### Example: Get and Print MAC Address (String Version)

Source: https://github.com/esp8266/arduino/blob/master/doc/esp8266wifi/station-class.md

Demonstrates retrieving the MAC address as a formatted string and printing it when connected to WiFi.

```cpp
if (WiFi.status() == WL_CONNECTED)
{
  Serial.printf("Connected, mac address: %s\n", WiFi.macAddress().c_str());
}
```

--------------------------------

### Setup for Web Browser OTA Updates

Source: https://github.com/esp8266/arduino/blob/master/doc/ota_updates/readme.md

This code initializes mDNS, sets up the HTTP update server, and starts the web server. Ensure the ESP and computer are on the same network.

```cpp
MDNS.begin(host);

httpUpdater.setup(&httpServer);
httpServer.begin();

MDNS.addService("http", "tcp", 80);
```

--------------------------------

### List Available Examples

Source: https://github.com/esp8266/arduino/blob/master/tests/host/README.txt

Run this command to display a list of all available example sketches for the ESP8266 Arduino core.

```bash
make list
```

--------------------------------

### Build WiFiClient Example

Source: https://github.com/esp8266/arduino/blob/master/tests/host/README.txt

Compile the WiFiClient example for network connectivity. 'D=1' enables debug messages.

```bash
make D=1 ../../libraries/ESP8266WiFi/examples/WiFiClient/WiFiClient
```

--------------------------------

### Example: Get and Print MAC Address

Source: https://github.com/esp8266/arduino/blob/master/doc/esp8266wifi/station-class.md

Demonstrates how to retrieve the MAC address using a pointer and print it to the serial monitor when connected to WiFi.

```cpp
if (WiFi.status() == WL_CONNECTED)
{
  uint8_t macAddr[6];
  WiFi.macAddress(macAddr);
  Serial.printf("Connected, mac address: %02x:%02x:%02x:%02x:%02x:%02x\n", macAddr[0], macAddr[1], macAddr[2], macAddr[3], macAddr[4], macAddr[5]);
}
```

--------------------------------

### Initialize Soft AP with Custom Configuration

Source: https://github.com/esp8266/arduino/blob/master/doc/esp8266wifi/soft-access-point-class.md

This example demonstrates how to configure the soft AP's network interface with a specific IP address, gateway, and subnet, then starts the soft AP, and prints its IP address.

```cpp
#include <ESP8266WiFi.h>

IPAddress local_IP(192,168,4,22);
IPAddress gateway(192,168,4,9);
IPAddress subnet(255,255,255,0);

void setup()
{
  Serial.begin(115200);
  Serial.println();

  Serial.print("Setting soft-AP configuration ... ");
  Serial.println(WiFi.softAPConfig(local_IP, gateway, subnet) ? "Ready" : "Failed!");

  Serial.print("Setting soft-AP ... ");
  Serial.println(WiFi.softAP("ESPsoftAP_01") ? "Ready" : "Failed!");

  Serial.print("Soft-AP IP address = ");
  Serial.println(WiFi.softAPIP());
}

void loop() {}
```

--------------------------------

### Example: Get and Print Gateway IP Address

Source: https://github.com/esp8266/arduino/blob/master/doc/esp8266wifi/station-class.md

Illustrates how to retrieve and print the gateway IP address to the serial monitor.

```cpp
Serial.printf("Gataway IP: %s\n", WiFi.gatewayIP().toString().c_str());
```

--------------------------------

### Example: Get and Print DNS IP Addresses

Source: https://github.com/esp8266/arduino/blob/master/doc/esp8266wifi/station-class.md

Shows how to retrieve and print the IP addresses of the first and second DNS servers to the serial monitor.

```cpp
Serial.print("DNS #1, #2 IP: ");
WiFi.dnsIP().printTo(Serial);
Serial.print(", ");
WiFi.dnsIP(1).printTo(Serial);
Serial.println();
```

--------------------------------

### Build HelloServer Example

Source: https://github.com/esp8266/arduino/blob/master/tests/host/README.txt

Compile the basic HelloServer example for the ESP8266 web server. 'D=1' enables debug messages.

```bash
make D=1 ../../libraries/ESP8266WebServer/examples/HelloServer/HelloServer
```

--------------------------------

### Example: Get and Print Local IP Address

Source: https://github.com/esp8266/arduino/blob/master/doc/esp8266wifi/station-class.md

Shows how to obtain and print the ESP station's local IP address to the serial monitor when connected to WiFi.

```cpp
if (WiFi.status() == WL_CONNECTED)
{
  Serial.print("Connected, IP address: ");
  Serial.println(WiFi.localIP());
}
```

--------------------------------

### Build and Run a Specific Example

Source: https://github.com/esp8266/arduino/blob/master/tests/host/README.txt

Compile a specific example sketch, such as 'Blink', and then run the compiled executable. 'D=1' enables debug messages.

```bash
make D=1 ../../libraries/esp8266/examples/Blink/Blink
./bin/Blink/Blink -h
```

--------------------------------

### Build UDP Example

Source: https://github.com/esp8266/arduino/blob/master/tests/host/README.txt

Compile the UDP networking example. 'D=1' enables debug messages.

```bash
make D=1 ../../libraries/ESP8266WiFi/examples/udp/udp
```

--------------------------------

### Example: Get and Print Subnet Mask

Source: https://github.com/esp8266/arduino/blob/master/doc/esp8266wifi/station-class.md

Demonstrates retrieving and printing the subnet mask of the station's interface to the serial monitor.

```cpp
Serial.print("Subnet mask: ");
Serial.println(WiFi.subnetMask());
```

--------------------------------

### Build mDNS Web Server Example

Source: https://github.com/esp8266/arduino/blob/master/tests/host/README.txt

Compile the mDNS_Web_Server example, which integrates mDNS for network discovery. 'D=1' enables debug messages.

```bash
make D=1 ../../libraries/ESP826mDNS/examples/mDNS_Web_Server/mDNS_Web_Server
```

