Industrial Reference Design Platform Ethernet and CAN Bus Interfaces

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Industrial Reference Design PlatformEthernet and
CAN Bus Interfaces
Release 1.0
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EthernetThe Basics

• An Ethernet network is a family of frame-based
  computer networking technologies for local area
  networks (LANs)
• Defines a number of wiring and signaling
  standards
• Physical layer
• Network access at the Media Access Control
  (MAC)/Data Link Layer
• Common addressing format
• Standardized as IEEE 802.3
• The most widespread wired LAN technology is a
  combination of the twisted pair versions of
  Ethernet for connecting end systems to the
  network, along with the fiber optic versions for
  site backbones,
• In use since 1980

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EthernetDetails the frame
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EthernetLPC2468 Basic Features

• Ethernet standards support
• Fully compliant with IEEE 802.3
• Including 802.3x Full Duplex Flow Control and
  Half Duplex Back Pressure
• Flexible transmit and receive frame options
• Virtual Local Area Network (VLAN) frame support
• Memory Management
• Independent transmit and receive buffers memory
  mapped to shared SRAM
• DMA managers with scatter/gather DMA and arrays
  of frame descriptors
• Memory traffic optimized by buffering and
  pre-fetching
• Physical interface
• Attachment of external PHY chip through standard
  MII or RMII interface
• 10 Mbits/s or 100 Mbits/s PHY devices including
  10 Base-T, 100 Base-TX, 100 Base-FX, and 100
  Base-T4
• PHY register access is available via the MIIM
  interface

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EthernetLPC2468 Enhanced Ethernet Features

• Receive filtering
• Multicast and broadcast frame support for both
  transmit and receive
• Optional automatic Frame Check Sequence (FCS)
  insertion with Cyclic Redundancy Check (CRC) for
  transmit
• Selectable automatic transmit frame padding
• Over-length frame support for both transmit and
  receive allows for any length frames
• Promiscuous receive mode
• Automatic collision back-off and frame
  retransmission
• Power management by clock switching
• Wake-up on LAN power management support allows
  system wake-up using the receive filters or a
  magic frame detection filter

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IRD Ethernet InterfaceFunctional Overview

• Complete 10/100 Ethernet Interface
• LPC2468 has fully-implemented Ethernet MAC
• PHY is implemented on the Embedded Artists Core
  module
• Physical Ethernet interface coupling LED
  indications embedded in connector

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IRD Ethernet InterfaceBlock Diagram
IRD Board
PHY
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IRD Ethernet InterfaceHardware - Embedded
Artists Board

• 10/100 PHY implemented with Micrel KSZ8001L
• Utilizes the MII interface, not the RMII
• Other common PHYs available
• National
• RealTek
• Crystal
• Marvel
• AMD

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IRD Ethernet InterfaceSI-50170

• An integrated connector
• Transformers
• Status LEDs

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IRD Ethernet InterfaceSchematic
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IRD Ethernet InterfaceSoftware

• Embedded in the Micrium OS-II RTOS

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IRD Ethernet DemonstrationProcedure

• This demonstration allows the user to test the
  Ethernet capabilities of the IRD Platform
• The PC must be set up properly to communicate
  with the IRD
• Set a fixed IP address on the PC
• Connect an Ethernet Cable between the PC and the
  IRD
• Type a command to send packets to the IRD via the
  Ethernet connection

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IRD Ethernet DemonstrationPreparing to Configure
the IP Address

• The IP address must be a static address within
  the range of the IRDs fixed IP address
• On the PC, open up the Windows Control Panel
• Double-click on the Network Connections icon
• Find the Wired 10/100 connection (usually called
  Local Area Connection) icon and right-click on
  itclick on Properties to open up that
  connection configuration
• Click on the Internet Protocol(TCP/IP) selection
  and then click on Properties

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IRD Ethernet DemonstrationSetting the Proper IP
Address

• Select Use the following IP Address
• Type in an IP Address of 192.168.2.70
• In the subnet mask type in 255.255.255.0
• Click on OK to close this window.
• Click on OK again to close the network
  properties

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IRD Ethernet DemonstrationRunning the
Demonstration

• Connect a standard Ethernet cable between the
  IRDs Ethernet Jack and the PCs Ethernet Jack
• Open up a Command Prompt Window
• Click on Start
• Click on Run
• In the pop up type cmd
• Click on OK
• A command prompt window will appear
• Type ping 192.168.2.80
• You will see the response back from the IRD

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Controller Area Network (CAN) BusThe basics

• CAN-bus is a computer network protocol and bus
  standard designed to allow microcontrollers and
  devices to communicate with each other without a
  host computer
• Originally developed in 1988 by Intel and Robert
  Bosch GmbH for the vehicle industry
• The CAN bus may be used in vehicles to connect
  the engine control unit and transmission, or (on
  a different bus) to connect the door locks,
  climate control, seat control, etc.
• The CAN bus is also used as a fieldbus in general
  automation (industrial) environments
• Any official use of CAN requires a fee for the
  CAN Protocol License to be paid to Bosch who
  developed the protocol and hold patents.

