Using UPD to find IP addresses for a TCP network in 5 parts.

1. The UDP/TCP client

   //UDP_TCPclient1.js
   //2 Oct 2016
   //espruino board with ESP8266
   //PICO  with ESP8266
   //var BroadIP="255.255.255.255";
   var BroadIP="192.168.1.255";
   //var LocalIP;
   var UDPport=1234;
   var TCPport=9988;
   //var Hardware=0; //Espruino board
   var Hardware =1; //PICO
   var SSID="ssid";
   var key= "router passcode";
   var Serial;
   var Wifi;
   function UDPmsg(a,b,c,d){
   this.ClientName=a;
   this.ClientIP=b;
   this.ServerName=c;
   this.ServerIP=d;
   }
   var UDP1=new UDPmsg("Bob",0,"Bill",0);
   var UDP2;//=new UDPmsg("",0,"",0);
   var ServerIP=0;
   var ddata="";
   function test(){
   if(Hardware===1)Serial=Serial2;
   if(Hardware===0)Serial=Serial4;
   if(Hardware===1){
   digitalWrite(B9,1); // enable on Pico Shim V2
   Serial.setup(115200, { rx: A3, tx : A2 }); //Pico
   }
   if(Hardware===0)Serial.setup(115200, { rx: C11, tx : C10 }); 
   //espruino board
   console.log("Start connection process");
   var wifi = require("UDP").connect(Serial, function(err) {
   if (err)return 1;// throw err;
   Wifi=wifi;
   console.log("Reset the ESP8266");
   wifi.reset(function(err) {
   if (err)return 1;// throw err;
   Wifi.at.cmd("AT+CWMODE_CUR=3\r\n", 1000, function(d){console.log(d+"xx1");});
   Wifi.at.cmd("AT+CIPMUX=1\r\n", 1000, function(d){console.log(d+"xx2");});
   console.log("Connecting to WiFi");
   wifi.connect(SSID,key, function(err) {
   if (err)return 1;//throw err;
   wifi.getIP(function(l,ip){console.log("IP= ",ip,"\n\r");
    UDP1.ClientIP=ip;
    console.log("Wi-Fi Connected");
   // Setup UDP Client 
    wifi.SetUDP();
    var client = require("net").connect({host: BroadIP, port: UDPport,protocolVersion: 17}, function() {
     console.log('client connected');
     console.log(UDP1.ClientIP);
     client.write(JSON.stringify(UDP1));
     client.on('data', function(data) {
      ddata+=data;
       if(ddata.charAt(ddata.length-1)==='}'){
        UDP2=JSON.parse(ddata);
        console.log(">"+ddata);
        ddata="";
         if((UDP1.ClientName===UDP2.ClientName)&&       (UDP1.ServerName===UDP2.ServerName)){
          ServerIP=UDP2.ServerIP;
   //HTTP or network client goes here
          menu();
         }else{
         }//endif
       }//endif ddata=}
     });//end client on data
     client.on('end', function() {
      console.log('client disconnected');
     });//client on end
     //client.end(");
    });//end client.net
   });//end wif.getIP
   ////////////////////////////////////////////////////////////
   });//end wifi.connect SSID
   });//end wifi.reset
   });//end wifi.connect serial
   }//end test
   //xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
   function sendit(msg){
   var reply="";
   Wifi.SetTCP();
   var client = require("net").connect({host: ServerIP, port: TCPport}, function() {
   //  console.log('client connected');
   client.write(msg);
   client.on('data', function(data) {
   reply+=data;
   console.log(">"+JSON.stringify(data));
   });
   client.on('end', function() {
   //    console.log('client disconnected');
   return reply;
   });
   });
   }
   ////////////////////////////////////////////////////////////////////////
   var sst="";
   //Menus
   menu=function(){
   USB.print(" \n\r");
   USB.print("Select using digit and return key\n\r");
   USB.print("1 LED Off\n\r");
   USB.print("2 LED On\n\r");
   USB.print("0 Exit\n\r");
   };
   parsecmd=function(){
   USB.print("\n\r");
   switch(this.sst.charAt(0)){
   case "1"://LED off
    sst="";
    USB.print("LED Off\n\r");
    sendit("LED Off");
   break;
   case "2"://LED On
    USB.print("LED On\n\r");
    sst="";
    sendit("LED On");
   break;
   case"0"://Exit
    LoopbackA.print("USB.setConsole();\n\r");
    sst="";
    USB.print("Exit\n\r");
   break;
   default:
    menu();
   break;
   }//end switch sst
   };//end parsecmd
   //input cmd from terminal,send it to parsecmd()
   USB.on('data', function (data) {
   var i;
   sst+=data;
   USB.print(data);
   if(sst.length>0)
   if(sst.charAt(sst.length-1)==="\r")parsecmd();
   });
   //Espruino replies here
   LoopbackA.on('data',function(data){
   USB.print(data); //sending data to terminal
   });
   /////////////////////////
   setTimeout(function () {
   var x;
   console.log("Start");
   LoopbackB.setConsole();
   x=test();
   if(x!==0)console.log("Try again");//error seen
   if(x===0) console.log("Exit Seen");
   }, 1000);
   

The WebIde screen:

>echo(0);
=undefined
Start
-> LoopbackB
<- USB
Start connection process
Try again
Reset the ESP8266
Connecting to WiFi
OKxx1
OKxx2
IP=  192.168.1.4
Wi-Fi Connected
Client
client connected
192.168.1.4
Send 0 {"ClientName":"Bob","ClientIP":"192.168.1.4","ServerName":"Bill","ServerIP":0}
>
Select using digit and return key
1 LED Off
2 LED On
0 Exit
>{"ClientName":"Bob","ClientIP":"192.168.1.4","ServerName":"Bill","ServerIP":"192.168.1.3"}
>1
LED Off
Client
Send 1 LED Off
>2
LED On
Client
Send 1 LED On
>0
Exit
<- LoopbackB
=undefined
=undefined
>USB.setConsole();
-> USB

And the server screen:

>{"ClientName":"Bob","ClientIP":"192.168.1.4","ServerName":"Bill","ServerIP":0}
Send 0 {"ClientName":"Bob","ClientIP":"192.168.1.4","ServerName":"Bill","ServerIP":"192.168.1.3"}
Socket accept 1 "LED O" undefined
Close false
LED O
Socket accept 1 "ff" undefined
Close false
ff
Socket accept 1 "LED On" undefined
Close false
LED On
>

1 Attachment

• UDP_TCPserver1.js