Section outline

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    Recap – Programming Basics

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    Programming Basics We’ve Learned So Far

    Before diving into more advanced Arduino programming, let’s take a quick look at the core concepts we’ve already explored in earlier courses. This will help you see how everything connects and why we are now ready to take the next step.

    • 🔌 What You’ve Already Done

      • Wired and programmed an LED to blink using digitalWrite().
      • Read button inputs using digitalRead() and made the LED respond.
      • Created simple logic for robots like the line follower using if-else conditions.
      • Viewed data using the Serial Monitor via Serial.print().

      📜 Structure You’ve Been Using

      You’ve worked with this basic Arduino sketch structure in almost every project:

      void setup() {
  // Runs once at the beginning
}

void loop() {
  // Runs again and again forever
}

      🧠 What You’ve Been Doing (Without Realizing)

      • Thinking logically: "If this happens, do that."
      • Creating simple functions like digitalWrite() and delay() in sequence.
      • Debugging issues by checking the Serial Monitor or adjusting values.

       

    • 🤔 Why Do We Need More?

      • Your programs are getting longer and harder to manage.
      • Copy-pasting the same lines makes your code messy.
      • You need to reuse code blocks with small changes.
      • You want smarter robots that respond to multiple inputs.

      ✅ What’s Coming Next?

      We’ll now learn how to:

      • Repeat actions using loops
      • Group tasks using custom functions
      • Use arrays to handle lots of similar values (like sensor readings)
      • Explore powerful libraries that save time and add new features

      This is where your journey from a beginner to a confident Arduino programmer truly begins.

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    Loops and Functions

    Making Your Code Smarter and Cleaner

    As your Arduino programs get more complex, you’ll want a cleaner, smarter way to repeat tasks and organize your code. That’s where loops and functions come in.

    • 🔁 Loops – Repeating Tasks Efficiently

      Loops help you repeat a set of instructions without writing them over and over again. Arduino already uses one loop automatically — the loop() function! But there are other types of loops:

      • for loop: Repeat a block a specific number of times.
      • while loop: Keep repeating as long as a condition is true.
      • do...while loop: Like while, but runs at least once before checking.
      Example: Blink an LED 5 times using a for loop
      void setup() {
  pinMode(13, OUTPUT);
  for (int i = 0; i < 5; i++) {
    digitalWrite(13, HIGH);
    delay(500);
    digitalWrite(13, LOW);
    delay(500);
  }
}

void loop() {
  // Empty because blinking was handled in setup()
}

    • 🧩 Functions – Reuse Your Code

      Functions help you write cleaner code by grouping repeated tasks. Instead of writing the same logic again and again, you just “call” the function.

      Example: Turning an LED ON and OFF using a function
      void blinkLED(int pin, int delayTime) {
  digitalWrite(pin, HIGH);
  delay(delayTime);
  digitalWrite(pin, LOW);
  delay(delayTime);
}

void setup() {
  pinMode(9, OUTPUT);
}

void loop() {
  blinkLED(9, 1000);
}

    • 🎯 Benefits of Using Loops and Functions

      • Write less code, do more!
      • Make your programs easier to read and fix.
      • Organize your project like a pro.

      🛠 Tip

      Always test your function with different inputs. Try changing blinkLED(9, 1000) to blinkLED(9, 300) to see what happens.

      Now that you know how to loop and reuse code, you’re ready to handle more complex behaviors. In the next section, we’ll explore how to store and manage more data using arrays.

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    Arrays

    Arrays – Handling Multiple Values Smartly

    As your projects grow, you might want to manage multiple values — like storing the readings from 3 sensors or controlling 4 LEDs. Instead of creating separate variables for each one, you can use an array.

    • 📦 What is an Array?

      An array is like a container that holds multiple values of the same type (like integers or floats), all under one name. Each item is stored at an index (starting from 0).

      Example: Store 4 LED pin numbers
      int ledPins[] = {3, 5, 6, 9};

      You can now access each LED pin using its index, like ledPins[0] or ledPins[3].

