STM32F407中PWM配置顺序导致TIM2中断失效问题咨询

问题描述 #

使用STM32F407G-DISC1开发板开发时，遇到定时器中断触发异常：

• 当先调用PWM_Configuration再初始化TIM2时，TIM2的更新中断完全无法触发；
• 调换调用顺序（先初始化TIM2再配置PWM），中断能正常运行；
• 加入printf调试后，无论调用顺序如何，中断均能触发，无法定位问题根源。

问题代码 #

#include "Main.h"

#define MAX_Intensity 1600

static volatile uint16_t Intensity = 10;

void Timer4_Configuration(void)
{
    TIM_TimeBaseInitTypeDef TIM_BaseStructure;

    RCC_APB1PeriphClockCmd(RCC_APB1Periph_TIM4, ENABLE);

    TIM_BaseStructure.TIM_Prescaler = 1 - 1;
    TIM_BaseStructure.TIM_CounterMode = TIM_CounterMode_Up;
    TIM_BaseStructure.TIM_Period = MAX_Intensity - 1;
    TIM_BaseStructure.TIM_ClockDivision = TIM_CKD_DIV1;
    TIM_TimeBaseInit(TIM4, &TIM_BaseStructure);
    TIM_Cmd(TIM4, ENABLE);
}

void PWM_Configuration()
{
    TIM_OCInitTypeDef TIM_OCStructure;
    TIM_OCStructure.TIM_OCMode = TIM_OCMode_PWM1;
    TIM_OCStructure.TIM_OutputState = TIM_OutputState_Enable;
    TIM_OCStructure.TIM_OCPolarity = TIM_OCPolarity_High;
    TIM_OCStructure.TIM_Pulse = 0;

    TIM_OC1Init(TIM4, &TIM_OCStructure);
    TIM_OC1PreloadConfig(TIM4, TIM_OCPreload_Enable);

    TIM_OC2Init(TIM4, &TIM_OCStructure);
    TIM_OC2PreloadConfig(TIM4, TIM_OCPreload_Enable);
    
    TIM_OC3Init(TIM4, &TIM_OCStructure);
    TIM_OC3PreloadConfig(TIM4, TIM_OCPreload_Enable);
    
    TIM_OC4Init(TIM4, &TIM_OCStructure);
    TIM_OC4PreloadConfig(TIM4, TIM_OCPreload_Enable);
}

void GPIO_PWM_Configuration()
{
    GPIO_InitTypeDef GPIO_InitStructure;
    RCC_AHB1PeriphClockCmd(RCC_AHB1Periph_GPIOD, ENABLE);

    GPIO_PinAFConfig(GPIOD, GPIO_PinSource12, GPIO_AF_TIM4);
    GPIO_PinAFConfig(GPIOD, GPIO_PinSource13, GPIO_AF_TIM4);
    GPIO_PinAFConfig(GPIOD, GPIO_PinSource14, GPIO_AF_TIM4);
    GPIO_PinAFConfig(GPIOD, GPIO_PinSource15, GPIO_AF_TIM4);

    GPIO_InitStructure.GPIO_Pin   = ALL_LEDS;
    GPIO_InitStructure.GPIO_Mode  = GPIO_Mode_AF;
    GPIO_InitStructure.GPIO_OType = GPIO_OType_PP;
    GPIO_InitStructure.GPIO_PuPd  = GPIO_PuPd_NOPULL;
    GPIO_Init(GPIOD, &GPIO_InitStructure);
}

void TIM2_Configuration(u32 Intervalms)
{
    RCC_APB1PeriphClockCmd(RCC_APB1Periph_TIM2, ENABLE);

    TIM_TimeBaseInitTypeDef TIM_TimeBaseStructure;

    TIM_TimeBaseStructure.TIM_Prescaler   = 16000-1;
    TIM_TimeBaseStructure.TIM_Period      = Intervalms-1;
    TIM_TimeBaseStructure.TIM_CounterMode = TIM_CounterMode_Up;
    TIM_TimeBaseInit(TIM2, &TIM_TimeBaseStructure);

    TIM_ITConfig(TIM2, TIM_IT_Update, ENABLE);
    TIM_Cmd(TIM2, ENABLE);

    NVIC_PriorityGroupConfig(NVIC_PriorityGroup_1);
    NVIC_InitTypeDef NVIC_InitStructure;

