ESP8266 is a very easy-to-use WIFI chip. Essence Technology has produced an ESP8266 module based on the Espressif ESP8266 chip, which is also very easy to use.
In actual use, you can use AT commands for configuration, and you can also use SDK for secondary development. It can be said that the function is very powerful.
After just purchasing it, the module comes with factory firmware, that is, the AT command program; but if the firmware in the module has been flashed, another program has been downloaded, and if you want to use the AT command again, you need to download the official program again. The firmware download is back. This article will briefly introduce the download of the firmware.
1. Hardware platform
NodeMCU+USB data cable
2. Obtaining firmware
Download address: http://wiki.ai-thinker.com/esp8266/sdk
After downloading, there are two folders inside, corresponding to different firmwares of 8Mbit and 32Mbit.
Choose according to the storage capacity of your board ( if you use the first download tool below to download, there is no need to find the firmware, the software tool comes with factory firmware )
3. Download the tool and obtain it (both tools have examples)
Download address: https://github.com/nodemcu/nodemcu-flasher
Also available: http://wiki.ai-thinker.com/esp_download
The tool is shown below
Taking the first tool as an example,
Use default configuration:
Select the firmware you want to download (the firmware downloaded in the second step)
Or use the default download file
There are instructions on the download address on the website of Anxinke Technology
The program we download is the merged firmware. Just download it directly to the 0x00000 address. This can be found by observing the bin file. Opening it in the file, you can find that the downloaded bin file happens to be 4096KB, which has just filled 32Mbit. space, so start downloading directly from address 0
When downloading, be sure to select the small cross on the left (selected by default) so that you can download
After selecting, you only need to click 
the button to automatically start downloading (connect NodeMCU to PC, and the serial port is working normally), just wait for the download to complete...
At this point the download is successful.
Take the second download tool as an example:
Select the firmware you want to download, then fill in the address 0x0
Select Flash Size, I chose 32Mbit
Select the serial port, set the download baud rate, and then start (you can also click Erase first to clear it before downloading)
After the download is completed, press the reset button and you can use AT commands to interact.
