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

1. Modify ESP8266WiFi_0v25.js to do UDP and TCP
   Add UDPflag and CIPstartSTR.

   var at;
   var UDPflag=0;
   var CIPstartStr="";
   var socks = [];
   

Modify the code to CIPstart a client in the create: function

  create : function(host, port) {
    /* Create a socket and return its index, host is a string, port is an integer.
    If host isn't defined, create a server socket */  
    if (host===undefined) {
console.log("Server");
      sckt = MAXSOCKETS;
      socks[sckt] = "Wait";
      sockData[sckt] = "";
      at.cmd("AT+CIPSERVER=1,"+port+"\r\n", 10000, function(d) {
        if (d=="OK") {
          socks[sckt] = true;
        } else {
          socks[sckt] = undefined;
          setTimeout(function() {
            throw new Error("CIPSERVER failed ("+(d?d:"Timeout")+")");
          }, 0);
        }
      });
      return MAXSOCKETS;
    } else {  
console.log("Client");
      var sckt = 0;
      while (socks[sckt]!==undefined) sckt++; // find free socket
      if (sckt>=MAXSOCKETS) throw new Error("No free sockets");
      socks[sckt] = "Wait";
      sockData[sckt] = "";

if(UDPflag){//UDP client
 CIPstartStr='AT+CIPSTART='+sckt+',"UDP",'+JSON.stringify(host)+','+port+','+port+',0\r\n';

}else{//TCP client
 CIPstartStr='AT+CIPSTART='+sckt+',"TCP",'+JSON.stringify(host)+','+port+'\r\n';
}//end else
at.cmd(CIPstartStr,10000, function cb(d) {

Add code to set and reset the UDP flag

"SetUDP":function(){ UDPflag=1;
},
"SetTCP" : function(){ UDPflag=0;
},

  "getIP" : function(callback) {

UDP.js placed in modules directory of WebIDE project.

AT commands for UDP
https://github.com/espressif/ESP8266_AT/wiki/at_example_0020000903
https://gist.github.com/mokogobo/3f4d2f074305d4d84344

https://cdn.sparkfun.com/assets/learn_tutorials/4/0/3/4A-ESP8266__AT_Instruction_Set__EN_v0.30.pdf
AT+CIPSTART – Establish TCP connection or register UDP port, start connection
Example
AT+CIPSTART="TCP","192.168.101.110",1000
Single connection
(+CIPMUX=0)
AT+CIPSTART=,,[,,]
[,]
Multiple connection
(+CIPMUX=1)
AT+CIPSTART=,,,[,,]
[,]
Response
OK
or
ERROR
If connection already exists, returns
ALREAY CONNECT
Parameters

ID of the connection (0~4), for multi-connect

string, "TCP" or "UDP"

string, remote IP

string, remote port
[]
for UDP only
[] In UDP transparent transmission, it has to be 0.
[] 0
: destination peer entity of UDP will not change.
[] 1
: destination peer entity of UDP can change once.
[] 2
: destination peer entity of UDP is allowed to change.
Note: [] can only be used when [] is set.
[]
default 0. unit: 500 milliseconds.
[] 0
: disable TCP keep-alive
[] 1 ~ 7200
: TCP keep-alive interval

AT+CIPSTART – Function 2: R
egister UDP port
Example
AT+CIPSTART="UDP", "192.168.101.110", 1000, 1002,
2
Single connection
(AT
+CIPMUX=0)
AT+CIPSTART=, , [, ,
]
Multiple connection
(AT+CIPMUX=1
)
AT+CIPSTART=, , , [, , ]
Response
OK or
ERROR
If connection already exists, returns
ALREADY CONNECT

1 Attachment

• UDP.js