cmsis_system.c File Reference

CMSIS Cortex-M3 Device Peripheral Access Layer System Source File. More...

#include "stm32f10x.h"

Go to the source code of this file.

Macros
#define	SYSCLK_FREQ_72MHz   72000000
#define	VECT_TAB_OFFSET   0x0

Functions
static void	SetSysClock (void)
	Configures the System clock frequency, HCLK, PCLK2 and PCLK1 prescalers. More...
static void	SetSysClockTo72 (void)
	Setup the external memory controller. Called in startup_stm32f10x.s before jump to __main. More...
void	SystemInit (void)
	Setup the microcontroller system Initialize the Embedded Flash Interface, the PLL and update the SystemCoreClock variable. More...
void	SystemCoreClockUpdate (void)
	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. More...

Variables
uint32_t	SystemCoreClock = SYSCLK_FREQ_72MHz
__I uint8_t	AHBPrescTable [16] = {0, 0, 0, 0, 0, 0, 0, 0, 1, 2, 3, 4, 6, 7, 8, 9}
uint32_t	hse_value = 8000000

Detailed Description

CMSIS Cortex-M3 Device Peripheral Access Layer System Source File.

Author

MCD Application Team

Version

V3.5.0

Date

11-March-2011

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 factors, AHB/APBx prescalers and Flash settings). This function is called at startup just after reset and before branch to main program. This call is made inside the "startup_stm32f10x_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 HSI (8 MHz) is used as system clock source. Then SystemInit() function is called, in "startup_stm32f10x_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 HSI 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 8 MHz (or 25 MHz, depedning on the product used), refer to "HSE_VALUE" define in "stm32f10x.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.

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.

© COPYRIGHT 2011 STMicroelectronics

Definition in file cmsis_system.c.