1.systick时钟来源

2.SysTick库函数

3.源码

/**

*@}

*/

/** @defgroup SysTick_clock_source

*@{

*/

#define SysTick_CLKSource_HCLK_Div8    ((uint32_t)0xFFFFFFFB)

#define SysTick_CLKSource_HCLK         ((uint32_t)0x00000004)

#define IS_SYSTICK_CLK_SOURCE(SOURCE) (((SOURCE) == SysTick_CLKSource_HCLK) || \

((SOURCE) == SysTick_CLKSource_HCLK_Div8))

/**

*@brief  Configures the SysTick clocksource.

*@param  SysTick_CLKSource: specifies theSysTick clock source.

*   This parameter can be one ofthe following values:

*     @argSysTick_CLKSource_HCLK_Div8: AHB clock divided by 8 selected as SysTick clocksource.

*     @arg SysTick_CLKSource_HCLK:AHB clock selected as SysTick clock source.

*@retval None

*/

void SysTick_CLKSourceConfig(uint32_t SysTick_CLKSource)

{

/* Check the parameters */

assert_param(IS_SYSTICK_CLK_SOURCE(SysTick_CLKSource));

if (SysTick_CLKSource == SysTick_CLKSource_HCLK)

{

SysTick->CTRL |= SysTick_CLKSource_HCLK;

}

else

{

SysTick->CTRL &= SysTick_CLKSource_HCLK_Div8;

}

}

/*##################################   SysTick function ############################################ */

#if (!defined (__Vendor_SysTickConfig)) || (__Vendor_SysTickConfig == 0)

/**

*@brief  Initialize and start the SysTickcounter and its interrupt.

*

*@param   ticks   number of ticks between two interrupts

*@return  1 = failed, 0 = successful

*

*Initialise the system tick timer and its interrupt and start the

*system tick timer / counter in free running mode to generate

*periodical interrupts.

*/

static __INLINE uint32_t SysTick_Config(uint32_t ticks)

{

if (ticks > SysTick_LOAD_RELOAD_Msk)  return (1);            /* Reload value impossible */

SysTick->LOAD  = (ticks & SysTick_LOAD_RELOAD_Msk) - 1;      /* set reload register */

NVIC_SetPriority (SysTick_IRQn, (1VAL   = 0;                                          /* Load the SysTick Counter Value */

SysTick->CTRL  = SysTick_CTRL_CLKSOURCE_Msk |

SysTick_CTRL_TICKINT_Msk   |

SysTick_CTRL_ENABLE_Msk;                   /* Enable SysTick IRQ and SysTick Timer*/

return (0);                                                 /* Function successful */

}

#endif

#ifdefSYSCLK_FREQ_HSE

uint32_t SystemCoreClock         = SYSCLK_FREQ_HSE;        /*!#elif defined SYSCLK_FREQ_24MHz

uint32_t SystemCoreClock         = SYSCLK_FREQ_24MHz;        /*!< System Clock Frequency (Core Clock) */

#elif defined SYSCLK_FREQ_36MHz

uint32_t SystemCoreClock         = SYSCLK_FREQ_36MHz;        /*!#elif defined SYSCLK_FREQ_48MHz

uint32_t SystemCoreClock         = SYSCLK_FREQ_48MHz;        /*!#elif defined SYSCLK_FREQ_56MHz

uint32_t SystemCoreClock         = SYSCLK_FREQ_56MHz;        /*!#elif defined SYSCLK_FREQ_72MHz

uint32_t SystemCoreClock         = SYSCLK_FREQ_72MHz;        /*!#else /*!< HSI Selected as System Clock source */

uint32_t SystemCoreClock         = HSI_VALUE;        /*!< System Clock Frequency (Core Clock) */

#endif

///

/* Configure the SysTick */

SysTick_Config(SystemCoreClock / RT_TICK_PER_SECOND);//8000000/1000=>1ms

/**

*This is the timer interrupt service routine.

*

*/

void SysTick_Handler(void)

{

/* enter interrupt */

rt_interrupt_enter();

rt_tick_increase();

/* leave interrupt */

rt_interrupt_leave();

}

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