STM32F103ZET6 — EXTI

STM32F103ZET6 supports 20 external interrupt inputs (EXIT0~EXIT19), of which there are 4:

EXTI line 16 is connected to the PVD output

EXTI line 17 is connected to the RTC alarm event

EXTI line 18 is connected to the USB wake-up event

EXTI line 19 is connected to Ethernet wake-up event (only for interconnection products)

The other 16 can be used as external input interrupts, including:

EXIT0~EXIT4 have independent interrupt vectors

EXIT6~EXIT9 share an interrupt vector EXTI9_5_IRQHandler

EXIT10~EXIT16 share an interrupt vector EXTI15_10_IRQHandler

The shared interrupt vector needs to read the pending flag in the corresponding ISR to determine which signal triggered the interrupt.

On the board, the PE5/PE6 pins are connected to Key1 and Key2 through pull-up resistors, and the other ends of Key1 and Key2 are connected to GND.

The process of initializing and configuring PE5/PE6 to become an external interrupt is as follows:

1. Enable the clocks of AFIO and GPIO

2. Configure GPIO PE5/PE6 as pull-up input

3. Configure PE5/PE6 as the input pin of external EXIT interrupt through the EXITCR register group of AFIO

4. Configure the EXIT register to enable the interrupt of PE5/PE6

5. Since the level is low after the key is pressed, it is configured to generate an interrupt on the falling edge.

void SK_EXITInit(void)

{

    GPIO_InitTypeDef stGpioInit;

    EXTI_InitTypeDef stEXTIInit;

    /// Step 1: Power On the AFIO and GPIOE

    RCC_APB2PeriphClockCmd(RCC_APB2Periph_GPIOE | RCC_APB2Periph_AFIO, ENABLE);

    /// Step 2: Configure the NVIC

    SK_SK_EXITNVICConfig();

    /// Step 3: Config (PE5/PE6) As pull up input

    stGpioInit.GPIO_Pin = GPIO_Pin_5 | GPIO_Pin_6;

    stGpioInit.GPIO_Mode = GPIO_Mode_IPD;

    GPIO_Init(GPIOE, &stGpioInit);

    /// Step 4: Select the output interrupt source

    GPIO_EXTILineConfig(GPIO_PortSourceGPIOE, GPIO_PinSource5);

    GPIO_EXTILineConfig(GPIO_PortSourceGPIOE, GPIO_PinSource6);

    /// Step 5: Select the output interrupt source

    stEXTIInit.EXTI_Line = EXTI_Line5 | EXTI_Line6;

    stEXTIInit.EXTI_Mode = EXTI_Mode_Interrupt;

    stEXTIInit.EXTI_Trigger = EXTI_Trigger_Falling;

    stEXTIInit.EXTI_LineCmd = ENABLE;

    EXTI_Init(&stEXTIInit);

}

Since EXIT5~EXIT9 share an interrupt vector, it is necessary to determine the pending flag in the interrupt to know which interrupt line caused the interrupt:

void EXTI9_5_IRQHandler(void)

{

    if(EXTI_GetITStatus(EXTI_Line5) != RESET)

    {

        EXTI_ClearITPendingBit(EXTI_Line5);

        SK_SetLedStatus(SK_LED_1, SK_LED_ON);

        delay_ms(5000);

        SK_SetLedStatus(SK_LED_1, SK_LED_OFF);

    }

    if(EXTI_GetITStatus(EXTI_Line6) != RESET)

    {

        EXTI_ClearITPendingBit(EXTI_Line6);

        SK_SetLedStatus(SK_LED_2, SK_LED_ON);

        delay_ms(5000);

        SK_SetLedStatus(SK_LED_2, SK_LED_OFF);

    }

}