WiFi with ESP8266/ESP32 in Arduino - Mini Project: Build & Apply

WiFi with ESP8266/ESP32

📖 Scenario: You want to connect your ESP8266 or ESP32 microcontroller to a WiFi network so it can communicate with other devices or the internet.

🎯 Goal: Build a simple Arduino program that connects your ESP8266/ESP32 to a WiFi network and prints the connection status and IP address to the Serial Monitor.

📋 What You'll Learn

Create variables for WiFi network name and password

Initialize WiFi connection using the variables

Check connection status in a loop until connected

Print connection status and IP address to Serial Monitor

💡 Why This Matters

🌍 Real World

Connecting ESP8266 or ESP32 to WiFi is the first step to making smart devices that can send data to the internet or be controlled remotely.

💼 Career

Understanding how to connect microcontrollers to WiFi networks is essential for IoT developers and embedded systems engineers.

1

Set up WiFi network credentials

Create two variables called ssid and password and set them to the exact strings "YourNetworkName" and "YourNetworkPassword" respectively.

Arduino

// Create variables for WiFi network name and password
// Your code here

Hint

Use const char* type for the network name and password strings.

2

Start Serial and WiFi connection

Add void setup() function. Inside it, start Serial communication at 115200 baud with Serial.begin(115200);. Then start WiFi connection using WiFi.begin(ssid, password);.

Arduino

const char* ssid = "YourNetworkName";
const char* password = "YourNetworkPassword";

void setup() {
  // Start Serial communication
  // Start WiFi connection
  // Your code here
}

Hint

Use Serial.begin(115200); to start serial and WiFi.begin(ssid, password); to start connecting.

3

Wait for WiFi connection

Inside void setup(), add a while loop that waits until WiFi.status() == WL_CONNECTED. Inside the loop, print "Connecting to WiFi..." to Serial and add a 500 ms delay.

Arduino

const char* ssid = "YourNetworkName";
const char* password = "YourNetworkPassword";

void setup() {
  Serial.begin(115200);
  WiFi.begin(ssid, password);
  // Wait for connection
  // Your code here
}

Hint

Use while loop to check connection status and delay(500); to wait half a second each time.

4

Print connection success and IP address

After the while loop in setup(), print "WiFi connected!" and then print the IP address using WiFi.localIP() with Serial.println().

Arduino

const char* ssid = "YourNetworkName";
const char* password = "YourNetworkPassword";

void setup() {
  Serial.begin(115200);
  WiFi.begin(ssid, password);

  while (WiFi.status() != WL_CONNECTED) {
    Serial.println("Connecting to WiFi...");
    delay(500);
  }
  // Print connection success and IP address
  // Your code here
}

Hint

Use Serial.println("WiFi connected!"); and Serial.println(WiFi.localIP()); to show the IP address.

Practice

1. What is the main purpose of WiFi.begin(ssid, password) in ESP8266/ESP32 programming?

easy

A. To start connecting the device to a WiFi network

B. To disconnect from the current WiFi network

C. To check the current WiFi signal strength

D. To get the IP address of the device

Solution

1. Step 1: Understand the function purpose

   WiFi.begin(ssid, password) is used to initiate connection to a WiFi network using the given network name (SSID) and password.

2. Step 2: Compare with other options

   Disconnecting, checking signal strength, or getting IP address are done by other functions, not WiFi.begin.

3. Final Answer:

   To start connecting the device to a WiFi network -> Option A

4. Quick Check:

   WiFi.begin starts connection [OK]

Hint: Remember: begin means start connection [OK]

Common Mistakes:

• Confusing begin with disconnect
• Thinking it returns IP address
• Assuming it checks signal strength

2. Which of the following is the correct syntax to check if the ESP8266 is connected to WiFi?

easy

A. if (WiFi.connected())

B. if (WiFi.checkConnection())

C. if (WiFi.isConnected())

D. if (WiFi.status() == WL_CONNECTED)

Solution

1. Step 1: Recall the correct method to check WiFi connection

   The standard way is to use WiFi.status() and compare it to WL_CONNECTED to confirm connection.

2. Step 2: Verify other options

   Methods like WiFi.connected(), WiFi.isConnected(), or WiFi.checkConnection() do not exist in the ESP8266 WiFi library.

