Health monitoring and heartbeat in FreeRTOS - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to create a heartbeat task that toggles an LED.

FreeRTOS

void HeartbeatTask(void *pvParameters) {
    for(;;) {
        ToggleLED();
        vTaskDelay([1]);
    }
}

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

A100 / portTICK_PERIOD_MS

B10 / portTICK_PERIOD_MS

C1000 / portTICK_PERIOD_MS

D5000 / portTICK_PERIOD_MS

Attempts:

3 left

💡 Hint

Common Mistakes

Using too long or too short delay causing no visible heartbeat.

The heartbeat task should delay for 100 milliseconds to toggle the LED regularly.

2fill in blank

medium

Complete the code to initialize the watchdog timer with a timeout.

FreeRTOS

void InitWatchdog() {
    Watchdog_Config config = {
        .timeout = [1]
    };
    Watchdog_Init(&config);
}

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

A5000

B20000

C1000

D10000

Attempts:

3 left

💡 Hint

Common Mistakes

Setting timeout too short causing frequent resets.

The watchdog timeout is set to 10000 milliseconds (10 seconds) to allow enough time for system checks.

3fill in blank

hard

Fix the error in the watchdog refresh function to prevent system reset.

FreeRTOS

void RefreshWatchdog() {
    [1]();
}

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

AWatchdog_Feed

BWatchdog_Reset

CWatchdog_Refresh

DWatchdog_Kick

Attempts:

3 left

💡 Hint

Common Mistakes

Using a non-existent function name causing compile errors.

The correct function to refresh the watchdog timer is Watchdog_Feed().

4fill in blank

hard

Fill both blanks to create a health check task that signals system status.

FreeRTOS

void HealthCheckTask(void *pvParameters) {
    for(;;) {
        if(SystemIsHealthy()) {
            SignalStatus([1]);
        } else {
            SignalStatus([2]);
        }
        vTaskDelay(1000 / portTICK_PERIOD_MS);
    }
}

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

ALED_GREEN

BLED_RED

CLED_BLUE

DLED_YELLOW

Attempts:

3 left

💡 Hint

Common Mistakes

Swapping LED colors causing confusing signals.

Use LED_GREEN to indicate healthy status and LED_RED for unhealthy status.

5fill in blank

hard

Fill all three blanks to create a dictionary mapping task names to their heartbeat intervals.

FreeRTOS

const TaskHeartbeatConfig taskHeartbeats = {
    [1]: [2],
    [3]: 500
};

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

A"SensorTask"

B1000

C"CommTask"

D2000

Attempts:

3 left

💡 Hint

Common Mistakes

Mixing keys and values or using wrong data types.

SensorTask has a heartbeat interval of 2000 ms, CommTask has 500 ms.

Practice

1. What is the main purpose of a heartbeat task in FreeRTOS?

easy

A. To permanently block other tasks from running

B. To repeatedly indicate the system is running and healthy

C. To increase CPU usage by running continuously without delay

D. To handle user input events exclusively

Solution

1. Step 1: Understand heartbeat task role

   A heartbeat task runs repeatedly to show the system is alive and working properly.

2. Step 2: Eliminate incorrect options

   Blocking other tasks or handling user input are not typical heartbeat functions.

3. Final Answer:

   To repeatedly indicate the system is running and healthy -> Option B

4. Quick Check:

   Heartbeat = system health indicator [OK]

Hint: Heartbeat tasks show system health by running repeatedly [OK]

Common Mistakes:

• Thinking heartbeat blocks other tasks
• Assuming heartbeat handles user input
• Believing heartbeat increases CPU load unnecessarily

2. Which FreeRTOS function is best to use inside a heartbeat task to wait without blocking other tasks?

easy

A. vTaskResume()

B. vTaskSuspend()

C. vTaskDelete()

D. vTaskDelay()

Solution

1. Step 1: Identify delay function for non-blocking wait

   vTaskDelay() suspends the task for a time, allowing others to run.