      💡 Using Arrays in a Loop

      This is where arrays really shine! Combine arrays with for loops to control many pins easily.

      Example: Turn ON all LEDs one by one
      int ledPins[] = {3, 5, 6, 9};

void setup() {
  for (int i = 0; i < 4; i++) {
    pinMode(ledPins[i], OUTPUT);
  }
}

void loop() {
  for (int i = 0; i < 4; i++) {
    digitalWrite(ledPins[i], HIGH);
    delay(300);
    digitalWrite(ledPins[i], LOW);
    delay(300);
  }
}

    • 🔍 When to Use Arrays?

      • When you have multiple sensors or outputs that behave similarly.
      • When you want to store multiple readings or values together.
      • When writing repeated logic with minimal code.

      ⚠️ Array Tips

      • Always start counting from index 0.
      • Make sure you don’t access an index outside the array size — it may cause bugs!
      • You can create arrays for int, float, char, and even custom data types.

      Now that you’ve learned how to group and use multiple values, let’s take it further and bring in some ready-made tools with libraries in the next section.

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    Libraries

    Libraries – Using Powerful Pre-Built Code

    As projects grow more complex, we often need to do things like read temperature from a sensor, display text on an LCD, or connect via Bluetooth. Instead of writing everything from scratch, we can use libraries.

    • 📚 What is a Library?

      A library in Arduino is a set of pre-written code that adds new capabilities to your sketch. Libraries are written by other developers to make your life easier.

      Examples of Popular Arduino Libraries:
      • LiquidCrystal – for controlling LCD displays
      • Servo – for controlling servo motors
      • DHT – for temperature and humidity sensors

    • 🔧 How to Use a Library?

      1. Install the library: In Arduino IDE, go to Sketch > Include Library > Manage Libraries
      2. Search and install: Type the name (e.g., “DHT”) and install it
      3. Include in your sketch: Use #include at the top of your code
      Example: Using the Servo Library
      #include <Servo.h>

Servo myServo;

void setup() {
  myServo.attach(9);  // Connect servo to pin 9
}

void loop() {
  myServo.write(0);    // Move to 0 degrees
  delay(1000);
  myServo.write(90);   // Move to 90 degrees
  delay(1000);
}

    • 🎯 Why Use Libraries?

      • Save time by avoiding complex coding from scratch
      • Work with popular sensors and modules easily
      • Code is cleaner, shorter, and easier to maintain

      🛠 Tips When Using Libraries

      • Always check the example sketches that come with libraries
      • Not all libraries support every board — check documentation
      • Keep libraries updated via Library Manager

      Libraries unlock powerful capabilities without needing deep code knowledge. In the next section, we'll see how to combine inputs from multiple sensors — a skill called Sensor Fusion.

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    Sensor Fusion

    Sensor Fusion – Combining Multiple Sensor Inputs

    Imagine a robot that avoids walls using an ultrasonic sensor and also follows a line using IR sensors. These are multiple inputs working together – this concept is called Sensor Fusion.

    • 🤖 What is Sensor Fusion?

      Sensor fusion is the process of using data from two or more sensors and combining them to make better decisions. It helps robots perform smarter actions based on a combination of inputs.

      🔄 Why Use Sensor Fusion?

      • One sensor might not be enough – combining improves reliability
      • Allows more accurate environment understanding
      • Reduces errors due to noise or limitations in one sensor

    • 📌 Real-life Examples:

      • Self-driving cars use cameras + radar + lidar
      • Smartphones use gyroscope + accelerometer for screen orientation
      • Drones use GPS + compass + barometer for stable flight

      🛠 Arduino Example: IR + Ultrasonic

      Let’s say we want a robot that follows a line but stops if there’s an obstacle ahead. Here's how logic works:

