void TIM3_Configuration(void) //每0.5ms發(fā)生一次更新事件(進入中斷服務程序).
{
TIM_TimeBaseInitTypeDef TIM_TimeBaseStructure;
NVIC_InitTypeDef NVIC_InitStructure;

RCC_APB1PeriphClockCmd(RCC_APB1Periph_TIM3, ENABLE);

TIM_DeInit(TIM3); //重新將Timer設置為缺省值
TIM_InternalClockConfig(TIM3); //采用內(nèi)部時鐘給TIM3提供時鐘源
TIM_ARRPreloadConfig(TIM3, DISABLE); //禁止ARR預裝載緩沖器 預裝載寄存器的內(nèi)容被立即傳送到影子寄存器

TIM_TimeBaseStructure.TIM_Prescaler = 24-1; //預分頻系數(shù)為24-1，這樣計數(shù)器計數(shù)頻率為48MHz/24 = 2MHz
TIM_TimeBaseStructure.TIM_ClockDivision = TIM_CKD_DIV1; //設置時鐘分割
TIM_TimeBaseStructure.TIM_CounterMode = TIM_CounterMode_Up; //設置計數(shù)器模式為向上計數(shù)模式
TIM_TimeBaseStructure.TIM_Period = 1000; //設置計數(shù)溢出大小，每計1000個數(shù)就產(chǎn)生一個更新事件
TIM_TimeBaseInit(TIM3, &TIM_TimeBaseStructure); //將配置應用到TIM3中

TIM_ClearFlag(TIM3, TIM_FLAG_Update); //清除溢出中斷標志
TIM_ITConfig(TIM3, TIM_IT_Update, ENABLE); //使能TIM3的更新中斷
TIM_Cmd(TIM3, ENABLE); //開啟定時器3

//Enable the TIM3 Interrupt
NVIC_InitStructure.NVIC_IRQChannel = TIM3_IRQn;
NVIC_InitStructure.NVIC_IRQChannelPriority = 2;
NVIC_InitStructure.NVIC_IRQChannelCmd = ENABLE;
NVIC_Init(&NVIC_InitStructure);
}