Wilamowski B.M., Irwin J.D. The Industrial Electronics Handbook. Second Edition: Industrial Communication Systems

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FlexRay 44-5

44.3.2 Node architecture

A.typical.node.architecture.consists.of.a.host.CPU.subsystem,.a.network.controller,.and.bus.drivers.

for.the.separate.channels;.see.Figure.44.5..Interfacing.between.the.host.and.the.network.subsystem.is.

facilitated.via.a.controller.host.interface.employing.some.kind.of.dual-ported.memory.. is.choice.of.an.

interface.allows.separating.control.from.data.ow,.creating.some.kind.of.temporal.rewalls.restricting.

error.propagation.to.dened.areas..Optional.bus-guardians.may.be.installed.either.at.the.nodes.or.at.

central,.active.star.couplers.. e.bus-guardians.oversee.and.inhibit.bus.access.whenever.a.node.is.not.

allowed.to.transmit.in.order.to.avoid.so-called.babbling.idiot.failures;.situations.where.a.node.playing.

havoc.disrupts.the.entire.communication.

44.3.3 Star Couplers

Both.passive.and.active.star.couplers.are.supported.by.the.FlexRay.protocol..Whereas.passive.star.cou-

plers

.are.simply.circuits.that.relay.the.signal.received.on.one.branch.to.all.other.branches;.active.star.

couplers.provide.logic.and.circuitry.for.power-down.and.wakeup,.error.detection.and.isolation,.as.well.

as.signal.reshaping..Typically,.an.active.star.coupler.listens.on.all.branches.for.trac.and.when.a.signal.

is.detected.it.is.relayed—in.an.error.free.case—to.all.other.branches..Whenever.an.error.occurs.or.before.

a.cluster.is.synchronized,.collisions.of.data.frames.or.symbols.may.occur..In.this.case,.an.active.star-

coupler

.relays.the.superimposed.signal.to.the.other.branches.

44.4 System Design Considerations

Guaranteed.bandwidth.and.reliable.operation.are.some.of.the.benets.of.time-triggered.communica-

tion

.systems..On.the.other.hand,.such.systems.may.become.less.exible.(especially.when.frequent.sys-

tem

.changes.occur).and.require.higher.eorts.at.design.time.

44.4.1 Conguration

Next.to.topology.considerations,.one.has.to.congure.which.nodes.act.as.coldstarters.and.participate.

at.the.clock.synchronization.(sending.of.sync.frames)..At.least.two.or.more.nodes.should.be.assigned.

therefore;.in.fact,.more.of.these.nodes.enhance.the.availability.of.the.cluster.but.increase,.however,.the.

likeliness.for.the.establishment.of.cliques.(cliques.are.groups.of.nodes.that.are.able.to.communicate.with.

each.other,.however,.not.with.other.nodes),.cf..[MHS08].

Furthermore,

.the.physical.distribution.of.these.nodes.as.well.as.the.distribution.of.their.slots.impairs.

the.overall.robustness.of.the.cluster..In.fact,.having.these.nodes.and.slots.evenly.dispersed.over.the.

cluster.and.schedule,.respectively,.will.likely.improve.the.overall.availability..Furthermore,.conguring.

more.nodes.as.the.minimum.to.transmit.the.specied.wakeup.patterns.and.perform.coldstart.attempts.

will.improve.the.startup.mechanism..When.one.of.these.so.congured.nodes,.however,.is.faulty,.a.higher.

FlexRay controller

Controller

host

interface

Protocol

engine

Bus guardian

Host

subsystem

Bus

driver

Communication channels

FIGURE 44.5 Node.architecture.

44-6 Industrial Communication Systems

number.of.attempts.will.elongate.the.startup.time..Figure.44.6.along.with.Table.44.1.depicts.some.exam-

ples

.that.illustrate.the.eect.of.sync.node.distribution.on.the.system.behavior.when.either.a.fault.aects.

one.branch.(i).or.the.star-coupler.(ii).