--------------------------------

### Build AdvancedWebServer Example

Source: https://github.com/esp8266/arduino/blob/master/tests/host/README.txt

Compile the AdvancedWebServer example, showcasing more complex web server functionalities. 'D=1' enables debug messages.

```bash
make D=1 ../../libraries/ESP8266WebServer/examples/AdvancedWebServer/AdvancedWebServer
```

--------------------------------

### Server Lifecycle Methods

Source: https://github.com/esp8266/arduino/blob/master/libraries/ESP8266WebServer/README.rst

Methods for starting, handling, and stopping the web server.

```cpp
void begin();
```

```cpp
void handleClient();
```

```cpp
void close();
void stop();
```

--------------------------------

### Basic ESP8266 Web Server Setup

Source: https://github.com/esp8266/arduino/blob/master/libraries/ESP8266WebServer/examples/Graph/readme.md

This is a minimal setup for an ESP8266 web server. It includes basic WiFi connection and a handler for serving files from the filesystem. The `index.htm` file is served by default when no specific filename is requested.

```c++
void setup() {
  Serial.begin(115200);
  Serial.println("Booting...");

  // Initialize SPIFFS or other filesystem
  if (!SPIFFS.begin(true)){
    Serial.println("SPIFFS Mount Failed");
    return;
  }

  // Connect to WiFi
  WiFi.begin(STASSID, STAPSK);
  while (WiFi.status() != WL_CONNECTED) {
    delay(500);
    Serial.print(".");
  }
  Serial.println("WiFi connected");
  Serial.println("IP address: " + WiFi.localIP());

  // Serve files from filesystem
  server.on("/", HTTP_GET, []() {
    server.send(200, "text/html", "Hello from ESP8266!");
  });

  // Start server
  server.begin();
  Serial.println("HTTP server started");
}

void loop() {
  server.handleClient();
}
```

--------------------------------

### Serial Monitor Output Examples

Source: https://github.com/esp8266/arduino/blob/master/doc/esp8266wifi/station-examples.md

Example logs showing the ESP8266 connection lifecycle, including initial connection and switching between access points.

```default
f r0, scandone
f r0, scandone
state: 0 -> 2 (b0)
state: 2 -> 3 (0)
state: 3 -> 5 (10)

add 0
aid 1
cnt
chg_B1:-40

connected with sensor-net-1, channel 1
dhcp client start...
ip:192.168.1.10,mask:255.255.255.0,gw:192.168.1.9
```

```default
bcn_timout,ap_probe_send_start
ap_probe_send over, rest wifi status to disassoc
state: 5 -> 0 (1)
rm 0
f r-40, scandone
f r-40, scandone
f r-40, scandone
state: 0 -> 2 (b0)
state: 2 -> 3 (0)
state: 3 -> 5 (10)
add 0

aid 1
cnt

connected with sensor-net-2, channel 11
dhcp client start...
ip:192.168.1.102,mask:255.255.255.0,gw:192.168.1.234
```

```default
bcn_timout,ap_probe_send_start
ap_probe_send over, rest wifi status to disassoc
state: 5 -> 0 (1)
rm 0
f r-40, scandone
f r-40, scandone
f r-40, scandone
state: 0 -> 2 (b0)
state: 2 -> 3 (0)
state: 3 -> 5 (10)
add 0
aid 1
cnt

connected with sensor-net-1, channel 6
dhcp client start...
ip:192.168.1.10,mask:255.255.255.0,gw:192.168.1.9
```

--------------------------------

### Start GDB on Linux

Source: https://github.com/esp8266/arduino/blob/master/doc/gdb.md

Navigate to the ESP8266 toolchain directory and run this command to start the GDB executable for debugging on Linux.

```bash
~/.arduino15/packages/esp8266/tools/xtensa-lx106-elf-gcc/2.5.0-4-b40a506/bin/xtensa-lx106-elf-gdb
```

--------------------------------

### Initialize GDB Stub in Setup

Source: https://github.com/esp8266/arduino/blob/master/doc/gdb.md

Ensure the serial port is initialized and call gdbstub_init() within your void setup() function to prepare for GDB debugging.

```cpp
Serial.begin(115200);
gdbstub_init();
```

--------------------------------

### Example Sketch Implementation

Source: https://github.com/esp8266/arduino/blob/master/doc/faq/a06-global-build-options.md

A sample sketch demonstrating the use of globally defined macros.

```cpp
#include <umm_malloc/umm_malloc.h>  // has prototype for umm_free_heap_size_min()

void setup() {
  Serial.begin(115200);
  delay(200);
#ifdef MYTITLE1
  Serial.printf("\r\n" MYTITLE1 MYTITLE2 "\r\n");
#else
  Serial.println("ERROR:  MYTITLE1 not present");
#endif
  Serial.printf("Heap Low Watermark %u\r\n", umm_free_heap_size_min());
}

void loop() {}
```

--------------------------------

### Start GDB on Windows (Git)

Source: https://github.com/esp8266/arduino/blob/master/doc/gdb.md

Navigate to the ESP8266 toolchain directory and run this command to start the GDB executable for debugging on Windows using the Git version.

```bash
%userprofile%\Documents\Arduino\hardware\esp8266com\esp8266\tools\xtensa-lx106-elf\bin\xtensa-lx106-elf-gdb.exe
```

--------------------------------

### Python Setup and Teardown for WiFiClient Test

Source: https://github.com/esp8266/arduino/blob/master/tests/README.md

Use the `@setup` and `@teardown` decorators to bind Python functions to specific test cases. These functions can create resources like TCP servers and manage environment variables passed to the device test. Ensure environment variables are correctly set and validated.

```python
from mock_decorators import setup, teardown, setenv, request_env

@setup('WiFiClient test')
def setup_wificlient_test(e):
    # create a TCP server
    # pass environment variable to the test
    setenv(e, 'SERVER_PORT', '10000')
    setenv(e, 'SERVER_IP', repr(server_ip))

@teardown('WiFiClient test')
def teardown_wificlient_test(e):
    # delete TCP server
    # request environment variable from the test, compare to the expected value
    read_bytes = request_env(e, 'READ_BYTES')
    assert(read_bytes == '4096')
```