2. Step 2: Understand other functions

   vTaskSuspend() pauses a task indefinitely, vTaskDelete() removes it, and vTaskResume() restarts a suspended task.

3. Final Answer:

   vTaskDelay() -> Option D

4. Quick Check:

   Use vTaskDelay() for timed waits [OK]

Hint: Use vTaskDelay() to wait without blocking [OK]

Common Mistakes:

• Using vTaskSuspend() which blocks indefinitely
• Confusing vTaskDelete() with delay
• Trying vTaskResume() to wait

3. Given this heartbeat task snippet, what will be the output if the task runs correctly?

void vHeartbeatTask(void *pvParameters) {
  for (;;) {
    printf("Heartbeat\n");
    vTaskDelay(pdMS_TO_TICKS(1000));
  }
}

medium

A. Prints "Heartbeat" once and stops

B. Prints "Heartbeat" continuously without delay

C. Prints "Heartbeat" every second repeatedly

D. Does not print anything due to syntax error

Solution

1. Step 1: Analyze the infinite loop

   The for(;;) loop runs forever, printing "Heartbeat" each cycle.

2. Step 2: Check the delay function

   vTaskDelay(pdMS_TO_TICKS(1000)) pauses the task for 1000 ms (1 second) between prints.

3. Final Answer:

   Prints "Heartbeat" every second repeatedly -> Option C

4. Quick Check:

   Infinite loop + vTaskDelay(1s) = repeated print every second [OK]

Hint: Infinite loop with vTaskDelay prints repeatedly [OK]

Common Mistakes:

• Thinking it prints only once
• Ignoring the delay causing continuous print
• Assuming syntax error without checking code

4. Identify the error in this heartbeat task code snippet:

void vHeartbeatTask(void *pvParameters) {
  while(1) {
    printf("Heartbeat\n");
    vTaskDelay(1000);
  }
}

medium

A. vTaskDelay() argument should be in ticks, not milliseconds

B. printf() cannot be used inside tasks

C. while(1) should be for(;;)

D. Missing task notification call

Solution

1. Step 1: Check vTaskDelay argument type

   vTaskDelay() expects delay in ticks, not milliseconds directly.

2. Step 2: Correct usage

   Use pdMS_TO_TICKS(1000) to convert 1000 ms to ticks for vTaskDelay.

3. Final Answer:

   vTaskDelay() argument should be in ticks, not milliseconds -> Option A

4. Quick Check:

   vTaskDelay(ms) wrong, use pdMS_TO_TICKS(ms) [OK]

Hint: Always convert ms to ticks with pdMS_TO_TICKS() [OK]

Common Mistakes:

• Passing milliseconds directly to vTaskDelay()
• Thinking printf() is disallowed in tasks
• Believing while(1) is invalid syntax

5. You want to implement a heartbeat task that signals system health by toggling an LED every 500 ms and also logs a message every 5 seconds. Which approach is best?

hard

A. Create two separate tasks: one toggling LED every 500 ms, another logging every 5 seconds

B. Use one task with vTaskDelay(500) to toggle LED and count loops to log every 5 seconds

C. Use a single task with vTaskDelay(5000) to do both toggle and log at once

D. Toggle LED and log message without any delay to maximize responsiveness

Solution

1. Step 1: Understand timing requirements

   LED toggles every 500 ms, logging every 5 seconds require different intervals.

2. Step 2: Evaluate task design options

   Two separate tasks allow independent timing without complex counting or blocking.

3. Step 3: Consider drawbacks of other options

   Single task with 500 ms delay and counting adds complexity; 5000 ms delay misses LED timing; no delay wastes CPU.

4. Final Answer:

   Create two separate tasks: one toggling LED every 500 ms, another logging every 5 seconds -> Option A

5. Quick Check:

   Separate tasks for different intervals = clean design [OK]

Hint: Use separate tasks for different heartbeat intervals [OK]

Common Mistakes:

• Trying to handle all timing in one task
• Using long delays missing faster toggles
• No delays causing CPU overload