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NodeMCU is an [eLua](http://www.eluaproject.net/) based firmware for the [ESP32 WiFi SOC from Espressif](http://http://espressif.com/en/products/hardware/esp32/overview). The firmware is based on the [Espressif IoT Development Framework](https://github.com/espressif/esp-idf) and uses a file system based on [spiffs](https://github.com/pellepl/spiffs). The code repository consists of 98.1% C-code that glues the thin Lua veneer to the SDK.
The NodeMCU *firmware* is a companion project to the popular [NodeMCU dev kits](https://github.com/nodemcu/nodemcu-devkit-v1.0), ready-made open source development boards with ESP8266-12E chips.
# Summary
- Easy to program wireless node and/or access point
- Based on Lua 5.1.4 (without *debug, os* modules)
- Asynchronous event-driven programming model
- 10+ built-in modules
- Firmware available with or without floating point support (integer-only uses less memory)
- Up-to-date documentation at [https://nodemcu.readthedocs.io](https://nodemcu.readthedocs.io)
# Programming Model
The NodeMCU programming model is similar to that of [Node.js](https://en.wikipedia.org/wiki/Node.js), only in Lua. It is asynchronous and event-driven. Many functions, therefore, have parameters for callback functions. To give you an idea what a NodeMCU program looks like study the short snippets below. For more extensive examples have a look at the [`/lua_examples`](lua_examples) folder in the repository on GitHub.
The entire [NodeMCU documentation](https://nodemcu.readthedocs.io/en/dev-esp32/) is maintained right in this repository at [/docs](docs). The fact that the API documentation is maintained in the same repository as the code that *provides* the API ensures consistency between the two. With every commit the documentation is rebuilt by Read the Docs and thus transformed from terse Markdown into a nicely browsable HTML site at [https://nodemcu.readthedocs.io/en/dev-esp32/](https://nodemcu.readthedocs.io/en/dev-esp32/).
- How to [build the firmware](https://nodemcu.readthedocs.io/en/dev-esp32/en/build/)
- How to [flash the firmware](https://nodemcu.readthedocs.io/en/dev-esp32/en/flash/)
- How to [upload code and NodeMCU IDEs](https://nodemcu.readthedocs.io/en/dev-esp32/en/upload/)
- API documentation for every module
# Support
See [https://nodemcu.readthedocs.io/en/dev/en/support/](https://nodemcu.readthedocs.io/en/dev/en/support/).
There are essentially three ways to build your NodeMCU firmware: cloud build service, Docker image, dedicated Linux environment (possibly VM).
**Building manually**
## Tools
## Cloud Build Service
NodeMCU "application developers" just need a ready-made firmware. There's a [cloud build service](http://nodemcu-build.com/) with a nice UI and configuration options for them.
### Cloud Build Service
~NodeMCU "application developers" just need a ready-made firmware. There's a [cloud build service](http://nodemcu-build.com/) with a nice UI and configuration options for them.~
## Docker Image
Occasional NodeMCU firmware hackers don't need full control over the complete tool chain. They might not want to setup a Linux VM with the build environment. Docker to the rescue. Give [Docker NodeMCU build](https://hub.docker.com/r/marcelstoer/nodemcu-build/) a try.
Not available yet.
## Linux Build Environment
NodeMCU firmware developers commit or contribute to the project on GitHub and might want to build their own full fledged build environment with the complete tool chain. There is a [post in the esp8266.com Wiki](http://www.esp8266.com/wiki/doku.php?id=toolchain#how_to_setup_a_vm_to_host_your_toolchain) that describes this.
### Docker Image
~Occasional NodeMCU firmware hackers don't need full control over the complete tool chain. They might not want to setup a Linux VM with the build environment. Docker to the rescue. Give [Docker NodeMCU build](https://hub.docker.com/r/marcelstoer/nodemcu-build/) a try.~
Not available yet.
### Linux Build Environment
NodeMCU firmware developers commit or contribute to the project on GitHub and might want to build their own full fledged build environment with the complete tool chain.
Run the following command for a new checkout from scratch. This will fetch the nodemcu repo, checkout the `dev-esp32` branch and finally pull all submodules:
The `make` command initiates the build process, which will start with the configuration menu to set the build options.
Updating your clone from upstream needs an additional command to update the submodules as well:
```
git pull origin dev-esp32
git submodule update --recursive
```
## Build Options
All configuration options are accessed from the file `sdkconfig`. It's advisable to set it up with the interactive `make menuconfig` - on a fresh checkout you're prompted to run through it by default.
The most notable options are described in the following sections.
### Select Modules
Follow the menu path
```
Component config --->
NodeMCU modules --->
```
Tick or untick modules as required.
### UART default bit rate
Follow the menu path
```
Component config --->
Platform config --->
UART console default bit rate --->
```
### CPU Frequency
Follow the menu path
```
Component config --->
ESP32-specific --->
CPU frequency --->
```
### Stack Size
If you experience random crashes then increase the stack size and feed back your observation on the project's issues list.
Follow the menu path
```
Component config --->
ESP32-specific --->
Main task stack size --->
```
### Flashing Options
Default settings for flashing the firmware with esptool.py are also configured with menuconfig:
Below you'll find all necessary information to flash a NodeMCU firmware binary to ESP32. Note that this is a reference documentation and not a tutorial with fancy screen shots. Turn to your favorite search engine for those.
!!! attention
Keep in mind that the ESP32 needs to be [put into flash mode](#putting-device-into-flash-mode) before you can flash a new firmware!
## Tool overview
### esptool.py
> A Python-based, open source, platform independent, utility to communicate with the ROM bootloader in Espressif ESP8266.
NodeMCU is an [eLua](http://www.eluaproject.net/) based firmware for the [ESP8266 WiFi SOC from Espressif](http://espressif.com/en/products/esp8266/). The NodeMCU *firmware* is a companion project to the popular [NodeMCU dev kits](https://github.com/nodemcu/nodemcu-devkit-v1.0), ready-made open source development boards with ESP8266-12E chips.
NodeMCU is an [eLua](http://www.eluaproject.net/) based firmware for the [ESP32](http://http://espressif.com/en/products/hardware/esp32/overview) and [ESP8266 WiFi SOC from Espressif](http://espressif.com/en/products/esp8266/). The NodeMCU *firmware* is a companion project to the popular [NodeMCU dev kits](https://github.com/nodemcu/nodemcu-devkit-v1.0), ready-made open source development boards with ESP8266-12E chips.
Support for the new [ESP32 WiFi/BlueTooth SOC from Espressif](http://www.espressif.com/en/products/hardware/esp32/overview) is under way.