Logic analyzer for signal debugging in Embedded C - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to initialize the logic analyzer input pin.

Embedded C

void init_logic_analyzer() {
    DDRD &= ~[1]; // Set PD2 as input
}

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A(1 << PD4)

B(1 << PD2)

C(1 << PD3)

D(1 << PD5)

Attempts:

3 left

💡 Hint

Common Mistakes

Setting the wrong bit for the input pin.

Using |= instead of &= ~ to clear the bit.

We clear the bit for PD2 in DDRD to set it as input.

2fill in blank

medium

Complete the code to read the logic analyzer input pin state.

Embedded C

uint8_t read_signal() {
    return (PIND & [1]) ? 1 : 0;
}

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A(1 << PD2)

B(1 << PD3)

C(1 << PD4)

D(1 << PD5)

Attempts:

3 left

💡 Hint

Common Mistakes

Using the wrong pin mask.

Not using bitwise AND operator.

We mask PIND with (1 << PD2) to read the state of PD2 pin.

3fill in blank

hard

Fix the error in the code to store signal samples in the buffer.

Embedded C

void sample_signal(uint8_t *buffer, uint16_t length) {
    for (uint16_t i = 0; i < length; i++) {
        buffer[i] = [1];
    }
}

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Aread_signal()

Bread_signal

C*read_signal()

D&read_signal()

Attempts:

3 left

💡 Hint

Common Mistakes

Using function name without parentheses.

Dereferencing the function pointer incorrectly.

We must call the function read_signal() to get the current signal value.

4fill in blank

hard

Fill both blanks to configure the timer for sampling at 1 kHz frequency.

Embedded C

void setup_timer() {
    TCCR1B = (1 << [1]) | (1 << [2]); // Prescaler 64
    OCR1A = 249;
    TIMSK1 = (1 << OCIE1A);
}

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ACS11

BCS10

CCS12

DWGM12

Attempts:

3 left

💡 Hint

Common Mistakes

Using wrong CS bits for prescaler.

Confusing WGM bits with CS bits.

Setting CS11 and CS10 bits in TCCR1B sets the prescaler to 64 for the timer.

5fill in blank

hard

Fill all three blanks to implement the interrupt service routine that stores samples.

Embedded C

ISR(TIMER1_COMPA_vect) {
    static uint16_t index = 0;
    if (index < [1]) {
        sample_buffer[[2]] = [3];
        index++;
    }
}

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ABUFFER_SIZE

Bindex

Cread_signal()

Dlength

Attempts:

3 left

💡 Hint

Common Mistakes

Using wrong variable names.

Not calling read_signal() function.

The ISR stores samples in sample_buffer at position index until BUFFER_SIZE is reached, reading the signal each time.