Polling vs interrupt-driven execution in Embedded C - Interactive Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to check the button state using polling.

Embedded C

while(1) {
    if (GPIO_ReadInputDataBit(GPIOA, GPIO_Pin_0) == [1]) {
        // Button pressed action
    }
}

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A2

B0

C1

D-1

Attempts:

3 left

💡 Hint

Common Mistakes

Using 0 instead of 1 for pressed state.

The button is considered pressed when the input pin reads 1 (high).

2fill in blank

medium

Complete the code to enable the interrupt for the button pin.

Embedded C

EXTI_InitTypeDef EXTI_InitStructure;

EXTI_InitStructure.EXTI_Line = EXTI_Line0;
EXTI_InitStructure.EXTI_Mode = EXTI_Mode_[1];
EXTI_InitStructure.EXTI_Trigger = EXTI_Trigger_Rising;
EXTI_InitStructure.EXTI_LineCmd = ENABLE;
EXTI_Init(&EXTI_InitStructure);

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AInterrupt

BPolling

CTimer

DDMA

Attempts:

3 left

💡 Hint

Common Mistakes

Using Polling mode instead of Interrupt mode.

The EXTI mode must be set to Interrupt to enable interrupt-driven execution.

3fill in blank

hard

Fix the error in the interrupt handler function name.

Embedded C

void [1](void) {
    if (EXTI_GetITStatus(EXTI_Line0) != RESET) {
        // Handle button press
        EXTI_ClearITPendingBit(EXTI_Line0);
    }
}

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AEXTI_IRQHandler

BEXTI1_IRQHandler

CEXTI0_Handler

DEXTI0_IRQHandler

Attempts:

3 left

💡 Hint

Common Mistakes

Using wrong handler names like EXTI1_IRQHandler or EXTI0_Handler.

The correct interrupt handler name for EXTI line 0 is EXTI0_IRQHandler.

4fill in blank

hard

Fill both blanks to create a polling loop that waits for a button press and then toggles an LED.

Embedded C

while(1) {
    if (GPIO_ReadInputDataBit(GPIOB, GPIO_Pin_[1]) == [2]) {
        GPIO_ToggleBits(GPIOC, GPIO_Pin_13);
    }
}

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A0

B1

Attempts:

3 left

💡 Hint

Common Mistakes

Using wrong pin number or wrong pressed state value.

The button is connected to pin 0 and is pressed when the input reads 1.

5fill in blank

hard

Fill all three blanks to define an interrupt-driven setup: enable clock, configure GPIO pin as input, and enable NVIC interrupt.

Embedded C

RCC_AHB1PeriphClockCmd(RCC_AHB1Periph_GPIOA, [1]);

GPIO_InitTypeDef GPIO_InitStructure;
GPIO_InitStructure.GPIO_Pin = GPIO_Pin_[2];
GPIO_InitStructure.GPIO_Mode = GPIO_Mode_IN;
GPIO_Init(GPIOA, &GPIO_InitStructure);

NVIC_InitTypeDef NVIC_InitStructure;
NVIC_InitStructure.NVIC_IRQChannel = EXTI[3]_IRQn;
NVIC_InitStructure.NVIC_IRQChannelCmd = ENABLE;
NVIC_Init(&NVIC_InitStructure);

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AENABLE

B5

C0

D1

Attempts:

3 left

💡 Hint

Common Mistakes

Using DISABLE instead of ENABLE, wrong pin number, or wrong IRQ channel.

Clock must be enabled (ENABLE), GPIO pin 0 is configured as input, and NVIC interrupt for EXTI0 is enabled.