WiFi with ESP8266/ESP32 in Arduino - Step-by-Step Execution

Concept Flow - WiFi with ESP8266/ESP32

Start

↓

Include WiFi library

↓

Set WiFi SSID and Password

↓

Begin WiFi connection

↓

Check connection status

↓

Connected

↓

Use WiFi connection

↓

End

This flow shows how the ESP connects to WiFi: include library, set credentials, start connection, check status, retry if needed, then use connection.

Execution Sample

Arduino

#include <WiFi.h>
const char* ssid = "MyWiFi";
const char* password = "pass1234";
void setup() {
  Serial.begin(115200);
  WiFi.begin(ssid, password);
}
void loop() {}

This code starts WiFi connection on ESP32/ESP8266 using given network name and password.

Execution Table

Step	Action	WiFi Status	Output
1	Include WiFi library	Disconnected	No output
2	Set SSID and Password	Disconnected	No output
3	Call WiFi.begin(ssid, password)	Connecting	No output
4	Check WiFi.status()	Connecting	No output
5	Wait and retry	Connecting	No output
6	Check WiFi.status()	Connected	Connected to MyWiFi
7	Use WiFi connection	Connected	Ready for network tasks
8	Loop continues	Connected	No output

💡 WiFi.status() returns WL_CONNECTED, connection established successfully

Variable Tracker

Variable	Start	After Step 3	After Step 6	Final
WiFi.status()	Disconnected	Connecting	Connected	Connected
ssid	"MyWiFi"	"MyWiFi"	"MyWiFi"	"MyWiFi"
password	"pass1234"	"pass1234"	"pass1234"	"pass1234"

Key Moments - 2 Insights

Why does WiFi.status() return CONNECTING before it returns CONNECTED?

Because the ESP is trying to connect to the network; it takes some time to establish the connection as shown in steps 4 and 5 of the execution table.

What happens if the SSID or password is wrong?

The WiFi.status() will never return CONNECTED, it will stay in CONNECTING or eventually fail, so the code should handle retries or errors (not shown in this simple example).

Visual Quiz - 3 Questions

Look at the execution table, what is WiFi.status() at step 5?

A Connected

B Disconnected

C Connecting

D Failed

💡 Hint

Check the 'WiFi Status' column at step 5 in the execution table.

At which step does the ESP successfully connect to WiFi?

A Step 3

B Step 6

C Step 4

D Step 8

💡 Hint

Look for the step where WiFi.status() changes to Connected in the execution table.

If the password is incorrect, how would the variable tracker change?

A WiFi.status() would stay Connecting and never become Connected

B WiFi.status() would stay Disconnected

C WiFi.status() would become Connected immediately

D ssid variable would change

💡 Hint

Refer to the variable tracker and key moments about connection status when credentials are wrong.

Concept Snapshot

WiFi with ESP8266/ESP32:
- Include WiFi library
- Set SSID and password
- Call WiFi.begin(ssid, password)
- Check WiFi.status() until WL_CONNECTED
- Use connection for network tasks
- Handle retries if connection fails

Full Transcript

This visual execution shows how an ESP8266 or ESP32 connects to WiFi. First, the WiFi library is included. Then, the network name (SSID) and password are set. The program calls WiFi.begin() to start connecting. The WiFi.status() is checked repeatedly: it starts as Disconnected, then Connecting, and finally Connected when successful. If the credentials are wrong, the device stays Connecting or fails. Once connected, the ESP can use the network. Variables like WiFi.status() change over time, reflecting connection progress. This step-by-step helps beginners see how WiFi connection works on ESP devices.

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