Diff: system_stm32l4xx.c

Revision:

0:d4e5ad7ad71c

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/system_stm32l4xx.c	Mon Nov 23 19:37:13 2015 +0000
@@ -0,0 +1,354 @@
+/**
+  ******************************************************************************
+  * @file    system_stm32l4xx.c
+  * @author  MCD Application Team
+  * @version V1.1.0
+  * @date    16-September-2015
+  * @brief   CMSIS Cortex-M4 Device Peripheral Access Layer System Source File
+  *
+  *   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_stm32l4xx.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.
+  *
+  *   After each device reset the MSI (4 MHz) is used as system clock source.
+  *   Then SystemInit() function is called, in "startup_stm32l4xx.s" file, to
+  *   configure the system clock before to branch to main program.
+  *
+  *   This file configures the system clock as follows:
+  *=============================================================================
+  *-----------------------------------------------------------------------------
+  *        System Clock source                    | MSI
+  *-----------------------------------------------------------------------------
+  *        SYSCLK(Hz)                             | 4000000
+  *-----------------------------------------------------------------------------
+  *        HCLK(Hz)                               | 4000000
+  *-----------------------------------------------------------------------------
+  *        AHB Prescaler                          | 1
+  *-----------------------------------------------------------------------------
+  *        APB1 Prescaler                         | 1
+  *-----------------------------------------------------------------------------
+  *        APB2 Prescaler                         | 1
+  *-----------------------------------------------------------------------------
+  *        PLL_M                                  | 1
+  *-----------------------------------------------------------------------------
+  *        PLL_N                                  | 8
+  *-----------------------------------------------------------------------------
+  *        PLL_P                                  | 7
+  *-----------------------------------------------------------------------------
+  *        PLL_Q                                  | 2
+  *-----------------------------------------------------------------------------
+  *        PLL_R                                  | 2
+  *-----------------------------------------------------------------------------
+  *        PLLSAI1_P                              | NA
+  *-----------------------------------------------------------------------------
+  *        PLLSAI1_Q                              | NA
+  *-----------------------------------------------------------------------------
+  *        PLLSAI1_R                              | NA
+  *-----------------------------------------------------------------------------
+  *        PLLSAI2_P                              | NA
+  *-----------------------------------------------------------------------------
+  *        PLLSAI2_Q                              | NA
+  *-----------------------------------------------------------------------------
+  *        PLLSAI2_R                              | NA
+  *-----------------------------------------------------------------------------
+  *        Require 48MHz for USB OTG FS,          | Disabled
+  *        SDIO and RNG clock                     |
+  *-----------------------------------------------------------------------------
+  *=============================================================================
+  ******************************************************************************
+  * @attention
+  *
+  * <h2><center>&copy; COPYRIGHT(c) 2015 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 stm32l4xx_system
+  * @{
+  */
+
+/** @addtogroup STM32L4xx_System_Private_Includes
+  * @{
+  */
+
+#include "stm32l4xx.h"
+
+#if !defined  (HSE_VALUE)
+  #define HSE_VALUE    ((uint32_t)8000000) /*!< Value of the External oscillator in Hz */
+#endif /* HSE_VALUE */
+
+#if !defined  (MSI_VALUE)
+  #define MSI_VALUE    ((uint32_t)4000000) /*!< Value of the Internal oscillator in Hz*/
+#endif /* MSI_VALUE */
+
+#if !defined  (HSI_VALUE)
+  #define HSI_VALUE    ((uint32_t)16000000) /*!< Value of the Internal oscillator in Hz*/
+#endif /* HSI_VALUE */
+
+/**
+  * @}
+  */
+
+/** @addtogroup STM32L4xx_System_Private_TypesDefinitions
