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标题: NuMicro M058S 库函数中CLK_SysTickDelay函数延时不准是什么情况.. [打印本页]

作者: Seaber 时间: 2017-2-16 16:38
标题: NuMicro M058S 库函数中CLK_SysTickDelay函数延时不准是什么情况..

小弟刚接触 NuMicro M058S, 对他库的使用方法不很了解，遇到如下问题请教高手。

在官方的M058SSAN开发上写了一个LED 闪烁的程序，闪烁延时调用的是官方库中的CLK_SysTickDelay()函数。
但是实际的延时时长要比设置的延时时长短很多。是不是我的使用方法不对呢。请教高手。
代码如下：

#include <stdio.h>
#include "M058S.h"

#define PLL_CLOCK          50000000
void SYS_Init(void)
{
/* Unlock protected registers */
SYS_UnlockReg();
      /* Enable Internal RC 22.1184MHz clock */
CLK_EnableXtalRC(CLK_PWRCON_OSC22M_EN_Msk);

/* Waiting for Internal RC clock ready */
CLK_WaitClockReady(CLK_CLKSTATUS_OSC22M_STB_Msk);

/* Switch HCLK clock source to Internal RC and HCLK source divide 1 */
CLK_SetHCLK(CLK_CLKSEL0_HCLK_S_HIRC, CLK_CLKDIV_HCLK(1));

/* Enable external XTAL 12MHz clock */
CLK_EnableXtalRC(CLK_PWRCON_XTL12M_EN_Msk);

/* Waiting for external XTAL clock ready */
CLK_WaitClockReady(CLK_CLKSTATUS_XTL12M_STB_Msk);

/* Set core clock as PLL_CLOCK from PLL */
CLK_SetCoreClock(PLL_CLOCK);

SYS_LockReg();
}

int main()
{
SYS_Init();
      CLK_SetSysTickClockSrc(CLK_CLKSEL0_STCLK_S_HXT_DIV2);
      GPIO_SetMode(P3, BIT6, GPIO_PMD_OUTPUT);
while(1)
            {
                     P36 = 0 ;
                     CLK_SysTickDelay(5000000);//设置5秒的延时，实际大概有0.5秒
                     P36 = 1 ;
                     CLK_SysTickDelay(5000000);//设置5秒的延时，实际大概有0.5秒
            }
}

作者: Seaber 时间: 2017-2-16 21:56
问题解决；原因如下：

作者: Seaber 时间: 2017-2-16 21:57
/**
  * @brief  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 ...
  * @return None
  * @Details 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.
  */
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);
SysTick->CTRL = 0;
}

作者: a_ziliu 时间: 2017-2-23 11:40
只能到2^24，程式有註解，最多3秒多。

* @brief    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 ...
  * @return    None

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