SYS_SysTickDelay函数的延时单位是us吗？

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yiyigirl2014| 资深工程师

楼主 | 2024-10-13 21:26 | 只看该作者回帖奖励

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TI, ck, ic, kd, systick, 函数

看到示例里面的SYS_Init()中有几行

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    /* Update System Core Clock */

    /* User can use SystemCoreClockUpdate() to calculate PllClock, SystemCoreClock and CycylesPerUs automatically. */

    //SystemCoreClockUpdate();

    PllClock        = PLL_CLOCK;            // PLL

    SystemCoreClock = PLL_CLOCK / 1;        // HCLK

    CyclesPerUs     = PLL_CLOCK / 1000000;  // For SYS_SysTickDelay()

那么这个是为了延时1us吗?
在clk.h

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/**

  * [url=home.php?mod=space&uid=247401]@brief[/url]      This function execute delay function.

  * @param[in]  us  Delay time. The Max value is 2^24 / CPU Clock(MHz). Ex:

  *                             50MHz => 335544us, 48MHz => 349525us, 28MHz => 699050us ...

  * [url=home.php?mod=space&uid=266161]@return[/url]     None

  * [url=home.php?mod=space&uid=1543424]@Details[/url]    Use the SysTick to generate the delay time and the UNIT is in us.

  *             The SysTick clock source is from HCLK, i.e the same as system core clock.

  *             User can use SystemCoreClockUpdate() to calculate CyclesPerUs automatically before using this function.

  */

__STATIC_INLINE void CLK_SysTickDelay(uint32_t us)

{

    SysTick->LOAD = us * CyclesPerUs;

    SysTick->VAL  = (0x00);

    SysTick->CTRL = SysTick_CTRL_CLKSOURCE_Msk | SysTick_CTRL_ENABLE_Msk;



    /* Waiting for down-count to zero */

    while((SysTick->CTRL & SysTick_CTRL_COUNTFLAG_Msk) == 0);



    /* Disable SysTick counter */

    SysTick->CTRL = 0;

}