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1
C164CI - CAN-Interface
C166-Core
16
64 K ROM (C164 CI-8RM) or OTP (C164CI-8EM)
Data
RAM
CPU
Dual Port
Instr./Data
Data
2 KByte
32
16
PLL-Oscillator prog. Multiplier 0.5 1 1.5
2 2.5 3 4 5
Watchdog
PEC
External Instr./Data
13 ext. IR
RTC
P4.5/ CAN RxD
Interrupt Controller
Full-CAN Interface V2.0B active
16
Interrupt Bus
Peripheral Data
16
P4.6/ CAN TxD
XBUS (16-bit NON MUX Data / Addresses)
10-Bit ADC
CAPCOM6 Unit for PWM Generation
GPT1
Sync. Channel
CAPCOM 2
USART
External Bus 8/16 bit MUX only XBUS Control
T2
(SPI)
Port 0
16
8-Channel
8-Channels
ASC
SSC
Timer 13
T3
Timer 7
Timer 8
BRG
BRG
T4
1 Comp. Channel
3/6 CAPCOM Channels
Port 5
Port 3
Port 8
Port 4
Port 1
6
8
9
16
4
2
Controller Area Network - CAN

• CAN is a protocol for serial communication that
  supplies distributed realtime tasks with very
  high safety-requirements

• CAN is standardized
• ISO-DIS 11898 (high speed applications)
• ISO-DIS 11519-2 (low speed applications)

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CAN - features

• Low costs
• Serial BUS for 2-wire-lines
• High number of CAN-nodes in the automotive sector
  and in industrial electronics

• Reliability/Data Integrity
• Sophisticated mechanisms for error detection and
  handling result in high reliability of the
  transmissionExample
• 500 kbit/s, 25 bus-load, 2000 operating hours a
  yearResult Only one undetected error in 1000
  years!
• Defective messages are detected and repeated
• Every bus-node will be informed in case of an
  error
• Low susceptibility against electromagnetic
  interference

• Flexibility
• Nodes can be very easily added or removed (plug
  play).
• The number of nodes isnt limited by the protocol

4
CAN - Features

• High performance realtime-behaviour
• Short messages 0 to 8 bytes data per message.
• Short time of latency between the request of a
  message and the start of the transmission
• Prioritization of messages (Arbitration on
  Message Priority - AMP)
• Multi Master protocol with CSMA/CD

• High performance transmission rate
• maximum transfer rate is 1 MBit/s at 40m
  bus-length and still about 40 kBit/s at
  bus-length of 1000m

• Multi-Master-Operations
• Every node can be the master
• The bus-communication is not prevented by
  defective nodes
• Defective nodes switch off from the bus by
  themselves

• Flexible addressing mechanisms
• Messages can be sent to only one or to several
  nodes
• All modes receive simultaneously public data
  simultaneously

5
CAN Typical application
6
Protocol layers of the CAN
Process-Application
Layer
Application Layer
7
Logical Link Control Error detection, error
handling Control of data-flow Acceptance
filtering.
Data Link Layer
2
Medium Access Control Bit-Stuffing, Framing,
Arbitration
Management
Physical Signalling (Bit coding, -timing,
-synchron.)
Physical Layer
1
Physical Medium Attachment (Transmitter/Receiver-S
pec.)
Medium Dependent Interface (Cable, Plug...)
7
Higher Protocol Layers

• CAN Application Layer (CAL)
• Layer-7 Standard defined by CAN in Automation
  (CiA)
• Network-Management for initialisation, monitoring
  and configuration of nodes in standardised form
• Takes into account all aspects for the
  realisation of open communication via CAN
  (provides the cooperation of producer specific
  systems)
• Available implementations of CAL simplify the
  user getting sophisticated Controller Area
  Networks

• CANopen
• Applications are based on CAL.
• CANopen dertermines the mode of communication, an
  application- profile defines the meaning of
  certain messages) for the considered application
  
• aim Changeabilty of the subsystems of dedicated
  applications

• Further higher protocol layers (standards)
• Automotive-sector VOLCANO, OSEK
• Industrial Automation DeviceNet (ODVA), SDS
  (Honeywell)

8
CAN Protocol Layers
Process-Application
Layer
Application Layer
7
Medium Access Control Bit-Stuffing, Framing,
Arbitration
Data Link Layer
2
Logical Link Control Error detection, error
handling Control of data-flow Acceptance
filtering.
Management
Physical Signalling (Bit coding, -timing,
-synchron.)
Physical Layer
1
Physical Medium Attachment (Transmitter/Receiver-S
pec.)
Medium Dependent Interface (Cable, Plug...)
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Basic Characteristics of CAN

• Asynchronous serial bus with linear bus-structure
  and identical nodes (Multi-Master-BUS)
• Nodes wont be addressed - the addresses are
  parts of the message and are related to those,
  just as the priority is a characteristic of the
  message
• Two bus-states dominant and recessive
• the bus-activation is realized according to the
  "Wired-AND-mechanismdominant bits (logical 0)
  overwrite recessive bits (logical 1)
• Bus-access via CSMA/CD with NDA (Carrier Sense
  Multiple Access/ Collision Detection with
  Non-Destructive Arbitration)
• Before transmission it is tested whether the bus
  is free
• Each sender tests whether the bus level is
  consistent to its transmission level
• In case of discrepancy transmission is stopped
  and switched to receiving mode

