In this post, we are going to upload firmware to ESP8266 (ESP-01) . The firmware can be updated by both arduino as well as usb-ttl module.
ESP-01 is wifi SoC module and it has two GPIO pins i.e. GPIO0 AND GPIO2
For using ESP8266, we can use either AT commands using any terminal software/ esplorer ide (it supports lua programmming and AT commands) or we can use arduino library.
ESP8266 is a 8-pin SoC having two GPIO pins, it requires 3.3 volt and the current consumed by wifi module can't be attained through arduino. Therefore, if we are using arduino we need external 3.3 volt power supply.
Esp8266 wifi module can act as STA as well as AP or both