Wi-Fi Module

Communication PIC-Microcontroller Lab
Course by JAOM Center, Feb. 2013

Wi-Fi Module

Instructor:
Mohsen Sarakbi

Wi-Fi Definition
 Wi-Fi is the name of a popular wireless networking technology that uses radio waves to
provide wireless high-speed Internet and network connections.
 A common misconception is that the term Wi-Fi is short for “Wireless Fidelity“

 The Protocol
 Built on the IEEE802.11 standards
 Wireless Local area Network (WLAN)

 Consumer Wi-Fi growth (2009-2010)
 158% growth in Wi-Fi consumer electronics
 90% Wi-Fi enabled cell phones
 3 in 4 consumers considered buying a Wi-Fi enabled device

 Embedded Systems
 'Evangelizes on the huge availability of “hotspots‟
 Provides data with a ultra low cost transport

Specification
 A computer's wireless adapter translates data into a radio signal
and transmits it using an antenna.

 A wireless router receives the signal and decodes it. The router
sends the information to the Internet Ethernet connection.

 Wi-Fi communication can transmit and receive radio waves

 They transmit at frequencies of 2.4 GHz or 5 GHz.The higher
frequency allows the signal to carry more data.

Specification
 They use 802.11 networking standards, which come in several flavors

 802.11a transmits at 5 GHz and can move up to 54 Mbps. It also
uses orthogonal frequency-division multiplexing (OFDM). This
greatly reduces interference.
 802.11b is the slowest and least expensive standard, it transmits in the 2.4
GHz frequency band. It can handle up to 11 Mbps, and it
uses complementary code keying (CCK) modulation to improve
speeds.
 802.11g transmits at 2.4 GHz, it can handle up to 54 Mbps. 802.11g is
faster because it uses the same OFDM
 802.11n is the newest standard that is widely available. It can achieve speeds
as high as 140 Mbps.

Specification

 Wi-Fi radios can transmit on any of three frequency bands. Or,
they can "frequency hop" rapidly between the different bands.
Frequency hopping helps reduce interference and lets multiple
devices use the same wireless connection simultaneously.

 13 Channels
 Android App

Ad-hoc vs. Infrastructure Networks

UDP vs. TCP

• UDP
Low-level, connectionless
No reliability guarantee
Faster
2-ways handshaking
• TCP
Connection-oriented
Slower
3-ways handshaking (use comm feedback as open & close)

WiFly Module
 Roving’s Wi-Fi Solution

 Industry’s lowest power, complete system-on-module solution
 30mA Rx
 Tx variable depending on configuration

 Quick and simple to integrate
 CompleteTCP/IP solution – No external processor or drivers required

WiFly Specification

SPI: Serial Peripheral Interface

Data Mode and Command Mode

 Data Mode (Default State)
 TheWiFLY module is effectively a data pipe
 TCP/UDP header are stripped or added transparent to the UART
 Data written to the UART is sent out over Wi-Fi
 Data received overWi-Fi is read from the UART
 Command Mode ($$$)
 Special configuration mode entered by $$$ (Default)
 Used to assign data such as SSID, IP, pass phrases etc.

Command Mode
 Entered by $$$

 Performed using ASCII commands

 Configuration setting are stored in the modules flash
 Changes are persistent and are reloaded after power cycling
 Changes are kept using the “SAVE” command

 Many settings require a reboot to take effect.

Command Mode
 Commands use a keyword followed by additional information

 Command rules
 Case sensitive
 Spaces cannot be used, a “$‟ is a substitute (Default).
e.g. “MY NETWORK” = “MY$NETWORK”

 Shorthand's can be used
 set uart baudrate 115200 valid
 set uart b 115200 valid
 set u b 115200 valid
 s uart baudrate 115200 NOT valid.

Command Mode

 Set: Immediate effect, permanent if saved to config file

 Get: Retrieve and display the permanently stored information

 Status: Current status of interface, IP address, etc.

 Action: Perform actions such as scan, connect, disconnect

 File: Upgrade, load and save configuration, delete files, etc.

Join Network
 Search for networks
 scan
 Join a network
 join # 1 (remember the spaces)
 leave
 join <SSID string>
 leave
 Auto join a network with persistent configurations
 set wlan ssid <string>
 set wlan pass <string>
 save
 reboot

Join modes
 Turn off auto join and join manually
 set wlan join 0
 save and reboot
 Go into command mode
 join
 The module will join the access point
 Auto join to any Access Point with open security
 set wlan ssid xxx
 set wlan join 2
 set wlan auth 0
 save and reboot
 The module will now attempt to join any network that is in open mode (no security)

Authentications mode

 set wlan auth <value>
 You only need to set this parameter if you are using automatic join mode 2, i.e., the
set wlan join 2 command.

Channel

 set wlan channel <value>

 This command sets the WLAN channel, where <value> is a decimal number
from 1 to 13 representing a fixed channel

 If you set the channel to 0, the modules performs a scan using the SSID for
all the channels set in the channel mask.

Password Phrase

 set wlan phrase PASSWORD

 This command sets the passphrase for WPA and WPA2 security
modes, where <string> is 1 to 64 characters (64 bytes)

Password Phrase

 set wlan rate <value>
 This command sets the wireless data rate, where <value> is a value shown 0-
15.
 Lowering the data rate increases the effective range of the module.

Change Device ID

 Setting the Device ID
 Enter command mode
 get option
 set o d xxxxxx (o=optional, d=deviceID)
 save and reboot

Connect to Host (TCP)

 Auto connect requires remote host’s IP address & port #
to be stored in the module:

 set ip host <host IP address>
 set ip remote <port>

 TCP port on the module is 2000
 TCP client and server mode
 Default mode initiates and accepts TCP connections
 Currently support only one active connection at a time.
 Concurrent TCP connections will be supported in the future

Comm. Strings
 A microcontroller can look for the comm strings on a UART as an indication of
TCP connection status:
 reboot
 Associate with your AP
 set ip host <Host IP address>
 set ip remote 5000
 set comm open HAPPY
 set comm close HOLIDAYS
 set comm remote NEW_YEAR
 save and reboot
 open
 Close

 Tip:The microcontroller can read the open and close strings on the UART to determine
the status of TCP connection

Forwarding TCP packets
 Forwarding packets based on Flush Timer
 set comm timer 1000
 save
 open
 Type any text once the TCP connection is opened. After you stop, a TCP packet will
be sent out 1 second later
 Forward packets based on a “match character‟
 set comm timer 0
 set comm match 65
 This parameter expects either an ASCII decimal character or a HEX value of the
match character. {65=CAPS A}
 save then open
 Type 12345678A
 A TCP packet will be sent out after you type the character “A”.

Port Seeker

 Configure & Capture UDP (5555)/TCP (5000) with Port Peeker

Lab
 Test the Module on TeraTerm Pro
 Moving Car application
 Android APK

Wi-Fi Module

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Wi-Fi Module