Problem saving the IP address for later use.

[espruino-discuss]

Posted at 2016-09-26 by ClearMemory041063

PICO shimmed to ESP8266.
I use wifi.getIP() and print the resulting IP address, then assign it to a global variable.
Printing the global variable MyIP doesn’t work.
Later typing MyIP; into the left pane I get the IP address.
So what’s going on and is there a solution?

//MyIP.js
//26Sep 2016
//espruino board with ESP8266
//PICO  with ESP8266
//var Hardware=0; //Espruino board
var Hardware =1; //PICO
var SSID="ssis";
var key= "routerpw";
var Serial;
var MyIP="";
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("ESP8266WiFi_0v25").connect(Serial, function(err) {
  if (err)return 1;// throw err;
console.log("Reset the ESP8266");
  wifi.reset(function(err) {
    if (err)return 1;// throw err;
    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"+l);MyIP=ip;});
      console.log("Wi-Fi Connected");
      console.log("MyIP= ",MyIP,"XXX");
      console.log("MyIP= "+MyIP+"XXX");
// Now you can do something, 
 var server = require("net").createServer(function(c) {
  // A new client as connected
  c.write("Hello");
  c.on('data', function(data) {
    console.log(">"+JSON.stringify(data));
  });
  c.end();
});
server.listen(1234);
    });
  });
});
}//end test
var x;
console.log("Start");
x=test();
if(x!==0)console.log("Try again");//error seen
if(x===0) console.log("Exit Seen");

The output:

>echo(0);
Start
Start connection process
Try again
=undefined
Reset the ESP8266
Connecting to WiFi
Wi-Fi Connected
MyIP=   XXX
MyIP= XXX
IP=  192.168.1.3
null
>MyIP;
="192.168.1.3"
>

---

Attachments:

• MyIPpost.js

[gfwilliams]

Posted at 2016-09-26 by @gfwilliams

I think that's as expected. wifi.getIP returns almost immediately, and only calls the callback when the ESP8266 responds with the IP address. It means that the callback won't have got called by the time your console.log calls execute, and the IP will stay empty.

... if we could get the IP address immediately, wifi.getIP could have returned it directly, rather than faffing with the callbacks :)

[espruino-discuss]

Posted at 2016-09-26 by ClearMemory041063

The assignment MyIP=ip; is done in the callback. That's what's puzzling. The console.log(ip) is also done in the callback before the assignment and displays the IP address. It's likely a timing issue but still puzzling.

I've got UDP working (not this example code). I broadcast using IP=255.255.255.255 and send a keyword and local IP address. If the keyword matches, the other end broadcasts using a keyword and it's local IP address. So I need the local IP address from the getIP function to finish this.
Msg1: Hi I'm Billy Bob at IPxxx, where are you Sally?
Msg2: Hi I'm Sally at IPyyy.
Then Billy Bob can use IPyyy to contact Sally.
Right now I'm hard coding the local IP addresses, but that defeats the purpose since the next time my router resets the IP addresses will be reassigned.

[espruino-discuss]

Posted at 2016-09-26 by ClearMemory041063

I found a solution:
Use a SetInterval and wait for the IP address to show up.

      wifi.getIP(function(l,ip){console.log("IP= ",ip,"\n\r"+l);xIP=ip;});
id=setInterval(function () {
  console.log("Hello World");
  if(xIP!==undefined){
   console.log("xIP= ",xIP);
  clearInterval(id);
      console.log("Wi-Fi Connected ");
// Now you can do something, 
      var client = require("net").connect({host: IP, port: 1234,protocolVersion: 17}, function() {
  console.log('client connected');
  client.write("Jello"+xIP);
  client.on('data', function(data) {
    console.log(">"+JSON.stringify(data)+"xjello");
  client.write("Reply"+xIP);
  });
  client.on('end', function() {
    console.log('client disconnected');
  });

//client.end("UTLEY");
});
  }
}, 1000);

And the output:

>echo(0);
Start
Start connection process
Try again
=undefined
Reset the ESP8266
Connecting to WiFi
OKxx1
OKxx2
IP=  192.168.1.3
null
Hello World
xIP=  192.168.1.3
Wi-Fi Connected
Client
client connected
Send 0 Jello192.168.1.3
> 

And the Billy Bob device

>echo(0);
Start
Start connection process
Try again
=undefined
Reset the ESP8266
Connecting to WiFi
OKxx1
OKxx2
Wi-Fi Connected
Client
client connected
IP=  192.168.1.4
null
"192.168.1.4"
Send 0 XX 192.168.1.4Jello
>"Reply192.168.1.3"xjello
>
Disconnected

I expect to post the UDP in a few days after some code cleanup.
It modifies the ESP8266WiFi_0v25 module to allow UDP.
var wifi = require("UDP").connect(Serial, function(err) {
//var wifi = require("ESP8266WiFi_0v25").connect(Serial, function(err) {

[gfwilliams]

Posted at 2016-09-26 by @gfwilliams

wifi.getIP(function(l,ip){console.log("I­P= ",ip,"\n\r"+l);xIP=ip;});

I don't see this is puzzling: You're logging ip, the parameter - so of course it's going to be right.

You could always do what you want from the getIP callback itself, rather than using setInterval?