用的原子个的mini板，本来定时的50us，出来确实250us。头都大了。

这是我的定时器程序：
void TIM1_Int_Init(void)
{
TIM_TimeBaseInitTypeDef TIM_TimeBaseStructure;
NVIC_InitTypeDef NVIC_InitStructure;

RCC_APB2PeriphClockCmd(RCC_APB2Periph_TIM1,ENABLE);

TIM_DeInit(TIM1); 

TIM_TimeBaseStructure.TIM_Period = 49;
TIM_TimeBaseStructure.TIM_Prescaler = 71;
TIM_TimeBaseStructure.TIM_CounterMode = TIM_CounterMode_Up;
TIM_TimeBaseStructure.TIM_ClockDivision = TIM_CKD_DIV1;
TIM_TimeBaseInit(TIM1,&TIM_TimeBaseStructure);


    NVIC_PriorityGroupConfig(NVIC_PriorityGroup_1); //设置NVIC中断分组1： 1位抢占优先级，3位响应优先级

NVIC_InitStructure.NVIC_IRQChannel = TIM1_UP_IRQn;
NVIC_InitStructure.NVIC_IRQChannelPreemptionPriority = 0;
NVIC_InitStructure.NVIC_IRQChannelSubPriority = 3;
NVIC_InitStructure.NVIC_IRQChannelCmd = ENABLE;
NVIC_Init(&NVIC_InitStructure);

TIM_ClearFlag(TIM1, TIM_FLAG_Update); 
TIM_ITConfig(TIM1,TIM_IT_Update,ENABLE);

TIM_Cmd(TIM1,ENABLE);

}

void TIM1_UP_IRQHandler(void)
{
if(TIM_GetITStatus(TIM1,TIM_IT_Update) !=RESET )
{
LED1 = !LED1; 
TIM_ClearITPendingBit(TIM1,TIM_IT_Update);
}
}
附上我的程序，希望各位朋友能解决，我们共同学习！谢谢！