写一段独立按键产生的高低电平作为中断的信号源,中断方式点亮和熄灭 L0 发光二极管的代码

以下是基于STM32F103C8T6的代码实现：

先定义按键引脚和LED引脚：

#define KEY_PIN GPIO_Pin_0
#define KEY_PORT GPIOA
#define LED_PIN GPIO_Pin_0
#define LED_PORT GPIOB

初始化按键引脚为输入，上拉模式：

GPIO_InitTypeDef GPIO_InitStructure;
RCC_APB2PeriphClockCmd(RCC_APB2Periph_GPIOA, ENABLE);
GPIO_InitStructure.GPIO_Pin = KEY_PIN;
GPIO_InitStructure.GPIO_Mode = GPIO_Mode_IPU;
GPIO_Init(KEY_PORT, &GPIO_InitStructure);

初始化LED引脚为输出，低电平：

GPIO_InitStructure.GPIO_Pin = LED_PIN;
GPIO_InitStructure.GPIO_Mode = GPIO_Mode_Out_PP;
GPIO_InitStructure.GPIO_Speed = GPIO_Speed_50MHz;
GPIO_Init(LED_PORT, &GPIO_InitStructure);
GPIO_SetBits(LED_PORT, LED_PIN);

定义中断服务函数：

void EXTI0_IRQHandler(void)
{
    if(EXTI_GetITStatus(EXTI_Line0) != RESET)
    {
        GPIO_WriteBit(LED_PORT, LED_PIN, (BitAction)(1 - GPIO_ReadOutputDataBit(LED_PORT, LED_PIN)));
        EXTI_ClearITPendingBit(EXTI_Line0);
    }
}

初始化外部中断0：

NVIC_InitTypeDef NVIC_InitStructure;
EXTI_InitTypeDef EXTI_InitStructure;
RCC_APB2PeriphClockCmd(RCC_APB2Periph_AFIO, ENABLE);
GPIO_EXTILineConfig(GPIO_PortSourceGPIOA, GPIO_PinSource0);
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);
NVIC_InitStructure.NVIC_IRQChannel = EXTI0_IRQn;
NVIC_InitStructure.NVIC_IRQChannelPreemptionPriority = 0x00;
NVIC_InitStructure.NVIC_IRQChannelSubPriority = 0x00;
NVIC_InitStructure.NVIC_IRQChannelCmd = ENABLE;
NVIC_Init(&NVIC_InitStructure);

在主循环中不断检测按键状态：

while(1)
{
    if(GPIO_ReadInputDataBit(KEY_PORT, KEY_PIN) == RESET)
    {
        GPIO_WriteBit(LED_PORT, LED_PIN, (BitAction)(1 - GPIO_ReadOutputDataBit(LED_PORT, LED_PIN)));
        delay_ms(100);
    }
}

其中，delay_ms() 函数为延时函数，可以使用 SysTick 系统滴答定时器实现。