Example of a persistent TCP server using WiFiManager and ESP8266Wifi

esp8266-wifimanager-tcp.ino

/*
   SocketServer.ino

    Created on: 4.11.2023
    Author: miceno.atreides@gmail.com

*/

#include <ESP8266WiFi.h>
#include <WiFiManager.h>

// If there is difficulty getting the INDI roof driver to connect, need to establish that the
// WiFi network is working and that the Arduino is connected. Running the Arduino IDE and
// using its serial monitor can be helpful to see any diagnostic messages.
// INIT_DELAY_SECS can be defined to wait a number of seconds after starting the Arduino
// to have time to get the serial monitor display started and see network startup messages.
#define INIT_DELAY_SECS 0

#define MAX_BAUD_RATE 115200
String strData = "";             // a string to hold incoming data

uint16_t port = 8888;            // Port number
WiFiServer server(port);

//Static IP address configuration
IPAddress staticIP(192, 168, 1, 61);  // Board static ip
IPAddress gateway(192, 168, 1, 1);    // WiFi Router Gateway IP Address
IPAddress subnet(255, 255, 255, 0);   // Subnet mask
IPAddress dns(8, 8, 8, 8);            // DNS
WiFiClient client;

bool setup_wifi() {
  delay(INIT_DELAY_SECS * 1000);  // diagnostic, allow time to get serial monitor displayed
  WiFi.mode(WIFI_STA);            // explicitly set mode, esp defaults to STA+AP
  // it is a good practice to make sure your code sets wifi mode how you want it.

  // put your setup code here, to run once:
  Serial.begin(MAX_BAUD_RATE);

  //WiFiManager, Local intialization. Once its business is done, there is no need to keep it around
  WiFiManager wm;

  // reset settings - wipe stored credentials for testing
  // these are stored by the esp library
  // wm.resetSettings();

  // Automatically connect using saved credentials,
  // if connection fails, it starts an access point with the specified name ( "AutoConnectAP"),
  // if empty will auto generate SSID, if password is blank it will be anonymous AP (wm.autoConnect())
  // then goes into a blocking loop awaiting configuration and will return success result

  bool res;
  // res = wm.autoConnect(); // auto generated AP name from chipid
  // res = wm.autoConnect("AutoConnectAP"); // anonymous ap
  res = wm.autoConnect("AutoConnectAP", "password");  // password protected ap

  if (!res) {
    Serial.println("Failed to connect");
    // ESP.restart();
  } else {
    //if you get here you have connected to the WiFi
    Serial.println("connected...yeey :)");
  }
  return res;
}


void setup() {
  bool res = false;
  Serial.begin(MAX_BAUD_RATE);
  while (Serial.available() > 0)
    ;

  WiFi.disconnect();  //Prevent connecting to wifi based on previous configuration
  ESP.eraseConfig();

  res = setup_wifi();
  if(!res){
    Serial.println("Unable to start wifi... aborting");
    exit(-1);
  }
  Serial.println("\nWiFi connected");
  Serial.print("START MIRRORING SERIAL: ");
  Serial.println(WiFi.localIP());

  // Start server
  server.begin();
}

void loop() {
  // Serial.println("looping..."); // DEBUG
  if (!client){
    // Only request a client in case there is no valid one.
    // The client should persist on the loop so it is a global variable.
    client = server.available();
  }

  if (client) {
    // Serial.println("client...");
    while (client.available() > 0) {
      char c;
      // Serial.println("data is available...");
      // read data from the connected client
      c = client.read();
      strData += c;
    }

    // Serial.println("\nNo more data available");
    if( strData.length()>0){
      Serial.printf("Message received is %s\n", strData.c_str());
      client.write("Response received");
      client.flush();
      strData = "";
    }
  }
}