/** ****************************************************************************** * @file system_stm32u5xx.c * @author MCD Application Team * @brief CMSIS Cortex-M33 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_stm32u5xx.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_stm32u5xx.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 *----------------------------------------------------------------------------- * APB3 Prescaler | 1 *----------------------------------------------------------------------------- * PLL1_SRC | No clock *----------------------------------------------------------------------------- * PLL1_M | 1 *----------------------------------------------------------------------------- * PLL1_N | 8 *----------------------------------------------------------------------------- * PLL1_P | 7 *----------------------------------------------------------------------------- * PLL1_Q | 2 *----------------------------------------------------------------------------- * PLL1_R | 2 *----------------------------------------------------------------------------- * PLL2_SRC | NA *----------------------------------------------------------------------------- * PLL2_M | NA *----------------------------------------------------------------------------- * PLL2_N | NA *----------------------------------------------------------------------------- * PLL2_P | NA *----------------------------------------------------------------------------- * PLL2_Q | NA *----------------------------------------------------------------------------- * PLL2_R | NA *----------------------------------------------------------------------------- * PLL3_SRC | NA *----------------------------------------------------------------------------- * PLL3_M | NA *----------------------------------------------------------------------------- * PLL3_N | NA *----------------------------------------------------------------------------- * PLL3_P | NA *----------------------------------------------------------------------------- * Require 48MHz for USB FS, | Disabled * SDIO and RNG clock | *----------------------------------------------------------------------------- *============================================================================= ****************************************************************************** * @attention * * Copyright (c) 2021 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 STM32U5xx_system * @{ */ /** @addtogroup STM32U5xx_System_Private_Includes * @{ */ #include "stm32u5xx.h" #include /** * @} */ /** @addtogroup STM32U5xx_System_Private_TypesDefinitions * @{ */ /** * @} */ /** @addtogroup STM32U5xx_System_Private_Defines * @{ */ #if !defined (HSE_VALUE) #define HSE_VALUE 16000000U /*!< 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 */ /************************* 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 0x00000000UL /*!< Vector Table base offset field. This value must be a multiple of 0x200. */ /******************************************************************************/ /** * @} */ /** @addtogroup STM32U5xx_System_Private_Macros * @{ */ /** * @} */ /** @addtogroup STM32U5xx_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[16] = {48000000U,24000000U,16000000U,12000000U, 4000000U, 2000000U, 1500000U,\ 1000000U, 3072000U, 1536000U,1024000U, 768000U, 400000U, 200000U, 150000U, 100000U}; /** * @} */ /** @addtogroup STM32U5xx_System_Private_FunctionPrototypes * @{ */ /** * @} */ /** @addtogroup STM32U5xx_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 << 20U)|(3UL << 22U)); /* set CP10 and CP11 Full Access */ #endif /* Reset the RCC clock configuration to the default reset state ------------*/ /* Set MSION bit */ RCC->CR = RCC_CR_MSISON; /* Reset CFGR register */ RCC->CFGR1 = 0U; RCC->CFGR2 = 0U; RCC->CFGR3 = 0U; /* Reset HSEON, CSSON , HSION, PLLxON bits */ RCC->CR &= ~(RCC_CR_HSEON | RCC_CR_CSSON | RCC_CR_PLL1ON | RCC_CR_PLL2ON | RCC_CR_PLL3ON); /* Reset PLLCFGR register */ RCC->PLL1CFGR = 0U; /* Reset HSEBYP bit */ RCC->CR &= ~(RCC_CR_HSEBYP); /* Disable all interrupts */ RCC->CIER = 0U; /* Configure the Vector Table location add offset address ------------------*/ #ifdef VECT_TAB_SRAM SCB->VTOR = SRAM1_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 stm32u5xx_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 stm32u5xx_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 stm32u5xx_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 pllr, pllsource, pllm , tmp, pllfracen, msirange; float_t fracn1, pllvco; /* Get MSI Range frequency--------------------------------------------------*/ if(READ_BIT(RCC->ICSCR1, RCC_ICSCR1_MSIRGSEL) == 0U) { /* MSISRANGE from RCC_CSR applies */ msirange = (RCC->CSR & RCC_CSR_MSISSRANGE) >> RCC_CSR_MSISSRANGE_Pos; } else { /* MSIRANGE from RCC_CR applies */ msirange = (RCC->ICSCR1 & RCC_ICSCR1_MSISRANGE) >> RCC_ICSCR1_MSISRANGE_Pos; } /*MSI frequency range in HZ*/ msirange = MSIRangeTable[msirange]; /* Get SYSCLK source -------------------------------------------------------*/ switch (RCC->CFGR1 & RCC_CFGR1_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->PLL1CFGR & RCC_PLL1CFGR_PLL1SRC); pllm = ((RCC->PLL1CFGR & RCC_PLL1CFGR_PLL1M)>> RCC_PLL1CFGR_PLL1M_Pos) + 1U; pllfracen = ((RCC->PLL1CFGR & RCC_PLL1CFGR_PLL1FRACEN)>>RCC_PLL1CFGR_PLL1FRACEN_Pos); fracn1 = (float_t)(uint32_t)(pllfracen* ((RCC->PLL1FRACR & RCC_PLL1FRACR_PLL1FRACN)>> RCC_PLL1FRACR_PLL1FRACN_Pos)); switch (pllsource) { case 0x00: /* No clock sent to PLL*/ pllvco = (float_t)0U; break; case 0x02: /* HSI used as PLL clock source */ pllvco = ((float_t)HSI_VALUE / (float_t)pllm); break; case 0x03: /* HSE used as PLL clock source */ pllvco = ((float_t)HSE_VALUE / (float_t)pllm); break; default: /* MSI used as PLL clock source */ pllvco = ((float_t)msirange / (float_t)pllm); break; } pllvco = pllvco * ((float_t)(uint32_t)(RCC->PLL1DIVR & RCC_PLL1DIVR_PLL1N) + (fracn1/(float_t)0x2000) + (float_t)1U); pllr = (((RCC->PLL1DIVR & RCC_PLL1DIVR_PLL1R) >> RCC_PLL1DIVR_PLL1R_Pos) + 1U ); SystemCoreClock = (uint32_t)((uint32_t)pllvco/pllr); break; default: SystemCoreClock = msirange; break; } /* Compute HCLK clock frequency --------------------------------------------*/ /* Get HCLK prescaler */ tmp = AHBPrescTable[((RCC->CFGR2 & RCC_CFGR2_HPRE) >> RCC_CFGR2_HPRE_Pos)]; /* HCLK clock frequency */ SystemCoreClock >>= tmp; } /** * @} */ /** * @} */ /** * @} */