3. Final Answer:

   if (WiFi.status() == WL_CONNECTED) -> Option D

4. Quick Check:

   WiFi.status() == WL_CONNECTED checks connection [OK]

Hint: Use WiFi.status() with WL_CONNECTED constant [OK]

Common Mistakes:

• Using non-existent methods like WiFi.connected()
• Confusing status check syntax
• Forgetting to compare with WL_CONNECTED

3. What will the following code print if the ESP8266 successfully connects to WiFi?

WiFi.begin("MySSID", "MyPass");
while (WiFi.status() != WL_CONNECTED) {
  delay(500);
}
Serial.println(WiFi.localIP());

medium

A. The IP address assigned to the ESP8266

B. The SSID of the WiFi network

C. The WiFi password

D. Nothing, it will cause an error

Solution

1. Step 1: Analyze the connection loop

   The code waits until WiFi.status() returns WL_CONNECTED, meaning the device is connected to WiFi.

2. Step 2: Understand the output command

   WiFi.localIP() returns the IP address assigned to the device by the router, which is printed to Serial.

3. Final Answer:

   The IP address assigned to the ESP8266 -> Option A

4. Quick Check:

   WiFi.localIP() prints device IP [OK]

Hint: localIP() shows device IP after connection [OK]

Common Mistakes:

• Thinking it prints SSID or password
• Assuming it prints connection status
• Believing it causes an error

4. Identify the error in this ESP32 WiFi connection code:

WiFi.begin(ssid, password);
while (WiFi.status() = WL_CONNECTED) {
  delay(1000);
}
Serial.println("Connected!");

medium

A. Missing WiFi.begin() call

B. Incorrect delay value

C. Using single '=' instead of '==' in the while condition

D. No Serial.begin() before printing

Solution

1. Step 1: Check the while loop condition

   The condition uses a single '=' which is an assignment, not a comparison. It should be '==' to compare values.

2. Step 2: Confirm other parts

   WiFi.begin() is called, delay is valid, and Serial.begin() is not shown but not the main error here.

3. Final Answer:

   Using single '=' instead of '==' in the while condition -> Option C

4. Quick Check:

   Use '==' for comparison in conditions [OK]

Hint: Use '==' to compare, '=' assigns value [OK]

Common Mistakes:

• Confusing '=' with '==' in conditions
• Ignoring Serial.begin() setup
• Assuming delay value causes error

5. You want your ESP32 to connect to WiFi and print its IP address only after a successful connection, but also stop trying after 10 seconds if it fails. Which code snippet correctly implements this?

hard

A. WiFi.begin(ssid, password);
while (WiFi.status() != WL_CONNECTED) {
delay(500);
if (millis() > 10000) break;
}
Serial.println(WiFi.localIP());

B. WiFi.begin(ssid, password);
unsigned long start = millis();
while (WiFi.status() != WL_CONNECTED && millis() - start < 10000) {
delay(500);
}
if (WiFi.status() == WL_CONNECTED) {
Serial.println(WiFi.localIP());
} else {
Serial.println("Failed to connect");
}

C. WiFi.begin(ssid, password);
for (int i = 0; i < 20; i++) {
if (WiFi.status() == WL_CONNECTED) break;
delay(500);
}
Serial.println(WiFi.localIP());

D. WiFi.begin(ssid, password);
while (WiFi.status() == WL_CONNECTED) {
delay(10000);
}
Serial.println(WiFi.localIP());

Solution

1. Step 1: Understand the timeout logic

   WiFi.begin(ssid, password); unsigned long start = millis(); while (WiFi.status() != WL_CONNECTED && millis() - start < 10000) { delay(500); } if (WiFi.status() == WL_CONNECTED) { Serial.println(WiFi.localIP()); } else { Serial.println("Failed to connect"); } uses millis() to track elapsed time and stops trying after 10 seconds (10000 ms) if not connected.

2. Step 2: Check connection and print accordingly

   It prints the IP only if connected; otherwise, it prints a failure message. This matches the requirement exactly.

3. Final Answer:

   The code with 10-second timeout using millis() and conditional IP printing -> Option B

4. Quick Check:

   Use millis() for timeout and check status before printing [OK]

Hint: Use millis() to limit connection wait time [OK]

Common Mistakes:

• Not stopping connection attempts after timeout
• Printing IP without checking connection
• Using wrong while condition logic