Modernized ESPAsyncTCP for ESP8266

This is a modernized fork of the original ESPAsyncTCP library, a fully asynchronous TCP library for the ESP8266 Arduino core. This version has been significantly updated to provide robust, multi-connection networking with enhanced security and performance.

Key Features & Enhancements

• Modern TLS/SSL Security: Upgraded from the outdated axTLS to the modern, secure BearSSL engine, leveraging the implementation included in the ESP8266 Arduino Core.
• Drastically Reduced RAM Usage: The new BearSSL integration uses memory-efficient, configurable I/O buffers, allowing for significantly more concurrent secure (HTTPS/WSS) clients on the memory-constrained ESP8266.
• Enhanced Stability: Resolves common LoadStoreError crashes by safely handling TLS certificates and private keys stored in PROGMEM (flash memory).
• Fully Asynchronous: Non-blocking operations for handling multiple simultaneous connections without complex multi-threading or delay().
• Drop-in Upgrade: Maintains full API compatibility with the original library. No changes are required in your application code (.ino sketch) to benefit from these improvements.

This library is the foundation for the powerful ESPAsyncWebServer.

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Installation

PlatformIO

It is recommended to install this library by referencing its Git repository in your platformio.ini file to ensure you are using the modernized version.

lib_deps =
    https://github.com/DhimasArdinata/ESPAsyncTCP.git
    ESPAsyncWebServer

Arduino IDE

1. Click on Code -> Download ZIP.
2. In the Arduino IDE, go to Sketch -> Include Library -> Add .ZIP Library... and select the downloaded file.
3. Important: If you have an older version of ESPAsyncTCP installed, you must remove it from your Arduino libraries folder first.

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Usage Example: A Secure HTTPS Web Server

This example demonstrates how to set up a secure web server using ESPAsyncWebServer and this library.

1. Generate Self-Signed Certificates Run this openssl command on your computer to generate a certificate (cert.pem) and a private key (private_key.pem):

openssl req -x509 -newkey rsa:2048 -nodes -keyout private_key.pem -out cert.pem -sha256 -days 3650 -subj "/CN=esp8266.local"

2. Convert Keys to C++ Headers Create two header files in your project, cert.h and private_key.h, and paste the contents of the .pem files into them as C-style strings.

cert.h:

const char cert_pem[] PROGMEM = R"EOF(
-----BEGIN CERTIFICATE-----
... (paste contents of cert.pem here) ...
-----END CERTIFICATE-----
)EOF";

private_key.h:

const char key_pem[] PROGMEM = R"EOF(
-----BEGIN PRIVATE KEY-----
... (paste contents of private_key.pem here) ...
-----END PRIVATE KEY-----
)EOF";

3. Your Arduino Sketch (.ino)

#include <ESP8266WiFi.h>
#include <ESPAsyncTCP.h>
#include <ESPAsyncWebServer.h>
#include "cert.h"
#include "private_key.h"

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

AsyncWebServer server(443); // Create a server on the HTTPS port

void setup() {
  Serial.begin(115200);
  WiFi.mode(WIFI_STA);
  WiFi.begin(ssid, password);
  while (WiFi.status() != WL_CONNECTED) {
    delay(500);
    Serial.print(".");
  }
  Serial.println("\nWiFi connected.");
  Serial.print("IP address: https://");
  Serial.println(WiFi.localIP());

  server.on("/", HTTP_GET, [](AsyncWebServerRequest *request){
    request->send(200, "text/plain", "Hello from ESP8266 HTTPS Server!");
  });

  // Start the secure server
  server.beginSecure(cert_pem, key_pem);
}

void loop() {
  // Loop is empty, everything is handled asynchronously!
}

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Library Components

• AsyncClient and AsyncServer: The powerful, low-level base classes for raw asynchronous TCP communication.
• AsyncPrinter: A Print interface wrapper for sending data, usable outside of async callbacks (e.g., in loop()).
• SyncClient: A standard, blocking TCP Client for simpler, synchronous tasks, similar to the one in ESP8266WiFi.

Libraries and Projects that use AsyncTCP

This library serves as a core dependency for many popular projects:

• ESP Async Web Server
• Async MQTT client
• arduinoWebSockets
• ESP8266 Smart Home

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Original Project Context

This project is a fork of the original work which has since moved to the ESP32Async organization.

• Original ESP8266 Repo: https://github.com/ESP32Async/ESPAsyncTCP
• ESP32 Version: https://github.com/ESP32Async/AsyncTCP
• Discord Server: https://discord.gg/X7zpGdyUcY