--------------------------------

### Launch ESP8266 GDB

Source: https://github.com/esp8266/arduino/blob/master/doc/gdb.md

Start the ESP8266-specific GDB instance.

```bash
earle@server:~$ ~/.arduino15/packages/esp8266/hardware/xtensa-lx106-elf/bin/xtensa-lx106-elf-gdb
GNU gdb (GDB) 8.2.50.20180723-git
Copyright (C) 2018 Free Software Foundation, Inc.
License GPLv3+: GNU GPL version 3 or later <https://gnu.org/licenses/gpl.html>
This is free software: you are free to change and redistribute it.
There is NO WARRANTY, to the extent permitted by law.
Type "show copying" and "show warranty" for details.
This GDB was configured as "--host=x86_64-linux-gnu --target=xtensa-lx106-elf".
Type "show configuration" for configuration details.
For bug reporting instructions, please see:
    <https://www.gnu.org/software/gdb/bugs/>.
Find the GDB manual and other documentation resources online at:
    <https://www.gnu.org/software/gdb/documentation/>.

For help, type "help".
Type "apropos word" to search for commands related to "word".
(gdb)
```

--------------------------------

### Restore Legacy Boot WiFi Behavior

Source: https://github.com/esp8266/arduino/blob/master/doc/esp8266wifi/generic-class.md

Example of using enableWiFiAtBootTime to restore automatic WiFi startup at boot.

```cpp
#include <ESP8266WiFi.h>

void setup () {
#ifdef WIFI_IS_OFF_AT_BOOT
    enableWiFiAtBootTime(); // can be called from anywhere with the same effect
#endif
    ....
}
```

--------------------------------

### Basic Mesh Network Example

Source: https://github.com/esp8266/arduino/blob/master/libraries/ESP8266WiFiMesh/README.md

Upload this example to multiple ESP8266 devices to create a working mesh network. Modify `useLED` to visualize message propagation, `floodingMesh.broadcast` to change transmitted data, and `meshMessageHandler` to alter node reactions.

```cpp
int useLED = false;
floodingMesh.broadcast("Hello Mesh!");
void meshMessageHandler(uint32_t from, String &from_node, String &message) {
  // Modify how mesh nodes react to received transmissions
}
```

--------------------------------

### Format Release Notes Example

Source: https://github.com/esp8266/arduino/blob/master/package/README.md

Structure for organizing breaking changes and library updates in the changelog.

```markdown
Breaking Changes
================
API xyz changed #1234
...

Library - xyz
=============
API xyz changed #1234 (Breaking change)
...
```

--------------------------------

### Start GDB on Windows (Board Manager)

Source: https://github.com/esp8266/arduino/blob/master/doc/gdb.md

Navigate to the ESP8266 toolchain directory and run this command to start the GDB executable for debugging on Windows using the Board Manager version.

```bash
%userprofile%\AppData\Local\Arduino15\packages\esp8266\tools\xtensa-lx106-elf-gcc\2.5.0-3-20ed2b9\bin\xtensa-lx106-elf-gdb.exe
```

--------------------------------

### Initialize Soft AP

Source: https://github.com/esp8266/arduino/blob/master/doc/esp8266wifi/soft-access-point-examples.md

Core function call to start the access point.

```cpp
boolean result = WiFi.softAP("ESPsoftAP_01", "pass-to-soft-AP");
```

--------------------------------

### Initialize GDBStub in Arduino Sketch

Source: https://github.com/esp8266/arduino/blob/master/doc/gdb.md

Include the GDBStub library and initialize it in the setup function to enable debugging.

```cpp
#include <GDBStub.h>

void setup() {
  Serial.begin(115200);
  gdbstub_init();
  Serial.printf("Starting...\n");
}

void loop() {
  static uint32_t cnt = 0;
  Serial.printf("%d\n", cnt++);
  delay(100);
}
```

--------------------------------

### Serial and Network Data Transfer Example

Source: https://github.com/esp8266/arduino/blob/master/doc/reference.md

This example demonstrates transferring data between a Telnet client and the UART (Serial). It shows byte-by-byte transfer from network to serial and buffered transfer from serial to network, including availability checks.

```cpp
//check clients for data
//get data from the telnet client and push it to the UART
while (serverClient.available()) {
  Serial.write(serverClient.read());
}

//check UART for data
if (Serial.available()) {
  size_t len = Serial.available();
  uint8_t sbuf[len];
  Serial.readBytes(sbuf, len);
  //push UART data to all connected telnet clients
  if (serverClient && serverClient.connected()) {
    serverClient.write(sbuf, len);
  }
}
```

--------------------------------

### Serial Monitor Output Example

Source: https://github.com/esp8266/arduino/blob/master/doc/esp8266wifi/station-examples.md

Sample output showing the connection status monitoring process.

```default
Looking for WiFi ..... connected to sensor-net-1
Looking for WiFi ....... connected to sensor-net-2
Looking for WiFi .... connected to sensor-net-1
```

--------------------------------

### Configuring Access Points

Source: https://github.com/esp8266/arduino/blob/master/doc/esp8266wifi/station-examples.md

Examples of adding multiple access points to the wifiMulti instance.

```cpp
wifiMulti.addAP("primary-network-name", "pass-to-primary-network");
wifiMulti.addAP("secondary-network-name", "pass-to-secondary-network");
```

```cpp
wifiMulti.addAP("tertiary-network-name", "pass-to-tertiary-network");
...
```

