stm32 系统嘀嗒(SysTick) 定时器

作者：时间：2016-11-13 来源：网络

系统嘀嗒校准值固定为9000，当系统嘀嗒时钟设定为9MHz(HCLK/8的最大值)，产生1ms时间基准。

在3.5 的库中

void SysTick_CLKSourceConfig(uint32_t SysTick_CLKSource)

位于 misc.c 文件中

然后在core_cm3.h 文件中，定义了一个内联函数，完成定时配置，中断开启， 定时器开启的功能。

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

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

/* SysTick constants */

#define SYSTICK_ENABLE 0 /* Config-Bit to start or stop the SysTick Timer */

#define SYSTICK_TICKINT 1 /* Config-Bit to enable or disable the SysTick interrupt*/

#define SYSTICK_CLKSOURCE 2 /* Clocksource has the offset 2 in SysTick Control and Status Register */

#define SYSTICK_MAXCOUNT ((1<<24) -1) /* SysTick MaxCount */

/**

* @brief Initialize and start the SysTick counter and its interrupt.

* @param uint32_t ticks is the number of ticks between two interrupts

* @return none

* 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_MAXCOUNT) return (1); /* Reload value impossible */

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

NVIC_SetPriority (SysTick_IRQn, (1<<__NVIC_PRIO_BITS) - 1); /* set Priority for Cortex-M0 System Interrupts */

SysTick->VAL = (0x00); /* Load the SysTick Counter Value */

SysTick->CTRL = (1 << SYSTICK_CLKSOURCE) | (1<

return (0); /* Function successful */

}

#endif

老的库文件的是6个函数

1.void SysTick_CLKSourceConfig(uint32_t SysTick_CLKSource)

下面的这几个的功能都已经被SysTick_Config() 所替代

2.voidSysTick_SetReload(void)

3.voidSysTick_CounterCmd(void)

4.voidSysTick_ITConfig(void)

5.voidSysTick_GetCounter(void)

6.voidSysTick_GetFlagStatus(void)

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