Error handling in embedded projects in Arduino - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to check if a sensor reading is valid before using it.

Arduino

int sensorValue = analogRead(A0);
if (sensorValue [1] 0) {
  Serial.println("Sensor reading is valid.");
}

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

A>

B<

C==

D!=

Attempts:

3 left

💡 Hint

Common Mistakes

Using '==' instead of '>' causes the check to only pass if sensorValue is exactly zero.

Using '<' will check for negative values, which sensorValue cannot be.

We check if the sensor value is greater than 0 to ensure it is valid.

2fill in blank

medium

Complete the code to retry reading the sensor if the value is invalid (zero).

Arduino

int sensorValue = 0;
while (sensorValue [1] 0) {
  sensorValue = analogRead(A1);
  delay(100);
}

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

A==

B>

C<

D!=

Attempts:

3 left

💡 Hint

Common Mistakes

Using '!=' will cause the loop to run when sensorValue is not zero, which is wrong.

Using '>' or '<' will not correctly check for zero.

The loop continues while sensorValue equals zero, retrying the read.

3fill in blank

hard

Fix the error in the code to handle sensor failure by setting an error flag.

Arduino

bool errorFlag = false;
int sensorValue = analogRead(A2);
if (sensorValue [1] 0) {
  errorFlag = true;
}

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

A<

B>

C==

D!=

Attempts:

3 left

💡 Hint

Common Mistakes

Using '!=' will set errorFlag when sensorValue is anything but 0.

Using '>' or '<' will not correctly detect the error code.

We check if sensorValue equals 0, which indicates a failure.

4fill in blank

hard

Fill the blank to set the sensor status if value is above threshold.

Arduino

const int threshold = 500;
int sensorValue = analogRead(A4);
String sensorStatus = (sensorValue [1] threshold) ? "OK" : "FAIL";

void setup() {
  Serial.begin(9600);
  Serial.println("Sensor status: " + sensorStatus);
}

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

A<

B>

C==

D!=

Attempts:

3 left

💡 Hint

Common Mistakes

Using '<' will invert the logic.

Using '==' or '!=' will only check equality, not greater than.

The ternary operator checks if sensorValue is greater than threshold to set status.

5fill in blank

hard

Fill all three blanks to log error messages only when errorFlag is true and sensorValue is invalid.

Arduino

bool errorFlag = false;
int sensorValue = analogRead(A3);

if (sensorValue [1] 0) {
  errorFlag = true;
}

if (errorFlag [2] true && sensorValue [3] 0) {
  Serial.println("Error: Sensor failure detected.");
}

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

A==

D!=

Attempts:

3 left

💡 Hint

Common Mistakes

Using '!=' will invert the logic and cause wrong behavior.

Mixing operators will cause syntax or logic errors.

All conditions check equality to detect error and print message.

Practice

1. What is the main purpose of error handling in embedded projects like Arduino?

easy

A. To increase the power consumption of the device

B. To make the code run faster without checks

C. To add more sensors to the project

D. To detect and manage problems to keep the project safe and reliable

Solution

1. Step 1: Understand the role of error handling

   Error handling is used to find and manage problems that may happen during the project operation.

2. Step 2: Identify the goal of error handling in embedded systems

   It helps keep the system safe and reliable by preventing crashes or unexpected behavior.

3. Final Answer:

   To detect and manage problems to keep the project safe and reliable -> Option D

4. Quick Check:

   Error handling = detect and manage problems [OK]

Hint: Error handling means catching problems early [OK]

Common Mistakes:

• Thinking error handling speeds up code
• Confusing error handling with adding features
• Ignoring safety and reliability

2. Which of the following is the correct way to check for an error after reading a sensor value in Arduino?

easy

A. if (sensorValue == -1) { handleError(); }

B. if sensorValue = -1 then handleError();

C. if (sensorValue = -1) { handleError(); }

D. if sensorValue == -1 { handleError(); }

Solution

1. Step 1: Identify correct syntax for if statement in Arduino (C++)

   The condition must be inside parentheses and use double equals (==) to compare.

