Based on ESP03, a new Wi-Fi module 2.4GHz 802.11 b / g / n fully programmable, this shield for Arduino provides WiFi connectivity and memory support of SD-Card; offering the best value of very low power consumption making it ideal for battery-powered applications. The ESP03 module is based on the ESP8266 chip made by Espressif Systems (http://espressif.com), the latter contains not only the RF stage, but also a fully-programmable microcontroller and a register which owns the I / O, in addition to the communication bus such as SPI and I²C. This means that the component can alone implement communication in WiFi; Furthermore, the possibility to run a program to the chip, allows the management of some pins (GPIO, various bus) in order to realize a system that can interface with external devices of various kinds or manage inputs and outputs. The shield has a jumper that selects the pin to be used for the management of SD (by default, the library uses the Arduino pin 4), a jumper that allows you to select the pin D7 to control the mode of operation of the form (in this case, via the Arduino D7 line you can turn on and off the module according to need), a male strip connector with all pin ESP8266-03 module (useful for those who want to manage the module directly). The communication between the shield and Arduino is a serial standard, and uses the two TX and RX data lines, which can be conveyed to the hardware serial, or on pins D8 and D9 (manageable with a serial software).

This project comes in kit. Some components have to be soldered to the included PCB.

• General functions
  AT – Test AT start up Test
  AT+RST – Restart module
  AT+GMR T+GMR – View version info
  AT+GSLP Enter deep-sleep mode
  ATE – AT commands echo
• WiFi functions
  AT+CWMODE – WIFI mode
  AT+CWJAP – Connect to AP
  AT+CWLAP – List available APs
  AT+CWQAP – Disconnect from AP
  AT+CWSAP – Configuration of softAP mode
  AT+CWLIF – IP of stations
  AT+CWDHCP – Enable/Disable DHCP
  AT+CIPSTAMAC – Set mac address of station
  AT+CIPAPMAC – Set mac address of softAP
  AT+ CIPSTA – Set ip address of station
  AT+ CIPAP – Set ip address of softAP
• TCP/IP functions
  AT+ CIPSTATUS – Information about connection
  AT+CIPSTART – Start connection
  AT+CIPSEND – Send data
  AT+CIPCLOSE – Close TCP or UDP connection
  AT+CIFSR – Get local IP address
  AT+ CIPMUX – Enable multiple connections
  AT+ CIPSERVER – Configure as TCP server
  AT+ CIPMODE – Set transfer mode
  AT+ CIPSTO – Set server timeout
  AT+ CIUPDATE – Update through network
  +IPD – Receive network data

Inside the ESP8266 chip we find a microcontroller chip 32-bit full ROM, RAM and SRAM for program and data; the chip has digital I / O lines and analog inputs, as well as communication ports as I²C, SPI, and UART. The communication ports may function as a slave in order to interface external memories to the module and to extend the operation. The available digital lines are sixteen, configurable as inputs or outputs, all with pull-up resistance and with the possibility of generating an interrupt. Also available are a number of input lines and the analog output based on a sigma-delta converter to PWM. The chip was designed to operate at a voltage of 3.3V with a maximum allowable
3.6V, the digital inputs have a special circuit (over voltage protection) to protect the built-in input voltages greater than 6V. Finally we mention the support for all the latest encryption protocols: WEP (RC4), CCMP (CBC-MAC, counting mode), TKIP (MIC, RC4) or WAPI (SMS4), WEP (RC4), CRC, WPA, WPA2 and WPS. Applications which the component is intended are home automation, mesh networks, industrial wireless, baby monitors, wireless network cameras, sensor networks, wearable electronics, wireless location location-aware devices devices, security ID tags etc.

The features and functions are implemented:
• compatibility 802.11 b / g / n;
• WiFi Direct (P2P), soft-AP;
• stack support TCP / IP;
• TR switch, balun, LNA, RF amplifier and coupled to the integrated network;
• Integrated PLL and power manager;
• Transmitting power of +19.5 dBm for 802.11b;
• Integrated thermal sensor;
• Support for antenna diversity;
• 32-bit CPU;
• 2.0 SDIO, SPI, UART;
• STBC, 1x1 MIMO, MIMO 2x1;
• A-MPDU, A-MSDU;
• only 2 ms for connection and transfer of data packets;
• Absorbed current state of lower off 10 uA;
• Consumption in standby less than 1 mW (DTIM3).

• Shield_ESP
• https://github.com/esp8266/esp8266-wiki/wiki