ESP8266 is relatively new and cheap in price. It comes with an inbuilt firmware which supports serial interface and can be controlled using AT commands. Even though we can use this module to offload WiFi functionality from another micro controller or any other processor, this module is not just a serial to WiFi transceiver!
It is comprised of
- 32bit 80MHz processor (Tensilica Xtensa LX3)
- 512KB SPI Flash (W25Q40BVNIG)
- RAM (64KB sram; 96KB dram)
- GPIO Pins
- WiFi tranceiver