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+/**

+  ******************************************************************************

+  * @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.

+  *

+  * 2. After each device reset the HSI (8 MHz) is used as system clock source.

+  *    Then SystemInit() function is called, in "startup_stm32f0xx.s" file, to

+  *    configure the system clock before to branch to main program.

+  *

+  * 3. This file configures the system clock as follows:

+  *=============================================================================

+  *                         Supported STM32F0xx device

+  *-----------------------------------------------------------------------------

+  *        System Clock source                    | HSI

+  *-----------------------------------------------------------------------------

+  *        SYSCLK(Hz)                             | 8000000

+  *-----------------------------------------------------------------------------

+  *        HCLK(Hz)                               | 8000000

+  *-----------------------------------------------------------------------------

+  *        AHB Prescaler                          | 1

+  *-----------------------------------------------------------------------------

+  *        APB1 Prescaler                         | 1

+  *-----------------------------------------------------------------------------

+  *=============================================================================

+  ******************************************************************************

+  * @attention

+  *

+  * <h2><center>&copy; COPYRIGHT(c) 2016 STMicroelectronics</center></h2>

+  *

+  * Redistribution and use in source and binary forms, with or without modification,

+  * are permitted provided that the following conditions are met:

+  *   1. Redistributions of source code must retain the above copyright notice,

+  *      this list of conditions and the following disclaimer.

+  *   2. Redistributions in binary form must reproduce the above copyright notice,

+  *      this list of conditions and the following disclaimer in the documentation

+  *      and/or other materials provided with the distribution.

+  *   3. Neither the name of STMicroelectronics nor the names of its contributors

+  *      may be used to endorse or promote products derived from this software

+  *      without specific prior written permission.

+  *

+  * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"

+  * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE

+  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE

+  * DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE

+  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL

+  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR

+  * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER

+  * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,

+  * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE

+  * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

+  *

+  ******************************************************************************

+  */

+

+/** @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 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.

+  *         Initialize the default HSI clock source, vector table location and the PLL configuration is reset.

+  * @param  None

+  * @retval None

+  */

+void SystemInit(void)

+{

+  /* Reset the RCC clock configuration to the default reset state ------------*/

+  /* Set HSION bit */

+  RCC->CR |= (uint32_t)0x00000001U;

+

+#if defined (STM32F051x8) || defined (STM32F058x8)

+  /* Reset SW[1:0], HPRE[3:0], PPRE[2:0], ADCPRE and MCOSEL[2:0] bits */

+  RCC->CFGR &= (uint32_t)0xF8FFB80CU;

+#else

+  /* Reset SW[1:0], HPRE[3:0], PPRE[2:0], ADCPRE, MCOSEL[2:0], MCOPRE[2:0] and PLLNODIV bits */

+  RCC->CFGR &= (uint32_t)0x08FFB80CU;

+#endif /* STM32F051x8 or STM32F058x8 */

+  

+  /* Reset HSEON, CSSON and PLLON bits */

+  RCC->CR &= (uint32_t)0xFEF6FFFFU;

+

+  /* Reset HSEBYP bit */

+  RCC->CR &= (uint32_t)0xFFFBFFFFU;

+

+  /* Reset PLLSRC, PLLXTPRE and PLLMUL[3:0] bits */

+  RCC->CFGR &= (uint32_t)0xFFC0FFFFU;

+

+  /* Reset PREDIV[3:0] bits */

+  RCC->CFGR2 &= (uint32_t)0xFFFFFFF0U;

+

+#if defined (STM32F072xB) || defined (STM32F078xx)

+  /* Reset USART2SW[1:0], USART1SW[1:0], I2C1SW, CECSW, USBSW and ADCSW bits */

+  RCC->CFGR3 &= (uint32_t)0xFFFCFE2CU;

+#elif defined (STM32F071xB)

+  /* Reset USART2SW[1:0], USART1SW[1:0], I2C1SW, CECSW and ADCSW bits */

+  RCC->CFGR3 &= (uint32_t)0xFFFFCEACU;

+#elif defined (STM32F091xC) || defined (STM32F098xx)

+  /* Reset USART3SW[1:0], USART2SW[1:0], USART1SW[1:0], I2C1SW, CECSW and ADCSW bits */

+  RCC->CFGR3 &= (uint32_t)0xFFF0FEACU;

+#elif defined (STM32F030x6) || defined (STM32F030x8) || defined (STM32F031x6) || defined (STM32F038xx) || defined (STM32F030xC)

+  /* Reset USART1SW[1:0], I2C1SW and ADCSW bits */

+  RCC->CFGR3 &= (uint32_t)0xFFFFFEECU;

+#elif defined (STM32F051x8) || defined (STM32F058xx)

+  /* Reset USART1SW[1:0], I2C1SW, CECSW and ADCSW bits */

+  RCC->CFGR3 &= (uint32_t)0xFFFFFEACU;

+#elif defined (STM32F042x6) || defined (STM32F048xx)

+  /* Reset USART1SW[1:0], I2C1SW, CECSW, USBSW and ADCSW bits */

+  RCC->CFGR3 &= (uint32_t)0xFFFFFE2CU;

+#elif defined (STM32F070x6) || defined (STM32F070xB)

+  /* Reset USART1SW[1:0], I2C1SW, USBSW and ADCSW bits */

+  RCC->CFGR3 &= (uint32_t)0xFFFFFE6CU;

+  /* Set default USB clock to PLLCLK, since there is no HSI48 */

+  RCC->CFGR3 |= (uint32_t)0x00000080U;  

+#else

+ #warning "No target selected"

+#endif

+

+  /* Reset HSI14 bit */

+  RCC->CR2 &= (uint32_t)0xFFFFFFFEU;

+

+  /* Disable all interrupts */

+  RCC->CIR = 0x00000000U;

+

+}

+

+/**

+   * @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.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.h file (default value

+  *              8 MHz), 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****/

+