diff --git a/system_stm32l1xx.c b/system_stm32l1xx.c new file mode 100644 --- /dev/null +++ b/system_stm32l1xx.c @@ -0,0 +1,382 @@ +/** + ****************************************************************************** + * @file system_stm32l1xx.c + * @author MCD Application Team + * @version V1.2.0 + * @date 11-July-2014 + * @brief CMSIS Cortex-M3 Device Peripheral Access Layer System Source File. + * This file contains the system clock configuration for STM32L1xx Ultra + * Low power devices, and is generated by the clock configuration + * tool STM32L1xx_Clock_Configuration_V1.2.0.xls + * + * 1. This file provides two functions and one global variable to be called from + * user application: + * - SystemInit(): Setups the system clock (System clock source, PLL Multiplier + * and Divider factors, AHB/APBx prescalers and Flash settings), + * depending on the configuration made in the clock xls tool. + * This function is called at startup just after reset and + * before branch to main program. This call is made inside + * the "startup_stm32l1xx_xx.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 MSI (2.1 MHz Range) is used as system clock source. + * Then SystemInit() function is called, in "startup_stm32l1xx_xx.s" file, to + * configure the system clock before to branch to main program. + * + * 3. If the system clock source selected by user fails to startup, the SystemInit() + * function will do nothing and MSI still used as system clock source. User can + * add some code to deal with this issue inside the SetSysClock() function. + * + * 4. The default value of HSE crystal is set to 8MHz, refer to "HSE_VALUE" define + * in "stm32l1xx.h" file. When HSE is used as system clock source, directly or + * through PLL, and you are using different crystal you have to adapt the HSE + * value to your own configuration. + * + * 5. This file configures the system clock as follows: + *============================================================================= + * System Clock Configuration + *============================================================================= + * System clock source | HSI + *----------------------------------------------------------------------------- + * SYSCLK | 16000000 Hz + *----------------------------------------------------------------------------- + * HCLK | 8000000 Hz + *----------------------------------------------------------------------------- + * AHB Prescaler | 2 + *----------------------------------------------------------------------------- + * APB1 Prescaler | 1 + *----------------------------------------------------------------------------- + * APB2 Prescaler | 1 + *----------------------------------------------------------------------------- + * HSE Frequency | 8000000 Hz + *----------------------------------------------------------------------------- + * PLL DIV | Not Used + *----------------------------------------------------------------------------- + * PLL MUL | Not Used + *----------------------------------------------------------------------------- + * VDD | 3.3 V + *----------------------------------------------------------------------------- + * Vcore | 1.5 V (Range 2) + *----------------------------------------------------------------------------- + * Flash Latency | 0 WS + *----------------------------------------------------------------------------- + * Require 48MHz for USB clock | Disabled + *----------------------------------------------------------------------------- + *============================================================================= + * @attention + * + *

© COPYRIGHT 2013 STMicroelectronics

+ * + * Licensed under MCD-ST Liberty SW License Agreement V2, (the "License"); + * You may not use this file except in compliance with the License. + * You may obtain a copy of the License at: + * + * http://www.st.com/software_license_agreement_liberty_v2 + * + * Unless required by applicable law or agreed to in writing, software + * distributed under the License is distributed on an "AS IS" BASIS, + * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. + * See the License for the specific language governing permissions and + * limitations under the License. + * + ****************************************************************************** + */ + +/** @addtogroup CMSIS + * @{ + */ + +/** @addtogroup stm32l1xx_system + * @{ + */ + +/** @addtogroup STM32L1xx_System_Private_Includes + * @{ + */ + +#include "stm32l1xx.h" + +/** + * @} + */ + +/** @addtogroup STM32L1xx_System_Private_TypesDefinitions + * @{ + */ + +/** + * @} + */ + +/** @addtogroup STM32L1xx_System_Private_Defines + * @{ + */ + +/*!