/** | |
****************************************************************************** | |
* @file system_stm32l4xx.c | |
* @author MCD Application Team | |
* @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>© Copyright (c) 2017 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 stm32l4xx_system | |
* @{ | |
*/ | |
/** @addtogroup STM32L4xx_System_Private_Includes | |
* @{ | |
*/ | |
#include "stm32l4xx.h" | |
#if !defined (HSE_VALUE) | |
#define HSE_VALUE 8000000U /*!< Value of the External oscillator in Hz */ | |
#endif /* HSE_VALUE */ | |
#if !defined (MSI_VALUE) | |
#define MSI_VALUE 4000000U /*!< Value of the Internal oscillator in Hz*/ | |
#endif /* MSI_VALUE */ | |
#if !defined (HSI_VALUE) | |
#define HSI_VALUE 16000000U /*!< 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 | |
* @{ | |
*/ | |
/* The SystemCoreClock 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 = 4000000U; | |
const uint8_t AHBPrescTable[16] = {0U, 0U, 0U, 0U, 0U, 0U, 0U, 0U, 1U, 2U, 3U, 4U, 6U, 7U, 8U, 9U}; | |
const uint8_t APBPrescTable[8] = {0U, 0U, 0U, 0U, 1U, 2U, 3U, 4U}; | |
const uint32_t MSIRangeTable[12] = {100000U, 200000U, 400000U, 800000U, 1000000U, 2000000U, \ | |
4000000U, 8000000U, 16000000U, 24000000U, 32000000U, 48000000U}; | |
/** | |
* @} | |
*/ | |
/** @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 = 0x00000000U; | |
/* Reset HSEON, CSSON , HSION, and PLLON bits */ | |
RCC->CR &= 0xEAF6FFFFU; | |
/* Reset PLLCFGR register */ | |
RCC->PLLCFGR = 0x00001000U; | |
/* Reset HSEBYP bit */ | |
RCC->CR &= 0xFFFBFFFFU; | |
/* Disable all interrupts */ | |
RCC->CIER = 0x00000000U; | |
/* 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 = 0U, msirange = 0U, pllvco = 0U, pllr = 2U, pllsource = 0U, pllm = 2U; | |
/* Get MSI Range frequency--------------------------------------------------*/ | |
if((RCC->CR & RCC_CR_MSIRGSEL) == RESET) | |
{ /* MSISRANGE from RCC_CSR applies */ | |
msirange = (RCC->CSR & RCC_CSR_MSISRANGE) >> 8U; | |
} | |
else | |
{ /* MSIRANGE from RCC_CR applies */ | |
msirange = (RCC->CR & RCC_CR_MSIRANGE) >> 4U; | |
} | |
/*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) >> 4U) + 1U ; | |
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) >> 8U); | |
pllr = (((RCC->PLLCFGR & RCC_PLLCFGR_PLLR) >> 25U) + 1U) * 2U; | |
SystemCoreClock = pllvco/pllr; | |
break; | |
default: | |
SystemCoreClock = msirange; | |
break; | |
} | |
/* Compute HCLK clock frequency --------------------------------------------*/ | |
/* Get HCLK prescaler */ | |
tmp = AHBPrescTable[((RCC->CFGR & RCC_CFGR_HPRE) >> 4U)]; | |
/* HCLK clock frequency */ | |
SystemCoreClock >>= tmp; | |
} | |
/** | |
* @} | |
*/ | |
/** | |
* @} | |
*/ | |
/** | |
* @} | |
*/ | |
/************************ (C) COPYRIGHT STMicroelectronics *****END OF FILE****/ |