Digilent chipKIT Network Shield Referenzhandbuch und Benutzerhandbuch - Seite 5
Blättern Sie online oder laden Sie pdf Referenzhandbuch und Benutzerhandbuch für Computer Hardware Digilent chipKIT Network Shield herunter. Digilent chipKIT Network Shield 11 Seiten. Chipkit network shield board
Auch für Digilent chipKIT Network Shield: Referenzhandbuch (11 seiten)
Seite druckenchipKIT Network Shield Reference Manual
protocol documentation, for operation of the
Ethernet interface.
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
Max32/Network Shield are 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 boot loader in the chipKIT Max32 board
sets this configuration by default. When using
the Network Shield within the MPIDE
environment no additional work is necessary.
When using it outside the MPIDE environment,
these configuration settings must be made.
The LAN8720 PHY has a reset signal, labeled
NRST in the schematic, that is used to reset
the PHY. This signal is connected to the
INT2/RE9 pin on the PIC32 microcontroller.
This pin is chipKIT digital pin 7 on the Max32
board. 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 Network Shield 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. When using the
chipKIT Ethernet library for the Network Shield,
this is done automatically by the library.
www.digilentinc.com
Copyright Digilent, Inc. All rights reserved. Other product and company names mentioned may be trademarks of their respective owners.
USB Interface
The PIC32MX795 microcontroller on the
Max32 contains a USB 2.0 Compliant, Full
Speed Device and On-The-Go (OTG)
controller. This controller provides the
following features:
USB full speed host and device support
Low speed host support
USB OTG support
Endpoint buffering anywhere in system
RAM
Integrated DMA to access system RAM
and Flash memory.
Connector J4 on the top left side of the board
is a standard USB type A receptacle. This
connector will generally be used when the
Max32/Network Shield has been programmed
to operate as a USB host. The USB device is
connected either directly, or via cable to this
connector.
Connector J2, on the bottom left side of the
Network Shield board is the Device/OTG
connector. This is a standard USB micro-AB
connector. Connect a cable with a micro-A
plug (optionally available from Digilent) from
this connector to an available USB port on a
PC or USB hub for device operation.
When the USB controller in the PIC32
microcontroller on the Max32 board is in use, it
takes over the use of several of the pins. The
signals provided by these pins appear on
connector J13 on the Network Shield
(connector J9 on the Max32). Two addition
signals are used, when doing USB hosting.
These signals appear on AN5 and digital pin 2.
These pins are not available when using the
USB interface.
When operating as a USB device, the chipKIT
Max32/Network Shield will normally be a self
powered device. To operate as a self powered
device, an external power supply should be
connected to the external power connector, J2
on the Max32 board. If the external power
supply is a regulated 5V supply, jumper JP1 on
page 5 of 11