--------------------------------

### SoftAP Setup

Source: https://github.com/esp8266/arduino/blob/master/doc/esp8266wifi/soft-access-point-class.md

Functions to set up and configure the ESP8266 in soft access point (soft-AP) mode.

```APIDOC
## POST /esp8266/arduino/softAP

### Description
Sets up a soft access point to establish a Wi-Fi network. Can be used to create an open network or a protected network with a pre-shared key.

### Method
POST

### Endpoint
/esp8266/arduino/softAP

### Parameters
#### Query Parameters
- **ssid** (string) - Required - Character string containing network SSID (max. 32 characters).
- **psk** (string) - Optional - Character string with a pre-shared key (minimum 8 characters, maximum 64 characters). If not specified, the access point will be open.
- **channel** (integer) - Optional - Wi-Fi channel from 1 to 13. Defaults to 1.
- **hidden** (boolean) - Optional - If set to `true`, the SSID will be hidden.
- **max_connection** (integer) - Optional - Maximum simultaneous connected stations, from 0 to 8. Defaults to 4.

### Request Example
```json
{
  "ssid": "MyESP8266AP",
  "psk": "MyPassword123",
  "channel": 6,
  "hidden": false,
  "max_connection": 8
}
```

### Response
#### Success Response (200)
- **success** (boolean) - Indicates if the soft-AP setup was successful.

#### Response Example
```json
{
  "success": true
}
```
```

```APIDOC
## POST /esp8266/arduino/softAPConfig

### Description
Configures the soft access point's network interface with a specific IP address, gateway, and subnet mask.

### Method
POST

### Endpoint
/esp8266/arduino/softAPConfig

### Parameters
#### Request Body
- **local_ip** (IPAddress) - Required - The IP address of the soft access point.
- **gateway** (IPAddress) - Required - The gateway IP address.
- **subnet** (IPAddress) - Required - The subnet mask.

### Request Example
```json
{
  "local_ip": "192.168.4.22",
  "gateway": "192.168.4.1",
  "subnet": "255.255.255.0"
}
```

### Response
#### Success Response (200)
- **success** (boolean) - Indicates if the configuration was successful.

#### Response Example
```json
{
  "success": true
}
```
```

--------------------------------

### Asynchronous Scan Implementation Example

Source: https://github.com/esp8266/arduino/blob/master/doc/esp8266wifi/scan-class.md

Demonstrates using scanNetworksAsync with a callback function to process scan results.

```cpp
#include "ESP8266WiFi.h"

void prinScanResult(int networksFound)
{
  Serial.printf("%d network(s) found\n", networksFound);
  for (int i = 0; i < networksFound; i++)
  {
    Serial.printf("%d: %s, Ch:%d (%ddBm) %s\n", i + 1, WiFi.SSID(i).c_str(), WiFi.channel(i), WiFi.RSSI(i), WiFi.encryptionType(i) == ENC_TYPE_NONE ? "open" : "");
  }
}


void setup()
{
  Serial.begin(115200);
  Serial.println();

  WiFi.mode(WIFI_STA);
  WiFi.disconnect();
  delay(100);

  WiFi.scanNetworksAsync(prinScanResult);
}


void loop() {}
```

--------------------------------

### Initialize ESP8266WebServer

Source: https://github.com/esp8266/arduino/blob/master/libraries/ESP8266WebServer/README.rst

Creates an instance of the web server on a specified port.

```cpp
ESP8266WebServer server(80);
```

--------------------------------

### begin(port)

Source: https://github.com/esp8266/arduino/blob/master/doc/esp8266wifi/server-class.md

Initializes the server on a specific port. If no port is provided, it defaults to port 23.

```APIDOC
## begin(uint16_t port)

### Description
Starts the server on the specified port. If the port is not specified in the constructor or begin method, the server defaults to port 23.

### Parameters
#### Method Parameters
- **port** (uint16_t) - Optional - The TCP port number to listen on.
```

--------------------------------

### Initialize and Fetch Data

Source: https://github.com/esp8266/arduino/blob/master/libraries/ESP8266WebServer/examples/Graph/data/index.htm

Initializes the digital chart and fetches the first sample of data to start the visualization process.

```javascript
// Configure the digital chart
initDigitalChart();
// Get first sample
fetchNewData();
```

--------------------------------

### WiFi.begin()

Source: https://github.com/esp8266/arduino/blob/master/doc/esp8266wifi/station-class.md

Initializes the ESP8266 in station mode and establishes a connection to an access point using various configuration options.

```APIDOC
## WiFi.begin()

### Description
Initializes the ESP8266 station mode. Multiple overloads allow for connecting to a specific SSID, reconnecting to the last saved access point, or providing detailed network parameters.

### Parameters
#### Request Body
- **ssid** (string) - Optional - SSID of the Access Point (up to 32 characters).
- **password** (string) - Optional - Password for the Access Point (8-64 characters).
- **channel** (int) - Optional - Specific channel of the AP.
- **bssid** (string) - Optional - MAC address of the AP.
- **connect** (boolean) - Optional - If false, saves parameters without establishing an immediate connection.

### Request Example
WiFi.begin("mySSID", "myPassword", 6, "AA:BB:CC:DD:EE:FF", true)
```

--------------------------------

### Error Message for Generic ESP8266 Module

Source: https://github.com/esp8266/arduino/blob/master/doc/faq/a04-board-generic-is-unknown.md

This is an example of the error message encountered when the Arduino IDE cannot recognize the 'Generic ESP8266 Module'. This typically happens after package installation issues.

```default
Board generic (platform esp8266, package esp8266) is unknown
Error compiling for board Generic ESP8266 Module.
```

--------------------------------

### Error Message for Adafruit HUZZAH ESP8266

Source: https://github.com/esp8266/arduino/blob/master/doc/faq/a04-board-generic-is-unknown.md

