[嵌入式]stm32主从模式定时器产生精确脉冲个数

我这边使用的是STM32F103R8T6。设定主定时器为TIM4，从定时器为TIM3，由TIM4发送PWM,当TIM4的PWM溢出时，会进入TIM3的update中断，此时将TIM4的计数值清空，这样只要每次清空之前设定一下下一次PWM的计数值就可以做到对TIM4的脉冲精确计数了。

代码如下：

//TIM4主模式
void TIM4_config(u32 Cycle)
{
    GPIO_InitTypeDef GPIO_InitStructure;
    TIM_TimeBaseInitTypeDef  TIM_TimeBaseStructure;
    TIM_OCInitTypeDef  TIM_OCInitStructure;
    RCC_APB1PeriphClockCmd(RCC_APB1Periph_TIM4, ENABLE); 
    RCC_APB2PeriphClockCmd(RCC_APB2Periph_GPIOB , ENABLE); 

    GPIO_InitStructure.GPIO_Pin = GPIO_Pin_7;                   //TIM2_CH2 PB7
    GPIO_InitStructure.GPIO_Mode = GPIO_Mode_AF_PP;             //复用推挽输出
    GPIO_InitStructure.GPIO_Speed = GPIO_Speed_50MHz;
    GPIO_Init(GPIOB, &GPIO_InitStructure);

    TIM_TimeBaseStructure.TIM_Period = Cycle-1;                                                   
    TIM_TimeBaseStructure.TIM_Prescaler = 48;                    //设置用来作为TIMx时钟频率除数的预分频值                                                     
    TIM_TimeBaseStructure.TIM_ClockDivision = TIM_CKD_DIV1;     //设置时钟分割：TDTS= Tck_tim            
    TIM_TimeBaseStructure.TIM_CounterMode = TIM_CounterMode_Up; //TIM向上计数模式
    TIM_TimeBaseInit(TIM4, &TIM_TimeBaseStructure);                                       

    TIM_OCInitStructure.TIM_OCMode = TIM_OCMode_PWM1;          //选择定时器模式：TIM脉冲宽度调制模式1       
    TIM_OCInitStructure.TIM_OutputState = TIM_OutputState_Enable; //比较输出使能
    TIM_OCInitStructure.TIM_Pulse = (Cycle + 1)/2;                    //设置待装入捕获寄存器的脉冲值                                   
    TIM_OCInitStructure.TIM_OCPolarity = TIM_OCPolarity_Low;      //输出极性       
    TIM_OC2Init(TIM4, &TIM_OCInitStructure);

    TIM_SelectMasterSlaveMode(TIM4, TIM_MasterSlaveMode_Enable);
    TIM_SelectOutputTrigger(TIM4, TIM_TRGOSource_Update);

    TIM_OC2PreloadConfig(TIM4, TIM_OCPreload_Enable);                              
    TIM_ARRPreloadConfig(TIM4, ENABLE);                                                          
}
//TIM3从模式
void TIM3_config(u32 PulseNum)
{
    TIM_TimeBaseInitTypeDef  TIM_TimeBaseStructure;
    NVIC_InitTypeDef NVIC_InitStructure; 
    RCC_APB1PeriphClockCmd(RCC_APB1Periph_TIM3, ENABLE);

    TIM_TimeBaseStructure.TIM_Period = PulseNum-1;   
   TIM_TimeBaseStructure.TIM_Prescaler =0;    
    TIM_TimeBaseStructure.TIM_ClockDivision = 0;     
    TIM_TimeBaseStructure.TIM_CounterMode = TIM_CounterMode_Up;  
    TIM_TimeBaseInit(TIM3, &TIM_TimeBaseStructure);  

    TIM_SelectInputTrigger(TIM3, TIM_TS_ITR3);
    //TIM_InternalClockConfig(TIM3);
    TIM3->SMCR|=0x37;                                  //设置从模式寄存器 
    //TIM_ARRPreloadConfig(TIM3, ENABLE);         
    TIM_ITConfig(TIM3,TIM_IT_Update,DISABLE);

    NVIC_PriorityGroupConfig(NVIC_PriorityGroup_3);
    NVIC_InitStructure.NVIC_IRQChannel = TIM3_IRQn;        
    NVIC_InitStructure.NVIC_IRQChannelPreemptionPriority = 0;
    NVIC_InitStructure.NVIC_IRQChannelSubPriority = 1;     
    NVIC_InitStructure.NVIC_IRQChannelCmd = ENABLE; 
    NVIC_Init(&NVIC_InitStructure);
}
void Pulse_output(u32 Cycle,u32 PulseNum)
{
    TIM3_config(PulseNum);
    TIM_Cmd(TIM3, ENABLE);
    TIM_ClearITPendingBit(TIM3,TIM_IT_Update);
    TIM_ITConfig(TIM3,TIM_IT_Update,ENABLE);
    TIM4_config(Cycle);
    TIM_Cmd(TIM4, ENABLE);
}
int main(void)
{
    Pulse_output(1000,2000);     //发出1000Hz的脉冲，计数到2000个的时候就进入一次TIM3的Update
    while(1)
    {
        
    }
}

void TIM3_IRQHandler(void)   
{
  if (TIM_GetITStatus(TIM3, TIM_IT_Update) != RESET)  
  {
    
    //可以在这里写个IO翻转即可看到效果
    TIM_ClearITPendingBit(TIM3, TIM_IT_Update);
  }
}

具体的参数还需各位同学按照自己的环境小调一下，我这边主频是48Mhz的

需要注意的是，若需要移植到其它定时器，请翻阅数据手册，找到SMCR寄存器的使用说明，并且注意它的赋值更改。