+  * @{
+  */
+
+/**
+  * @}
+  */
+
+/** @addtogroup STM32L4xx_System_Private_Defines
+  * @{
+  */
+
+/************************* Miscellaneous Configuration ************************/
+/*!< Uncomment the following line if you need to relocate your vector Table in
+     Internal SRAM. */
+/* #define VECT_TAB_SRAM */
+#define VECT_TAB_OFFSET  0x00 /*!< Vector Table base offset field.
+                                   This value must be a multiple of 0x200. */
+/******************************************************************************/
+/**
+  * @}
+  */
+
+/** @addtogroup STM32L4xx_System_Private_Macros
+  * @{
+  */
+
+/**
+  * @}
+  */
+
+/** @addtogroup STM32L4xx_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 = 4000000;
+
+  const uint8_t  AHBPrescTable[16] = {0, 0, 0, 0, 0, 0, 0, 0, 1, 2, 3, 4, 6, 7, 8, 9};
+  const uint32_t MSIRangeTable[12] = {100000, 200000, 400000, 800000, 1000000, 2000000, \
+                                      4000000, 8000000, 16000000, 24000000, 32000000, 48000000};
+/**
+  * @}
+  */
+
+/** @addtogroup STM32L4xx_System_Private_FunctionPrototypes
+  * @{
+  */
+
+/**
+  * @}
+  */
+
+/** @addtogroup STM32L4xx_System_Private_Functions
+  * @{
+  */
+
+/**
+  * @brief  Setup the microcontroller system.
+  * @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 MSION bit */
+  RCC->CR |= RCC_CR_MSION;
+
+  /* Reset CFGR register */
+  RCC->CFGR = 0x00000000;
+
+  /* Reset HSEON, CSSON , HSION, and PLLON bits */
+  RCC->CR &= (uint32_t)0xEAF6FFFF;
+
+  /* Reset PLLCFGR register */
+  RCC->PLLCFGR = 0x00000800;
+
+  /* Reset HSEBYP bit */
+  RCC->CR &= (uint32_t)0xFFFBFFFF;
+
+  /* Disable all interrupts */
+  RCC->CIER = 0x00000000;
+
+  /* Configure the Vector Table location add offset address ------------------*/
+#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 MSI, SystemCoreClock will contain the MSI_VALUE(*)
+  *
+  *           - 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(*) or MSI_VALUE(*) multiplied/divided by the PLL factors.
+  *
+  *         (*) MSI_VALUE is a constant defined in stm32l4xx_hal.h file (default value
+  *             4 MHz) but the real value may vary depending on the variations
+  *             in voltage and temperature.
+  *
+  *         (**) HSI_VALUE is a constant defined in stm32l4xx_hal.h file (default value
+  *              16 MHz) but the real value may vary depending on the variations
+  *              in voltage and temperature.
+  *
+  *         (***) HSE_VALUE is a constant defined in stm32l4xx_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, msirange = 0, pllvco = 0, pllr = 2, pllsource = 0, pllm = 2;
+
+  /* Get MSI Range frequency--------------------------------------------------*/
+  if((RCC->CR & RCC_CR_MSIRGSEL) == RESET)
+  { /* MSISRANGE from RCC_CSR applies */
+    msirange = (RCC->CSR & RCC_CSR_MSISRANGE) >> 8;
+  }
+  else
+  { /* MSIRANGE from RCC_CR applies */
+    msirange = (RCC->CR & RCC_CR_MSIRANGE) >> 4;
+  }
+  /*MSI frequency range in HZ*/
+  msirange = MSIRangeTable[msirange];
+
+  /* Get SYSCLK source -------------------------------------------------------*/
+  switch (RCC->CFGR & RCC_CFGR_SWS)
+  {
+    case 0x00:  /* MSI used as system clock source */
+      SystemCoreClock = msirange;
+      break;
+
+    case 0x04:  /* HSI used as system clock source */
+      SystemCoreClock = HSI_VALUE;
+      break;
+
+    case 0x08:  /* HSE used as system clock source */
+      SystemCoreClock = HSE_VALUE;
+      break;
+
+    case 0x0C:  /* PLL used as system clock  source */
+      /* PLL_VCO = (HSE_VALUE or HSI_VALUE or MSI_VALUE/ PLLM) * PLLN
+         SYSCLK = PLL_VCO / PLLR
+         */
+      pllsource = (RCC->PLLCFGR & RCC_PLLCFGR_PLLSRC);
+      pllm = ((RCC->PLLCFGR & RCC_PLLCFGR_PLLM) >> 4) + 1 ;
+
+      switch (pllsource)
+      {
+        case 0x02:  /* HSI used as PLL clock source */
+          pllvco = (HSI_VALUE / pllm);
+          break;
+
+        case 0x03:  /* HSE used as PLL clock source */
+          pllvco = (HSE_VALUE / pllm);
+          break;
+
+        default:    /* MSI used as PLL clock source */
+          pllvco = (msirange / pllm);
+          break;
+      }
+      pllvco = pllvco * ((RCC->PLLCFGR & RCC_PLLCFGR_PLLN) >> 8);
+      pllr = (((RCC->PLLCFGR & RCC_PLLCFGR_PLLR) >> 25) + 1) * 2;
+      SystemCoreClock = pllvco/pllr;
+      break;
+
+    default:
+      SystemCoreClock = msirange;
+      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****/
+