GD32 ------ 使用外部中断，中断函数需要延时才能读到真正电平

MCU：GD32F103RCT6

中断引脚没有外界上拉电阻

中断配置如下：

    RCC_APB2PeriphClockCmd(RCC_APB2Periph_GPIOC|RCC_APB2Periph_AFIO, ENABLE);

    GPIO_InitStructure.GPIO_Mode=GPIO_Mode_IPU;

    GPIO_InitStructure.GPIO_Pin=GPIO_Pin_9;

    GPIO_InitStructure.GPIO_Speed=GPIO_Speed_50MHz;

    GPIO_Init(GPIOC, &GPIO_InitStructure);

    GPIO_EXTILineConfig(GPIO_PortSourceGPIOC,GPIO_PinSource9);

    EXTI_InitStructure.EXTI_Line=EXTI_Line9;

    EXTI_InitStructure.EXTI_Mode = EXTI_Mode_Interrupt;    

    EXTI_InitStructure.EXTI_Trigger = EXTI_Trigger_Rising_Falling;

    EXTI_InitStructure.EXTI_LineCmd = ENABLE;

    EXTI_Init(&EXTI_InitStructure);

中断函数如下：

void EXTI9_5_IRQHandler(void)

{

    BaseType_t xHigherPriorityTaskWoken = pdFALSE;

    if(EXTI_GetITStatus(EXTI_Line9) != RESET)

    {

        debug('%d',GPIO_ReadInputDataBit(GPIOC, GPIO_Pin_9));

        debug('%d',GPIO_ReadInputDataBit(GPIOC, GPIO_Pin_9));

        debug('%d',GPIO_ReadInputDataBit(GPIOC, GPIO_Pin_9));

        if(GPIO_ReadInputDataBit(GPIOC, GPIO_Pin_9) != 0)

        {

            debug('relay power on, device_power_on is 1');

            xTaskNotifyFromISR( xTaskHandleLoadDatatoServerBuf, g_flag_event[RELAY_POWER_ON], eSetBits, &xHigherPriorityTaskWoken );

            g_data_info.power_on = 1;

        }else

        {

            debug('relay power off, device_power_on is 0');

            xTaskNotifyFromISR( xTaskHandleLoadDatatoServerBuf, g_flag_event[RELAY_POWER_OFF], eSetBits, &xHigherPriorityTaskWoken );

            g_data_info.power_on = 0;

        }

        EXTI_ClearITPendingBit(EXTI_Line9);

    }

    portYIELD_FROM_ISR( xHigherPriorityTaskWoken );

}

当检测到上升沿，在中断函数中，第一次读电平是0，之后读的几次都是1