This is an example of the error message when the 'Adafruit HUZZAH ESP8266' board is not recognized. This error is related to the esp8266 package installation within the Arduino IDE.

```default
Board huzzah (platform esp8266, package esp8266) is unknown
Error compiling for board Adafruit HUZZAH ESP8266.
```

--------------------------------

### Error Message for WeMos D1 R2 & mini

Source: https://github.com/esp8266/arduino/blob/master/doc/faq/a04-board-generic-is-unknown.md

This is an example of the error message when the 'WeMos D1 R2 & mini' board is not recognized by the Arduino IDE. It indicates a problem with the esp8266 package installation.

```default
Board d1_mini (platform esp8266, package esp8266) is unknown
Error compiling for board WeMos D1 R2 & mini.
```

--------------------------------

### Initialize WiFiServer

Source: https://github.com/esp8266/arduino/blob/master/doc/esp8266wifi/server-examples.md

Create a server object listening on port 80, the standard port for web traffic.

```cpp
WiFiServer server(80);
```

--------------------------------

### Initialize Git Submodules

Source: https://github.com/esp8266/arduino/blob/master/doc/installing.md

After cloning the repository, run this command to fetch external libraries required by the ESP8266 core. Failure to do so may result in build errors.

```bash
cd esp8266
git submodule update --init
```

--------------------------------

### Build BearSSL Validation Example

Source: https://github.com/esp8266/arduino/blob/master/tests/host/README.txt

Compile the BearSSL_Validation example, used for testing SSL/TLS certificate validation. 'D=1' enables debug messages.

```bash
make D=1 ../../libraries/ESP8266WiFi/examples/BearSSL_Validation/BearSSL_Validation
```

--------------------------------

### Complete ESP8266 WiFi Connection and Event Handling Example

Source: https://github.com/esp8266/arduino/blob/master/doc/esp8266wifi/generic-examples.md

This code sets up Wi-Fi connection with event handlers for IP acquisition and disconnection. It also blinks an LED in the main loop, demonstrating asynchronous task handling.

```cpp
#include <ESP8266WiFi.h>

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

WiFiEventHandler gotIpEventHandler, disconnectedEventHandler;

bool ledState;


void setup()
{
  Serial.begin(115200);
  Serial.println();

  pinMode(LED_BUILTIN, OUTPUT);

  gotIpEventHandler = WiFi.onStationModeGotIP([](const WiFiEventStationModeGotIP& event)
  {
    Serial.print("Station connected, IP: ");
    Serial.println(WiFi.localIP());
  });

  disconnectedEventHandler = WiFi.onStationModeDisconnected([](const WiFiEventStationModeDisconnected& event)
  {
    Serial.println("Station disconnected");
  });

  Serial.printf("Connecting to %s ...\n", ssid);
  WiFi.begin(ssid, password);
}


void loop()
{
  digitalWrite(LED_BUILTIN, ledState);
  ledState = !ledState;
  delay(250);
}

```

--------------------------------

### Create an HTTP Web Server

Source: https://context7.com/esp8266/arduino/llms.txt

Implements a basic web server with route handlers for GET requests and LED control. Requires the ESP8266WebServer library.

```cpp
#include <ESP8266WiFi.h>
#include <ESP8266WebServer.h>

ESP8266WebServer server(80);

int ledState = LOW;

void handleRoot() {
  String html = "<html><head><title>ESP8266 Web Server</title></head><body>";
  html += "<h1>ESP8266 Control Panel</h1>";
  html += "<p>LED State: " + String(ledState ? "ON" : "OFF") + "</p>";
  html += "<a href='/led/on'><button>Turn ON</button></a>";
  html += "<a href='/led/off'><button>Turn OFF</button></a>";
  html += "</body></html>";
  server.send(200, "text/html", html);
}

void handleLedOn() {
  ledState = HIGH;
  digitalWrite(LED_BUILTIN, LOW);  // LED is active-low
  server.sendHeader("Location", "/");
  server.send(303);
}

void handleLedOff() {
  ledState = LOW;
  digitalWrite(LED_BUILTIN, HIGH);
  server.sendHeader("Location", "/");
  server.send(303);
}

void handleNotFound() {
  String message = "404 Not Found\n\n";
  message += "URI: " + server.uri() + "\n";
  message += "Method: " + String((server.method() == HTTP_GET) ? "GET" : "POST") + "\n";
  message += "Arguments: " + String(server.args()) + "\n";

  for (uint8_t i = 0; i < server.args(); i++) {
    message += " " + server.argName(i) + ": " + server.arg(i) + "\n";
  }

  server.send(404, "text/plain", message);
}

void setup() {
  Serial.begin(115200);
  pinMode(LED_BUILTIN, OUTPUT);
  digitalWrite(LED_BUILTIN, HIGH);

  WiFi.mode(WIFI_STA);
  WiFi.begin("your-ssid", "your-password");

  while (WiFi.status() != WL_CONNECTED) {
    delay(500);
  }

  Serial.print("Server IP: ");
  Serial.println(WiFi.localIP());

  // Define routes
  server.on("/", HTTP_GET, handleRoot);
  server.on("/led/on", HTTP_GET, handleLedOn);
  server.on("/led/off", HTTP_GET, handleLedOff);
  server.onNotFound(handleNotFound);

  server.begin();
  Serial.println("HTTP server started");
}

void loop() {
  server.handleClient();
}
```

--------------------------------

### Configure Filesystem Parameters

Source: https://github.com/esp8266/arduino/blob/master/doc/filesystem.md

Use setConfig to define filesystem behavior before mounting. This must be called before begin() to override default settings like auto-formatting.

```cpp
SPIFFSConfig cfg;
cfg.setAutoFormat(false);
SPIFFS.setConfig(cfg);
```

--------------------------------

### Install Python SSL Certificates on macOS

Source: https://github.com/esp8266/arduino/blob/master/doc/installing.md

If you encounter SSL certificate verification errors when running 'python3 get.py' on macOS, use this command to install the required certificates.

```bash
cd "/Applications/Python 3.7/" && sudo "./Install Certificates.command"
```

