Error handling in embedded projects in Arduino - Practice Problems & Coding Challenges

Challenge - 5 Problems

❓ Predict Output

intermediate

What is the output of this Arduino error handling code?

Consider this Arduino sketch snippet that reads a sensor value and checks for errors. What will be printed to the serial monitor?

Arduino

int sensorValue = analogRead(A0);
if (sensorValue < 0) {
  Serial.println("Error: Sensor read failed");
} else {
  Serial.print("Sensor value: ");
  Serial.println(sensorValue);
}

A No output

B Error: Sensor read failed

C Sensor value: 512

D Sensor value: 0

💡 Hint

analogRead returns values from 0 to 1023. Negative values do not occur.

analogRead returns a value between 0 and 1023. It never returns negative values, so the error condition is never true. The code prints the sensor value, which is 0 if nothing is connected.

🧠 Conceptual

intermediate

Which method is best for detecting sensor failure in Arduino?

In embedded projects, sensors may fail or give invalid data. Which approach below is the best way to detect a sensor failure?

A Check if sensor value is outside expected range

B Check if sensor value is exactly zero

C Check if sensor value is negative

D Ignore sensor values and use fixed defaults

💡 Hint

Think about what real sensor values look like and how to spot invalid readings.

Checking if the sensor value is outside the expected range is the best way to detect failure. Sensors rarely produce exactly zero or negative values unless faulty.

🔧 Debug

advanced

Why does this Arduino error handler always print the error message?

Examine the code below. The error message always appears even when the sensor is disconnected. Why?

Arduino

int sensorValue = analogRead(A0);
if (sensorValue == -1) {
  Serial.println("Sensor error detected");
} else {
  Serial.println(sensorValue);
}

A The condition uses assignment (=) instead of comparison (==)

B analogRead never returns -1

C Serial.println is not initialized

D sensorValue is not declared

💡 Hint

Look closely at the if condition syntax.

The condition uses '=' which assigns -1 to sensorValue instead of comparing. This always evaluates to true, but sensorValue is set to -1, which is invalid for analogRead. The error message should print but the logic is flawed.

📝 Syntax

advanced

Which option fixes the syntax error in this Arduino error handling snippet?

Identify the option that corrects the syntax error in this code:

if sensorValue < 0 {
  Serial.println("Error");
}

A

if sensorValue < 0:
  Serial.println("Error")

B

if (sensorValue < 0)
  Serial.println("Error");

C

if (sensorValue < 0) {
  Serial.println("Error");
}

D

if sensorValue < 0 then {
  Serial.println("Error");
}

💡 Hint

Arduino uses C++ syntax for conditions.

Arduino requires parentheses around the condition and braces for the block. Option C correctly uses parentheses and braces.

🚀 Application

expert

How many times will the error handler run in this Arduino loop?

Given this code snippet, how many times will the error message print if the sensor is disconnected and analogRead returns 0 every time?

void loop() {
  int val = analogRead(A0);
  if (val < 10) {
    Serial.println("Sensor error");
  }
  delay(1000);
}

A It prints once and stops

B It prints every second indefinitely

C It never prints

D It prints twice then stops

💡 Hint

Consider the loop behavior and delay.

The loop runs repeatedly. Since analogRead returns 0 (less than 10), the error message prints every time the loop runs, which is every second due to delay(1000).