ESP8266 Community Forum

- Sat Apr 01, 2017 10:29 am #64482 WiFiClient has to be defined before the setup() routine. I changed the port, and then long after setting up variables (from reading the EEPROM) and other routines, I finally change the client.

Here is the stripped down code in Setup():

Code: Select allWiFiClient tcpClient;              // enable the client
WiFiServer tcpServer(LISTEN_PORT); // enable server listening on port 6400

void setup() {

  Serial.begin(serialspeed);    // enable serial port at specfic baud rate
  WiFi.begin("", "");         // connect to router with stored ssid and password

  tcpServer.close();
  tcpServer.setPort(6969);
  tcpServer.begin();
  tcpServer.setNoDelay(true);
 
  WiFiClient tempClient = tcpServer.available();  // this is the key to keeping the connection open
  tcpClient = tempClient;       // hand over the new connection to the global client
  tempClient.stop();            // stop the temporary one
  tcpClient.flush();            // flush out all data
}


- Sat Apr 01, 2017 10:38 am #64483 Can you post you test code that worked? I have tried dozens of variations on this.

The reason why I made this thread is because I had read in several forums (including the Esprif forum) that it was not possible to do this. If you look at the Arduino github you will find this has been a requested feature since early 2015, but has not been implemented because the underlying SDK doesn't have a function for this. That certainly could be wrong, especially since you have stated it works. It's definitely something that people want to be able to do. Thanks!

- Sat Apr 01, 2017 2:40 pm #64487 I beleave that what you read in different threads is that you can not switch port on existing connections or on existing listening server, that's why we need to do close()/begin(). And also that the setPort() I've provided didn't exist yet in any releases.

Here is the testing sketch :

Code: Select all#include <ESP8266WiFi.h>

WiFiServer tcpserver(23); // Telnet Port
WiFiClient client;
uint current_port = 23;

void setup() {
  int timeout = 60;
  Serial.begin(115200);
  WiFi.mode(WIFI_STA);
  WiFi.begin("Giroles-Salon", "PitchouFacePouding");
  while (WiFi.status() != WL_CONNECTED) {
    delay(500);
    Serial.print(".");
    timeout--;
    if (timeout <= 0) {
      Serial.printf("\r\nWiFi connect aborted !\r\n");
      while(1) {};
    }
  }
  String str = "\r\nWiFi connected !\r\nIP = ";
  str += WiFi.localIP().toString();
  Serial.println(str);
  tcpserver.begin();
}

void loop() {
  if (client) {
    if (client.status() == CLOSED) {
      client.stop();
      Serial.println("connection closed !");
    }
    if (client.available()) {
      client.setNoDelay(1);
      String req = client.readStringUntil('\r');
      client.flush();     
      if (req.equals("hello")) {
        client.println("Hello from ESP8266 !");
      }
      else if (req.equals("switch")) {
        tcpserver.close();
        if (current_port == 23)
          current_port = 24;
        else
          current_port = 23;
        tcpserver.setPort(current_port);
        tcpserver.begin();
      }
      else if (req.equals("exit")) {
        client.stop();
      }
      else if (req.length() > 0)
        client.println("Unknown command !");
      else
        client.print(">");
    }
  }
  else {
    client = tcpserver.available();
  }
}


To execute, simply do "telnet <esp_ipaddr> 23", then type command "hello" just for test, and real "switch" command will switch port to 24, then type "exit". Trying again "telnet <esp_ipaddr> 23" will fail, but doing "telnet <esp_ipaddr> 24" will succeed. Doing "switch" again will bring it back to 23...

- Sat Apr 01, 2017 4:13 pm #64488 Thanks for the example code. I am going to change the router info and run this as-is to see if it works.

I don't see anything any different than what I have implemented from your previous example.