      1. IR sensors detect line and control steering
      2. Ultrasonic sensor checks for obstacles in front
      3. If obstacle < 10 cm, robot stops even if line is visible
      🧪 Sample Code Snippet:
      int distance = readUltrasonic();
int lineLeft = digitalRead(2);
int lineRight = digitalRead(3);

if (distance < 10) {
  stopMotors();
} else {
  if (lineLeft == LOW && lineRight == LOW) {
    moveForward();
  } else if (lineLeft == LOW) {
    turnLeft();
  } else if (lineRight == LOW) {
    turnRight();
  } else {
    stopMotors();
  }
}

      💡 Tips for Sensor Fusion

      • Start with simple logic — avoid overcomplicating
      • Test each sensor separately before combining
      • Use comments to keep logic clear and maintainable

      Sensor fusion helps your robot make better decisions — a critical step in moving from basic bots to intelligent ones. Up next, we’ll build a live multi-sensor display to visualize all this in action!

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    Coding Lab

    Coding Lab – Multi-Sensor Data Display

    Now that we understand how multiple sensors can work together, it’s time to bring it all into a visual format. In this coding lab, we will learn how to read sensor data and display it on the Serial Monitor for debugging, analysis, and interaction.

    • 🎯 Objective:

      Build an Arduino sketch that reads values from multiple sensors (IR, Ultrasonic, Temperature, etc.) and prints them clearly on the Serial Monitor.

      📦 What You’ll Need:

      • 1 x Ultrasonic sensor (HC-SR04)
      • 2 x IR sensors (line tracking type)
      • 1 x Temperature sensor (e.g., LM35 or DHT11)
      • Arduino board + USB cable
      • Jumper wires and breadboard

      🔌 Circuit Setup Overview:

      • Connect ultrasonic sensor to digital pins (e.g., 7 for Trigger, 6 for Echo)
      • Connect IR sensors to digital pins (e.g., 2 and 3)
      • Connect temperature sensor to analog pin (e.g., A0)

    • 💻 Sample Code:

      long readUltrasonicDistance() {
  digitalWrite(7, LOW);
  delayMicroseconds(2);
  digitalWrite(7, HIGH);
  delayMicroseconds(10);
  digitalWrite(7, LOW);
  return pulseIn(6, HIGH) / 58;
}

void setup() {
  Serial.begin(9600);
  pinMode(2, INPUT);
  pinMode(3, INPUT);
  pinMode(7, OUTPUT); // Trigger
  pinMode(6, INPUT);  // Echo
}

void loop() {
  int irLeft = digitalRead(2);
  int irRight = digitalRead(3);
  long distance = readUltrasonicDistance();
  int tempReading = analogRead(A0);
  float voltage = tempReading * 5.0 / 1024.0;
  float temperatureC = voltage * 100;

  Serial.print("IR Left: ");
  Serial.print(irLeft);
  Serial.print(" | IR Right: ");
  Serial.print(irRight);
  Serial.print(" | Distance: ");
  Serial.print(distance);
  Serial.print(" cm | Temp: ");
  Serial.print(temperatureC);
  Serial.println(" C");

  delay(1000);
}

      📊 What to Observe:

      • Watch how the data updates every second
      • Try placing your hand in front of the ultrasonic sensor and see the change
      • Warm up the temperature sensor gently and observe value increase
      • Move the robot over dark/white surfaces to test IR values

      🔍 Debugging Tips:

      • If no values are showing, check sensor connections and power
      • Use Serial.println() to isolate specific values
      • Use LEDs or buzzers to provide physical feedback for sensor ranges

      This lab sets the foundation for real-world monitoring. In later courses, we’ll use LCD screens or Bluetooth apps to view sensor data remotely!

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    Summary and Quiz

    Congratulations on completing Intermediate Arduino Programming!

    • In this course, you explored loops, functions, arrays, and how to use libraries effectively.
    • You also learned how to fuse sensor data for better decision-making in robotic systems.
    • Your final coding lab helped you display multiple sensor outputs in a structured way.
    • Now it's time to check your understanding with a quick quiz. Good luck!
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