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CAN BusThe details

• CAN is a differential serial broadcast bus
• Two states
• Dominant (a 0)
• Recessive (a 1)
• Each node is able to send and receive messages,
  but not simultaneously
• Message format
• an ID - chosen to identify the message type and
  sender
• up to 8 message bytes
• sensed by all nodes
• If the bus is free, any node may begin to
  transmit
• If two or more nodes begin sending messages at
  the same time, the message with the more dominant
  ID (which has more dominant bits) will overwrite
  other nodes' less dominant IDs
• eventually (after this arbitration on the ID)
  only the dominant message remains and is received
  by all nodes
• Bit Rates up to 1 Mbits/s possible at network
  lengths below 40m
• Decreasing the bit rate allows longer network
  distances (e.g. 125 kbits/s at 500 m).

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CAN BusFrame Format
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CAN BusNode Hardware Requirements

• Host Processor
• Decides what received messages mean, and which
  messages it wants to transmit itself
• Sensors, actuators and control devices can be
  connected to the host-processor (if desired)
• CAN Controller
• Receiving CAN Controller stores received bits
  (one by one) from the bus until an entire message
  is available, that can then be fetched by the
  host processor (usually after the CAN Controller
  has triggered an interrupt)
• Sending Host processor stores its
  transmit-messages into a CAN Controller, which
  transmits the bits serially onto the bus
• Transceiver
• Receiving Adapts signal levels from the bus to
  levels that the CAN Controller expects and has
  protective circuitry that protect the CAN
  Controller
• Sending Converts the transmit-bit signal
  received from the CAN Controller into a signal
  that is sent onto the bus
• Possibly integrated into the CAN Controller

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CAN BusLPC2468 Features

• Two CAN controllers and buses
• Data rates to 1 Mbits/s on each bus
• 32-bit register and RAM access
• Compatible with CAN specification 2.0b, ISO
  11898-1
• Global Acceptance Filter recognizes 11-bit and
  29-bit receiver identifiers
• Acceptance Filter can provide FullCAN-style
  automatic reception for selected Standard
  Identifiers
• Full CAN messages can generate interrupts

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IRD CAN InterfaceHardware Description

• Utilizes NXP TJA1040 CAN Transceiver
• NXP PSD1CAN protection device
• Interface to CAN bus off-board via (2) DB-9
  Connectors
• Option to provide power to remote CAN devices via
  DB-9 connectors
• On-board jumpers allow for connecting both
  channels together for loopback testing
• On-board header allows for easy connection to a
  CAN Analyzer

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IRD CAN InterfaceBlock Diagram

• Majority of CAN functionality provided by LPC2468
• IRD Board provides CAN Transceivers, Protection,
  and Connectors

CAN Board Connectors
TJA1040 CAN Transceiver
PESD1CAN Protection Device
TJA1040 CAN Transceiver
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IRD CAN InterfaceHardware
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IRD CAN InterfaceHardware Connector Power
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IRD CAN InterfaceHardware Loopback
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IRD CAN InterfaceHardware CAN Analyzer
Connection
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IRD CAN InterfaceTJA1040

• Interface between the CAN protocol controller and
  the physical bus
• Fully compatible with the ISO 11898 standard
• High speed - up to 1 MBaud
• Very low-current standby mode with remote wake-up
  capability via the bus
• Differential receiver with high common-mode range
  for EMI immunity
• Automatic no-load to bus when device is unpowered
• Voltage source for stabilizing the recessive bus
  level if split termination is used
• At least 110 nodes can be connected
• Transmit Data dominant time-out function
• Bus pins short circuit proof from battery and
  ground

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IRD CAN InterfaceDevice Protection PESD1CAN

• Designed to provide ESD and other transients
  protection to CAN bus lines
• One SOT23 device protects two CAN lines
• Max. peak pulse power PPP 200 W at tp 8/20
  ms
• VCL 40 V at IPP 1 A
• Ultra low leakage current IRM lt 1 nA
• ESD protection up to 23 kV

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IRD CAN InterfaceSoftware

• Embedded in the Micrium OS-II RTOS

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IRD CAN InterfaceLoopback Demonstration

• Loops CAN0 and CAN1 channels together
• Message transmitted from CAN0 channel is received
  by CAN1 channel
• Need to connect the CAN TEST jumpers on the board
• Be sure to set up PC IP Address as per Ethernet
  Demonstration previously shown
• Demonstration Accessed via the HTTP Webserver
  Application
• Menu choice Demonstrations - CAN Loopback
  Demonstration

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IRD CANLoopback Demonstration - Jumpers
Ensure these jumpers are in place
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IRD CANLoopback Demonstration - IP Setup

• Set up the PCs IP Address to 192.168.2.70
• As done previously in the Ethernet Demonstration

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IRD CANLoopback Demonstration Starting the Web
Server Application

• Start up the IRD Platform with the USB
  Stick-Based Web Server
• Open a Web Browser and enter the URL
  192.168.2.80/index.html

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IRD CAN Loopback DemonstrationAccess the
Demonstrations Menu

• Click on the Demonstrations Link

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IRD CAN Loopback DemonstrationAccess the CAN
Loopback Demonstration

• Click on the CAN Loopback Link

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IRD CAN Loopback DemonstrationRunning the
Loopback Demonstration

• Follow the instructions on the Web Page to run
  the demonstration

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IRD CAN Loopback DemonstrationSending the CAN
Message
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