This cycle is repeated for every subsequent update. ESP8266 comes pre-programmed with an AT command set firmware, meaning, you can simply hook this up to your Arduino device and get about as much WiFi-ability as a WiFi Shield offers.
#Backing up esp8266 firmware update
This new update is downloaded as user1.bin.
When a system restart is triggered, the ESP8266 boots into the updated user2.bin, which now becomes the primary firmware binary file until another update is available for download. The user1.bin, when executed, connects to the update server and downloads user2.bin (updated firmware) into the flash memory. The demonstration initially runs the user1.bin as the primary firmware. However, with appropriate build settings based on your application flash configuration, the test can be made to run on any ESP8266-based system. In order to download the AT Commands Firmware for ESP8266, visit the official link here or directly download from this link. Now since I will be using only the AT Command Set of the ESP8266, I will download only the Bin Files associated with the AT Commands. The FOTA test has been demonstrated and run on the ESP-Launcher, an ESP8266 evaluation board designed by Espressif. The ESP8266 Firmware files are in the form of Binary Files i.e.bin files. This guide is intended to help you run a FOTA demonstration on the ESP8266 easily and quickly, with a PC acting as the local update server. Then, run the rpi-update command to update the firmware. ESP8266 device will download a new version of firmware from the update server over Wi-Fi and run it. Before updating the firmware, you can check the firmware version number with the command uname -a uname -a Linux raspberrypi 4.4.26-v7+ 915 SMP Thu Oct 20 17:08: armv7l GNU/Linux. Espressif provides guidelines and a sample implementation of FOTA (Firmware Over-The-Air) function to upgrade the firmware on devices powered by the ESP8266.