All

.these.issues.have.to.be.considered.when.determining.the.large.number.of.conguration.param-

eters

.and.constants.of.the.FlexRay.protocol.for.an.actual.cluster.implementation..Here,.proper.planning.

and.tool.support.are.of.utmost.importance.

44.4.2 aUtOSar

In.practice,.when.designing.a.cluster.that.shall.be.built.with.hardware.and.soware.from.dierent.ven-

dors,

.the.AUTOSAR.standard.must.be.considered.. e.goals.of.the.latter.are.to.provide.for.system-wide.

TABLE 44.1 Consequences.of.Faults.in.the.Congurations.Shown.

inFigure.44.6

Conguration.(a) (i).. e.aected.branch.loses.communication

(ii)

.All.nodes.lose.communication

Conguration

.(b) (i).. e.aected.branch.loses.communication

(ii)

..Two.cliques.are.formed;.the.branches.without.sync.

nodes.lose.communication

Conguration

.(c) (i)...In.the.case.when.the.branch.with.the.sync.nodes.is.

aected,.all.nodes.will.lose.communication;.when.

another.branch.is.aected,.the.respective.branch.

will.lose.communication

(ii)

.. e.branch.with.the.sync.nodes.stays.synchronized;.

allother.branches.lose.communication

s s

s s s

Sync node

Node

Starcoupler

Conguration

(c)Conguration (b)Conguration (a)

FIGURE 44.6 Sync.node.distribution.examples.

Application layer

Runtime environment

Service layer

ECU abstraction layer

Microcontroller abstraction layer

Microcontroller

Complex drivers

Basic software

FIGURE 44.7 AUTOSAR.layer.model.

FlexRay 44-7

optimizations.with.regard.to.modularity,.scalability,.interchangeability,.and.reuse..To.that.end.it.

pro

vides

.sta

ndard

.int

erfaces

.and.abs

tractions

.bet

ween

.the.app

lication

.so

ware

.and.the.basi

.sys

tem

so

ware

.as.we

.as.an.im

plementation

.of.th

.la

tter.

.a.fun

ctional

.mod

el,

.so

ware

.com

ponents

.com

municate

.wit

.eac

.oth

.via.a.vir

tual

.fun

ctional

bus.usin

.sta

ndardized

.int

erfaces.

.In.the.dep

loyment

.pha

se,

.the.fun

ctional

.mod

.is.map

ped

.to.a.str

uc-

tural

.mod

el;

.her

eby,

.the.com

ponents

.are.map

ped

.to.the.app

lication

.lay

.and.the.vir

tual

.fun

ction

.bus.

to.the.run

-time

.env

ironment

.at.dis

crete

.ECU

. e.basi

.so

ware

.is.com

posed

.of.fou

.lay

ers

.and.one.

dri

ver

.mod

ule

.as.dep

icted

.in.Fig

ure

.44.

.and.imp

lements

.abs

tractions,

.dri

vers,

.and.ser

vices

.for.bot

Fle

xRay

.an

.co

ntroller

.ar

.ne

twork

.(C

AN).

Herein,

.the.mic

rocontroller

.and.ECU a

bstraction layers

.pro

vide

.abs

tractions

.fro

.the.spe

cic

.und

er-

lying

.har

dware,

.whe

reas

.the.ser

vice layer

.add

.thi

ngs

.lik

.tra

nsport

.pro

tocols,

.dia

gnostic

.ser

vices,

.and.

net

work

.man

agement

.ser

vices.

.Fin

ally,

.the.com

plex drivers’

.mod

ule

.all

ows

.cir

cumventing

.the

.mod

ules

.by.im

plementing

.sp

ecic

.dr

ivers

.wh

enever

.ti

.cr

itical

.im

plementations

.ar

.re

quired.

references

[FE05].FlexRay.Communications.Systems—Electrical.Physical.Layer.Specication.Version.2.1.,.available.

at.ht

tp://www.exray.com,

.FlexRa

.Co

nsortium,

.2005.

