📘Loops

🎯 Lesson Objective

By the end of this lesson, students will:

• Understand what a loop is

• Learn how for loop works

• Learn how while loop works

• Understand infinite loop concept

• Understand how loop() function is an infinite loop

• Apply loops in IoT logic

1️⃣ What is a Loop?

A loop is a programming structure that repeats a block of code multiple times.

In simple words:

A loop allows a program to do something again and again.

Repetition is essential in automation systems.

2️⃣ Why Loops Are Important in IoT

IoT systems must:

• Continuously read sensors

• Continuously check conditions

• Continuously send data

• Continuously monitor state

Without loops:

System would run once and stop.

Microcontrollers must keep working forever.

3️⃣ Types of Loops in Arduino / C++

We will focus on:

1️⃣ for loop
2️⃣ while loop
3️⃣ Infinite loop concept

🔹 4️⃣ The for Loop

Used when you know how many times to repeat something.

🔹 Syntax

for (initialization; condition; update) {
// code block
}

Structure:

1. Initialization → runs once

2. Condition → checked before each iteration

3. Update → runs after each iteration

📌 Example 1 – Count from 1 to 5

Output:
1
2
3
4
5

Explanation:

• i starts at 1

• Runs while i <= 5

• After each loop → i increases

📌 Real IoT Example – LED Blink 5 Times

for (int i = 0; i < 5; i++) {
digitalWrite(2, HIGH);
delay(500);
digitalWrite(2, LOW);
delay(500);
}

LED blinks exactly 5 times.

🔹 5️⃣ The while Loop

Used when repetition depends on a condition.

🔹 Syntax

while (condition) {
// code block
}

The loop runs as long as condition is true.

📌 Example – Count Until 5

int i = 1;

while (i <= 5) {
Serial.println(i);
i++;
}

Runs until condition becomes false.

📌 Real IoT Example – Wait for WiFi Connection

while (WiFi.status() != WL_CONNECTED) {
delay(500);
Serial.println("Connecting...");
}

Loop runs until WiFi connects.

This is very common in IoT systems.

6️⃣ Infinite Loop Concept

An infinite loop runs forever.

Example:

This loop never stops.

🔹 How Arduino Uses Infinite Loop

Remember:

Arduino has:

void loop() {
}

Internally, it behaves like:

while(true) {
loop();
}

That means:

loop() runs forever.

Microcontrollers are designed for continuous operation.

7️⃣ Difference Between for and while

8️⃣ Using break in Loops

Sometimes we want to stop loop early.

Example:

for (int i = 0; i < 10; i++) {
if (i == 5) {
break;
}
Serial.println(i);
}

Stops at 5.

Break exits loop immediately.

9️⃣ Using continue in Loops

Continue skips current iteration.

Example:

for (int i = 0; i < 5; i++) {
if (i == 2) {
continue;
}
Serial.println(i);
}

Skips printing 2.

🔟 Real IoT Example – Sensor Monitoring

void loop() {
int temperature = analogRead(34);

if (temperature > 30) {
Serial.println("High Temperature");
}

delay(1000);
}

loop() keeps checking sensor continuously.

This is real-time monitoring.

1️⃣1️⃣ Dangerous Infinite Loop

Example:

while (true) {
Serial.println("Hello");
}

This will:

• Flood Serial Monitor

• Freeze system

Always use delay or proper condition.

1️⃣2️⃣ Blocking vs Non-Blocking Thinking

Using delay():

delay(5000);

System waits 5 seconds doing nothing.

In advanced IoT systems, this is not ideal.

Later in course, you may learn:

millis() based timing (non-blocking logic).

For now, delay is acceptable.

1️⃣3️⃣ Combining Loops and Conditions

Example:

int gasValue = 0;

while (gasValue < 1000) {
gasValue = analogRead(34);
Serial.println(gasValue);
}

System keeps checking gas until threshold reached.

This builds safety monitoring logic.

1️⃣4️⃣ Common Beginner Mistakes

❌ Forgetting to update variable in while loop
❌ Creating infinite loop accidentally
❌ No delay → too fast execution
❌ Using loop inside loop() unnecessarily

Example mistake:

while (i < 5) {
}

If i never changes → infinite loop.

📌 Lesson Summary

In this lesson, we learned:

• What loops are

• for loop structure

• while loop structure

• Infinite loop concept

• How Arduino loop() works

• break and continue

• Real IoT examples

Loops allow systems to monitor continuously.

Without loops:
Automation is impossible.