ESP8266 Community Forum

Posted: **Fri May 08, 2015 2:20 am**

Hi guys

I'm completely new and just ditched the AT Firmware and flashed NodeMCU on my ESPs, so please bare with me

Im using NodeMCU 0.9.5 build 20150318 powered by Lua 5.1.4

My plan is to let the ESP scan for available networks when powering up, then check if a specific network already exists.
-If it does, it should join this network
-If it didn't find it, create it itself

Here is the (not working) code I am using:

Code: Select all

print("Set up wifi mode..")
wifi.setmode(wifi.STATIONAP)
wifi.sta.config("MyTest","87654321")


     
--Scan for available networks
print("Scanning for networks..")
  function listap(t)
      for k,v in pairs(t) do
        print(k.." : "..v)
      end
    end
    wifi.sta.getap(listap)
    tmr.delay(10000)
--Connect if network available, create if not found    
    if listap == "MyTest" then
        print("Found Network MyTest")
        wifi.sta.connect()

                   tmr.alarm(1, 1000, 1, function() 
                     if wifi.sta.getip()== nil then 
                       print("IP unavaiable, Waiting...") 
                          else 
                          tmr.stop(1)
                        print("Config done, IP is "..wifi.sta.getip())
                           --dofile("yourfile.lua")
                             end 
                         end)
 
    else  print("Network not Found! Creating..")
          cfg={}
          cfg.ssid="MyTest"
          cfg.pwd="87654321"
          wifi.ap.config(cfg)
          print(wifi.ap.getip())
 end

I see multiple issues, but since I'm completely new to lua i don't know how to fix them and so far didn't have any luck with google.

1. Because the wifi.sta.getap command needs a couple of seconds, I added a delay. But I'm not sure if this is the right way and works as it should? I simply wanted the following code to execute when the scanning for networks is finished.
2. I am then trying to see if the desired network is in this list (with: if listap == "MyTest" then). But this is surely the wrong way. How do I search the created table the right way so that if the network MyTest is there, it connects to this, rather than creating a new network with the same name?

This is what I get from the ESPlorer:

Code: Select all

> dofile("init.lua");
Set up wifi mode..
Scanning for networks..
Network not Found! Creating..
192.168.4.1   255.255.255.0   192.168.4.1
> randomAP: 3,-64,00:26:f2:f7:cf:1c,3
>randomAP2:3,-64,00:26:f2:f7:cf:1c,3

Any Help would be greatly appreciated! Thank you for any tips!

Posted: **Sat May 09, 2015 4:59 am**

Don't use tmr.delay in this use case. It disables interrupts in order to do an accurate delay. Use a timer.alarm with a callback.

Posted: **Tue May 12, 2015 4:48 am**

Thanks for the reply!

I tried with a modified version and added the tmr.alarm as you suggested:

Code: Select all

print("Set up wifi mode..")
wifi.setmode(wifi.STATIONAP)
wifi.sta.config("TestAP","87654321")


     
--Scan for available networks
print("Scanning for networks..")
  function listap(t)
      for k,v in pairs(t) do
        print(k.." : "..v)
      end
    end
    wifi.sta.getap(listap)
   -- tmr.delay(10000) --> use tmr.alarm instead

   tmr.alarm(1,10000, 1, function() 
   print("Test")
 
 function table.contains(listap, TestAP)
  for _, value in pairs(listap) do
    if value == TestAP then
      print("success")
    end
  end
  print("Not Found")
end
end)

I get the following output:

Code: Select all

Set up wifi mode..
Scanning for networks..
> AP1: 0,-40,88:75:56:87:5a:54,11
AP2 : 0,-39,88:75:56:87:5a:53,11
AP3 : 0,-40,88:75:56:87:5a:52,11
Test
Test
Test
Test

The tmr.alarm is a good start as i get the table before any of the following lines are executed.

However..the function 'table.contains' was supposed to read the values in the table and decide if the specific AP is in there. It seems however that this function doesn't execute as i get neither 'success' nor 'not found'?!

Why is that and do you see any solution?

EDIT:
I also tried the Example function (from http://wiki.mudlet.org/w/Manual:Lua_Fun ... _Functions)

Code: Select all

local test_table = { "value1", "value2", "value3", "value4" }
if table.contains(test_table, "value1") then 
   echo("Got value 1!")
else
   echo("Don't have it. Sorry!")
end

which returns: "PANIC: unprotected error in call to Lua API (init.lua:21: attempt to call field 'contains' (a nil value))"

Is .contains not implemented in the NodeMCU?

Thanks for your help
Ben

Posted: **Tue May 12, 2015 11:17 am**

I was also looking for something to a slightly similar task -> check if one of the SSIDS saved are available, if so connect to them. was wondering if you ran into something like that?

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