ESP8266 is low-cost WI-FI Microcontroller. It has 32-bit RISC CPU with 64 KiB of instruction RAM and 96 KiB of data RAM. It comes under IEEE 802.11 b/g/n Wi-Fi.
It has three modes,
- Station Mode(STA) – ESP8266 acts as station and connects to hotspot.
- AP Mode(AP) – ESP8266 acts as Access Point.
- Station Mode+AP Mode(STA+AP) – ESP8266 connects to hotspot at the same times it acts as Access point.
It can be programmed using any one of the following methods,
1. As an interface module to Arduino
In this type of connection Arduino is connected to ESP8266 using GPIO pins and it communicates with it using AT commands, which is liitle bit time consuming. This type of connection is explained in my page here.
2. As Standalone module
Since ESP8266 is itself a microcontroller, it can be programmed directly. NodeMcu uses Esp8266-12 as standalone module.