[FP05]

.FlexRay.Comm

unications

.Syst

ems—Protocol

.Spe

cication

.Versio

.2.1,.avai

lable

.at.htt

p://www.

exray.com,

.FlexRa

.Co

nsortium,

.2005.

[H05]

. Han

sen,

. P.,.New.S-Cla

. Merce

des:

. Pion

eering

. elec

tronics,

. e H

ansen Report on Automotive

Electronics,

.18(8),.1–2,.Oc

tober

.2005.

[MHS08]

.Mil

bredt,

.P.,.Hora

uer,

.M.,.and.Steinin

ger

.A.,.An.inves

tigation

.of.the.clique.pro

blem

.in.FlexRay

Pro

ceedings of the ird IEEE Symposium on Industrial Embedded Systems

.(SIES

2008),

.Mon

tpellier,

Fran

ce,

.Jun

.11–13,.2008,.pp

.224–231..

[R08].Ra

uch,

.M.,.FlexRa

.Ha

nser,

.Munic

.Ger

many,

.2008.

[WL88]

.Welc

.J.L..and.Lyn

ch,

.N.A.,.A.new.faul

t-tolerant

.algo

rithm

.for.cloc

.sync

hronization,

.Inf

ormation

and Computation,

.77(1),.1–36,.1988.

45-1

45.1 LIN Background

Modern.cars.contain.a.large.number.of.electronic.control.units.(ECU)..For.example,.the.BMW.AG.

7-se

ries

.(mod

.2008

)

.has.over.70.ECUs.and.abou

.100.die

rent

.elec

tric

.moto

rs.

. e.car’

.comf

ort

doma

.has.been.much.impr

oved

.in.rece

.year

.Comf

ort

.func

tions

.such.as.elec

tric

.wind

.lie

rs,

elec

tric

.outs

ide

.mirr

ors,

.cent

ral

.lock

ing,

.air.cond

itioning,

.elec

tric

.seat.adju

stment,

.and.an.elec

trical

slid

ing

.roof.are.comm

.feat

ures

.in.toda

y’s

.cars

.In.the.past

.when.the.numb

.of.feat

ures

.was.low,.

the.vari

ous

.elec

trical

.devi

ces

.were.conv

entionally

.wire

.Howe

ver,

.as.the.numb

.of.feat

ures

.grew

the.wiri

.harn

ess

.beca

.unma

nageable,

.and.the.diag

nostics

.for.such.comp

lex

.syst

ems

.beca

comp

lex.

.For.thes

.reas

ons,

.the.car.manu

facturers

.intr

oduced

.mult

iplexed

.wire

.comm

unication

syst

ems.

.Howe

ver,

.an.unco

ntrolled

.grow

.evol

ved

.as.the.vari

ous

.manu

facturers

.deve

loped

.pro-

rietary

.prot

ocols

.for.in-v

ehicle

.cont

rol

.netw

orks

.(e.g

.BMW.AG’s.K/I-

BUS,

.Toyo

ta’s

.BEAN

.GM’s.

Sine

bus,

.and.E&C)

.prop

rietary

.proto

cols

.prov

.expe

nsive

.and.oen.had.depe

ndence

.on.singl

.supp

liers.

.In.an.

atte

mpt

.to.devi

.a.stan

dardized

.solu

tion,

.the.car.make

.BMW.Grou

.Daim

ler-Benz

.(now.Daim

ler),

Audi

. and. VW,. the. semi

conductor

. comp

any

. Motor

ola

. (now. Free

scale),

. and. the. netw

ork

. spec

ial-

ist

.Volc

ano

.Comm

unications

.Tech

nologies

.(now.Mento

.Grap

hics)

.foun

ded

.the.LIN.Cons

ortium

.to.

deve

lop

.a.low-

cost

.comm

unications

.stan

dard

.for.the.so-c

alled

.Soci

ety

.of.Autom

otive

.Engi

neers

.(SAE

)

comm

unication

.clas

.A.(sys

tems

.up.to.20.kbps

)

.syst

ems.

