Error handling in embedded projects in Arduino - Mini Project: Build & Apply

Error handling in embedded projects

📖 Scenario: You are building a simple embedded system using an Arduino board. The system reads temperature data from a sensor and displays it on the serial monitor. Sometimes, the sensor might fail or give invalid readings. You want to handle these errors gracefully to keep your system running smoothly.

🎯 Goal: Create an Arduino program that reads temperature values from a sensor, checks for errors, and prints either the temperature or an error message to the serial monitor.

📋 What You'll Learn

Create a variable to store the temperature reading.

Create a variable to represent an error code.

Use an if-else statement to check if the temperature reading is valid.

Print the temperature if valid, or print an error message if invalid.

💡 Why This Matters

🌍 Real World

Embedded systems often read sensors that can fail or give bad data. Handling errors prevents crashes and helps maintain reliable operation.

💼 Career

Understanding error handling in embedded projects is essential for developing robust firmware in IoT devices, automotive systems, and consumer electronics.

1

DATA SETUP: Create variables for temperature and error code

Create a variable called temperature of type float and set it to -1000.0 to represent an invalid initial reading. Also create an int variable called errorCode and set it to 0 to represent no error.

Arduino

# Create variables temperature and errorCode
// Your code here

Hint

Use float temperature = -1000.0; and int errorCode = 0;

2

CONFIGURATION: Simulate reading temperature and error code

Set temperature to 25.5 to simulate a valid sensor reading. Set errorCode to 0 to indicate no error.

Arduino

float temperature = -1000.0;
int errorCode = 0;
// Simulate sensor reading and error code
// Your code here

Hint

Assign temperature = 25.5; and errorCode = 0;

3

CORE LOGIC: Check for errors and handle invalid readings

Write an if statement that checks if errorCode is 0. If yes, do nothing. Otherwise, set temperature to -1000.0 to mark it invalid.

Arduino

float temperature = 25.5;
int errorCode = 0;
// Check errorCode and update temperature if error
// Your code here

Hint

Use if (errorCode != 0) and inside set temperature = -1000.0;

4

OUTPUT: Print temperature or error message to Serial Monitor

Use Serial.begin(9600); in setup(). In loop(), use an if statement to check if temperature is not -1000.0. If valid, print "Temperature: " followed by temperature. Otherwise, print "Error reading temperature!".

Arduino

float temperature = 25.5;
int errorCode = 0;

if (errorCode != 0) {
  temperature = -1000.0;
}

void setup() {
  Serial.begin(9600);
}

void loop() {
  // Print temperature or error message
  // Your code here
}

Hint

Use Serial.print and Serial.println inside loop() with an if to check temperature.

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