The first ESP8266 (the -01 model shown on right) came on the market in August 2014 as a product from the Chinese manufacturer Espressif. The very low priced (now starting at $1.50) micro-controller also includes built-in Wi-Fi and two general purpose input output ports. Initially the board came with firmware for attaching this board to others (often the Arduino) so that the other board would have simple TCP/IP access.


Picture of 3 ESP boards 

Shortly after the C language software development kit was released by Espressif in late 2014, open-source developers rewrote the firmware to support the small footprint scripting language called Lua. Subsequently others released Javascript for the device. The ESP8266 is frequently operated as a very small battery powered remote "computer" that accepts commands and sends status over the Wi-Fi network using sensors and actuators.

13 or more newer models of the ESP8266 have since been release, each model supporting more and more general purpose input output connections (the model -12 costing around $4 as shown above supports 9 ports). The ESP8266's will require regulated power and to program it or change the firmware you will need a device to convert your computer to the serial connectors of the ESP8266. Usually these USB to serial connectors are based on several IO adapter chips but before buying one be sure that working drivers are available for your computers operating system. Small development boards are now available (like the one that cost $13 as shown on left) that contain both the power regulator, the USB to serial converter, and have pins suitable for breadboarding.

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