. e.Loca

.Inte

rconnect

.Netw

ork

.(LIN

)

.is.a.

low-

cost

.solu

tion,

.whic

.is.a.univ

ersal

.asyn

chronous

.rece

iver

.tran

smitter

.(UAR

.base

.singl

e-master,

mult

iple-slave

.arch

itecture,

.deve

loped

.for.autom

otive

.sens

.and.actu

ator

.appl

ications.

. e.LIN.mast

node.conn

ects

.the.LIN.netw

ork

.with.high

.leve

.netw

orks,

.usua

lly

.the.cont

roller

.area.netw

ork

.(CAN

 e.LIN.is.positioned.below.CAN.and.it.does.not.replace.CAN.

LIN-Bus

45.1. LIN.Background..............................................................................45-1

45.2

. LIN.His

tory

.and.Ver

sions..............................................................45-2

45.3

. Comm

unication

.Con

cept...............................................................45-3

45.4

. Physi

cal

.Lay

er...................................................................................45-3

Signal.Specication. •. Topology

45.5. LIN.Message.Frames.......................................................................45-6

Break.Field. •. Sync.Byte.Field. •. Identier. •. DataField. •. .

Checksum. •. Frame.Length. •. Time-Triggered.

DataTransmission. •. Frame.Types. •. Diagnostic.Frame

45.6. Network.and.Status.Management...............................................45-10

45.7

. Tran

sport

.Lay

.Pro

tocol.............................................................45-11

45.8

. Con

guration.................................................................................45-12

45.9

. Rela

tionship

.bet

ween

.SAE.J26

.and.LIN

2.0...........................45-12

45.10

.Conc

lusion......................................................................................45-12

References...................................................................................................45-13

Andreas Grzemba

University of Applied

Scie

nces

Deg

gendorf

Donal Heffernan

University of Limerick

Thomas Lindner

BMW Group

45-2 Industrial Communication Systems

Figure.45.1.shows.an.example.of.an.automotive.communication.architecture.with.a.central.gateway..

Here,.LIN.controls.the.damper.motors.of.the.air-conditioning.system.. e.LIN.specication.denotes.

aLIN.subbus.as.a.LIN.cluster.

45.2 LIN History and Versions

In.the.summer.of.1999,.the.rst.version.[LIN1.0].of.the.LIN.specication.package.was.published..

It.contained.specication.information.to.describe.a.full.network.including.the.parts.protocol,.the.

physical.layer,.and.the.application.program.interface..It.also.specied.the.conguration.language.

description.(CLD).with.which.a.LIN.cluster.can.be.described.in.a.LIN.description.le.(LDF).. is.

specication.package.enforced.a.development.workow.to.allow.the.ecient.development.of.a.LIN.

cluster,.where.all.the.communication.parameters.of.a.LIN.cluster.are.dened.in.the.LDF,.which.is.also.

machine.readable.

.LIN.Consortium.was.constituted.in.March.2000.at.the.SAE.congress.in.Detroit..Version.1.1.of.

the.LIN.specication.was.released.in.April.2000,.followed.by.version.1.2.in.November..Both.versions.

contained.only.editorial.modications.. e.next.important.step.was.the.release.of.the.version.1.3.

[LIN1.3].in.November.2002,.which.made.LIN.more.versatile..Version.2.0.[LIN2.0].realized.a.compre-

hensive

.expansion.of.the.LIN.standard,.although.it.retained.backward.compatibility.with.previous.

versions..One.of.the.main.innovations.of.LIN2.0.was.the.introduction.of.the.so-called.o-the-shelf.

slave.nodes..LIN.slave.nodes.can.be.simply.integrated.into.a.new.cluster.without.any.modications.

to. the.slave.nodes.. To.allow. this. concept.to.be.supported. by.appropriate. network.dening. tools,.

