stm32L151如何实现微秒级延时？

只看该作者 · 2014-7-17 20:39

stm32l151如何实现微秒级延时，下面这个函数哪里配置不对啊？主函数里是这样调用的delay_init(16);
#include "delay.h"

static uint8_t  fac_us=0;
static uint16_t fac_ms=0;
void delay_init(uint8_t SYSCLK)
{
SysTick_CLKSourceConfig(SysTick_CLKSource_HCLK_Div8);
fac_us=SYSCLK/16;
fac_ms=(uint16_t)fac_us*1000;
}
void delay_ms(uint16_t nms)
{
uint32_t temp;
SysTick->LOAD=(uint32_t)nms*fac_ms;
SysTick->VAL =0x00;
SysTick->CTRL=0x01 ;
do
{
temp=SysTick->CTRL;
}
while(temp&0x01&&!(temp&(1<<16)));
SysTick->CTRL=0x00;
SysTick->VAL =0X00;
}
void delay_us(uint32_t nus)
{
uint32_t temp;
SysTick->LOAD=nus*fac_us;
SysTick->VAL=0x00;
SysTick->CTRL=0x01 ;
do
{
temp=SysTick->CTRL;
}
while(temp&0x01&&!(temp&(1<<16)));
SysTick->CTRL=0x00;
SysTick->VAL =0X00;
}