    NVIC_InitStructure.NVIC_IRQChannel = TIM2_IRQn;
    NVIC_InitStructure.NVIC_IRQChannelPreemptionPriority = 1;
    NVIC_InitStructure.NVIC_IRQChannelSubPriority = 1;
    NVIC_InitStructure.NVIC_IRQChannelCmd = ENABLE;

    NVIC_Init(&NVIC_InitStructure);
}

void TIM2_IRQHandler()
{
    if(TIM_GetITStatus(TIM2, TIM_IT_Update) != RESET)
    {
        if(Intensity > MAX_Intensity)
        {
            Intensity = 10;
        }
        TIM4->CCR1 = Intensity;
        TIM4->CCR2 = Intensity;
        TIM4->CCR3 = Intensity;
        TIM4->CCR4 = Intensity;

        Intensity = Intensity * 2;
        
        TIM_ClearITPendingBit(TIM2, TIM_IT_Update);
    }
}

int main(void)
{
    GPIO_PWM_Configuration();
            
    Timer4_Configuration();
    
    // 无法正常工作
    PWM_Configuration();
    TIM2_Configuration(500);
    
    // 可正常工作
    //TIM2_Configuration(500);
    //PWM_Configuration();
    
    while(1)
    {
    }
}

问题分析 #

核心问题出在NVIC优先级分组的调用时机和定时器与中断控制器的初始化顺序：

1. NVIC_PriorityGroupConfig函数应在系统初始化阶段仅调用一次，当前代码将其放在TIM2_Configuration中，导致当先配置PWM再初始化TIM2时，优先级分组在TIM2启用后才设置，可能破坏中断优先级的正确映射；
2. 当前TIM2_Configuration先启用TIM2再配置NVIC，若TIM2在NVIC通道启用前产生中断请求，该请求会被丢弃，后续中断也无法正常触发；
3. 加入printf调试时，串口输出的延时使TIM2中断请求在NVIC配置完成后才产生，因此中断能正常触发。

解决方案 #

方案1：调整NVIC优先级分组的调用时机 #

将NVIC_PriorityGroupConfig移到main函数最开头，确保全局仅调用一次：

int main(void)
{
    // 全局仅需调用一次的NVIC优先级分组配置
    NVIC_PriorityGroupConfig(NVIC_PriorityGroup_1);

    GPIO_PWM_Configuration();
            
    Timer4_Configuration();
    
    PWM_Configuration();
    TIM2_Configuration(500);
    
    while(1)
    {
    }

同时修改TIM2_Configuration，移除其中的NVIC_PriorityGroupConfig调用。

方案2：调整TIM2初始化顺序 #

修改TIM2_Configuration，先完成NVIC配置再启用TIM2，同时提前清除中断标志位：

void TIM2_Configuration(u32 Intervalms)
{
    RCC_APB1PeriphClockCmd(RCC_APB1Periph_TIM2, ENABLE);

    TIM_TimeBaseInitTypeDef TIM_TimeBaseStructure;

    TIM_TimeBaseStructure.TIM_Prescaler   = 16000-1;
    TIM_TimeBaseStructure.TIM_Period      = Intervalms-1;
    TIM_TimeBaseStructure.TIM_CounterMode = TIM_CounterMode_Up;
    TIM_TimeBaseInit(TIM2, &TIM_TimeBaseStructure);

    // 提前清除可能残留的中断标志
    TIM_ClearITPendingBit(TIM2, TIM_IT_Update);
    TIM_ITConfig(TIM2, TIM_IT_Update, ENABLE);

    // 先配置NVIC再启用定时器
    NVIC_InitTypeDef NVIC_InitStructure;

    NVIC_InitStructure.NVIC_IRQChannel = TIM2_IRQn;
    NVIC_InitStructure.NVIC_IRQChannelPreemptionPriority = 1;
    NVIC_InitStructure.NVIC_IRQChannelSubPriority = 1;
    NVIC_InitStructure.NVIC_IRQChannelCmd = ENABLE;

    NVIC_Init(&NVIC_InitStructure);

    TIM_Cmd(TIM2, ENABLE);
}

方案3：合并优化 #

将上述两个方案结合，既保证NVIC优先级分组全局唯一设置，又确保定时器与中断控制器的初始化顺序正确，这是最稳妥的做法。

内容的提问来源于stack exchange，提问作者이석희