Error handling in embedded projects in Arduino

Introduction

Error handling helps your device keep working even when something goes wrong. It makes your project more reliable and safe.

When reading data from sensors that might fail or give wrong values.

When communicating with other devices and the connection might drop.

When saving data to memory that might be full or corrupted.

When controlling motors or actuators that might get stuck or overload.

Syntax

Arduino

// Example of simple error check
if (sensorValue == ERROR_CODE) {
  // handle error
} else {
  // normal operation
}

Arduino C++ does not support try-catch like some languages.

Use if-else checks and return codes to detect errors.

Examples

Check if sensor returns -1 as error, then print message.

Arduino

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

Check if writing to memory failed and print error.

Arduino

bool success = writeMemory(data);
if (!success) {
  Serial.println("Memory write failed");
}

Simple check for input pin state, can detect if button is pressed or not.

Arduino

if (digitalRead(buttonPin) == LOW) {
  // Button pressed
} else {
  // Button not pressed
}

Sample Program

This program reads a sensor value. If the value is too high (above threshold), it treats it as an error and prints an error message. Otherwise, it prints the sensor value.

Arduino

#include <Arduino.h>

const int sensorPin = A0;
const int errorThreshold = 1000; // example error threshold

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

int readSensor() {
  int value = analogRead(sensorPin);
  if (value > errorThreshold) {
    return -1; // error code
  }
  return value;
}

void loop() {
  int sensorValue = readSensor();
  if (sensorValue == -1) {
    Serial.println("Error: Sensor reading out of range!");
  } else {
    Serial.print("Sensor value: ");
    Serial.println(sensorValue);
  }
  delay(1000);
}

Important Notes

Always define clear error codes or conditions for your sensors or devices.

Use Serial prints or LEDs to show errors for easier debugging.

Keep error handling simple to avoid slowing down your embedded system.

Summary

Error handling keeps your embedded project safe and reliable.

Use if-else checks and return codes to detect problems.

Show errors clearly using Serial or LEDs for easy fixing.

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