CAN FD with Dynamic Multi-PDU-to-Frame...

V0.1 | 2015-09-25

Flexible Network Architectures

CAN FD with Dynamic Multi-PDU-to-Frame Mapping

2

E/E Trends and Challenges

Why is Dynamic Multi-PDU-to-Frame Mapping required?

The Trend:

Demand for communication bandwidth

The Solution:

Faster network protocols with higher payloads

The Challenge:

Flexible E/E architectures that abstract the data link layer

3

Central Gateway Architecture

A new Network Protocol: FlexRay

A new Architecture: Backbone

The CAN Evolution: CAN FD

Dynamic Multi-PDU-to-Frame Mapping

Ethernet and SOME/IP

Testing and Analyzing Dynamic PDUs

Summary

Agenda

4


Splitting Networks

To gain more bandwidth CAN networks were splitted into functional clusters

The functional clusters were connected with a central gateway

5








Summary

Agenda

6


FlexRay Features

FlexRay Features

Payload of up to 254 bytes

Bit rate of up to 10 Mbit/s

Two channels: A/B

Time Triggered communication

Frame ID

Length Header

CRC Cycle DATA CRC

Data

11 Bit 7 Bit 11 Bit 6 Bit 0-254 Byte 24 Bit

NM Msg ID

Data

Sync f

ram

e indic

ato

r

Reserv

ed

Paylo

ad p

ream

ble

indic

ato

r

Null fra

me indic

atior

16 Bit 0-12 Byte

Header, 5 Bytes Payload, 0...254 Bytes Trailer, 3 Bytes

Sta

rtup f

ram

e

indic

ato

r

7








Summary

Agenda

8


Domain Controllers

Functional clusters are controlled by a domain controller

The domain controllers are interconnected by a backbone network

9


Information Exchange

Is a signal based information exchange still sufficient?

Introduction of static PDUs

10








Summary

Agenda

11


CAN FD Features

CAN FD Features:


Data phase bit rate of currently 2 Mbit/s

Event Triggered communication

CAN FD Frame

Arbitration Phase

(arbitration bit rate)

Arbitration Phase

(arbitration bit rate)

Data Phase

(optional high bit rate)

SO

F

1

RR

S

IDE

FD

F

res

ES

I

AC

K

AC

K D

elim

iter

CR

C D

elim

iter

1

BR

S

1

1

1

1

1

1

1

1

Identifier

11

DLC

4

Data

0..512

CRC

17 / 21

EOF

7

IFS

3

Stuff

Count

4

12








Summary

Agenda

13


General Concept

Dynamic PDU

A header with ID and DLC is required

To abstract the data link protocol a frame is modeled as a Container-PDU

14


Transmission Behavior

Dynamic PDU Triggering

The triggering for a dynamic concept must be determined at runtime

PDU2

Container-PDU transmission timeout

Transmission trigger

PDU3 PDU2 PDU1

PDU transmission timeout Transmission trigger

Transmission trigger PDU transmission trigger

Transmission trigger Buffer threshold trigger

Buffer exceeded trigger

PDU1

Transmission trigger

PDU trigger

15


PDU Mapping: Communication Patterns

Two communication patterns

Queued communication

Last-is-best-communication

16


Benefits and Drawbacks

Benefits

Easier variant management

Function mapping becomes more independent of the network design

Transmitting node can be moved within the network > No modification of the receiving node required

New functions can be added to the network > Not affected ECUs require no update

> Unknown PDUs are just skipped

Drawbacks

Higher resource demand > Interrupt latencies increase

> Reason: Each Container-PDU must be scanned for relevant PDUs

Design rule for networks > Irrelevant messages must be kept away

> E.g. using a domain architecture where the domain controller takes care of forwarded messages

17


Gateway Routing

Signal Routing

PDU Routing

18








Summary

Agenda

19


Automotive Ethernet

Ethernet:


Bit rate of up to 100 Mbit/s

Switched Network

Peer-to-Peer communication

Ethernet Communication Concepts

Classical signal based communication > Multi-PDU-to-Frame Mapping applied like for CAN FD

SOME/IP > Middleware for serializing/de-serializing data

> Support of Publish-Subscribe Pattern

> Support of service oriented communication

> Data updates make use of the Dynamic PDU concept

20


Automotive Ethernet

Interoperability SOME/IP – Multi PDU-to-Frame Mapping

0 – 7 Bit 8 – 15 Bit 16 – 23 Bit 24 –31 Bit

Message ID/Service ID Method ID

Length

Request ID Session ID

Message Type Protocol Version Interface Version Return Code

Payload

DLC

ID

Payload

SOME/IP Header AUTOSAR PDU

21








Summary

Agenda

22


Tool Requirements

How can dynamic PDUs be analyzed?

CAN Data Link Ethernet Data Link FlexRay Data Link

Script Engine

“on canframe”

Analysis Engine

“can-frame”

CAN-Event

CAN-Event

Script Engine

“on ethernetframe”

Analysis Engine

“ethernet-frame”

Ethernet-Event

Ethernet-Event

Script Engine

“on flexrayframe”

Analysis Engine

“flexray-frame”

FlexRay-Event

FlexRay-Event

Test- and Analysis-Tool Architecture: Frame Layer

Event - Flow

23


Tool Requirements

Introduction of a PDU Layer

CAN Data Link Ethernet Data Link FlexRay Data Link

PDU Extraction

PDU-Event

CAN-Event

PDU Extraction

Analysis Engine

“PDU”

PDU-Event

Ethernet-Event

PDU Extraction

PDU-Event

FlexRay-Event

Test- and Analysis-Tool Architecture: PDU Layer

Event - Flow

Script Engine

“on PDU”

PDU-Event

24








Summary

Agenda

25

Summary

Dynamic Multi PDU-to-Frame Mapping

CAN FD and Ethernet introduces new communication principles

These require an abstraction between the signal and the data link layer

The Dynamic Multi-PDU-to-Frame Mapping concept offers an ideal platform for these use cases

The concept convinces with its high flexibility especially in event driven environments

New approaches within tools are necessary for analyzing and testing PDUs

26 © 2015. Vector Informatik GmbH. All rights reserved. Any distribution or copying is subject to prior written approval by Vector. V0.1 | 2015-09-25

For more information about Vector and our products please visit www.vector.com

Author: Decker, Peter Vector Germany

http://www.vector.com/

CAN FD with Dynamic Multi-PDU-to-Frame...

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