void NVIC_Configuration(void) { NVIC_InitTypeDef NVIC_InitStructure; //声明一个中断初始化结 NVIC_PriorityGroupConfig(NVIC_PriorityGroup_0); //设成优先级组0：先占优先级2位 从优先级2位 NVIC_InitStructure.NVIC_IRQChannel=TIM2_IRQn; //设置TIM3中断优先级 NVIC_InitStructure.NVIC_IRQChannelPreemptionPriority=0; //中断占先等级 NVIC_InitStructure.NVIC_IRQChannelSubPriority=2; //中断响应优先级 NVIC_InitStructure.NVIC_IRQChannelCmd=ENABLE; //使能 NVIC_Init(&NVIC_InitStructure);

这段代码是用来配置 NVIC（Nested Vectored Interrupt Controller）的，它是 ARM Cortex-M 系列处理器中用来管理中断的模块。在这段代码中，首先声明了一个中断初始化结构体 NVIC_InitTypeDef，然后配置了中断优先级组为 0，设置了 TIM2 中断的优先级为 0，响应优先级为 2，最后使能了 TIM2 中断。这样就完成了对 NVIC 的配置。

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#include <nvic.h> void NVIC_Configuration(void) { NVIC_InitTypeDef NVIC_InitStructure; /* Configure the NVIC Preemption Priority Bits */ NVIC_PriorityGroupConfig(NVIC_PriorityGroup_2); /* Enable the USARTy Interrupt */ NVIC_InitStructure.NVIC_IRQChannel = USART1_IRQn; NVIC_InitStructure.NVIC_IRQChannelPreemptionPriority = 3; NVIC_InitStructure.NVIC_IRQChannelSubPriority = 3; NVIC_InitStructure.NVIC_IRQChannelCmd = ENABLE; NVIC_Init(&NVIC_InitStructure); NVIC_InitStructure.NVIC_IRQChannel = TIM3_IRQn; NVIC_InitStructure.NVIC_IRQChannelPreemptionPriority = 0; NVIC_InitStructure.NVIC_IRQChannelSubPriority = 0; NVIC_InitStructure.NVIC_IRQChannelCmd = ENABLE; NVIC_Init(&NVIC_InitStructure); }

这是一个配置STM32F4微控制器中NVIC（Nested Vectored Interrupt Controller）的函数。在STM32F4中，NVIC用于管理中断，并且可以配置中断优先级。在这个函数中，首先通过调用NVIC_PriorityGroupConfig函数配置NVIC的优先级分组，然后通过配置NVIC_InitStructure结构体中的各个参数来初始化NVIC。在这个函数中，配置了USART1_IRQn和TIM3_IRQn两个中断的优先级和使能状态。USART1_IRQn用于USART1串口通信的中断处理函数，而TIM3_IRQn用于定时器3的中断处理函数。配置NVIC后，就可以启用这两个中断，并且可以在中断处理函数中进行相应的操作。

为下面每一行代码添加注释：#include "stm32f10x.h" void RCC_Configuration(void) { /* Enable GPIOA, GPIOC and AFIO clocks / RCC_APB2PeriphClockCmd(RCC_APB2Periph_GPIOA | RCC_APB2Periph_GPIOC | RCC_APB2Periph_AFIO, ENABLE); / Enable SYSCFG clock / RCC_APB2PeriphClockCmd(RCC_APB2Periph_SYSCFG, ENABLE); } void GPIO_Configuration(void) { GPIO_InitTypeDef GPIO_InitStructure; / Configure PA0 pin as input floating / GPIO_InitStructure.GPIO_Pin = GPIO_Pin_0; GPIO_InitStructure.GPIO_Mode = GPIO_Mode_IN_FLOATING; GPIO_Init(GPIOA, &GPIO_InitStructure); / Configure PC13 pin as output push-pull / GPIO_InitStructure.GPIO_Pin = GPIO_Pin_13; GPIO_InitStructure.GPIO_Speed = GPIO_Speed_50MHz; GPIO_InitStructure.GPIO_Mode = GPIO_Mode_Out_PP; GPIO_Init(GPIOC, &GPIO_InitStructure); } void NVIC_Configuration(void) { NVIC_InitTypeDef NVIC_InitStructure / Configure the NVIC Preemption Priority Bits / NVIC_PriorityGroupConfig(NVIC_PriorityGroup_0); / Enable the EXTI0 Interrupt / NVIC_InitStructure.NVIC_IRQChannel = EXTI0_IRQn; NVIC_InitStructure.NVIC_IRQChannelPreemptionPriority = 0; NVIC_InitStructure.NVIC_IRQChannelSubPriority = 0; NVIC_InitStructure.NVIC_IRQChannelCmd = ENABLE; NVIC_Init(&NVIC_InitStructure); } void EXTI_Configuration(void) { EXTI_InitTypeDef EXTI_InitStructure; / Configure EXTI Line0 to generate an interrupt on falling edge / EXTI_InitStructure.EXTI_Line = EXTI_Line0; EXTI_InitStructure.EXTI_Mode = EXTI_Mode_Interrupt; EXTI_InitStructure.EXTI_Trigger = EXTI_Trigger_Falling; EXTI_InitStructure.EXTI_LineCmd = ENABLE; EXTI_Init(&EXTI_InitStructure); / Connect EXTI Line0 to PA0 pin / GPIO_EXTILineConfig(GPIO_PortSourceGPIOA, GPIO_PinSource0); } void SysTick_Configuration(void) { / Configure SysTick to generate an interrupt every 1ms / if (SysTick_Config(SystemCoreClock / 1000)) { / Capture error / while (1); } } void Delay(__IO uint32_t nTime) { / Wait for nTime millisecond / TimingDelay = nTime; while (TimingDelay != 0); } void TimingDelay_Decrement(void) { if (TimingDelay != 0x00) { TimingDelay--; } } int main(void) { RCC_Configuration(); GPIO_Configuration(); NVIC_Configuration(); EXTI_Configuration(); SysTick_Configuration(); / Infinite loop / while (1) { / Toggle PC13 LED every 500ms / GPIOC->ODR ^= GPIO_Pin_13; Delay(500); } } void EXTI0_IRQHandler(void) { / Check if PA0 button is pressed / if (GPIO_ReadInputDataBit(GPIOA, GPIO_Pin_0) == RESET) { / Reset MCU / NVIC_SystemReset(); } / Clear EXTI Line0 pending bit */ EXTI_ClearITPendingBit(EXTI_Line0); }

