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Diffstat (limited to 'Core/Src/system_stm32l4xx.c')
| -rw-r--r-- | Core/Src/system_stm32l4xx.c | 332 |
1 files changed, 332 insertions, 0 deletions
diff --git a/Core/Src/system_stm32l4xx.c b/Core/Src/system_stm32l4xx.c new file mode 100644 index 0000000..be9cfee --- /dev/null +++ b/Core/Src/system_stm32l4xx.c @@ -0,0 +1,332 @@ +/** + ****************************************************************************** + * @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 + * + * Copyright (c) 2017 STMicroelectronics. + * All rights reserved. + * + * This software is licensed under terms that can be found in the LICENSE file + * in the root directory of this software component. + * If no LICENSE file comes with this software, it is provided AS-IS. + * + ****************************************************************************** + */ + +/** @addtogroup CMSIS + * @{ + */ + +/** @addtogroup stm32l4xx_system + * @{ + */ + +/** @addtogroup STM32L4xx_System_Private_Includes + * @{ + */ + +#include "stm32l4xx.h" + +/** + * @} + */ + +/** @addtogroup STM32L4xx_System_Private_TypesDefinitions + * @{ + */ + +/** + * @} + */ + +/** @addtogroup STM32L4xx_System_Private_Defines + * @{ + */ + +#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 */ + +/* Note: Following vector table addresses must be defined in line with linker + configuration. */ +/*!< Uncomment the following line if you need to relocate the vector table + anywhere in Flash or Sram, else the vector table is kept at the automatic + remap of boot address selected */ +/* #define USER_VECT_TAB_ADDRESS */ + +#if defined(USER_VECT_TAB_ADDRESS) +/*!< Uncomment the following line if you need to relocate your vector Table + in Sram else user remap will be done in Flash. */ +/* #define VECT_TAB_SRAM */ + +#if defined(VECT_TAB_SRAM) +#define VECT_TAB_BASE_ADDRESS SRAM1_BASE /*!< Vector Table base address field. + This value must be a multiple of 0x200. */ +#define VECT_TAB_OFFSET 0x00000000U /*!< Vector Table base offset field. + This value must be a multiple of 0x200. */ +#else +#define VECT_TAB_BASE_ADDRESS FLASH_BASE /*!< Vector Table base address field. + This value must be a multiple of 0x200. */ +#define VECT_TAB_OFFSET 0x00000000U /*!< Vector Table base offset field. + This value must be a multiple of 0x200. */ +#endif /* VECT_TAB_SRAM */ +#endif /* USER_VECT_TAB_ADDRESS */ + +/******************************************************************************/ +/** + * @} + */ + +/** @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. + * @retval None + */ + +void SystemInit(void) +{ +#if defined(USER_VECT_TAB_ADDRESS) + /* Configure the Vector Table location -------------------------------------*/ + SCB->VTOR = VECT_TAB_BASE_ADDRESS | VECT_TAB_OFFSET; +#endif + + /* FPU settings ------------------------------------------------------------*/ +#if (__FPU_PRESENT == 1) && (__FPU_USED == 1) + SCB->CPACR |= ((3UL << 20U)|(3UL << 22U)); /* set CP10 and CP11 Full Access */ +#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. + * + * @retval None + */ +void SystemCoreClockUpdate(void) +{ + uint32_t tmp, msirange, pllvco, pllsource, pllm, pllr; + + /* Get MSI Range frequency--------------------------------------------------*/ + if ((RCC->CR & RCC_CR_MSIRGSEL) == 0U) + { /* 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****/ |