| /** |
| ****************************************************************************** |
| * @file system_stm32g4xx.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_stm32g4xx.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 HSI (16 MHz) is used as system clock source. |
| * Then SystemInit() function is called, in "startup_stm32g4xx.s" file, to |
| * configure the system clock before to branch to main program. |
| * |
| * This file configures the system clock as follows: |
| *============================================================================= |
| *----------------------------------------------------------------------------- |
| * System Clock source | HSI |
| *----------------------------------------------------------------------------- |
| * SYSCLK(Hz) | 16000000 |
| *----------------------------------------------------------------------------- |
| * HCLK(Hz) | 16000000 |
| *----------------------------------------------------------------------------- |
| * AHB Prescaler | 1 |
| *----------------------------------------------------------------------------- |
| * APB1 Prescaler | 1 |
| *----------------------------------------------------------------------------- |
| * APB2 Prescaler | 1 |
| *----------------------------------------------------------------------------- |
| * PLL_M | 1 |
| *----------------------------------------------------------------------------- |
| * PLL_N | 16 |
| *----------------------------------------------------------------------------- |
| * PLL_P | 7 |
| *----------------------------------------------------------------------------- |
| * PLL_Q | 2 |
| *----------------------------------------------------------------------------- |
| * PLL_R | 2 |
| *----------------------------------------------------------------------------- |
| * Require 48MHz for RNG | Disabled |
| *----------------------------------------------------------------------------- |
| *============================================================================= |
| ****************************************************************************** |
| * @attention |
| * |
| * <h2><center>© Copyright (c) 2019 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 stm32g4xx_system |
| * @{ |
| */ |
| |
| /** @addtogroup STM32G4xx_System_Private_Includes |
| * @{ |
| */ |
| |
| #include "stm32g4xx.h" |
| |
| #if !defined (HSE_VALUE) |
| #define HSE_VALUE 24000000U /*!< Value of the External oscillator in Hz */ |
| #endif /* HSE_VALUE */ |
| |
| #if !defined (HSI_VALUE) |
| #define HSI_VALUE 16000000U /*!< Value of the Internal oscillator in Hz*/ |
| #endif /* HSI_VALUE */ |
| |
| /** |
| * @} |
| */ |
| |
| /** @addtogroup STM32G4xx_System_Private_TypesDefinitions |
| * @{ |
| */ |
| |
| /** |
| * @} |
| */ |
| |
| /** @addtogroup STM32G4xx_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 0x00UL /*!< Vector Table base offset field. |
| This value must be a multiple of 0x200. */ |
| /******************************************************************************/ |
| /** |
| * @} |
| */ |
| |
| /** @addtogroup STM32G4xx_System_Private_Macros |
| * @{ |
| */ |
| |
| /** |
| * @} |
| */ |
| |
| /** @addtogroup STM32G4xx_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 = HSI_VALUE; |
| |
| 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}; |
| |
| /** |
| * @} |
| */ |
| |
| /** @addtogroup STM32G4xx_System_Private_FunctionPrototypes |
| * @{ |
| */ |
| |
| /** |
| * @} |
| */ |
| |
| /** @addtogroup STM32G4xx_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 |
| |
| /* 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 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 stm32g4xx_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 stm32g4xx_hal.h file (default value |
| * 24 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, pllvco, pllr, pllsource, pllm; |
| |
| /* Get SYSCLK source -------------------------------------------------------*/ |
| switch (RCC->CFGR & RCC_CFGR_SWS) |
| { |
| 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 / PLLM) * PLLN |
| SYSCLK = PLL_VCO / PLLR |
| */ |
| pllsource = (RCC->PLLCFGR & RCC_PLLCFGR_PLLSRC); |
| pllm = ((RCC->PLLCFGR & RCC_PLLCFGR_PLLM) >> 4) + 1U ; |
| if (pllsource == 0x02UL) /* HSI used as PLL clock source */ |
| { |
| pllvco = (HSI_VALUE / pllm); |
| } |
| else /* HSE used as PLL clock source */ |
| { |
| pllvco = (HSE_VALUE / pllm); |
| } |
| pllvco = pllvco * ((RCC->PLLCFGR & RCC_PLLCFGR_PLLN) >> 8); |
| pllr = (((RCC->PLLCFGR & RCC_PLLCFGR_PLLR) >> 25) + 1U) * 2U; |
| SystemCoreClock = pllvco/pllr; |
| break; |
| |
| default: |
| 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****/ |
| |