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Basic Characteristics of CAN
recessive
NODE A
dominant
recessive
NODE B
dominant
bus idle
recessive
CAN BUS
dominant
Node B transmits recessive levelbut reads back
dominant level
Node B loses arbitrationand switches to receive
mode
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Typical Structure of CAN-Nodes
Node A
Node B
z.B. ABS
z.B. EMS
Application
z.B. 80C166
z.B. C164CR oder C515C
Host-Controller
(further nodes)
z.B. SAE81C90
CAN-Controller
CAN
CAN-Transceiver
CAN_H
CAN-BUS
UDiff
CAN_L
12
CAN data frames

• There are two situations in communication
• One node is transmitting (talker), all other
  nodes are receiving (listener)
• Nodes A requires (from an other node) anything
  and gets the answer
• In Talk-mode CAN-nodes use data frames
• data frames consist of
• an identifier
• the data, which should be transmitted
• and a CRC-checksum

• The Identifier specifies the content of the
  message (car velocity , oil temperature,
  etc.) and the priority of the message
• The data field contains the appropriate value
  (36 m/s, 110C, etc.).
• The Cyclic Redundancy Check provides detection
  of transmission errors
• All nodes receive the data frames, unaffected
  nodes ignore it

Base Can Frame
13
CAN Remote Frames

• In order to get information Remote Frames are
  used
• A Remote Frame consists of the identifier and the
  CRC-checksum, no data are contained

• The identifier refers to the information to be
  queried (car velocity ', oil temperature',
  etc.) and the priority of the message
• Every node having available the required
  information (e.g. the sensor for the oil
  temperature) reacts with transmission of the
  appropriate Data Frame (same identifier, the
  data field contains the required information).

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Standard CAN / Extended CAN

• CAN Version 2.0A - Standard CAN
• The Standard-Frame contains an 11 Bit identifier
• With that 211 (2048) different messages can be
  addressed

• CAN Version 2.0B (active) - Extended CAN
• The Extended Frame has got an identifier with a
  length of 29 Bit
• Via that more than 536 Million (229) different
  messages can be addressed

• CAN Version 2.0B (passive)
• Some Standard-CAN-Nodes are not able to receive
  Extended Frames, but they are tolerating them
  and ignore their messages. They dont receive
  any data, as they dont produce any errors.
• These CAN-Nodes use CAN Version 2.0A, but they
  are also denoted as nodes Version 2.0B passive
• They are used in networks, in which Standard
  Frames as well as Extended Frames are worked
  with

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CAN-Contoller

• Infineon C164CI V2.0B active

• CAN-Controllers perform the management of the
  messages and its acceptance filtering
  autonomouslyFull-CAN-Controller
• There are a lot of Message-Objects with its
  appropriate identifier.
• Only if a message with one of the specified
  identifiers is received, it will be saved and the
  execution of the program will be interrupted
• In that way the load of the CPU can be kept low

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Characteristics of the C164CI CAN-Module

• The characteristics are comparable with the
  common CAN-Controller AN82527
• All requirements of CAN spec. V2.0B active are
  met(Standard- und Extended-CAN)
• Maximum CAN-transfer rate of 1 MBit/s
• Full CAN Device
• 15 Message-Objects with appropriate identifiers
  and appropriate state- und control-Bits
• Each Message-Object can be defined as transmit -
  or receive-object.

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Characteristics of the C164CI CAN-Module

• Programmable mask-register for acceptance-Filterin
  g
• Global mask for incoming messages
  (Full-CAN-Objects)
• Additional mask for message-object 15(Basic
  -CAN-) Characteristic
• Basis-CAN- Characteristic (of Message-Object 15)
• Two receiver buffers
• Separate global mask-register for
  acceptance-filtering
• Connection to CPU (C166-Core)
• The module is connected via the chip-internal
  XBUS(16-Bit BUS-Width)
• Interrupts directly to the CPU with all
  facilities of the interrupt handling
• To connect with the CAN-BUS only physical level
  conversion via a Standard-CAN-Transceiver is
  needed

18
Connection of the C164CI to the CAN-BUS
C164CI
CAN-Bus
Transceiver
CAN_L
CAN_H
P4.5
Pa.b
Receive
CAN_RxD
CAN_H
Connectionto theapplication
P4.6
Transmit
CAN_TxD
CAN_L
Pc.d
(Standby)
z.B. P8.0
R(opt)

• The CAN-Module uses 2 pins of Port 4 as interface
  to a BUS-Transceiver (P4.5 - CAN_RxD, P4.6 -
  CAN_TxD).

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ACCEPTANCE FILTERING
Remark If data frames from more than one
Message Object are accepted, so the data frame
is stored in the object with the lowest
number. If remote frames from more than one
Message Object are accepted, so the data of the
Object with the lowest number are transmitted
Because of the "don't care"-Bits also messages
with identifiers b)..d) are acceppted
20
Bit-Timing

• The Bit-Timing is derived from the system clock
  fPERIPHERAL and is programmable up to the data
  rate of 1 MBaud (_at_ f CPU 16 MHz)

SFRcan
21
Register of the CAN-Controller
SFRcan
22
Message Object
SFRcan
CAN-SW