LIN2.0.species.the.slave.node.conguration,.which.allows.the.assignment.of.a.node.address.(NAD).

and.frame.identiers..It.also.denes.the.syntax.of.the.node.capability.le.(NCF),.which.contains.all.

parameters.of.the.o-the-shelf.slave.nodes,.using.the.node.capability.language.description.(NCLD)..

 ese.features.allow.plug-and-play.functionality.to.be.used.in.a.LIN.cluster..Figure.45.2.illustrates.

the.interaction.

.latest.LIN.version.2.1.[LIN2.1].was.released.in.November.2006..Mainly,.the.document.has.a.bet-

ter

.structure.and.mostly.contains.clarications.on.the.functionality..But.there.are.also.some.specic.

modications,.including.diagnostic.and.conguration.classes.for.the.slave.nodes.

Central gateway

Body CAN 500 kbps

FlexRay

10 Mbps

Powertrain CAN

500 kbps

LIN

19.2 kbps

Diagnostic CAN/K-line

500 kbps (ODB)

Dashboard CAN

500 kbps

Navigation

Phone

Mobile phone

Air

condition

(LIN master)

Bluetooth

3 Mbps

Receiver

MOST

25 Mbps

Infotainment

HMI

FIGURE 45.1 Automotive.communication.architecture.with.a.central.gateway.

LIN-Bus 45-3

45.3 Communication Concept

LIN.uses.the.master–slave.principle.for.the.medium.access.control.feature.. is.principle.allows.master.

and.slave.nodes.to.be.implemented.with.minimal.hardware.resources.. e.master.node.is.usually.imple-

mented

.in.a.control.unit.or.in.a.gateway.that.possesses.the.necessary.resources.

.specication.also.denes.a.master.task.and.a.slave.task.. e.master.task.initiates.every.commu-

nication.

.A.message.will.always.consist.of.a.header.generated.by.the.master.task.and.a.response.from.

the.slave.task..As.the.master.node.should.also.be.able.to.send.messages.to.the.slave.nodes,.along.with.

the.master.task.a.slave.task.can.also.be.integrated.into.the.master.node.(see.Figure.45.3).[Grz05].. is.

provides.the.possibility.of.integrating.several.slave.tasks.onto.a.hardware.platform.

.LIN.communication.scheme.is.based.on.the.producer–consumer.model.. erefore,.the.specica-

tion

.denotes.the.transmitter.as.the.“publisher”.of.the.message.and.the.receiver(s).as.“subscriber(s).”.LIN,.

like.CAN,.uses.identiers.to.uniquely.identify.a.message..As.well.as.a.point-to-point.communication.

scheme,.multicast.and.broadcast.communication.schemes.are.also.supported..Figure.45.4.shows.the.

three.possible.communication.relationships:

. a.. A.slave.module.responds.to.a.master.request

. b.. e.master.sends.a.message.to.one.or.more.slave.nodes

. c.. e.master.initiates.the.communication.between.two.slave.nodes

45.4 Physical Layer

It.was.a.goal.of.the.LIN.design.to.achieve.a.simplistic.wiring.topology..The.simple.single-wire.bus.

connects.to.each.node.in.the.cluster.and.switches.from.ground.to.battery-level.voltage.

.physical.layer.is.based.on.the.ISO.9141.standard.[ISO9141]..It.consists.of.the.bidirectional.single-

wire

.bus.line.(LIN).that.is.connected.via.a.pull-up.resistor.(R).and.a.diode.to.the.internal.supply.voltage.

SUP

).via.a.transistor.(component.of.the.transceiver).to.the.ground.(GND).(see.Figure.45.5a).. e.diode.

LIN description

file (LDF)

System design

tool

LIN

System

generator

LIN analyzer/

emulator

Cluster design

Cluster

Debugging

Slave 1

Slave 2

Master

Node capability

files (NCF)

Off-the-shelf

slave node

FIGURE 45.2 Workow.with.o-the-shelf.slave.nodes.

45-4 Industrial Communication Systems

LIN master task

LIN slave task

Master node

Slave node 2

Slave node 1

Lin-subbus

CAN

LIN slave task

Master task header

time

Slave task node 1

Slave task node 2

header

response

FIGURE 45.3 Master–slave.concept.of.LIN.

