nodemcu how to cut down the time required to acquire ip address

Question

With NodeMCU in station mode with the following snippet of code in init.lua it still takes on average about 6 iterations of the loop before an IP address is reported (or IP stack ready state is achieved)

wifi.sta.disconnect()
--settings.lua
SSID    = "xxxx"
APPWD   = "yyyy"

cfg =
  {
    ip="192.168.0.85",
    netmask="255.255.255.0",
    gateway="192.168.0.1"
  }
wifi.sta.setip(cfg)
wifi.sta.config(SSID,APPWD)
wifi.sta.autoconnect(1)

-- wait for WIFI ----
function checkWIFI() 
    print("Waiting for WIFI...")
    ipAddr = wifi.sta.getip()
    if ( ( ipAddr ~= nil ) and  ( ipAddr ~= "0.0.0.0" ) )then
        print("IP Address: " ..ipAddr)

    else
      -- schedule try again 
      tmr.alarm( 0 , 1000 , 0 , checkWIFI)
    end  
end
tmr.alarm( 0 , 1000 , 0 , checkWIFI)

Tried with and without static IP configuration, seems no different Is this normal? Is there a way to make faster? Am I just doing it wrong?

Eyal · Answer 1 · 2015-12-20T03:05:12.687

The following is my practical experience, which may be out of date now. I need to retest these...

I do a similar thing and it works well. However, while WiFi is not available quickly after a "reset", it is available very quickly on wakeup from deep sleep.

After first use (settings are saved automatically) I later simply do this lua wifi.sta.setip(cfg) wifi.sta.status() -- this used to speed things up

I also set wifi.sta.autoconnect(0) to avoid dhcp delays.

BTW, to check for a connection it is best to wait for wifi.sta.status() == 5.

HTH

Andy Joiner · Answer 2 · 2022-01-11T13:18:42.170

Based on @Eyal's answer, I was able to get an IP address typically in 415-470ms from deep sleep (based on the timer), or 3.25 seconds from cold power on.

NOTE: There is no DNS resolution with this solution

Save your network config to flash

wifi.sta.clearconfig()
wifi.setmode(wifi.STATION)
station_cfg={}
station_cfg.ssid="MyWiFiNetwork"
station_cfg.pwd="MyWiFiPassword"
station_cfg.save=true
station_cfg.auto=false
wifi.sta.config(station_cfg)

On every boot

cfg =
  {
    ip="192.168.0.99",
    netmask="255.255.255.0",
    gateway="192.168.0.1"
  }
wifi.sta.setip(cfg)
wifi.sta.connect()

Test it with

function checkWIFI() 
    ipAddr = wifi.sta.getip()
    
    if ( wifi.sta.status() == wifi.STA_GOTIP )then
        --LED On
        gpio.write(4, gpio.LOW)
        gpio.mode(4, gpio.OUTPUT)
        print("Time " .. tmr.now()/1000 .. "ms")           
        print("IP Address: " ..ipAddr)

    else
      -- schedule try again 
      tmr.create():alarm(50, tmr.ALARM_SINGLE, checkWIFI)
    end  
    print("WiFi Status "  ..  wifi.sta.status())
end
tmr.create():alarm(50, tmr.ALARM_SINGLE, checkWIFI)

nodemcu how to cut down the time required to acquire ip address

2 Answers2