MEET THE ESP8266
https://www.nutsvolts.com/magazine/article/October2015_Lindley
It is not very often that a new piece of hardware comes along and immediately captures the attention of the entire maker community. The Raspberry Pi and the $9 C.H.I.P. are a couple of recent examples, but the ESP8266 module from Espressif Systems (espressif.com) wins this prize. This little board — PHOTO 1 above - The ESP8266 module (ESP-01) — is only about the size of a nickel, yet contains a powerful 32-bit microcontroller and a Wi-Fi interface, and it can be purchased for around $4 in single unit quantities
The first projects built with this module all used a microcontroller to control the ESP8266 as a Wi-Fi peripheral using an AT command set over a serial interface. While this was made to work, some of the projects suffered from stability problems as the ESP8266 firmware continued to evolve. Lately, however, a group of enterprising individuals have made the ESP8266 Arduino compatible. This is important for numerous reasons:
It allows people familiar with the Arduino IDE (Integrated Development Environment) to develop software for the ESP8266 module.
It allows the software developed in the Arduino IDE to be run directly on the 32-bit microcontroller on the ESP8266 module, eliminating the need (in many cases) for a separate microcontroller altogether.
It allows the use of numerous third-party Arduino libraries, as long as they don't depend on direct access to the underlying AVR hardware.
Arduino compatibility and the low cost of the ESP8266 are major developments for the Internet of Things (IoT) movement currently sweeping the tech world. Using the ESP8266 allows for very small and inexpensive products to be created that can be controlled and/or monitored remotely.
Note if you plan on putting an ESP8266 module into a commercial product, you will have to pass FCC certification, which can take considerable time and be rather costly.
To understand what a breakthrough this is, consider the cost and size of a traditional Arduino approach to Wi-Fi enabled monitoring and control. First, you have to have an Arduino board (say, an Arduino Uno) from a reputable source which costs between $20 - $30. Then, you have to purchase a Wi-Fi shield for around $20 - $40, bringing the basic system cost to between $40 - $70. Then, consider size. The Uno's dimensions are 2.1” x 2.7”. Attach the Wi-Fi shield and the sandwich is between 1.25” to 1.75” deep and a bit harder to package than the ESP8266 (again, which is the size of a nickel).
Finally, when you consider the ESP8266 has a 32-bit processor which can run at 160 MHz — 10x the speed of the Uno's eight-bit processor — and that it has 512K (minimum) of Flash memory program space to the Uno's 32K, the Uno Wi-Fi solution is looking a little dated.