Digilent chipKIT Pro MX7 Reference Manual page 12

chipKIT™ Pro MX7 Board Reference Manual
PIC32MX795 device is programmed at the factory to have a unique MAC address that will be loaded by default
when the device is reset.
Digilent provides another unique MAC address that can be used as well. This address is printed on a sticker
attached to the bottom of the board. The Digilent provided MAC address is a twelve digit hexadecimal number of
the form: 00183Exxxxxx, where xxxxxx represents six hexadecimal digits. This value is used to initialize the Ethernet
Controller MAC Station Address registers in the Ethernet controller of the PIC32MX795 microcontroller.
In order to connect to and operate with an Ethernet network, the PIC32 microcontroller must be running network
protocol stack firmware. Normally, the TCP/IP (Transmission Control Protocol/Internet Protocol) network protocol
is used and "TCP/IP Stack" software must be used. The Microchip Applications Library, available for download from
the Microchip web site, provides full protocol stack support compatible with the PIC32MX795 MAC and the
LAN8720 PHY. Microchip also provides numerous example programs illustrating the use of their network protocol
stack for various applications.
When not using the Microchip network protocol stack, refer to the manufacturer documentation for the
PIC32MX795 and LAN8720, plus network protocol documentation, for operation of the Ethernet interface.
Digilent has Network libraries available that can be used to develop both client and server applications when using
the board with the MPIDE development environment. These libraries are built on a custom version of the
Microchip Applications Library network stack and support various network protocols such as TCP, UDP, DHCP and
others to provide complete Ethernet network support. These libraries can be downloaded from the chipKIT Pro
MX7 product page on the Digilent web site.
The Digilent chipKIT libraries contain examples illustrating various network applications.
The PIC32MX795 microcontroller provides two alternate sets of pins that can be used to connect the MAC to the
external PHY. It also provides two alternate standard MAC/PHY interface signaling conventions. The chipKIT Pro
MX7 is designed to use the standard (not the alternate) pins, and to use the RMII (not the MII) interface signaling
convention. These options are selected using the configuration variables in the PIC32 microcontroller and are
specified using the #pragma config statement. To enable the Ethernet controller in the correct configuration,
the following statements must appear in the main program module:
#pragma config FETHIO=ON
#pragma config FMIIEN=OFF
The MPIDE boot loader sets these configuration variables, so no action is necessary when using the MPIDE
software system.
The LAN8720 PHY has a reset signal, labeled NRST in the schematic, used to reset the PHY. This signal is connected
to the TRCLK/RA6 pin on the PIC32 microcontroller. The NRST signal is active low. Configure the microcontroller
pin as an output and drive it low to reset the PHY, or drive it high to allow the PHY to come out of reset and begin
operation. The NRST signal is pulled low on the board, so that the PHY is held in reset by default. To allow the PHY
to operate, this pin must be driven high. This reset operation is not part of the Microchip network protocol stack,
and so driving NRST high must be done before initializing the Microchip network stack.
The Digilent chipKIT network libraries perform this automatically, and so no action is necessary when using the
board with the MPIDE software system and the Digilent libraries.
Copyright Digilent, Inc. All rights reserved.
Other product and company names mentioned may be trademarks of their respective owners.
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