--------------------------------

### Manual Binary Signing Setup

Source: https://github.com/esp8266/arduino/blob/master/doc/ota_updates/readme.md

Integrate these declarations and function call in your main code before enabling any update methods to enable manual signature verification for OTA updates.

```cpp
<in globals>
BearSSL::PublicKey signPubKey( ... key contents ... );
BearSSL::HashSHA256 hash;
BearSSL::SigningVerifier sign( &signPubKey );
...
<in setup()>
Update.installSignature( &hash, &sign );
```

--------------------------------

### TCP/IP Mesh Backend Example Callbacks

Source: https://github.com/esp8266/arduino/blob/master/libraries/ESP8266WiFiMesh/README.md

Key functions to modify in the TcpIpMeshBackend example for customizing network behavior. These include handling incoming requests, managing responses, filtering networks, and updating transmission outcomes.

```cpp
manageRequest(requestHandler);
manageResponse(responseHandler);
networkFilter;
exampleTransmissionOutcomesUpdateHook;
```

--------------------------------

### Connect with Advanced Parameters

Source: https://github.com/esp8266/arduino/blob/master/doc/esp8266wifi/station-class.md

This overload of `begin` allows specifying additional parameters such as channel, BSSID, and a flag to control immediate connection. Use this for fine-grained control over the connection process.

```cpp
WiFi.begin(ssid, password, channel, bssid, connect)
```

--------------------------------

### Make HTTP GET and POST Requests

Source: https://context7.com/esp8266/arduino/llms.txt

Perform HTTP GET and POST requests to web APIs using the ESP8266HTTPClient library. Handles connection management, headers, and response parsing. Ensure WiFi is connected before making requests.

```cpp
#include <ESP8266WiFi.h>
#include <ESP8266HTTPClient.h>
#include <WiFiClient.h>

void setup() {
  Serial.begin(115200);
  WiFi.mode(WIFI_STA);
  WiFi.begin("your-ssid", "your-password");

  while (WiFi.status() != WL_CONNECTED) {
    delay(500);
  }
}

void loop() {
  if (WiFi.status() == WL_CONNECTED) {
    WiFiClient client;
    HTTPClient http;

    // GET request
    Serial.println("[HTTP] GET request...");
    if (http.begin(client, "http://httpbin.org/get")) {
      http.addHeader("Accept", "application/json");

      int httpCode = http.GET();

      if (httpCode > 0) {
        Serial.printf("Response code: %d\n", httpCode);
        if (httpCode == HTTP_CODE_OK) {
          String payload = http.getString();
          Serial.println(payload);
        }
      } else {
        Serial.printf("GET failed: %s\n", http.errorToString(httpCode).c_str());
      }
      http.end();
    }

    delay(2000);

    // POST request with JSON
    Serial.println("[HTTP] POST request...");
    if (http.begin(client, "http://httpbin.org/post")) {
      http.addHeader("Content-Type", "application/json");

      String jsonPayload = "{\"sensor\":\"temperature\",\"value\":23.5}";
      int httpCode = http.POST(jsonPayload);

      if (httpCode > 0) {
        Serial.printf("Response code: %d\n", httpCode);
        String response = http.getString();
        Serial.println(response);
      }
      http.end();
    }
  }

  delay(30000);
}
```

--------------------------------

### WiFi.hostname

Source: https://github.com/esp8266/arduino/blob/master/doc/esp8266wifi/station-class.md

Get or set the DHCP hostname for the ESP station.

```APIDOC
## GET/SET WiFi.hostname

### Description
Retrieves the current DHCP hostname or sets a new one. The default format is ESP_24xMAC.

### Parameters
#### Request Body
- **aHostname** (String/char*) - Optional - The new hostname to set (max 32 characters).

### Response
- **Return Value** (String/bool) - Returns the current hostname as a String, or a boolean indicating success/failure when setting a new one.
```

--------------------------------

### Initialize and Configure Ace Editor

Source: https://github.com/esp8266/arduino/blob/master/libraries/ESP8266WebServer/examples/FSBrowser/data/edit/index.htm

