Diff: src/system_stm32f30x.c

Revision:

0:404f5a4f1385

Child:

1:f8e3e71af478

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/src/system_stm32f30x.c	Mon May 09 04:00:25 2016 +0000
@@ -0,0 +1,370 @@
+/**
+  ******************************************************************************
+  * @file    system_stm32f30x.c
+  * @author  MCD Application Team
+  * @version V1.2.2
+  * @date    27-February-2015
+  * @brief   CMSIS Cortex-M4 Device Peripheral Access Layer System Source File.
+  *          This file contains the system clock configuration for STM32F30x devices,
+  *          and is generated by the clock configuration tool
+  *          stm32f30x_Clock_Configuration_V1.0.0.xls
+  *             
+  * 1.  This file provides two functions and one global variable to be called from 
+  *     user application:
+  *      - SystemInit(): Setups the system clock (System clock source, PLL Multiplier
+  *                      and Divider factors, AHB/APBx prescalers and Flash settings),
+  *                      depending on the configuration made in the clock xls tool. 
+  *                      This function is called at startup just after reset and 
+  *                      before branch to main program. This call is made inside
+  *                      the "startup_stm32f30x.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_stm32f30x.s" file, to
+  *    configure the system clock before to branch to main program.
+  *
+  * 3. If the system clock source selected by user fails to startup, the SystemInit()
+  *    function will do nothing and HSI still used as system clock source. User can 
+  *    add some code to deal with this issue inside the SetSysClock() function.
+  *
+  * 4. The default value of HSE crystal is set to 8MHz, refer to "HSE_VALUE" define
+  *    in "stm32f30x.h" file. When HSE is used as system clock source, directly or
+  *    through PLL, and you are using different crystal you have to adapt the HSE
+  *    value to your own configuration.
+  *
+  * 5. This file configures the system clock as follows:
+  *=============================================================================
+  *                         Supported STM32F30x device                          
+  *-----------------------------------------------------------------------------
+  *        System Clock source                    | PLL (HSE)
+  *-----------------------------------------------------------------------------
+  *        SYSCLK(Hz)                             | 72000000
+  *-----------------------------------------------------------------------------
+  *        HCLK(Hz)                               | 72000000
+  *-----------------------------------------------------------------------------
+  *        AHB Prescaler                          | 1
+  *-----------------------------------------------------------------------------
+  *        APB2 Prescaler                         | 1
+  *-----------------------------------------------------------------------------
+  *        APB1 Prescaler                         | 2
+  *-----------------------------------------------------------------------------
+  *        HSE Frequency(Hz)                      | 8000000
+  *----------------------------------------------------------------------------
+  *        PLLMUL                                 | 9
+  *-----------------------------------------------------------------------------
+  *        PREDIV                                 | 1
+  *-----------------------------------------------------------------------------
+  *        USB Clock                              | DISABLE
+  *-----------------------------------------------------------------------------
+  *        Flash Latency(WS)                      | 2
+  *-----------------------------------------------------------------------------
+  *        Prefetch Buffer                        | ON
+  *-----------------------------------------------------------------------------
+  *=============================================================================
+  ******************************************************************************
+  * @attention
+  *
+  * <h2><center>&copy; COPYRIGHT 2015 STMicroelectronics</center></h2>
+  *
+  * Licensed under MCD-ST Liberty SW License Agreement V2, (the "License");
+  * You may not use this file except in compliance with the License.
+  * You may obtain a copy of the License at:
+  *
+  *        http://www.st.com/software_license_agreement_liberty_v2
+  *
+  * Unless required by applicable law or agreed to in writing, software 
+  * distributed under the License is distributed on an "AS IS" BASIS, 
+  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+  * See the License for the specific language governing permissions and
+  * limitations under the License.
+  *
+  ******************************************************************************
+  */
+/** @addtogroup CMSIS
+  * @{
+  */
+
+/** @addtogroup stm32f30x_system
+  * @{
+  */  
+  
+/** @addtogroup STM32F30x_System_Private_Includes
+  * @{
+  */
+