Header

Response

LIN master task

LIN slave task

Master node

(a)

(b)

LIN slave task

Slave node 1

Header

Response

LIN master task

LIN slave task

Master node

LIN slave task

Slave node 1

Slave node 2

Header

Response

LIN master task

LIN slave task

Master node

(c)

LIN slave task

Slave node 1

Slave node 2

FIGURE 45.4 Communication.relationships.within.a.LIN.cluster:.(a).a.slave.responds.to.a.master’s.request,.

(b).the.master.sends.a.message.to.one.or.more.slaves,.and.(c).the.master.initiates.the.communication.betweeen.

the.two.slaves.

LIN-Bus 45-5

is.mandatory.to.prevent.uncontrolled.powering.of.the.node.from.the.bus.line,.in.the.case.of.a.battery.

loss,.that.is,.if.V

BAT

.is.disconnected.in.Figure.45.5b.. e.pull-up.resistor.is.specied.at.30.kΩ.on.a.slave.

node.and.at.1.kΩ.on.a.master.node.. e.baud.rate.is.specied.in.the.range.of.1–20.kbps.but.typical.baud.

rates.are.9.6.or.19.2.kbps,.or.10.4.kbps.according.to.SAE.J2602,.as.will.be.discussed.later.

45.4.1 Signal Specication

 e.V

SUP

.and.GND.form.the.reference.potential.of.the.voltage.divider.to.determine.the.logical.value.of.a.bit..

A.voltage.level.below.40%.V

SUP

.represents.logical.0.and.a.level.above.60%.V

SUP

.represents.a.logical.1.. e.

transmitter.has.to.ensure.that.the.receiver.receives.valid.voltage.levels.. e.specication.does.not.dene.

transmitter.voltage.levels.

Because

.any.node.determines.the.logical.bit.values.in.reference.to.its.own.V

SUB

.and.GND,.a.dri.has.

an.impact.on.this.process.(see.Figure.45.6).. e.specication.margins.the.dri.of.V

BAT

.(V

Shi_BAT

).and.

GND.(V

Shi_GND

).at.about.10%..Note.that.V

SUP

,.seen.in.Figure.45.5b,.can.be.computed.as

V V V

SUP BAT D1

= −

(45.1)

Rx—max. duty

cycle

Rx—50% duty

cycle

Rx—min. duty

cycle

LIN signal

FIGURE 45.6 Inuence.of.the.dri.

(a)

LIN

GND

SCI

SUP

GND

BAT

BATTERY

Shift_GND

Only within

a master node

LIN node

Transceiver IC

Reverse battery protection

diode (D1)

Voltage divider

ser_int

ser_Master

Bus

(LIN)

1 K

30 K

SUP

(b)

Shift_BAT

FIGURE 45.5 (a).Basic.principle.of.the.physical.layer.according.to.ISO.9141..(b).Basic.structure.of.a.LIN.master.node.

45-6 Industrial Communication Systems

 e.duty.cycle.parameters.are.very.important.for.the.waveform.of.the.LIN.signal.. ey.establish.

limits.that.ensure.the.correct.determination.of.the.logical.bit.value.for.the.serial.communication.inter-

face

.(SCI).of.the.receiver.. ey.cover.the.issues.of.dri,.oscillator.tolerances,.and.asymmetries.of.

receiver.propagation.delay.rising.edge.with.respect.to.the.falling.edge.[TR0363].

45.4.2 topology

 e.specication.does.not.regulate.the.wire.topology..One.can.use.a.line,.tree,.or.star.topology..However,.

the.length.of.the.bus.line.must.be.limited.to.40.m.. e.eective.criterion.of.a.bus.line.is.the.RC.time.

constant.τ..It.covers.the.capacitances.and.loads.of.all.nodes.and.the.bus.line.. e.RC.time.constant.must.

be.in.the.range.of.1–5.μs.

