Digilent 410-231P-KIT - Manual (Page 2)

chipKIT™ WiFi Shield Reference Manual
www.digilentinc.com page 2 of 4
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Functional Description
Overview
Depending on the production version, the
chipKIT WiFi Shield provides support for either
IEEE 802.11b or IEEE 802.11b/g wireless
networks. It is compatible with 802.11b/g/n
networks, and is designed for use with
chipKIT™ and chipKIT™ compatible
microcontroller boards.
The initial production version of the WiFi Shield
uses the Microchip MRF24WB0MA WiFi
module. This modules supports IEEE 802.11b
networks at 1 and 2 Mbps data rates.
Later productions versions of the WiFi Shield
use the improved Microchip MRF24WG0MA
module. This module provides IEEE 802.11b/g
support for embedded applications at data
rates of 1, 2, 5.5 and 11 Mbps for 802.11b or 6,
9, 12, 18, 24, 36, 48, and 54 Mbps for 802.11g.
The production version of the board can be
determined by reading the part number of the
MRF24Wx0MA module from the sticker or
engraved on the metal shield of the module.
The WiFi Shield is intended to be used with the
Digilent network libraries, DNETcK and
DWIFIcK, available for free download from the
Digilent web site. The DNETcK and DWIFIcK
libraries are intended for use with the chipKIT
MPIDE development environment. These
libraries contain Microchip Applications Library
code licensed for use by Digilent from
Microchip.
To use the chipKIT WiFi Shield outside of the
MPIDE development environment, the
Microchip Applications Library, available from
www.microchip.com , can be used as a starting
point to create custom library code to work with
the WiFi Shield.
The WiFi shield also provides a micro-SD card
connector and four discrete LEDs. The micro-
SD card connector provides the ability to
access files stored on a micro-SD size flash
memory card using the chipKIT MPIDE SD
library.
The discrete LEDs are connected to four digital
I/O pins on the chipKIT microcontroller board
and can be accessed using the pinMode()
and digitalWrite() functions in the MPIDE
software.
Refer to the chipKit WiFi Shield schematic,
available on the Digilent web site, for detailed
information about the circuits on the board.
802.11b/g Interface
The 802.11b/g compatible WiFi interface on
the chipKIT WiFi Shield is provided by a
Microchip MRF24Wx0MA WiFi module. This
module provides the radio transceiver,
antenna, and 802.11 compatible network
firmware.
The MRF24Wx0MA firmware provides the
802.11 network protocol software support. The
DNETcK and DWIFIcK libraries provide the
TCP/IP network protocol support that works
with the 802.11 protocol support provided by
the WiFi module.
The primary communications interface with the
WiFi module is a 4 wire SPI bus. The
MRF24Wx0MA WiFi module supports SPI
clock speeds up to 25MHz. An active low
RESET signal can be used to reset the WiFi
module, and an external interrupt signal, INT,
is used by the module to signal to the host
microcontroller that it needs servicing by the
microcontroller software.
The MRF24Wx0MA provides the following
additional control signals: write protect (WP);
HIBERNATE; RESET; and INT.
More detailed information about the operation
of the MRF24Wx0MA can be obtained from the
manufacturer data sheet available from the
Microchip web site.