// 引入STM32F10x库
#include "stm32f10x.h"

// 配置RCC
void RCC_Configuration(void) {
// 使能GPIOA, GPIOC和AFIO时钟
RCC_APB2PeriphClockCmd(RCC_APB2Periph_GPIOA | RCC_APB2Periph_GPIOC | RCC_APB2Periph_AFIO, ENABLE);
// 使能SYSCFG时钟
RCC_APB2PeriphClockCmd(RCC_APB2Periph_SYSCFG, ENABLE);
}

// 配置GPIO
void GPIO_Configuration(void) {
GPIO_InitTypeDef GPIO_InitStructure;

// 配置PA0引脚为浮空输入模式
GPIO_InitStructure.GPIO_Pin = GPIO_Pin_0;
GPIO_InitStructure.GPIO_Mode = GPIO_Mode_IN_FLOATING;
GPIO_Init(GPIOA, &GPIO_InitStructure);

// 配置PC13引脚为推挽输出模式，速率50MHz
GPIO_InitStructure.GPIO_Pin = GPIO_Pin_13;
GPIO_InitStructure.GPIO_Speed = GPIO_Speed_50MHz;
GPIO_InitStructure.GPIO_Mode = GPIO_Mode_Out_PP;
GPIO_Init(GPIOC, &GPIO_InitStructure);
}

// 配置NVIC
void NVIC_Configuration(void) {
NVIC_InitTypeDef NVIC_InitStructure;

// 配置NVIC抢占优先级位数
NVIC_PriorityGroupConfig(NVIC_PriorityGroup_0);

// 使能EXTI0中断
NVIC_InitStructure.NVIC_IRQChannel = EXTI0_IRQn;
NVIC_InitStructure.NVIC_IRQChannelPreemptionPriority = 0;
NVIC_InitStructure.NVIC_IRQChannelSubPriority = 0;
NVIC_InitStructure.NVIC_IRQChannelCmd = ENABLE;
NVIC_Init(&NVIC_InitStructure);
}

// 配置EXTI
void EXTI_Configuration(void) {
EXTI_InitTypeDef EXTI_InitStructure;

// 配置EXTI Line0在下降沿触发中断
EXTI_InitStructure.EXTI_Line = EXTI_Line0;
EXTI_InitStructure.EXTI_Mode = EXTI_Mode_Interrupt;
EXTI_InitStructure.EXTI_Trigger = EXTI_Trigger_Falling;
EXTI_InitStructure.EXTI_LineCmd = ENABLE;
EXTI_Init(&EXTI_InitStructure);

// 将EXTI Line0连接至PA0引脚
GPIO_EXTILineConfig(GPIO_PortSourceGPIOA, GPIO_PinSource0);
}

// 配置SysTick
void SysTick_Configuration(void) {
// 配置SysTick使其每1ms产生一次中断
if (SysTick_Config(SystemCoreClock / 1000)) {
// 发生错误
while (1);
}
}

// 延时函数
void Delay(__IO uint32_t nTime) {
// 等待nTime毫秒
TimingDelay = nTime;
while (TimingDelay != 0);
}

// 延时计数器递减函数
void TimingDelay_Decrement(void) {
if (TimingDelay != 0x00) {
TimingDelay--;
}
}

// 主函数
int main(void) {
RCC_Configuration();
GPIO_Configuration();
NVIC_Configuration();
EXTI_Configuration();
SysTick_Configuration();

// 无限循环
while (1) {
// 每500ms交替改变PC13引脚的电平
GPIOC->ODR ^= GPIO_Pin_13;
Delay(500);
}
}

// EXTI0中断处理函数
void EXTI0_IRQHandler(void) {
// 检查PA0引脚的按键是否被按下
if (GPIO_ReadInputDataBit(GPIOA, GPIO_Pin_0) == RESET) {
// 复位MCU
NVIC_SystemReset();
}

// 清除EXTI Line0的中断挂起位
EXTI_ClearITPendingBit(EXTI_Line0);
}