreClockUpdate (void) |
| { |
| uint32_t tmp = 0, pllmull = 0, pllsource = 0, predivfactor = 0; |
| |
| /* Get SYSCLK source -------------------------------------------------------*/ |
| tmp = RCC->CFGR & RCC_CFGR_SWS; |
| |
| switch (tmp) |
| { |
| case RCC_CFGR_SWS_HSI: /* HSI used as system clock */ |
| SystemCoreClock = HSI_VALUE; |
| break; |
| case RCC_CFGR_SWS_HSE: /* HSE used as system clock */ |
| SystemCoreClock = HSE_VALUE; |
| break; |
| case RCC_CFGR_SWS_PLL: /* PLL used as system clock */ |
| /* Get PLL clock source and multiplication factor ----------------------*/ |
| pllmull = RCC->CFGR & RCC_CFGR_PLLMUL; |
| pllsource = RCC->CFGR & RCC_CFGR_PLLSRC; |
| pllmull = ( pllmull >> 18) + 2; |
| predivfactor = (RCC->CFGR2 & RCC_CFGR2_PREDIV) + 1; |
| |
| if (pllsource == RCC_CFGR_PLLSRC_HSE_PREDIV) |
| { |
| /* HSE used as PLL clock source : SystemCoreClock = HSE/PREDIV * PLLMUL */ |
| SystemCoreClock = (HSE_VALUE/predivfactor) * pllmull; |
| } |
| #if defined(STM32F042x6) || defined(STM32F048xx) || defined(STM32F072xB) || defined(STM32F078xx) || defined(STM32F091xC) || defined(STM32F098xx) |
| else if (pllsource == RCC_CFGR_PLLSRC_HSI48_PREDIV) |
| { |
| /* HSI48 used as PLL clock source : SystemCoreClock = HSI48/PREDIV * PLLMUL */ |
| SystemCoreClock = (HSI48_VALUE/predivfactor) * pllmull; |
| } |
| #endif /* STM32F042x6 || STM32F048xx || STM32F072xB || STM32F078xx || STM32F091xC || STM32F098xx */ |
| else |
| { |
| #if defined(STM32F042x6) || defined(STM32F048xx) || defined(STM32F070x6) \ |
| || defined(STM32F078xx) || defined(STM32F071xB) || defined(STM32F072xB) \ |
| || defined(STM32F070xB) || defined(STM32F091xC) || defined(STM32F098xx) || defined(STM32F030xC) |
| /* HSI used as PLL clock source : SystemCoreClock = HSI/PREDIV * PLLMUL */ |
| SystemCoreClock = (HSI_VALUE/predivfactor) * pllmull; |
| #else |
| /* HSI used as PLL clock source : SystemCoreClock = HSI/2 * PLLMUL */ |
| SystemCoreClock = (HSI_VALUE >> 1) * pllmull; |
| #endif /* STM32F042x6 || STM32F048xx || STM32F070x6 || |
| STM32F071xB || STM32F072xB || STM32F078xx || STM32F070xB || |
| STM32F091xC || STM32F098xx || STM32F030xC */ |
| } |
| break; |
| default: /* HSI used as system clock */ |
| SystemCoreClock = HSI_VALUE; |
| break; |
| } |
| /* Compute HCLK clock frequency ----------------*/ |
| /* Get HCLK prescaler */ |
| tmp = AHBPrescTable[((RCC->CFGR & RCC_CFGR_HPRE) >> 4)]; |
| /* HCLK clock frequency */ |
| SystemCoreClock >>= tmp; |
| } |
| |
| /** |
| * @} |
| */ |
| |
| /** |
| * @} |
| */ |
| |
| /** |
| * @} |
| */ |
| |
| /************************ (C) COPYRIGHT STMicroelectronics *****END OF FILE****/ |
| |
