Interrupt-driven button handling in Arduino - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to attach an interrupt to pin 2 that triggers on a falling edge.

Arduino

attachInterrupt(digitalPinToInterrupt(2), buttonPressed, [1]);

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ALOW

BFALLING

CCHANGE

DRISING

Attempts:

3 left

💡 Hint

Common Mistakes

Using RISING instead of FALLING causes the interrupt to trigger on button release.

The interrupt should trigger when the button is pressed, which pulls the pin LOW, so FALLING is used.

2fill in blank

medium

Complete the code to declare the interrupt service routine named buttonPressed.

Arduino

void [1]() {
  buttonState = !buttonState;
}

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AbuttonPressed

Bloop

Csetup

DhandleButton

Attempts:

3 left

💡 Hint

Common Mistakes

Naming the ISR differently than in attachInterrupt causes the interrupt not to work.

The interrupt service routine must have the same name as used in attachInterrupt, which is buttonPressed.

3fill in blank

hard

Fix the error in the code to correctly declare the buttonState variable as volatile.

Arduino

volatile [1] buttonState = false;

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Aint

Bchar

Cboolean

Dbool

Attempts:

3 left

💡 Hint

Common Mistakes

Using int instead of bool causes confusion in true/false logic.

The bool type is used in Arduino to represent true/false values and should be declared volatile for variables shared with interrupts.

4fill in blank

hard

Fill both blanks to read the button pin state and debounce it in the loop.

Arduino

int reading = digitalRead([1]);
if (reading != [2]) {
  delay(50);
  buttonState = !buttonState;
}

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AbuttonPin

BlastButtonState

CbuttonState

DpinMode

Attempts:

3 left

💡 Hint

Common Mistakes

Comparing reading to buttonState instead of lastButtonState causes incorrect debounce logic.

We read the buttonPin and compare it to lastButtonState to detect changes for debouncing.

5fill in blank

hard

Fill all three blanks to correctly initialize the button pin, attach the interrupt, and set the pin mode.

Arduino

const int [1] = 2;

void setup() {
  pinMode([2], INPUT_PULLUP);
  attachInterrupt(digitalPinToInterrupt([3]), buttonPressed, FALLING);
}

Drag options to blanks, or click blank then click option'

AbuttonPin

C2

D3

Attempts:

3 left

💡 Hint

Common Mistakes

Using different pin numbers or variable names causes the interrupt not to work.

The button pin is declared as buttonPin with value 2. We set pinMode for buttonPin and attach the interrupt to pin 2.