Error handling in embedded projects in Arduino - Step-by-Step Execution

Concept Flow - Error handling in embedded projects

Start Program

↓

Perform Operation

↓

Check for Error?

No→Continue Normal Flow

Yes↓

Handle Error

↓

Decide: Retry or Abort?

Retry→Perform Operation

↓

Stop or Safe State

↓

End

The program runs an operation, checks for errors, handles them if found, then decides to retry or stop safely.

Execution Sample

Arduino

int sensorValue = analogRead(A0);
if(sensorValue < 0 || sensorValue > 1023) {
  Serial.println("Error: Sensor out of range");
  // handle error
}

Reads a sensor value and checks if it is outside the valid range, printing an error message if so.

Execution Table

Step	Action	sensorValue	Condition	Result	Output
1	Read sensor value	512	512 < 0 or 512 > 1023?	False
2	Continue normal flow	512	-	-
3	Read sensor value	-5	-5 < 0 or -5 > 1023?	True
4	Print error message	-5	-	Error handled	Error: Sensor out of range
5	Decide next step	-5	Retry or Abort?	Abort	Stop or safe state
6	Program ends or waits	-5	-	-

💡 Program stops or waits after handling error and deciding to abort.

Variable Tracker

Variable	Start	After Step 1	After Step 3	Final
sensorValue	undefined	512	-5	-5

Key Moments - 3 Insights

Why do we check if sensorValue is less than 0 or greater than 1023?

Because analogRead returns values between 0 and 1023; values outside this range indicate an error, as shown in execution_table step 3.

What happens if an error is detected?

The program prints an error message and then decides whether to retry or stop, as seen in execution_table steps 4 and 5.

Why might the program choose to abort instead of retrying?

To avoid endless loops or unsafe states, the program stops safely after error handling, shown in execution_table step 5.

Visual Quiz - 3 Questions

Look at the execution table, what is sensorValue at step 3?

A -5

B 512

C 1023

D 0

💡 Hint

Check the 'sensorValue' column in execution_table row for step 3.

At which step does the program print the error message?

A Step 2

B Step 4

C Step 5

D Step 1

💡 Hint

Look at the 'Output' column in execution_table to find when the error message appears.

If sensorValue was always valid, which step would never occur?

A Step 2

B Step 1

C Step 3

D Step 6

💡 Hint

Step 3 shows the error condition; if no error, this step is skipped.

Concept Snapshot

Error handling in embedded projects:
- Check sensor or operation results for valid ranges
- If error detected, print message or signal error
- Decide to retry operation or stop safely
- Avoid infinite loops by aborting on persistent errors
- Use simple if conditions to detect errors

Full Transcript

This example shows how an embedded program reads a sensor value and checks if it is within the valid range of 0 to 1023. If the value is outside this range, it prints an error message and decides whether to retry the operation or stop safely. The execution table traces each step, showing variable values and decisions. Beginners often wonder why the range check is needed and what happens when an error occurs. The program avoids unsafe states by stopping if errors persist. This simple pattern helps embedded projects handle errors clearly and safely.

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