WiFi with ESP8266/ESP32 in Arduino - Cheat Sheet & Quick Revision

Recall & Review

beginner

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

It starts the WiFi connection process by trying to connect the ESP device to the specified WiFi network using the given SSID and password.

beginner

How can you check if the ESP8266/ESP32 is connected to WiFi?

Use WiFi.status() == WL_CONNECTED. If true, the device is connected to the WiFi network.

beginner

What does WiFi.localIP() return?

It returns the IP address assigned to the ESP device by the WiFi network, which you can use to communicate with it.

intermediate

Why is it important to include delay() or yield() inside the WiFi connection loop?

Because it allows the ESP to handle background tasks and prevents the watchdog timer from resetting the device during connection attempts.

intermediate

What is the difference between WiFi.begin() and WiFi.config()?

WiFi.begin() connects to a WiFi network using DHCP by default. WiFi.config() lets you set a static IP address, gateway, and subnet before connecting.

Which function starts the WiFi connection on ESP8266/ESP32?

A WiFi.open()

B WiFi.connect()

C WiFi.start()

D WiFi.begin(ssid, password)

The correct function to start connecting to a WiFi network is WiFi.begin(ssid, password).

How do you check if the ESP device is connected to WiFi?

A WiFi.connected()

B WiFi.isConnected()

C WiFi.status() == WL_CONNECTED

D WiFi.check()

WiFi.status() returns the connection status. WL_CONNECTED means the device is connected.

What does WiFi.localIP() provide?

A The IP address assigned to the device

B The password of the WiFi network

C The SSID of the connected network

D The MAC address of the device

WiFi.localIP() returns the IP address assigned to the ESP device by the router.

Why should you use delay() or yield() inside the WiFi connection loop?

A To prevent the watchdog timer from resetting the device

B To speed up the connection

C To disconnect from WiFi

D To save battery power

Including delay() or yield() lets the ESP handle background tasks and avoids watchdog resets.

What is the purpose of WiFi.config()?

A To disconnect from WiFi

B To set a static IP address before connecting

C To start the WiFi connection

D To scan available networks

WiFi.config() lets you set a static IP, gateway, and subnet before connecting to WiFi.

Explain the steps to connect an ESP8266 or ESP32 to a WiFi network using Arduino code.

Think about how you start, check, and confirm the WiFi connection.

Describe the difference between using DHCP and static IP configuration on ESP8266/ESP32 WiFi connection.

Consider how the device gets its 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