2. Step 2: Check each option for syntax correctness

   if (sensorValue == -1) { handleError(); } uses correct syntax: if (sensorValue == -1) { handleError(); }

3. Final Answer:

   if (sensorValue == -1) { handleError(); } -> Option A

4. Quick Check:

   Correct if syntax uses parentheses and '==' [OK]

Hint: Use '==' inside parentheses for comparisons [OK]

Common Mistakes:

• Using single '=' instead of '==' for comparison
• Missing parentheses around condition
• Using wrong keywords like 'then'

3. What will be the output on Serial Monitor if the following Arduino code runs and sensorValue is -1?

int sensorValue = -1;
void setup() {
  Serial.begin(9600);
  if (sensorValue == -1) {
    Serial.println("Error: Sensor not found");
  } else {
    Serial.println("Sensor OK");
  }
}
void loop() {}

medium

A. Sensor OK

B. Error: Sensor not found

C. No output

D. Compilation error

Solution

1. Step 1: Check the value of sensorValue

   sensorValue is set to -1 before setup runs.

2. Step 2: Evaluate the if condition in setup()

   Since sensorValue == -1 is true, the code prints "Error: Sensor not found" to Serial.

3. Final Answer:

   Error: Sensor not found -> Option B

4. Quick Check:

   sensorValue == -1 triggers error message [OK]

Hint: Trace variable values to predict output [OK]

Common Mistakes:

• Assuming else branch runs when condition is true
• Forgetting Serial.begin() before printing
• Confusing output with compilation errors

4. Identify the error in this Arduino code snippet for error handling:

int readSensor() {
  int val = analogRead(A0);
  if (val = -1) {
    return -1;
  }
  return val;
}

medium

A. Function should return void, not int

B. Missing semicolon after return statements

C. Using '=' instead of '==' in the if condition

D. analogRead() cannot return -1

Solution

1. Step 1: Check the if condition syntax

   The code uses single '=' which assigns -1 to val instead of comparing.

2. Step 2: Understand the impact of assignment in condition

   Assignment returns the assigned value, so condition is always true (-1 is true in C++), causing wrong behavior.

3. Final Answer:

   Using '=' instead of '==' in the if condition -> Option C

4. Quick Check:

   Use '==' to compare, not '=' [OK]

Hint: Use '==' for comparison, '=' for assignment [OK]

Common Mistakes:

• Confusing '=' and '==' in conditions
• Assuming analogRead returns -1 normally
• Ignoring return type correctness

5. You want to indicate an error in your Arduino project using an LED connected to pin 13. Which code snippet correctly turns the LED on when an error occurs (errorCode != 0) and off otherwise?

hard

A. if (errorCode != 0) { digitalWrite(13, HIGH); } else { digitalWrite(13, LOW); }

B. if (errorCode = 0) { digitalWrite(13, HIGH); } else { digitalWrite(13, LOW); }

C. if (errorCode != 0) { digitalWrite(13, LOW); } else { digitalWrite(13, HIGH); }

D. digitalWrite(13, errorCode);

Solution

1. Step 1: Understand the logic for error indication

   LED should be ON (HIGH) when errorCode is not zero, OFF (LOW) otherwise.

2. Step 2: Check each option for correct logic and syntax

   if (errorCode != 0) { digitalWrite(13, HIGH); } else { digitalWrite(13, LOW); } correctly uses '!=' to check error and sets pin 13 HIGH or LOW accordingly.

3. Final Answer:

   if (errorCode != 0) { digitalWrite(13, HIGH); } else { digitalWrite(13, LOW); } -> Option A

4. Quick Check:

   Use '!=' and digitalWrite HIGH/LOW correctly [OK]

Hint: Turn LED HIGH on error, LOW otherwise [OK]

Common Mistakes:

• Using '=' instead of '!=' in condition
• Reversing HIGH and LOW states
• Passing errorCode directly to digitalWrite