Input capture mode in Embedded C - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to initialize the input capture mode on Timer1.

Embedded C

TCCR1B = (1 << ICES1) | (1 << [1]);

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ACS12

BCS11

CCS10

DICNC1

Attempts:

3 left

💡 Hint

Common Mistakes

Using ICNC1 instead of a clock select bit.

Choosing CS11 or CS12 which set different prescalers.

The CS10 bit sets the clock prescaler to start the timer in input capture mode.

2fill in blank

medium

Complete the code to enable the input capture interrupt.

Embedded C

TIMSK1 |= (1 << [1]);

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AICIE1

BOCIE1A

COCIE1B

DTOIE1

Attempts:

3 left

💡 Hint

Common Mistakes

Using TOIE1 which is for overflow interrupt.

Using output compare interrupt enables OCIE1A or OCIE1B.

ICIE1 enables the input capture interrupt for Timer1.

3fill in blank

hard

Fix the error in the input capture ISR declaration.

Embedded C

ISR(TIMER1_[1]_vect) {
    // Handle input capture event
}

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ACAPT

BCOMPA

COVF

DCAPTURE

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'CAPTURE' instead of 'CAPT'.

Using overflow (OVF) or compare (COMPA) vectors by mistake.

The correct ISR vector name for input capture on Timer1 is TIMER1_CAPT_vect.

4fill in blank

hard

Fill both blanks to configure input capture to trigger on falling edge and enable noise canceler.

Embedded C

TCCR1B = (0 << [1]) | (1 << [2]);

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AICES1

BICNC1

CCS10

DCS11

Attempts:

3 left

💡 Hint

Common Mistakes

Confusing ICES1 and ICNC1 bits.

Using clock select bits instead of these control bits.

Setting ICES1 to 0 triggers on falling edge; setting ICNC1 to 1 enables noise canceler.

5fill in blank

hard

Fill all three blanks to read the input capture value, clear the flag, and start the timer with no prescaling.

Embedded C

uint16_t capture = ICR1;
TIFR1 |= (1 << [1]);
TCCR1B = (1 << [2]) | (0 << [3]);

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AICF1

BCS10

CICES1

DTOIE1

Attempts:

3 left

💡 Hint

Common Mistakes

Trying to clear the overflow flag instead of input capture flag.

Using wrong bits to start the timer.

Confusing edge select bit with timer start bits.

ICF1 is the input capture flag to clear; CS10 starts timer with no prescaling; ICES1 selects edge.