使用定时器代替Systick延时，不使用中断，不改变原子的接口

 C++ Code 

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static u32 fac_us=0;    //us延时倍乘数 void delay_init(u8 SYSCLK) {     TIM_TimeBaseInitTypeDef  TIM_TimeBaseStructure;          RCC_APB1PeriphClockCmd(RCC_APB1Periph_TIM14, ENABLE);           TIM_TimeBaseStructure.TIM_Period = 65535-1;         TIM_TimeBaseStructure.TIM_Prescaler = 1-1;       TIM_TimeBaseStructure.TIM_CounterMode = TIM_CounterMode_Up;      TIM_TimeBaseStructure.TIM_ClockDivision = TIM_CKD_DIV1 ;     TIM_TimeBaseInit(TIM14, &TIM_TimeBaseStructure);          fac_us = SYSCLK;     TIM_SetCounter(TIM14,0);     TIM_Cmd(TIM14, ENABLE);       }   void delay_us(u32 nus) {            u32 ticks;     u32 told,tnow,tcnt=0;     u32 reload=65535-1;                  ticks=nus*fac_us;                    told=TIM14->CNT;                     while(1)     {         tnow=TIM14->CNT;          if(tnow!=told)         {                    if(tnow>told)tcnt+=tnow-told;                else tcnt+=reload-told+tnow;                 told=tnow;             if(tcnt>=ticks)break;                    }       }; } void delay_ms(u32 nms) {     u32 i;     for(i=0;i<nms;i++) delay_us(1000); }