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diff --git a/src/system_stm32f3xx.c b/src/system_stm32f3xx.c
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+/**
+  ******************************************************************************
+  * @file    system_stm32f3xx.c
+  * @author  MCD Application Team
+  * @brief   CMSIS Cortex-M4 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_stm32f3xx.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_stm32f3xx.s" file, to
+  *    configure the system clock before to branch to main program.
+  *
+  * 3. This file configures the system clock as follows:
+  *=============================================================================
+  *                         Supported STM32F3xx device
+  *-----------------------------------------------------------------------------
+  *        System Clock source                    | HSI
+  *-----------------------------------------------------------------------------
+  *        SYSCLK(Hz)                             | 8000000
+  *-----------------------------------------------------------------------------
+  *        HCLK(Hz)                               | 8000000
+  *-----------------------------------------------------------------------------
+  *        AHB Prescaler                          | 1
+  *-----------------------------------------------------------------------------
+  *        APB2 Prescaler                         | 1
+  *-----------------------------------------------------------------------------
+  *        APB1 Prescaler                         | 1
+  *-----------------------------------------------------------------------------
+  *        USB Clock                              | DISABLE
+  *-----------------------------------------------------------------------------
+  *=============================================================================
+  ******************************************************************************
+  * @attention
+  *
+  * <h2><center>&copy; 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 stm32f3xx_system
+  * @{
+  */
+
+/** @addtogroup STM32F3xx_System_Private_Includes
+  * @{
+  */
+
+#include "stm32f3xx.h"
+
+/**
+  * @}
+  */
+
+/** @addtogroup STM32F3xx_System_Private_TypesDefinitions
+  * @{
+  */
+
+/**
+  * @}
+  */
+
+/** @addtogroup STM32F3xx_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 */
+
+/*!< Uncomment the following line if you need to relocate your vector Table in
+     Internal SRAM. */
+/* #define VECT_TAB_SRAM */
+#define VECT_TAB_OFFSET  0x0 /*!< Vector Table base offset field.
+                                  This value must be a multiple of 0x200. */
+/**
+  * @}
+  */
+
+/** @addtogroup STM32F3xx_System_Private_Macros
+  * @{
+  */
+
+/**
+  * @}
+  */
+
+/** @addtogroup STM32F3xx_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 STM32F3xx_System_Private_FunctionPrototypes
+  * @{
+  */
+
+/**
+  * @}
+  */
+
+/** @addtogroup STM32F3xx_System_Private_Functions
+  * @{
+  */
+
+/**
+  * @brief  Setup the microcontroller system
+  *         Initialize the FPU setting, vector table location and the PLL configuration is reset.
+  * @param  None
+  * @retval None
+  */
+void SystemInit(void)
+{
+  /* FPU settings ------------------------------------------------------------*/
+  #if (__FPU_PRESENT == 1) && (__FPU_USED == 1)
+    SCB->CPACR |= ((3UL << 10*2)|(3UL << 11*2));  /* set CP10 and CP11 Full Access */
+  #endif
+
+  /* Reset the RCC clock configuration to the default reset state ------------*/
+  /* Set HSION bit */
+  RCC->CR |= (uint32_t)0x00000001;
+
+  /* Reset CFGR register */
+  RCC->CFGR &= 0xF87FC00C;
+
+  /* Reset HSEON, CSSON and PLLON bits */
+  RCC->CR &= (uint32_t)0xFEF6FFFF;
+
+  /* Reset HSEBYP bit */
+  RCC->CR &= (uint32_t)0xFFFBFFFF;
+
+  /* Reset PLLSRC, PLLXTPRE, PLLMUL and USBPRE bits */
+  RCC->CFGR &= (uint32_t)0xFF80FFFF;
+
+  /* Reset PREDIV1[3:0] bits */
+  RCC->CFGR2 &= (uint32_t)0xFFFFFFF0;
+
+  /* Reset USARTSW[1:0], I2CSW and TIMs bits */
+  RCC->CFGR3 &= (uint32_t)0xFF00FCCC;
+
+  /* Disable all interrupts */
+  RCC->CIR = 0x00000000;
+
+#ifdef VECT_TAB_SRAM
+  SCB->VTOR = SRAM_BASE | VECT_TAB_OFFSET; /* Vector Table Relocation in Internal SRAM */
+#else
+  SCB->VTOR = FLASH_BASE | VECT_TAB_OFFSET; /* Vector Table Relocation in Internal FLASH */
+#endif
+}
+
+/**
+   * @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 stm32f3xx_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 stm32f3xx_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;
+
+#if defined (STM32F302xE) || defined (STM32F303xE) || defined (STM32F398xx)
+        predivfactor = (RCC->CFGR2 & RCC_CFGR2_PREDIV) + 1;
+      if (pllsource == RCC_CFGR_PLLSRC_HSE_PREDIV)
+      {
+        /* HSE oscillator clock selected as PREDIV1 clock entry */
+        SystemCoreClock = (HSE_VALUE / predivfactor) * pllmull;
+      }
+      else
+      {
+        /* HSI oscillator clock selected as PREDIV1 clock entry */
+        SystemCoreClock = (HSI_VALUE / predivfactor) * pllmull;
+      }
+#else      
+      if (pllsource == RCC_CFGR_PLLSRC_HSI_DIV2)
+      {
+        /* HSI oscillator clock divided by 2 selected as PLL clock entry */
+        SystemCoreClock = (HSI_VALUE >> 1) * pllmull;
+      }
+      else
+      {
+        predivfactor = (RCC->CFGR2 & RCC_CFGR2_PREDIV) + 1;
+        /* HSE oscillator clock selected as PREDIV1 clock entry */
+        SystemCoreClock = (HSE_VALUE / predivfactor) * pllmull;
+      }
+#endif /* STM32F302xE || STM32F303xE || STM32F398xx */
+      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****/
+