The ESP8266-01 is a highly compact board measuring with a WiFi radio. It can be used as a peripheral for any board through serial (RX/TX) but also as a standalone board.
The evaluation of this board was prompted by the article Installing and Building an Arduino Sketch for the $5 ESP8266 Microcontroller by Alasdair Allan on Make.
When used as a peripheral, the WiFi radio is managed through standard AT commands.
The board requires 3.3 V and can be programmed with any FTDI operating at 3.3 V.
The IDE or integrated development environment is a specific release of Arduino-Compatible IDE with ESP8266 Support developed by Ivan Grokhotkov. The IDE is thus platform-agnostic and runs on Windows, Mac OS X and Linux.
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Using the Board
Using the Board as WiFi Peripheral
Connection are the same expect GPIO0 is left floating.
The ESP8266-01 provides WiFi to an Arduino board but requires a logic level converter down to 3,3V, or to a computer through a FTDI cable.
The ESP8266 uses AT-commands and requires up to 375 mA.
At USD5, the ESP8266 provides a really affordable introduction to IoT. Unfortunately, documentation is scarce, sometimes in Chinese only. Getting the board working was a real challenge.
The www.esp8266.com community did a great job in exploring documenting, developing libraries and releasing the Arduino IDE for this SoC.