Arduino WIFI shield

Introduction

The Wifi Shield is based on Serial to Wi-Fi module Wizfi210 from Wiznet and compatible with Arduino and its clones. The Wifi Shield offers you a quick, easy, and effective way to add Wi-Fi capabilities to Arduino. The Wifi Shield allows you to achieve Wifi communication via UART by sending AT commands, which is an ideal solution for whom with limited or no Wi-Fi or RF expertise. The Shield supports data rates up to 11 Mbps, and is compliant with 802.11b.

Features

• Serial(UART) to Wifi.
• Simple AT commands for configuration and data communication.
• DHCP/Static IP, TCP/UDP, Server/Client, DNS.
• Operates with standard 802.11 b/g/n access points at speed up to 11 Mbps (802.11b).
• 802.11i Security (WEP, WPA, WPA2-PSK, Enterprise).
• High-throughput hardware AES and RC4 encryption/decryption engines.
• Limited AP Feature (Direct Connection to iPhone, iPad and Android-Phone without AP).
• Ultra low power consumption through dynamic power management.

Specifications

• Wifi Chip: WizFi210
• Radio Protocol: IEEE 802.11b/g/n Compatible
• Supported Data Rates: 11, 5.5, 2, 1 Mbps (IEEE 802.11b)
• Modulation: DSSS and CCK
• RF Operating Frequency: 2.4 - 2.497 GHz
• Antenna Options: Chip antenna and U.FL connector for external antenna
• Networking Protocols: UDP, TCP/IP (IPv4), DHCP, ARP, DNS, HTTP/HTTPS Client and Server(*)
• Power Consumption(Typical): Standby = 34.0 µA Receive = 125.0 mA Transmit = 135.0 mA
• RF Output Power (Typical): 8dBm ± 1dBm
• Security Protocols: WEP, WPA/WPA2–PSK, Enterprise, EAP-FAST, EAP-TLS, EAP-TTLS, PEAP
• I/O Interface: UART, SPI(*), I2C(*), WAKE, ALARM, GPIOs
• System Working Voltage: 3.3V

Getting Started

Selectable UART connection

Users can use the jumpers to connect the WIFI_TX and WIFI_RX pins(5V) of Wifi Module to any D0, D1, D4~D7 pin of Arduino.

Users must be aware that which Digital pin of Arduino connects to WIFI_TX needs to act as Arduino RX pin(Hardware/Software), and which connects to WIFI_RX needs to act as Arduino TX pin(Hardware/Software).

The following figure shows users how to use jumpers to configure UART communication between Wifi Shield and Arduino.

Indicator LEDs

There are four indicator LEDs(PWR, MODE, WIFI, LINK) on the Wifi Shield, users can know about the working phase of the shield based on the four indicator LEDs. Detailed information please refer to the following table:

Antenna Interface

The shield comes with a 2.4G antenna; Make sure the antenna is assembled and antenna pad is buckled properly.

Buttons

There are three Buttons on the Shield. Reset, Function and Alarm1.

• Reset Button is used to reset the Arduino.
• Function Button is connected to GPIO21 of Wizfi210. If you click the Function Button twice consecutively, the WizFi210 is restored to factory default and changed <Limited AP mode>. And if you click the GPIO21(GPIO10) button three times consecutively, the WizFi210 is restored to factory default and will change to ad hoc mode to configure the WizFi210 via WiFi. (IP:192.168.1.254/Subnet:255.255.255.0/Gateway:192.168.1.1)
• Alarm1 Button is used to wake up wifi module from Standby Mode.

Switch

There is a Data/Command Mode Swtich（connected to GPIO29） on the shield. This switch only operate when user already set up the connection(TCP server/TCP client/UDP), which means module is data mode(can data communication). In this case, when you switch it to command mode, you can setting the module by using AT commands. When you switch it to data mode, you can data communication.

The serial host may gain control of the interface by issuing the escape sequence “+++”, followed by a one-second gap where no characters are received on the serial port. When this sequence is encountered, the Adapter exits data mode and resumes command processing. The host then makes changes in the network configuration or other parameters as needed. However, the Adapter does not accept any new TCP/UDP client/server or data connection requests. The ATO command (terminated by the ASCII character “O”, not the number 0) is used to return to data mode.

Applying the <AT+XEHT> command (Enable Hardware Trigger), you can change between data mode and command mode using Data/Command Mode Swtich, without escape sequence (“+++”). BTW, the function of hardware trigger is similar to input "+++" in serial terminal. But when you use Data/Command Mode Swtich for data/command mode transition, there should be no UART input in 300mS before and after sending signal to Data/Command Mode Swtich for mode transition time and buffer processing time.