Sets up the Ace editor instance, including language detection, theme configuration, and custom command bindings.

```javascript
function createEditor(element, file, lang, theme, type){ function getLangFromFilename(filename){ var lang = "plain"; var ext = /(?:\\.(\\.[^.]+))?$/.exec(filename)[1]; if (ext !== undefined){ switch(ext){ case "txt": lang = "plain"; break; case "htm": lang = "html"; break; case "js": lang = "javascript"; break; case "c": lang = "c_cpp"; break; case "cpp": lang = "c_cpp"; break; case "css": case "scss": case "php": case "html": case "json": case "xml": lang = ext; } } return lang; } if (typeof file === "undefined") file = "/index.htm"; if (typeof lang === "undefined"){ lang = getLangFromFilename(file); } if (typeof theme === "undefined") theme = "textmate"; if (typeof type === "undefined"){ type = "text/"+lang; if (lang === "c_cpp") type = "text/plain"; } var xmlHttp = null; var editor = ace.edit(element); function filePosted(){ setLoading(false); if (xmlHttp.status != 200) showHttpError(xmlHttp); tree.refreshPath(getParentFolder(file)); // to update size in tree refreshStatus(); } function postFile(path, data, type){ setLoading(true, "Saving '" + path + "'..."); xmlHttp = new XMLHttpRequest(); xmlHttp.onload = filePosted; var formData = new FormData(); formData.append("data", new Blob([data], { type: type }), path); xmlHttp.open("POST", "/edit"); xmlHttp.send(formData); } function fileLoaded(){ setLoading(false); document.getElementById("preview").style.display = "none"; document.getElementById("editor").style.display = "block"; document.getElementById("editorButtons").style.display = "inline"; if (xmlHttp.status == 200) { editor.setValue(xmlHttp.responseText); editor.clearSelection(); enableSaveDiscardBtns(false); } else tree.clearMainPanel(); } function loadFile(path){ setLoading(true, "Loading '" + path + "'..."); xmlHttp = new XMLHttpRequest(); xmlHttp.onload = fileLoaded; xmlHttp.open("GET", path, true); xmlHttp.send(null); } if (lang !== "plain") editor.getSession().setMode("ace/mode/"+lang); editor.setTheme("ace/theme/"+theme); editor.$blockScrolling = Infinity; editor.getSession().setUseSoftTabs(true); editor.getSession().setTabSize(2); editor.setHighlightActiveLine(true); editor.setShowPrintMargin(false); editor.commands.addCommand({ name: 'save', bindKey: {win: 'Ctrl-S', mac: 'Command-S'}, exec: function(editor) { editor.save(); }, readOnly: false }); editor.commands.addCommand({ name: "showKeyboardShortcuts", bindKey: {win: "Ctrl-Alt-h", mac: "Command-Alt-h"}, exec: function(editor) { editor.showShortcuts(); } }) editor.session.on('change', function(delta) { enableSaveDiscardBtns(true); }); editor.loadUrl = function(path){ document.getElementById("pathInput").value = path; enableSaveDiscardBtns(false); file = path; lang = getLangFromFilename(file); type = "text/"+lang; if (lang !== "plain") editor.getSession().setMode("ace/mode/"+lang); loadFile(file); } editor.save = function() { enableSaveDiscardBtns(false); postFile(file, editor.getValue()+"", type); } editor.discard = function() { editor.loadUrl(file); enableSaveDiscardBtns(false); } editor.showShortcuts = function() { ace.config.loadModule("ace/ext/keybinding_menu", function(module) { module.init(editor); editor.showKeyboardShortcuts() }); } loadFile(file); return editor; }
```

--------------------------------

### Get File Size

Source: https://github.com/esp8266/arduino/blob/master/doc/filesystem.md

Returns the total size of the file in bytes.

```cpp
file.size()
```

--------------------------------

### Python Virtual Environment Setup

Source: https://github.com/esp8266/arduino/blob/master/tests/README.md

Command to prepare the Python virtual environment for the test runner. This should be run once on each machine where tests are executed.

```makefile
make virtualenv
```

--------------------------------

### WiFi.scanNetworksAsync

Source: https://github.com/esp8266/arduino/blob/master/doc/esp8266wifi/scan-class.md

Starts an asynchronous scan and executes a callback function upon completion.

```APIDOC
## scanNetworksAsync

### Description
Start scanning for available Wi-Fi networks. On completion execute another function.

### Parameters
#### Request Body
- **onComplete** (function) - Required - The event handler executed when the scan is done.
- **show_hidden** (boolean) - Optional - Set to true to scan for hidden networks.
```

--------------------------------

### Get Short File Name

Source: https://github.com/esp8266/arduino/blob/master/doc/filesystem.md

Retrieves the filename without the path component.

```cpp
String name = file.name();
```

--------------------------------

### Initialize Wi-Fi Connection

Source: https://github.com/esp8266/arduino/blob/master/doc/esp8266wifi/readme.md

Initiates the connection to a specified Wi-Fi network using the provided network name and password.

```cpp
WiFi.begin("network-name", "pass-to-network");
```

--------------------------------

### Get File Position

Source: https://github.com/esp8266/arduino/blob/master/doc/filesystem.md

Retrieves the current byte offset within the file.

```cpp
file.position()
```

--------------------------------

### Download Binary Tools for ESP8266 Core

Source: https://github.com/esp8266/arduino/blob/master/doc/installing.md

Navigate to the tools directory within the cloned ESP8266 Arduino core and execute the get.py script to download necessary binary tools.

```bash
cd tools
python3 get.py
```

--------------------------------

### Get Current WiFi Mode

Source: https://github.com/esp8266/arduino/blob/master/doc/esp8266wifi/generic-class.md

Retrieves the current active WiFi mode.

```cpp
WiFiMode_t getMode()
```

--------------------------------

### ESP8266 WiFiClient: Status

Source: https://github.com/esp8266/arduino/blob/master/doc/esp8266wifi/client-class.md

Get the current status of the WiFi client connection.

```cpp
uint8_t  status ()
```

--------------------------------

### Writing Firmware via Stream Interface

Source: https://github.com/esp8266/arduino/blob/master/doc/ota_updates/readme.md

Demonstrates how to use the Update class to write firmware from a stream source.

```cpp
Update.begin(firmwareLengthInBytes);
Update.writeStream(streamVar);
Update.end();
```

--------------------------------

### Create a TCP Server

Source: https://context7.com/esp8266/arduino/llms.txt

Set up a TCP server to listen for incoming client connections on a specified port. Useful for custom protocols or raw socket communication. Ensure to disable the Nagle algorithm for low latency.

```cpp
#include <ESP8266WiFi.h>

WiFiServer server(23);  // Telnet port

void setup() {
  Serial.begin(115200);
  WiFi.mode(WIFI_STA);
  WiFi.begin("your-ssid", "your-password");

  while (WiFi.status() != WL_CONNECTED) {
    delay(500);
  }

  server.begin();
  server.setNoDelay(true);  // Disable Nagle algorithm for low latency

  Serial.print("Telnet server started at ");
  Serial.print(WiFi.localIP());
  Serial.println(":23");
}

void loop() {
  // Check for new clients
  WiFiClient client = server.accept();

  if (client) {
    Serial.println("Client connected");
    client.println("Welcome to ESP8266 Telnet Server!");

    while (client.connected()) {
      // Echo received data
      while (client.available()) {
        char c = client.read();
        Serial.write(c);
        client.write(c);  // Echo back
      }

      // Send serial input to client
      while (Serial.available()) {
        char c = Serial.read();
        client.write(c);
      }

      yield();  // Allow background tasks
    }

    client.stop();
    Serial.println("Client disconnected");
  }
}
```

