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Diffstat (limited to 'src/system_stm32f3xx.c')
| -rw-r--r-- | src/system_stm32f3xx.c | 298 |
1 files changed, 298 insertions, 0 deletions
diff --git a/src/system_stm32f3xx.c b/src/system_stm32f3xx.c new file mode 100644 index 0000000..9e75a9e --- /dev/null +++ b/src/system_stm32f3xx.c @@ -0,0 +1,298 @@ +/** + ****************************************************************************** + * @file system_stm32f3xx.c + * @author MCD Application Team + * @brief CMSIS Cortex-M4 Device Peripheral Access Layer System Source File. + * + * 1. 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_stm32f3xx.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. + * + * 2. After each device reset the HSI (8 MHz) is used as system clock source. + * Then SystemInit() function is called, in "startup_stm32f3xx.s" file, to + * configure the system clock before to branch to main program. + * + * 3. This file configures the system clock as follows: + *============================================================================= + * Supported STM32F3xx device + *----------------------------------------------------------------------------- + * System Clock source | HSI + *----------------------------------------------------------------------------- + * SYSCLK(Hz) | 8000000 + *----------------------------------------------------------------------------- + * HCLK(Hz) | 8000000 + *----------------------------------------------------------------------------- + * AHB Prescaler | 1 + *----------------------------------------------------------------------------- + * APB2 Prescaler | 1 + *----------------------------------------------------------------------------- + * APB1 Prescaler | 1 + *----------------------------------------------------------------------------- + * USB Clock | DISABLE + *----------------------------------------------------------------------------- + *============================================================================= + ****************************************************************************** + * @attention + * + * <h2><center>© Copyright (c) 2016 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 stm32f3xx_system + * @{ + */ + +/** @addtogroup STM32F3xx_System_Private_Includes + * @{ + */ + +#include "stm32f3xx.h" + +/** + * @} + */ + +/** @addtogroup STM32F3xx_System_Private_TypesDefinitions + * @{ + */ + +/** + * @} + */ + +/** @addtogroup STM32F3xx_System_Private_Defines + * @{ + */ +#if !defined (HSE_VALUE) + #define HSE_VALUE ((uint32_t)8000000) /*!< Default value of the External oscillator in Hz. + This value can be provided and adapted by the user application. */ +#endif /* HSE_VALUE */ + +#if !defined (HSI_VALUE) + #define HSI_VALUE ((uint32_t)8000000) /*!< Default value of the Internal oscillator in Hz. + This value can be provided and adapted by the user application. */ +#endif /* HSI_VALUE */ + +/*!< Uncomment the following line if you need to relocate your vector Table in + Internal SRAM. */ +/* #define VECT_TAB_SRAM */ +#define VECT_TAB_OFFSET 0x0 /*!< Vector Table base offset field. + This value must be a multiple of 0x200. */ +/** + * @} + */ + +/** @addtogroup STM32F3xx_System_Private_Macros + * @{ + */ + +/** + * @} + */ + +/** @addtogroup STM32F3xx_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 there is no need to + call the 2 first functions listed above, since SystemCoreClock variable is + updated automatically. + */ +uint32_t SystemCoreClock = 8000000; + +const uint8_t AHBPrescTable[16] = {0, 0, 0, 0, 0, 0, 0, 0, 1, 2, 3, 4, 6, 7, 8, 9}; +const uint8_t APBPrescTable[8] = {0, 0, 0, 0, 1, 2, 3, 4}; + +/** + * @} + */ + +/** @addtogroup STM32F3xx_System_Private_FunctionPrototypes + * @{ + */ + +/** + * @} + */ + +/** @addtogroup STM32F3xx_System_Private_Functions + * @{ + */ + +/** + * @brief Setup the microcontroller system + * Initialize the FPU setting, vector table location and the PLL configuration is reset. + * @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 HSION bit */ + RCC->CR |= (uint32_t)0x00000001; + + /* Reset CFGR register */ + RCC->CFGR &= 0xF87FC00C; + + /* Reset HSEON, CSSON and PLLON bits */ + RCC->CR &= (uint32_t)0xFEF6FFFF; + + /* Reset HSEBYP bit */ + RCC->CR &= (uint32_t)0xFFFBFFFF; + + /* Reset PLLSRC, PLLXTPRE, PLLMUL and USBPRE bits */ + RCC->CFGR &= (uint32_t)0xFF80FFFF; + + /* Reset PREDIV1[3:0] bits */ + RCC->CFGR2 &= (uint32_t)0xFFFFFFF0; + + /* Reset USARTSW[1:0], I2CSW and TIMs bits */ + RCC->CFGR3 &= (uint32_t)0xFF00FCCC; + + /* Disable all interrupts */ + RCC->CIR = 0x00000000; + +#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 stm32f3xx_hal.h file (default value + * 8 MHz) but the real value may vary depending on the variations + * in voltage and temperature. + * + * (**) HSE_VALUE is a constant defined in stm32f3xx_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, pllmull = 0, pllsource = 0, predivfactor = 0; + + /* Get SYSCLK source -------------------------------------------------------*/ + tmp = RCC->CFGR & RCC_CFGR_SWS; + + switch (tmp) + { + case RCC_CFGR_SWS_HSI: /* HSI used as system clock */ + SystemCoreClock = HSI_VALUE; + break; + case RCC_CFGR_SWS_HSE: /* HSE used as system clock */ + SystemCoreClock = HSE_VALUE; + break; + case RCC_CFGR_SWS_PLL: /* PLL used as system clock */ + /* Get PLL clock source and multiplication factor ----------------------*/ + pllmull = RCC->CFGR & RCC_CFGR_PLLMUL; + pllsource = RCC->CFGR & RCC_CFGR_PLLSRC; + pllmull = ( pllmull >> 18) + 2; + +#if defined (STM32F302xE) || defined (STM32F303xE) || defined (STM32F398xx) + predivfactor = (RCC->CFGR2 & RCC_CFGR2_PREDIV) + 1; + if (pllsource == RCC_CFGR_PLLSRC_HSE_PREDIV) + { + /* HSE oscillator clock selected as PREDIV1 clock entry */ + SystemCoreClock = (HSE_VALUE / predivfactor) * pllmull; + } + else + { + /* HSI oscillator clock selected as PREDIV1 clock entry */ + SystemCoreClock = (HSI_VALUE / predivfactor) * pllmull; + } +#else + if (pllsource == RCC_CFGR_PLLSRC_HSI_DIV2) + { + /* HSI oscillator clock divided by 2 selected as PLL clock entry */ + SystemCoreClock = (HSI_VALUE >> 1) * pllmull; + } + else + { + predivfactor = (RCC->CFGR2 & RCC_CFGR2_PREDIV) + 1; + /* HSE oscillator clock selected as PREDIV1 clock entry */ + SystemCoreClock = (HSE_VALUE / predivfactor) * pllmull; + } +#endif /* STM32F302xE || STM32F303xE || STM32F398xx */ + break; + default: /* HSI used as system clock */ + SystemCoreClock = HSI_VALUE; + 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****/ + |