萌新求大伙看看为啥systick时间差的这么多

xwjniubi · 发表于 2020-11-22 11:01:07

因为原函数是静态的下面是把core_cm3.h里的systick配置函数直接搬过来了 (关闭了中断)
系统时钟配的72m 所以配置了72000 理论上这时候一次是1ms
但是实际上在main中写了一个小测试, delay_ms(1000000)结果led闪的还是很快
有没有好心人知道这是咋一回事  都要睡不着了谢谢
#include "SYSTICK.h"

uint32_t SysTick_Config_Delay(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, (1<<__NVIC_PRIO_BITS) - 1);  /* set Priority for Cortex-M0 System Interrupts */
  SysTick->VAL = 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 */
}

void SysTick_Dealy_ms(uint32_t ms)
{
SysTick_Config_Delay(72000);

for(int i=0;i<ms;i++)
{
while(!(SysTick->CTRL)&(1<<16));
}
SysTick->CTRL &= ~SysTick_CTRL_ENABLE_Msk;
}
-------------------------------------------------------------------------------------main.c
while(1)
{
LED0GO;
delay_ms(1000000);
LED0DOWN;
delay_ms(1000000);
}
}