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How to sort out the knowledge of NodeMcu, I believe that many inexperienced people are at a loss about it. Therefore, this paper summarizes the causes and solutions of the problem. Through this article, I hope you can solve this problem.

On the relationship between NODEMCU and ESP8266

My own understanding:

ESP8266 is the core chip.

NodeMcu development board is an extended development board with ESP8266 as the core.

The corresponding relationship between the two ports is as follows:

Some software and materials developed and designed by NodeMcu:

ESPlorer and getting started tutorials, IDE with integrated serial debugging interface and Lua development environment, official recommendation

Official lua firmware, including source code, LUA routines and documentation of each module, compiled to generate bin files, can be burned into flash.

Nodemcu flasher, nodemcu one button burn write tool, no need to set, one button burn write the latest nodemcu firmware

Nodemcu hardware data, nodemcu hardware schematics, gerber files, pin instructions

Nodemcu's lua application, which can be uploaded to nodemcu to run

Nodemcu API English and Chinese documents

There are errors in Chinese documents, but they are easy to retrieve

NodeMCU custom builds, you can customize your own nodmcu firmware on the website, which can include only the modules you need to reduce the running memory.

For ESP-12 firmware:

The esp-12 module we got can send AT instructions because the firmware containing the AT instructions has been burned into the mcu.

We can upload and run the program in Lua because the firmware containing lua modules and actuators has been burned into mcu

The relationship between NodeMcu hardware and lua firmware lua firmware written into nodemcu is more like an operating system, it has a corresponding file system SPIFFS

Upload the .lua file to the nodemcu file system SPIFFS using ESPlorer. Physically, the code is uploaded to flash and placed in the corresponding address of the file system.

The .lua code of the lua firmware and file system is loaded into memory to run, and the firmware is responsible for interpreting the code and executing it.

The difference between uploading lua firmware and burning flash firmware is that burning firmware erases and updates the original firmware and usually does not affect the file system. Esplore upload .lua is just an update to the file system. The file system and firmware occupy different addresses of flash and do not affect each other.

To burn the firmware of nodemcu, you need to compile the source code of linux under the VM virtual system under windows (Lexin's official compilation method), or use Anxinco's SDK. Of course, you can also order online, click NodeMCU custom builds, and you need the burning tool nodemcu flasher to write the bin file to flash.

Remember, once you burn the firmware of nodemcu, it means that you have updated the operating system. It may add or decrease several functional modules. The .lua files of the file system are generally retained. This is the same as reinstalling the c disk of the computer, and the files of the d disk will not be affected.

About SPIFFS

SPIFFS is the file system of nodemcu, which is used to place .lua files in falsh, and flash also places firmware. To see the description of SPIFFS in the official nodemcu documentation, click here, and here is a brief description:

SPIFFS, whose full name is SPI Flash File System, is used for SPI to read and write to the file system of flash. In fact, it can also be used for NOR flash.

The SPIFFS file system is used for SPI NOR flash devices on embedded platforms, and it is also suitable for falsh within MCU.

Nodmcu's lua firmware includes a tool for mirroring the SPIFFS file system. When writing flash for the first time, the file system in flash is not detected, and a new file system is created in flash. Start address of the file system = firmware end address + 64K~128K.

If the new firmware size

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