Temporary WiFi Info; Under Construction
The ESP8266 is a single chip with a microcontroller (ARM, I think) and a complete WiFi interface. Call it "ESP" for short.
With a few external parts (including an external Flash memory for program code) you have a complete system that can "talk" on WiFi.
There are several kinds of ESP8266 boards out there.
Some provide the support components and bring out only the minimum serial bus, power, and a few control signals to an 8 pin header. This board includes a PCB antenna for the module, so it is ready to rock and roll with no external antenna. This allows a minimum cost board. These would include the Sparkfun WRL-13252 that I am using to test the ESP tech. I think this is what some call the ESP-01 configuration.
Rui Santos wrote the book (literally) on using this board. But he immeditely reflashes it with firmware to run with Lua java script. You can buy the e-book here:
Thanks to him for great basic info, like this wiring diagram that nobody else thought to include...
ESP-01 pinout, viewed from component side
pins are sticking down away from you in this picture.
Other boards bring out more of the pins on the micro, to allow more I/O in autonomous applications. There is a port of the Arduino bootloader and IDE for the ESP. Marko Schwartz wrote the e-books on THAT.
The Yourduino.com ROBORed version of the Arduino is uniquely suited to operation with the ESP8266. For one thing, the ROBORed male pin headers make it easy to wire over to the male pin header on the ESP8266 module with just some female-female break away jumper wires.
More importantly, the ROBORed is an ideal host for an ESP because the ESP is a 3.3V only device, and it draws significant current in operation. The ROBORed has a very capable on-board power regulator, and can be switched to run at 3.3 V. With the ROBORed switched to 3.3 V, its onboard regulator can operate the ESP8266 just fine.
So...speaking of wired up, here is the plan:</span>
"Wall Wart" provides 5 V at 1 Amp maximum.
RoboRED (switch set to 3.3 V)
to Wires to the ESP-01:
"VCC" 3.3 V power.
"GND" Common Ground
"RX" Receive Data (Received by the ESP, so transmitted by host)
"TX" Transmit Data (Transmitted by the ESP, so received by host)
"RESET" (Active low reset, pull up to VCC to run, ground to force reset)
"GPIO0" is used as the Run / Program pin by the standard firmware.
Must be pulled high for normal operation, pull low to load new code at reset.
"GPIO2" free GPIO. Pulled up for now.
"CH_PD" is the Power Down signal, normally pulled up to VCC to run from reset. Tie to ground to put the module to sleep. Not clear yet how to sequence wake up. There are examples that use the internal RTC to wake the chip by wiring a GPIO back to the reset pin. Tricky.
For reliable operation, I think decoupling capacitor and reservoir capacitors are needed from VCC to GND right at the module pins.
I've added decoupling and reservoir capacitors to my setup because they are cheap insurance against the flakey operation that some people have reported with simpler but insufficient power supplies. YMMV but I like to concentrate on a cool application and not worry about dumb stuff like power supplies after its wired up.
Here is the link to the expressif docs for the AT command set: