Note that the NodeMCU serial interface uses 115'200bps at boot time. To change the speed after booting, issue `uart.setup(0,9600,8,0,1,1)`. ESPlorer will do this automatically when changing the speed in the dropdown list. If the device panics and resets at any time, errors will be written to the serial interface at 115'200 bps.
> The essential multiplatforms tools for any ESP8266 developer from luatool author’s, including Lua for NodeMCU and MicroPython. Also, all AT commands are supported. Requires Java (Standard Edition - SE ver 7 and above) installed.
You will see "lua: cannot open init.lua" printed to the serial console when the device boots after it's been freshly flashed. If NodeMCU finds a `init.lua` in the root of the file system it will execute it as part of the boot sequence (standard Lua feature). Hence, your application is initialized and triggered from `init.lua`. Usually you first set up the WiFi connection and only continue once that has been successful.
Be very careful not to lock yourself out! If there's a bug in your `init.lua` you may be stuck in an infinite reboot loop. It is, therefore, advisable to build a small delay into your startup sequence that would allow you to interrupt the sequence by e.g. deleting or renaming `init.lua` (see also [FAQ](lua-developer-faq.md#how-do-i-avoid-a-panic-loop-in-initlua)). Your `init.lua` is most likely going to be different than the one below but it's a good starting point for customizations:
```lua
-- load credentials, 'SSID' and 'PASSWORD' declared and initialize in there
dofile("credentials.lua")
function startup()
if file.open("init.lua") == nil then
print("init.lua deleted or renamed")
else
print("Running")
file.close("init.lua")
-- the actual application is stored in 'application.lua'
-- dofile("application.lua")
end
end
print("Connecting to WiFi access point...")
wifi.setmode(wifi.STATION)
wifi.sta.config(SSID, PASSWORD)
wifi.sta.connect()
tmr.alarm(1, 1000, 1, function()
if wifi.sta.getip() == nil then
print("Waiting for IP address...")
else
tmr.stop(1)
print("WiFi connection established, IP address: " .. wifi.sta.getip())
print("You have 3 seconds to abort")
print("Waiting...")
tmr.alarm(0, 3000, 0, startup)
end
end)
```
Inspired by [https://github.com/ckuehnel/NodeMCU-applications](https://github.com/ckuehnel/NodeMCU-applications)
