I have taken a copy of Ai Thinker firmware and have stored on my server. These original firmwares for ESP8266 are hard to find, with Google dropping me on to Chinese and dead links.
These firmwares come as a single bin file and its easy to flash. If you are looking to flash these to your ESP module, please find the links below
Use ‘SpiAutoSet’ if you are not sure about flash size & SPI settings. This is very important while flashing.
Firmware from AI Thinker:
These are the original AT firmware from board manufacturer. I had no problem in running this firmware for AT commands from Arduino/Serial to ESP8266
Before proceeding with flash, don’t forget to put your ESP module into flash mode! Its a single file flash (unlike the expressif’s firmware) so set the address on ADDR field to 0x00000
This comes in two varieties with default baud rate of 9600 & 115200
This firmware version works with any flash size.
!!!warning!!! – This version requires a flash size of 8Mbits (1MB) or more. Please check your flash size in your module before flashing! Usually the ones which are grey in color (like the one shown above) have 1MB flash size. Check yours before flashing!!
This is the latest firmware released by Ai Thinker but comes only with default baud rate of 115200. Use AT command to change it.
Default baud rate 115200 : ai-thinker-v1.1.1-115200.bin
This is what worked for me! I am not responsible for any damages or harm done to your modules. Please use it with caution and double check everything.