XBee-fy the ESP8266 WiFi module

With the new ESP8266 module, adding WiFi to any Arduino project became a lot cheaper.
This module has a serial interface; therefore it only requires connecting 4 pins: Tx, Rx, 3V3 and Ground, as shown in this image.

A few peculiar facts about ESP8266:

• default serial baud rate is 57600; since this rate is too high for SoftwareSerial library, a hardware port should be used;
• requires 3V3 for power and level shifting for Rx signal (5V to 3V3);
• physical interface is a 2x4 pin male header;
• firmware can be upgraded to a version that allows 9600 baud rate;
• can be used either as client or server.

The first two characteristics makes it a perfect candidate for a module with an XBee footprint, as is WiFly, for example.

It took me about half an hour to do it, following these steps.

1. cut a piece of 2-mm perfboard to the XBee dimensions;
2. solder two 10-pin the 2-mm-spaced male headers on the sides;
3. desolder (using wick) the 2x4 header;
4. mechanically attach the header-less ESP8266 module to the XBee perfbord, by soldering 4 pins into the corner holes, aligned with holes in the perfboard;
5. wire the pins 1, 2, 3 and 10 of the Xbee-type module to pins Vcc, Tx, Rx and Gnd of the ESP8266 module respectively.

And now a few photos. Start with these (XBee shown for comparison purpose):

to make this:

Then plug it any Xbee socket, like one on Wise Clock 4:

or Adafruit XBee adapter:

Hopefully now more people can try adding new WiFi features to their Wise Clocks without breaking the bank (paying $35 for WiFly).