STM32F407 ------ 使用定时器实现精确延时

测试环境：主频168M

#include "delay.h"

void delay_init()

{

    TIM_TimeBaseInitTypeDef  TIM_TimeBaseStructure;

    RCC_APB1PeriphClockCmd(RCC_APB1Periph_TIM4, ENABLE);

    TIM_TimeBaseStructure.TIM_Period = ;

    TIM_TimeBaseStructure.TIM_Prescaler = ;

    TIM_TimeBaseStructure.TIM_ClockDivision = ;

    TIM_TimeBaseStructure.TIM_CounterMode = TIM_CounterMode_Up;

    TIM_TimeBaseInit(TIM4, &TIM_TimeBaseStructure);

}

void delay_ms(u16 nms)

{

    u32 cnt;

    cnt = nms*;

    TIM_Cmd(TIM4, ENABLE);

    while(cnt--)

    {

        while(TIM_GetFlagStatus(TIM4, TIM_FLAG_Update) == RESET);

        TIM_ClearFlag(TIM4, TIM_FLAG_Update);

    }

    TIM_Cmd(TIM4, DISABLE);

}

//延时nus

//nus为要延时的us数.

void delay_us(u32 nus)

{

    u32 cnt;

    cnt = nus;

    TIM_Cmd(TIM4, ENABLE);

    while(cnt--)

    {

        while(TIM_GetFlagStatus(TIM4, TIM_FLAG_Update) == RESET);

        TIM_ClearFlag(TIM4, TIM_FLAG_Update);

    }

    TIM_Cmd(TIM4, DISABLE);

}

#ifndef __DELAY_H

#define __DELAY_H

#include "stm32f4xx_conf.h"

void delay_init();

void delay_ms(u16 nms);

void delay_us(u32 nus);

#endif