Why timers are needed in Embedded C - Test Your Understanding

Practice - 5 Tasks

1fill in blank

easy

Complete the code to start the timer.

Embedded C

TIMER_START([1]);

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Adelay

Btimer1

Cstart

Dcount

Attempts:

3 left

💡 Hint

Common Mistakes

Using action words like 'start' instead of the timer name.

Passing delay or count instead of the timer identifier.

The function TIMER_START needs the timer name to start it. Here, timer1 is the correct timer identifier.

2fill in blank

medium

Complete the code to check if the timer has expired.

Embedded C

if ([1]_expired()) {
    // Timer expired actions
}

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Atimer2

Btimer_expired

Ctimer1

Dexpired

Attempts:

3 left

💡 Hint

Common Mistakes

Using generic words like 'expired' without the timer name.

Using incorrect timer names like 'timer2' if not defined.

The function to check if a timer expired is usually named with the timer's name followed by _expired(). Here, timer1_expired() is correct.

3fill in blank

hard

Fix the error in the timer initialization code.

Embedded C

void init_timer() {
    [1] = 0;
    TIMER_CONFIGURE(timer1, 1000);
}

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Atimer

Btimer1

Ccount

Dtimer1_count

Attempts:

3 left

💡 Hint

Common Mistakes

Resetting the timer variable instead of the count variable.

Using generic names like 'count' without context.

The variable timer1_count should be reset to zero to initialize the timer count properly.

4fill in blank

hard

Fill both blanks to create a delay using the timer.

Embedded C

while (![1]_expired()) {
    [2]();
}

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Atimer3

Bdo_nothing

Ctimer1

Dwait

Attempts:

3 left

💡 Hint

Common Mistakes

Using wrong timer names in the expiration check.

Leaving the loop body empty causing high CPU usage.

The loop waits until timer1_expired() returns true. Inside the loop, do_nothing() is called to avoid busy waiting.

5fill in blank

hard

Fill all three blanks to set up and start a timer with a callback.

Embedded C

void setup() {
    [1] = 500;
    TIMER_CONFIGURE(timer2, [2]);
    TIMER_START([3]);
}

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Adelay_ms

Ctimer2

Dtimer1

Attempts:

3 left

💡 Hint

Common Mistakes

Using different variable names for delay in the first two blanks.

Starting the wrong timer.

The variable delay_ms is set to 500 milliseconds. Then TIMER_CONFIGURE uses delay_ms to set the timer period. Finally, TIMER_START(timer2) starts the timer.