The ESP8266 is a tiny, cheap MCU with integrated WiFi and impressive specs (datasheet here) and a lot of modules have been on the scene for quite a bit of time.
There are different versions of them, and this is the most common one:
The fact is that, even if those modules have mostly been used for WiFi-to-serial communication with Arduinos, the chip can do a lot more than that. In fact, it’s a 32-bit MCU, which has a lot of horsepower compared to your average Atmega. Also, many of the modules don’t have all the pins broken out (10 GPIOs).
I actually thought about designing a proper breakout board for this chip, but many people from the community preceded me.
There is a toolchain you can use to write bare C to the chipset and access all of its functions (including all the GPIO pins). It’s been out for quite a few time and many firmwares have been developed, extending and improving AT commands.
One of the best news I came across this week is the release of a new firmware for the device, called nodemcu, which supports Lua commands: programming becomes Arduino-easy!
The guys over at nodemcu also developed a nice breakout board: I just bought one and I hope it comes here soon. It has a CH340G USB-to-serial converter on board together with a microUSB connector. All pins are also broken out on pin headers!
This is very exciting news and, in my opinion, the start of a new era for makers! This is what I’ll use for all my future projects.
You can find more info on the ESP8266 forums.