+#include "stm32f30x.h"
+
+/**
+  * @}
+  */
+
+/* Private typedef -----------------------------------------------------------*/
+
+/** @addtogroup STM32F30x_System_Private_Defines
+  * @{
+  */
+/*!< 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. */  
+/**
+  * @}
+  */ 
+
+/* Private macro -------------------------------------------------------------*/
+
+/** @addtogroup STM32F30x_System_Private_Variables
+  * @{
+  */
+
+  uint32_t SystemCoreClock = 72000000;
+
+  __I uint8_t AHBPrescTable[16] = {0, 0, 0, 0, 0, 0, 0, 0, 1, 2, 3, 4, 6, 7, 8, 9};
+
+/**
+  * @}
+  */
+
+/** @addtogroup STM32F30x_System_Private_FunctionPrototypes
+  * @{
+  */
+
+static void SetSysClock(void);
+
+/**
+  * @}
+  */
+
+/** @addtogroup STM32F30x_System_Private_Functions
+  * @{
+  */
+
+/**
+  * @brief  Setup the microcontroller system
+  *         Initialize the Embedded Flash Interface, the PLL and update the 
+  *         SystemFrequency variable.
+  * @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;
+
+  /* Configure the System clock source, PLL Multiplier and Divider factors, 
+     AHB/APBx prescalers and Flash settings ----------------------------------*/
+  SetSysClock();
+  
+#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 stm32f30x.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 stm32f30x.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, prediv1factor = 0;
+
+  /* Get SYSCLK source -------------------------------------------------------*/
+  tmp = RCC->CFGR & RCC_CFGR_SWS;
+  
+  switch (tmp)
+  {
+    case 0x00:  /* HSI used as system clock */
+      SystemCoreClock = HSI_VALUE;
+      break;
+    case 0x04:  /* HSE used as system clock */
+      SystemCoreClock = HSE_VALUE;
+      break;
+    case 0x08:  /* PLL used as system clock */
+      /* Get PLL clock source and multiplication factor ----------------------*/
+      pllmull = RCC->CFGR & RCC_CFGR_PLLMULL;
+      pllsource = RCC->CFGR & RCC_CFGR_PLLSRC;
+      pllmull = ( pllmull >> 18) + 2;
+      
+      if (pllsource == 0x00)
+      {
+        /* HSI oscillator clock divided by 2 selected as PLL clock entry */
+        SystemCoreClock = (HSI_VALUE >> 1) * pllmull;
+      }
+      else
+      {
+        prediv1factor = (RCC->CFGR2 & RCC_CFGR2_PREDIV1) + 1;
+        /* HSE oscillator clock selected as PREDIV1 clock entry */
+        SystemCoreClock = (HSE_VALUE / prediv1factor) * pllmull; 
+      }      
+      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;  
+}
+
+/**
+  * @brief  Configures the System clock source, PLL Multiplier and Divider factors,
+  *               AHB/APBx prescalers and Flash settings
+  * @note   This function should be called only once the RCC clock configuration  
+  *         is reset to the default reset state (done in SystemInit() function).             
+  * @param  None
+  * @retval None
+  */
+static void SetSysClock(void)
+{
+  __IO uint32_t StartUpCounter = 0, HSEStatus = 0;
+
+/******************************************************************************/
+/*            PLL (clocked by HSE) used as System clock source                */
+/******************************************************************************/
+
+  /* SYSCLK, HCLK, PCLK2 and PCLK1 configuration -----------*/
+  /* Enable HSE */
+  RCC->CR |= ((uint32_t)RCC_CR_HSEON);
+ 
+  /* Wait till HSE is ready and if Time out is reached exit */
+  do
+  {
+    HSEStatus = RCC->CR & RCC_CR_HSERDY;
+    StartUpCounter++;
+  } while((HSEStatus == 0) && (StartUpCounter != HSE_STARTUP_TIMEOUT));
+
+  if ((RCC->CR & RCC_CR_HSERDY) != RESET)
+  {
+    HSEStatus = (uint32_t)0x01;
+  }
+  else
+  {
+    HSEStatus = (uint32_t)0x00;
+  }
+
+  if (HSEStatus == (uint32_t)0x01)
+  {
+    /* Enable Prefetch Buffer and set Flash Latency */
+    FLASH->ACR = FLASH_ACR_PRFTBE | (uint32_t)FLASH_ACR_LATENCY_1;
+ 
+     /* HCLK = SYSCLK / 1 */
+     RCC->CFGR |= (uint32_t)RCC_CFGR_HPRE_DIV1;
+       
+     /* PCLK2 = HCLK / 1 */
+     RCC->CFGR |= (uint32_t)RCC_CFGR_PPRE2_DIV1;
+     
+     /* PCLK1 = HCLK / 2 */
+     RCC->CFGR |= (uint32_t)RCC_CFGR_PPRE1_DIV2;
+
+    /* PLL configuration */
+    RCC->CFGR &= (uint32_t)((uint32_t)~(RCC_CFGR_PLLSRC | RCC_CFGR_PLLXTPRE | RCC_CFGR_PLLMULL));
+    RCC->CFGR |= (uint32_t)(RCC_CFGR_PLLSRC_PREDIV1 | RCC_CFGR_PLLXTPRE_PREDIV1 | RCC_CFGR_PLLMULL9);
+
+    /* Enable PLL */
+    RCC->CR |= RCC_CR_PLLON;
+
+    /* Wait till PLL is ready */
+    while((RCC->CR & RCC_CR_PLLRDY) == 0)
+    {
+    }
+    
+    /* Select PLL as system clock source */
+    RCC->CFGR &= (uint32_t)((uint32_t)~(RCC_CFGR_SW));
+    RCC->CFGR |= (uint32_t)RCC_CFGR_SW_PLL;
+
+    /* Wait till PLL is used as system clock source */
+    while ((RCC->CFGR & (uint32_t)RCC_CFGR_SWS) != (uint32_t)RCC_CFGR_SWS_PLL)
+    {
+    }
+  }
+  else
+  { /* If HSE fails to start-up, the application will have wrong clock
+         configuration. User can add here some code to deal with this error */
+  }
+}
+
+/**
+  * @}
+  */
+
+/**
+  * @}
+  */
+
+/**
+  * @}
+  */
+
+/************************ (C) COPYRIGHT STMicroelectronics *****END OF FILE****/
+