求助通用定时器TIM2延时不准确

爱好单片机 · 发表于 2012-9-14 19:42:13

求助大伙帮忙看看通用定时器TIM2 延时不准怎么回事 LED 2秒多闪一次公式计算72M / 时钟预分频 + 1

#include "stm32f10x.h "

unsigned char Count1;

/*
* GPIO端口配置寄存器子函数
*/
void GPIO_InitStructReadtempCmd(void)
{
GPIO_InitTypeDef GPIO_InitStruct;
GPIO_InitStruct.GPIO_Pin = GPIO_Pin_8 | GPIO_Pin_9 | GPIO_Pin_10 | GPIO_Pin_11;
GPIO_InitStruct.GPIO_Mode = GPIO_Mode_Out_PP;   //配置线路为推挽式输出
GPIO_InitStruct.GPIO_Speed = GPIO_Speed_50MHz;   //配置线路速率
GPIO_Init(GPIOD, &GPIO_InitStruct);      //初始化
}

/*
* RCC外设时钟配置寄存器子函数
*/
void RCC_APB2PeriphReadtempyCmd(void)
{
RCC_APB2PeriphClockCmd(RCC_APB2Periph_GPIOD, ENABLE); //打开GPIOD外设时钟
RCC_APB1PeriphClockCmd(RCC_APB1Periph_TIM2 , ENABLE); //打开TIM2定时器外设时钟
}

/*
* 配置中断向量控制器NVIC子函数
*/
void NVIC_InitStructReadtempCmd(void)
{
NVIC_InitTypeDef NVIC_InitStruct;
NVIC_PriorityGroupConfig(NVIC_PriorityGroup_0);     //配置中断分组
NVIC_InitStruct.NVIC_IRQChannel = TIM2_IRQn;     //选择中断通道
NVIC_InitStruct.NVIC_IRQChannelPreemptionPriority = 0;   //配置抢占优先级为0
NVIC_InitStruct.NVIC_IRQChannelSubPriority = 0;     //配置从占优先级为0
NVIC_InitStruct.NVIC_IRQChannelCmd = ENABLE;     //打开使能
NVIC_Init(&NVIC_InitStruct);         //初始化
}

/*
* TIMX定时器配置寄存器子函数
*/
void TIMX_InitStructReadtempCmd(void)
{
TIM_TimeBaseInitTypeDef TIM_TimeBaseInitStruct;
TIM_DeInit(TIM2);        //重设缺省值
TIM_TimeBaseInitStruct.TIM_Period = 2000;  //自动重载寄存器
TIM_TimeBaseInitStruct.TIM_Prescaler = (35999); //时钟预分频
TIM_TimeBaseInitStruct.TIM_ClockDivision = TIM_CKD_DIV1;   //时间分割值
TIM_TimeBaseInitStruct.TIM_CounterMode = 0x0000;           //配置向上计数
TIM_TimeBaseInit(TIM2, &TIM_TimeBaseInitStruct); //初始化定时器
TIM_ClearFlag(TIM2, TIM_FLAG_Update);    //清除溢出中断标志
TIM_ITConfig(TIM2, TIM_IT_Update, ENABLE);   //打开中断溢出中断
TIM_Cmd(TIM2, ENABLE);         //使能TIM2定时器
}

/*
* 函数主体
*/
int main(void)
{
SystemInit(); //初始化系统时钟进入72M主频
RCC_APB2PeriphReadtempyCmd();
GPIO_InitStructReadtempCmd();
NVIC_InitStructReadtempCmd();
TIMX_InitStructReadtempCmd();

while(1)
{

}
}

/*
* TIM2定时器中断服务程序
*/
void TIM2_IRQHandler(void)
{
Count1++;
if(Count1 == 2)
{
  Count1 = 0;
}
switch  (Count1)
{
  case  0:
    // GPIO_ResetBits(GPIOD, GPIO_Pin_8 | GPIO_Pin_11);
     GPIO_SetBits(GPIOD, GPIO_Pin_9 | GPIO_Pin_10);
     break;

  case  1:
     GPIO_ResetBits(GPIOD, GPIO_Pin_9 | GPIO_Pin_10);
    // GPIO_SetBits(GPIOD, GPIO_Pin_8 | GPIO_Pin_11);
     break;

default : break;
}
TIM_ClearFlag(TIM2, TIM_FLAG_Update); //清除溢出中断标志
}