--------------------------------

### Prepare HTML Page Content

Source: https://github.com/esp8266/arduino/blob/master/doc/esp8266wifi/server-examples.md

Construct the HTTP response string including headers and the analog input reading.

```cpp
String prepareHtmlPage()
{
  String htmlPage;
  htmlPage.reserve(1024);               // prevent ram fragmentation
  htmlPage = F("HTTP/1.1 200 OK\r\n"
               "Content-Type: text/html\r\n"
               "Connection: close\r\n"  // the connection will be closed after completion of the response
               "Refresh: 5\r\n"         // refresh the page automatically every 5 sec
               "\r\n"
               "<!DOCTYPE HTML>"
               "<html>"
               "Analog input:  ");
  htmlPage += analogRead(A0);
  htmlPage += F("</html>"
                "\r\n");
  return htmlPage;
}
```

--------------------------------

### Get MFLN Status

Source: https://github.com/esp8266/arduino/blob/master/doc/esp8266wifi/bearssl-client-secure-class.md

Returns the success status of MFLN negotiation after a connection is established.

```cpp
bool getMFLNStatus()
```

--------------------------------

### Configure Filesystem for Web Server

Source: https://github.com/esp8266/arduino/blob/master/libraries/ESP8266WebServer/examples/Graph/readme.md

Uncomment one of these directives to select the ESP filesystem for storing the index.htm file. Ensure WiFi credentials are provided.

```c++
#define USE_SPIFFS
// #define USE_LITTLEFS
// #define USE_SDFS
```

--------------------------------

### Filesystem Configuration and Lifecycle

Source: https://github.com/esp8266/arduino/blob/master/doc/filesystem.md

Methods for configuring, mounting, unmounting, and formatting SPIFFS or LittleFS filesystems on the ESP8266.

```APIDOC
## setConfig

### Description
Configures filesystem parameters before mounting. Must be called before begin().

### Parameters
- **cfg** (Object) - Required - A filesystem-specific config object (e.g., SPIFFSConfig, SDFSConfig).

### Request Example
```cpp
SPIFFSConfig cfg;
cfg.setAutoFormat(false);
SPIFFS.setConfig(cfg);
```

## begin

### Description
Mounts the filesystem. Must be called before any other FS APIs are used.

### Response
- **return** (boolean) - Returns true if mounted successfully, false otherwise.

## end

### Description
Unmounts the filesystem. Recommended before performing OTA updates.

## format

### Description
Formats the filesystem. Can be called before or after begin().

### Response
- **return** (boolean) - Returns true if formatting was successful.
```

--------------------------------

### Initializing String with Flash Content

Source: https://github.com/esp8266/arduino/blob/master/doc/PROGMEM.md

Example of initializing a String object using the F macro.

```cpp
String mystring(F("This string is stored in flash"));
```

--------------------------------

### Binary Generation Recipes

Source: https://github.com/esp8266/arduino/blob/master/platform.txt

Recipes for generating binary files, signing, and calculating sizes.

```text
recipe.objcopy.hex.1.pattern="{runtime.tools.python3.path}/python3" -I "{runtime.tools.elf2bin}" --eboot "{runtime.tools.eboot}" --app "{build.path}/{build.project_name}.elf" --flash_mode {build.flash_mode} --flash_freq {build.flash_freq} --flash_size {build.flash_size} --path "{runtime.tools.xtensa-lx106-elf-gcc.path}/bin" --out "{build.path}/{build.project_name}.bin"
recipe.objcopy.hex.2.pattern="{runtime.tools.python3.path}/python3" -I "{runtime.tools.signing}" --mode sign --privatekey "{build.source.path}/private.key" --bin "{build.path}/{build.project_name}.bin" --out "{build.path}/{build.project_name}.bin.signed" --legacy "{build.path}/{build.project_name}.bin.legacy_sig"
recipe.objcopy.hex.3.pattern="{runtime.tools.python3.path}/python3" -X utf8 -I "{runtime.tools.sizes}" --elf "{build.path}/{build.project_name}.elf" --path "{runtime.tools.xtensa-lx106-elf-gcc.path}/bin" --mmu "{build.mmuflags}"
```

--------------------------------

### Initialize Main Application Entry Point

Source: https://github.com/esp8266/arduino/blob/master/libraries/ESP8266WebServer/examples/FSBrowser/data/edit/index.htm

Handles page load events and dynamic loading of the Ace editor script if not already present.

```javascript
function onBodyLoad(){ var vars = {}; var parts = window.location.href.replace(/[?&]+([^=&]+)=([^&]*)/gi, function(m,key,value) { vars[key] = value; }); if (typeof ace != "undefined") { var editor = createEditor("editor", vars.file, vars.lang, vars.theme); } tree = createTree("tree", editor); createHeader("header", tree, editor); refreshStatus(); }; if (typeof ace == "undefined") { console.log("Cannot load ace.js from the web, trying local copy"); var script = document.createElement('script'); script.src = "/edit/ace.js"; script.async = false; document.head.appendChild(script); }
```

--------------------------------

### Serial Monitor Output

Source: https://github.com/esp8266/arduino/blob/master/doc/esp8266wifi/scan-examples.md

Example output displayed in the serial monitor after running the scan sketch.

```default
Scan start ... 5 network(s) found
Tech_D005107
HP-Print-A2-Photosmart 7520
ESP_0B09E3
Hack-4-fun-net
UPC Wi-Free
```

--------------------------------

### Get Full File Path

Source: https://github.com/esp8266/arduino/blob/master/doc/filesystem.md

Retrieves the full path of the file including directory structure.

```cpp
// Filesystem:
//   testdir/
//           file1
Dir d = LittleFS.openDir("testdir/");
File f = d.openFile("r");
// f.name() == "file1", f.fullName() == "testdir/file1"
```