< 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 STM32L1xx_System_Private_Macros + * @{ + */ + +/** + * @} + */ + +/** @addtogroup STM32L1xx_System_Private_Variables + * @{ + */ +uint32_t SystemCoreClock = 16000000; +__I uint8_t PLLMulTable[9] = {3, 4, 6, 8, 12, 16, 24, 32, 48}; +__I uint8_t AHBPrescTable[16] = {0, 0, 0, 0, 0, 0, 0, 0, 1, 2, 3, 4, 6, 7, 8, 9}; + +/** + * @} + */ + +/** @addtogroup STM32L1xx_System_Private_FunctionPrototypes + * @{ + */ + +static void SetSysClock(void); + +/** + * @} + */ + +/** @addtogroup STM32L1xx_System_Private_Functions + * @{ + */ + +/** + * @brief Setup the microcontroller system. + * Initialize the Embedded Flash Interface, the PLL and update the + * SystemCoreClock variable. + * @param None + * @retval None + */ +void SystemInit (void) +{ + /*!< Set MSION bit */ + RCC->CR |= (uint32_t)0x00000100; + + /*!< Reset SW[1:0], HPRE[3:0], PPRE1[2:0], PPRE2[2:0], MCOSEL[2:0] and MCOPRE[2:0] bits */ + RCC->CFGR &= (uint32_t)0x88FFC00C; + + /*!< Reset HSION, HSEON, CSSON and PLLON bits */ + RCC->CR &= (uint32_t)0xEEFEFFFE; + + /*!< Reset HSEBYP bit */ + RCC->CR &= (uint32_t)0xFFFBFFFF; + + /*!< Reset PLLSRC, PLLMUL[3:0] and PLLDIV[1:0] bits */ + RCC->CFGR &= (uint32_t)0xFF02FFFF; + + /*!< Disable all interrupts */ + RCC->CIR = 0x00000000; + + /* Configure the System clock frequency, AHB/APBx prescalers and Flash settings */ + SetSysClock(); + +#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 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 as defined by the MSI range. + * + * - 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 stm32l1xx.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 stm32l1xx.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, pllmul = 0, plldiv = 0, pllsource = 0, msirange = 0; + + /* Get SYSCLK source -------------------------------------------------------*/ + tmp = RCC->CFGR & RCC_CFGR_SWS; + + switch (tmp) + { + case 0x00: /* MSI used as system clock */ + msirange = (RCC->ICSCR & RCC_ICSCR_MSIRANGE) >> 13; + SystemCoreClock = (32768 * (1 << (msirange + 1))); + break; + case 0x04: /* HSI used as system clock */ + SystemCoreClock = HSI_VALUE; + break; + case 0x08: /* HSE used as system clock */ + SystemCoreClock = HSE_VALUE; + break; + case 0x0C: /* PLL used as system clock */ + /* Get PLL clock source and multiplication factor ----------------------*/ + pllmul = RCC->CFGR & RCC_CFGR_PLLMUL; + plldiv = RCC->CFGR & RCC_CFGR_PLLDIV; + pllmul = PLLMulTable[(pllmul >> 18)]; + plldiv = (plldiv >> 22) + 1; + + pllsource = RCC->CFGR & RCC_CFGR_PLLSRC; + + if (pllsource == 0x00) + { + /* HSI oscillator clock selected as PLL clock entry */ + SystemCoreClock = (((HSI_VALUE) * pllmul) / plldiv); + } + else + { + /* HSE selected as PLL clock entry */ + SystemCoreClock = (((HSE_VALUE) * pllmul) / plldiv); + } + break; + default: /* MSI used as system clock */ + msirange = (RCC->ICSCR & RCC_ICSCR_MSIRANGE) >> 13; + SystemCoreClock = (32768 * (1 << (msirange + 1))); + break; + } + /* Compute HCLK clock frequency --------------------------------------------*/ + /* Get HCLK prescaler */ + tmp = AHBPrescTable[((RCC->CFGR & RCC_CFGR_HPRE) >> 4)]; + /* HCLK clock frequency */ + SystemCoreClock >>= tmp; +} + +/** + * @brief Configures the System clock frequency, AHB/APBx prescalers and Flash + * settings. + * @note This function should be called only once the RCC clock configuration + * is reset to the default reset state (done in SystemInit() function). + * @param None + * @retval None + */ +static void SetSysClock(void) +{ + __IO uint32_t StartUpCounter = 0, HSIStatus = 0; + + /* SYSCLK, HCLK, PCLK2 and PCLK1 configuration ---------------------------*/ + /* Enable HSI */ + RCC->CR |= ((uint32_t)RCC_CR_HSION); + + /* Wait till HSI is ready and if Time out is reached exit */ + do + { + HSIStatus = RCC->CR & RCC_CR_HSIRDY; + } while((HSIStatus == 0) && (StartUpCounter != HSI_STARTUP_TIMEOUT)); + + if ((RCC->CR & RCC_CR_HSIRDY) != RESET) + { + HSIStatus = (uint32_t)0x01; + } + else + { + HSIStatus = (uint32_t)0x00; + } + + if (HSIStatus == (uint32_t)0x01) + { + /* Flash 0 wait state */ + FLASH->ACR &= ~FLASH_ACR_LATENCY; + + /* Disable Prefetch Buffer */ + FLASH->ACR &= ~FLASH_ACR_PRFTEN; + + /* Disable 64-bit access */ + FLASH->ACR &= ~FLASH_ACR_ACC64; + + + /* Power enable */ + RCC->APB1ENR |= RCC_APB1ENR_PWREN; + + /* Select the Voltage Range 2 (1.5 V) */ + PWR->CR = PWR_CR_VOS_1; + + + /* Wait Until the Voltage Regulator is ready */ + while((PWR->CSR & PWR_CSR_VOSF) != RESET) + { + } + + /* HCLK = SYSCLK /2*/ + RCC->CFGR |= (uint32_t)RCC_CFGR_HPRE_DIV2; + /* PCLK2 = HCLK /1*/ + RCC->CFGR |= (uint32_t)RCC_CFGR_PPRE2_DIV1; + + /* PCLK1 = HCLK /1*/ + RCC->CFGR |= (uint32_t)RCC_CFGR_PPRE1_DIV1; + + /* Select HSI as system clock source */ + RCC->CFGR &= (uint32_t)((uint32_t)~(RCC_CFGR_SW)); + RCC->CFGR |= (uint32_t)RCC_CFGR_SW_HSI; + + /* Wait till HSI is used as system clock source */ + while ((RCC->CFGR & (uint32_t)RCC_CFGR_SWS) != (uint32_t)RCC_CFGR_SWS_HSI) + { + } + } + else + { + /* If HSI fails to start-up, the application will have wrong clock + configuration. User can add here some code to deal with this error */ + } +} + +/** + * @} + */ + +/** + * @} + */ + +/** + * @} + */ + +/******************* (C) COPYRIGHT 2013 STMicroelectronics *****END OF FILE****/ +