用定时器9做的定时1秒试验，但定时不准偏差大

askh · 发表于 2015-5-19 10:19:29

[mw_shl_code=c,true]/*TIM9 */ void NVIC_TIM9Configuration(void) { NVIC_InitTypeDef NVIC_InitStructure; /* Set the Vector Table base address at 0x08000000 */ NVIC_SetVectorTable(NVIC_VectTab_FLASH, 0x0000); /* Enable the TIM9 gloabal Interrupt */ NVIC_InitStructure.NVIC_IRQChannel = TIM1_BRK_TIM9_IRQn; NVIC_InitStructure.NVIC_IRQChannelPreemptionPriority = 0; NVIC_InitStructure.NVIC_IRQChannelSubPriority = 2; NVIC_InitStructure.NVIC_IRQChannelCmd = ENABLE; NVIC_Init(&NVIC_InitStructure); } uint16_t TIM9_Con = 1000 ; uint16_t TIM9_Str = 8400 ; void TIM9_Init(void) { TIM_TimeBaseInitTypeDef TIM_TimeBaseStructure; /* TIM9 clock enable */ RCC_APB2PeriphClockCmd(RCC_APB2Periph_TIM9, ENABLE); /* Time base configuration */ //这个就是自动装载的计数值，由于计数是从0开始的，计数10000次后为9999 TIM_TimeBaseStructure.TIM_Period = (TIM9_Con - 1); // 这个就是预分频系数，当由于为0时表示不分频所以要减1 TIM_TimeBaseStructure.TIM_Prescaler = (TIM9_Str - 1); // 使用的采样频率之间的分频比例 TIM_TimeBaseStructure.TIM_ClockDivision = 0; //向上计数 TIM_TimeBaseStructure.TIM_CounterMode = TIM_CounterMode_Up; //初始化定时器9 TIM_TimeBaseInit(TIM9, &TIM_TimeBaseStructure); /* Clear TIM9 update pending flag[清除TIM9溢出中断标志] */ TIM_ClearITPendingBit(TIM9, TIM_IT_Update); /* TIM IT enable */ //打开溢出中断 TIM_ITConfig(TIM9, TIM_IT_Update, ENABLE); /* TIM9 enable counter */ /*TIM_Cmd(TIM9, ENABLE); //计数器使能，开始工作*/ /* 中断参数配置 */ NVIC_TIM9Configuration(); } //中断程序[/mw_shl_code] [mw_shl_code=c,true] [mw_shl_code=c,true] [mw_shl_code=c,true]uint16_t YanShi_Con=0；[/mw_shl_code] [/mw_shl_code] void TIM1_BRK_TIM9_IRQHandler(void) { if (TIM_GetITStatus(TIM9, TIM_IT_Update) != RESET) { TIM_ClearITPendingBit(TIM9, TIM_IT_Update); LED0=!LED0; YanShi_Con++; if(YanShi_Con>=(6)) { YanShi_Con=0; LED1=!LED1; } /*else { YanShi_Con++; }*/ } ｝[/mw_shl_code]

以上是定义1秒的程序，在实际运行时用示波器测量时间为大约5秒，不知道是什么原因？这是在探索者STM32F4开发板《网络实验5 RAW_TCP服务器实验》中加的一段小程序。