用主定时器TIM3去启动从定时器TIM4

可以使用主定时器TIM3去启动从定时器TIM4。具体实现方法如下：
1. 首先，需要初始化TIM3和TIM4定时器，设置它们的计数频率和计数周期。
2. 在TIM3的中断处理函数中，启动TIM4定时器。
3. 在TIM4的中断处理函数中，执行需要的操作，并停止TIM4定时器。

下面是示例代码：

// TIM3初始化函数
void TIM3_Int_Init(uint16_t arr, uint16_t psc)
{
    TIM_TimeBaseInitTypeDef TIM_TimeBaseStructure;
    NVIC_InitTypeDef NVIC_InitStructure;

    RCC_APB1PeriphClockCmd(RCC_APB1Periph_TIM3, ENABLE);

    TIM_TimeBaseStructure.TIM_Period = arr;
    TIM_TimeBaseStructure.TIM_Prescaler = psc;
    TIM_TimeBaseStructure.TIM_ClockDivision = TIM_CKD_DIV1;
    TIM_TimeBaseStructure.TIM_CounterMode = TIM_CounterMode_Up;
    TIM_TimeBaseInit(TIM3, &TIM_TimeBaseStructure);

    TIM_ClearFlag(TIM3, TIM_FLAG_Update);
    TIM_ITConfig(TIM3, TIM_IT_Update, ENABLE);

    NVIC_InitStructure.NVIC_IRQChannel = TIM3_IRQn;
    NVIC_InitStructure.NVIC_IRQChannelPreemptionPriority = 2;
    NVIC_InitStructure.NVIC_IRQChannelSubPriority = 2;
    NVIC_InitStructure.NVIC_IRQChannelCmd = ENABLE;
    NVIC_Init(&NVIC_InitStructure);

    TIM_Cmd(TIM3, ENABLE);
}

// TIM4初始化函数
void TIM4_Int_Init(uint16_t arr, uint16_t psc)
{
    TIM_TimeBaseInitTypeDef TIM_TimeBaseStructure;
    NVIC_InitTypeDef NVIC_InitStructure;

    RCC_APB1PeriphClockCmd(RCC_APB1Periph_TIM4, ENABLE);

    TIM_TimeBaseStructure.TIM_Period = arr;
    TIM_TimeBaseStructure.TIM_Prescaler = psc;
    TIM_TimeBaseStructure.TIM_ClockDivision = TIM_CKD_DIV1;
    TIM_TimeBaseStructure.TIM_CounterMode = TIM_CounterMode_Up;
    TIM_TimeBaseInit(TIM4, &TIM_TimeBaseStructure);

    TIM_ClearFlag(TIM4, TIM_FLAG_Update);
    TIM_ITConfig(TIM4, TIM_IT_Update, ENABLE);

    NVIC_InitStructure.NVIC_IRQChannel = TIM4_IRQn;    NVIC_InitStructure.NVIC_IRQChannelPreemptionPriority = 2;
    NVIC_InitStructure.NVIC_IRQChannelSubPriority = 2;
    NVIC_InitStructure.NVIC_IRQChannelCmd = ENABLE;
    NVIC_Init(&NVIC_InitStructure);
}

// TIM3中断处理函数
void TIM3_IRQHandler(void)
{
    if (TIM_GetITStatus(TIM3, TIM_IT_Update) != RESET)
    {
        TIM_Cmd(TIM4, ENABLE); // 启动TIM4定时器
        TIM_ClearITPendingBit(TIM3, TIM_FLAG_Update);
    }
}

// TIM4中断处理函数
void TIM4_IRQHandler(void)
{
    if (TIM_GetITStatus(TIM4, TIM_IT_Update) != RESET)
    {
        // 执行需要的操作

        TIM_Cmd(TIM4, DISABLE); // 停止TIM4定时器
        TIM_ClearITPendingBit(TIM4, TIM_FLAG_Update);
    }
}