ESP8266 AT Commands
The ESP8366 can be programmed to respond to a set of AT Commands, to allow a host processor to manage the ESP8266 as a WiFi slave. https://www.google.com/search?q=ESP8266-01+at+command+set https://www.google.com/search?q=espressif+at+command+set https://www.instructables.com/Getting-Started-With-the-ESP8266-ESP-01/ https://www.youtube.com/watch?v=MPyShmRcgD0 https://www.espressif.com/sites/default/files/4a-esp8266_at_instruction_set_en_v1.5.4_0.pdf Attempting to follow along with this example: https://www.instructables.com/Getting-Started-With-the-ESP8266-ESP-01/
Program ESP8266 Module with AT Commands Firmware See the following: https://www.instructables.com/Program-Any-ESP8266-Boardmodule-With-AT-Commands-F/ https://www.espressif.com/en/news/ESP8266_NonOS_3.0.3 <--- READ THIS! Espressif makes multiple SDK packages to provide AT Command support. The earlier is known as ESP8266 NONOS SDK. As the name implies, no RTOS is running. In December, 2019, it was announced that no new features would be added to this version of SDK, only bug fixes. The later SDK is known as ESP8266 RTOS SDK. This SDK includes FreeRTOS running on the device. This later SDK has plenty of code changes to support FreeRTOS and to add a significant set of new features.