WiFi with ESP8266/ESP32 in Arduino - Practice Problems & Coding Challenges

Challenge - 5 Problems

❓ Predict Output

intermediate

What is the output of this ESP8266 WiFi connection code?

Consider this Arduino code for ESP8266 that tries to connect to a WiFi network. What will be printed on the Serial Monitor?

Arduino

void setup() {
  Serial.begin(115200);
  WiFi.begin("MySSID", "WrongPassword");
  int attempts = 0;
  while (WiFi.status() != WL_CONNECTED && attempts < 5) {
    delay(1000);
    Serial.print(".");
    attempts++;
  }
  if (WiFi.status() == WL_CONNECTED) {
    Serial.println("Connected!");
  } else {
    Serial.println("Failed to connect");
  }
}

void loop() {}

A .....Failed to connect

B .....Connected!

C Connected!

D Failed to connect

💡 Hint

Think about what happens if the password is wrong and how many times the code tries to connect.

The code tries to connect 5 times, printing a dot each second. Since the password is wrong, it never connects, so after 5 dots it prints 'Failed to connect'.

🧠 Conceptual

intermediate

Which WiFi mode allows ESP32 to connect to another WiFi network?

ESP32 supports multiple WiFi modes. Which mode should you use if you want your ESP32 to connect to your home WiFi router?

A WiFi.mode(WIFI_STA);

B WiFi.mode(WIFI_AP);

C WiFi.mode(WIFI_AP_STA);

D WiFi.mode(WIFI_OFF);

💡 Hint

Think about the mode where the device acts as a client connecting to an access point.

WIFI_STA mode sets the ESP32 as a station (client) that connects to an existing WiFi network (access point).

🔧 Debug

advanced

Why does this ESP32 code fail to connect to WiFi?

Look at this code snippet. It never prints 'Connected!'. What is the bug?

Arduino

void setup() {
  Serial.begin(115200);
  WiFi.begin("SSID", "password");
  while (WiFi.status() != WL_CONNECTED) {
    delay(500);
    Serial.println("Connecting...");
  }
  Serial.println("Connected!");
}

void loop() {}

A The delay is too short to connect

B WiFi.begin() is missing WiFi.mode(WIFI_STA); before it

C Serial.begin() baud rate is incorrect

D WiFi.status() returns WL_DISCONNECTED instead of WL_CONNECTED

💡 Hint

ESP32 needs to be in the right mode before connecting.

Without setting WiFi.mode(WIFI_STA), the ESP32 may not connect properly because it defaults to AP mode or no mode.

📝 Syntax

advanced

Which option correctly initializes WiFi on ESP8266 to create an access point?

Choose the correct code snippet to start an access point named "MyESP" with password "12345678" on ESP8266.

A WiFi.createAP("MyESP", "12345678");

B WiFi.beginAP("MyESP", "12345678");

C WiFi.startAP("MyESP", "12345678");

D WiFi.softAP("MyESP", "12345678");

💡 Hint

Check the official ESP8266 WiFi library function names.

The correct function to start an access point on ESP8266 is WiFi.softAP().

🚀 Application

expert

How many IP addresses will be assigned after this ESP32 code runs?

Consider this ESP32 code that sets up both station and access point modes. How many IP addresses will the ESP32 have after setup?

Arduino

void setup() {
  WiFi.mode(WIFI_AP_STA);
  WiFi.softAP("ESP32_AP", "password");
  WiFi.begin("HomeSSID", "homepass");
  while (WiFi.status() != WL_CONNECTED) {
    delay(500);
  }
}

void loop() {}

A 1

B 3

C 2

D 0

💡 Hint

Think about IP addresses for both station and access point interfaces.

In WIFI_AP_STA mode, ESP32 acts as both access point and station, so it gets one IP for each interface, totaling 2 IP addresses.