This Tutorial shows you how to flash the new
nodeMCU firmware into a ESP8266. This is also useful to get back to the LUA interface if
you were uploading C/C++sketches using the Arduino IDE - which overwrites nodeMCU lua data.
This tutorial shows you how
download and flash the latest version - since Feb 2019 some older
library code has been deprecated - especially timer operation so its
best to get going with the new code rather than learn outdated methods.
This information allows you to switch between Lua scripting and Arduino IDE programming easily - just by reprogramming the ESP8266.
installing Lua on an ESP8266 will allow you to use the LUA
scripting language in an interactive terminal. This means code upload is
far faster than the Arduino IDE compile-link-upload process.
Note: Lua is not yet ready for the ESP32 but seems to be in progress so keep an eye on the site: nodemcu-build.com
languages are slower the processor is fast (which compensates for
scripting speed) and you don't wait around for an upload as you do with
the ESP8266 Arduino IDE - and
Arduino IDE uploading takes about a minute so making small frequent changes is a
pain. With scripting - its a few seconds and you're done. The only
disadvantage is that its not C so you're going to have to learn a bit.
Breakout Board Used
The board used for experiments here is the Lolin NodeMCU V3
which has a very convenient USB interface that allows you to plug it
into a PC - power is supplied from the USB port - but you will need up
to 300mA~400mA (depending on the WiFi activity!) so don't use a hub, use
a PC USB port or you might need an external power source.
NodeMCU firmware Update program
This is the easy-to use ESP8266 breakout board
Lolin nodeMCU V3 Board
Note: Other boards such as the ESP-01 and those without a USB interface
require you to keep GPIO0 low for programming. The Lolin nodeMCU board
however has this pin controlled using outputs from the USB serial chip -
so its all automatic - just plug in and flash the firmware.
External Power Source
You can add an external power source to the Vin connection on
the board with voltage >5V. Also connect ground labelled 'G' to complete the circuit.
Warning: The AMS1117 absolute maximum input voltage is 15V - do not go above this i.e. do not supply a voltage to 'Vin' above 15V.
Find out the NodeMCU serial port in use
You can find out which port your nodeMCU is attached to by starting Control panel and
navigating to hardware and "Device Manager" to find the following screen:
Reading the documents at : https://nodemcu.readthedocs.io/en/master/en/flash/
Says the following:
flash-mode is qio for most ESP8266 ESP-01/07 (512 kByte modules)
and dio for most ESP32 and ESP8266 ESP-12 (>=4 MByte modules).
ESP8285 requires dout.
ESP8266 Flash Downloader
This method of flashing the ESP8266 to install the latest nodeMCU firmware uses the latest tool - which is also
very easy to use, however you need to go and get a binary file for it to
program into the chip - not too difficult.
This will download the pyflasher that is python based but you won't need
to install other files just double click and go.
The downloaded filename is : NodeMCU-PyFlasher-4.0-x64.exe
It looks like this:
Get a nodeMCU firmware Cloud Built Binary
Before you can use pyflasher go and get a binary sent to your email
account (for the default settings this takes ~2 minutes). It sounds a
bit intimidating but the steps are easy - there's only a few and its not
...and keep the default options - at the moment only the ESP8266 is
supported and that's what's in the nodeMCU board so that's fine. Enter
your email, click the "Start Your Build" button and wait for the binary.
Here's what the options look like:
Note: You can see the functions available for each module by clicking on the book symbols next to each check box.
The idea is to include those you need since space is limited on the ESP8266.
Programming the ESP8266 using pyflasher
Again don't forget to close the ESP8266 serial port you may have been using!
Download the float version of your binary - this is recommended even though it uses more memory but is up to you.
Keep the serial speed at 115200.
Choose the serial port or use auto detect.
Choose DIO for ESp-12E
Choose Erase Flash - just to make sure!
Click "Flash NodeMCU":
Note: When you start the serial terminal this Lua interface uses 115200 baud not the 9600 as the previous version used.
Warning: The ESP8266 does not
start immediately - When you first start it it will format the ESP8266
file system - takes about 40 seconds.
This is the output you will see - not just one line as for the 2015 version of nodeMCU:
Note: this is all interactive - there was no compiling a C source file and waiting for upload.
NodeMCU 0.9.5 build 20150318 powered by Lua 5.1.4
lua: cannot open init.lua
> print("Hello World")
A Simple ESP8266 LUA Example
Controlling a GPIO pin using LUA
Now lets try and turn on an LED
LED Current calculation
If you don't want to add an external LED use pin 4. Current schematics
don't show it but I found it by accident. LED operation is
inverted, for this pin, since it is pulled high so digital write low sets the LED on.
Note: Some people do not use a resistor in series with the LED but that is relying on the max
current from the nodeMCU as 12mA - other boards will allow more current
out (and blow up the LED) so it is best practice to use a resistor - when you forget which board you are using!
use a 1k since you can see the LED even with that high value. For this
case current = (3.3-2)/1k = 1.3mA - you can se it so it is good enough
The usual case is
to use a 330R resistor in a 5 volt system. In that case you get (5-2)/330=10mA.
usually take 20mA so choosing 10mA for a 3V system gives R= (3.3-2)/10e-3 129R so 120R
Connect an LED and resistor on a breadboard to D0.
LED Round side to D0
LED flat side (look closely) to resistor
other end of resistor to Ground (G).
You can see the LED turning on and off using the interactive Lua script interface.
NEXT: Now you have updated
the Firmware and Lua is working on your ESP module. The next thing to do
is to install a Lua uploader/Editor. This makes it easy to upload files
to the device, and program it over the serial connection. One popular
uploader is ESPlorer.