Button debouncing in software in Embedded C - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to read the button state.

Embedded C

int buttonState = [1](buttonPin);

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AdigitalRead

BcheckButton

CgetButton

DreadButton

Attempts:

3 left

💡 Hint

Common Mistakes

Using a function that does not read input pins.

The function digitalRead() is commonly used to read the state of a button in embedded C environments.

2fill in blank

medium

Complete the code to check if the button is pressed (active low).

Embedded C

if (buttonState == [1]) {
    // Button pressed
}

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AHIGH

B1

C0

DLOW

Attempts:

3 left

💡 Hint

Common Mistakes

Checking for HIGH instead of LOW.

For an active low button, the pressed state corresponds to LOW.

3fill in blank

hard

Fix the error in the debounce delay function call.

Embedded C

delay([1]);

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A5

B50

C500

D0

Attempts:

3 left

💡 Hint

Common Mistakes

Using too short or too long delay causing missed presses or lag.

A debounce delay of around 50 milliseconds is typical to filter out button noise.

4fill in blank

hard

Fill both blanks to complete the debounce logic.

Embedded C

if (buttonState == [1] && lastButtonState == [2]) {
    lastDebounceTime = millis();
}

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ALOW

BHIGH

C0

D1

Attempts:

3 left

💡 Hint

Common Mistakes

Mixing up current and last button states.

The debounce logic checks if the current state is LOW (pressed) and the last state was HIGH (not pressed) to detect a change.

5fill in blank

hard

Fill all three blanks to complete the stable button press detection.

Embedded C

if ((millis() - lastDebounceTime) > [1]) {
    if (buttonState != [2]) {
        buttonState = [3];
        // Button state changed
    }
}

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A50

BlastButtonState

Creading

DdebounceDelay

Attempts:

3 left

💡 Hint

Common Mistakes

Using wrong variables for timing or state comparison.

The code waits for the debounce delay, then checks if the reading differs from the last state, and updates the button state accordingly.