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stlink/example/32l_dac/system_stm32l1xx.c

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/**
******************************************************************************
* @file system_stm32l1xx.c
* @author MCD Application Team
* @version V1.0.0
* @date 2-June-2011
* @brief CMSIS Cortex-M3 Device Peripheral Access Layer System Source File.
* This file contains the system clock configuration for STM32L1xx Ultra
* Low Medium-density devices, and is generated by the clock configuration
* tool "STM32L1xx_Clock_Configuration_V1.0.0.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_md.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_md.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 | 16000000 Hz
*-----------------------------------------------------------------------------
* AHB Prescaler | 1
*-----------------------------------------------------------------------------
* APB1 Prescaler | 1
*-----------------------------------------------------------------------------
* APB2 Prescaler | 1
*-----------------------------------------------------------------------------
* HSE Frequency | 8000000 Hz
*-----------------------------------------------------------------------------
* PLL DIV | Not Used
*-----------------------------------------------------------------------------
* PLL MUL | Not Used
*-----------------------------------------------------------------------------
* VDD | 3.3 V
*-----------------------------------------------------------------------------
* Vcore | 1.8 V (Range 1)
*-----------------------------------------------------------------------------
* Flash Latency | 0 WS
*-----------------------------------------------------------------------------
* Require 48MHz for USB clock | Disabled
*-----------------------------------------------------------------------------
*=============================================================================
******************************************************************************
* @attention
*
* THE PRESENT FIRMWARE WHICH IS FOR GUIDANCE ONLY AIMS AT PROVIDING CUSTOMERS
* WITH CODING INFORMATION REGARDING THEIR PRODUCTS IN ORDER FOR THEM TO SAVE
* TIME. AS A RESULT, STMICROELECTRONICS SHALL NOT BE HELD LIABLE FOR ANY
* DIRECT, INDIRECT OR CONSEQUENTIAL DAMAGES WITH RESPECT TO ANY CLAIMS ARISING
* FROM THE CONTENT OF SUCH FIRMWARE AND/OR THE USE MADE BY CUSTOMERS OF THE
* CODING INFORMATION CONTAINED HEREIN IN CONNECTION WITH THEIR PRODUCTS.
*
* <h2><center>&copy; COPYRIGHT 2010 STMicroelectronics</center></h2>
******************************************************************************
*/
/** @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
* @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 1 (1.8 V) */
PWR->CR = PWR_CR_VOS_0;
/* Wait Until the Voltage Regulator is ready */
while((PWR->CSR & PWR_CSR_VOSF) != RESET)
{
}
/* HCLK = SYSCLK /1*/
RCC->CFGR |= (uint32_t)RCC_CFGR_HPRE_DIV1;
/* 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 2010 STMicroelectronics *****END OF FILE****/
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