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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