.number.of.nodes.in.a.LIN.cluster.should.not.exceed.16..Every.additional.node.lowers.the.network.

resistance.by.approximately.3%,.because.it.integrates.a.parallel.30.kΩ.resistor.and.can.cause.communi-

cation

.errors.under.worst-case.conditions.

However,

.although.the.LIN.baud.rate.is.slow,.the.large.voltage.swing.can.be.a.source.of.radiated.emis-

sions;

.therefore,.attention.must.be.paid.to.physical.wiring.design.and.layout.

45.5 LIN Message Frames

 e.LIN.message.frame,.as.represented.in.Figure.45.7,.is.composed.of.a.header.and.a.message.eld,.

the.so-called.response.. e.header.eld.consists.of.the.break.eld.(Synch_Break),.the.synch.byte.eld.

(Synch_Field),.and.the.identier.eld,.which.is.designated.as.the.protected.identier.(PID).. e.mes-

sage

.eld.(response).consists.of.the.data.eld.with.one.to.eight.data.bytes.and.the.checksum..All.elds.

except.the.break.eld.are.byte.oriented.and.can.be.generated.with.the.integrated.serial.interface.of.a.

microcontroller.

Message

.activity.is.coordinated.by.the.periodic.execution.of.the.LIN.message.schedule..For.each.

frame.slot,.the.master.task.transmits.a.frame.header.with.a.frame.identier.(ID)..All.slaves.evaluate.

the.frame.header,.and.a.slave.immediately.transmits.the.frame.response.that.is.associated.with.the.ID..

 e.LIN.frame.is.the.combined.frame.header.and.response.

45.5.1 Break Field

A.synchronization.mechanism,.which.permits.slaves.without.stabilized.clock.frequencies.to.synchro-

nize

.themselves.from.the.master.clock,.is.implemented.in.the.protocol.. e.break.eld.informs.the.

slaves.in.the.network.when.the.data.transmission.of.a.frame.starts.. e.master.sends.a.zero,.13.bit.

Inter-byte

space

Data 1

Header

PID

Data 2

Data 3

Checksum

Response

Frame

Frame slot

Data N

Inter-byte

space

Inter-byte

space

Inter-frame

space

Idle

Inter-byte

space

Response

space

Break

eld

Break delimiter

>=1 bit

(recommend 2 bits)

Sync eld

FIGURE 45.7 LIN.message.frame.

LIN-Bus 45-7

times,.followed.by.a.so-called.delimiter.that.must.be.at.least.1.bit.time.long.(2.bits.are.recommended)..

 e.slav

.recog

nize

.this.break.aer.11.bit.time

. is.recog

nition

.can.be.carr

ied

.out.with.the.break.

dete

ction

.featu

.of.a.stand

ard

.SCI.. e.mast

.gener

ates

.a.break.sign

.that.is.abou

.two.bit.time

.lon-

.to.ensu

.a.safe.sync

hronization

.to.the.mast

.clock

.for.slav

.with

out

.a.crys

tal.

45.5.2 Sync Byte Field

 e.sync.byte.eld.follows.the.break.eld.and.supports.the.baud.rate.estimation.. e.master.sends.a.

0x55.data.byte.on.whic

.the.slav

.sync

hronize

.them

selves.

. e.slav

.meas

ure

.the.time.peri

.betw

een

the.fall

ing

.edge.of.the.star

.bit.and.thos

.of.the.seve

nth

.data.bit.. e.valu

.is.divi

ded

.by.8,.for.exam

ple,

by.simpl

.shi

ing

.the.meas

ured

.valu

.thre

.bits.to.the.righ

.Only.the.fall

ing

.edge

.are.allo

wed

.to.be.

used.for.the.meas

urement

.of.the.baud.rate.beca

use

.they.are.consi

derably

.stee

per

.than.risin

.ones.and.

ther

efore

.prov

ide

.more.exac

.resu

lts.

. e.die

rent

.edge.stee

pness

.is.due.to.the.char

acteristics

.of.the.

physi

cal

.laye

.as.the.bus.leve

.is.acti

vely

.draw

.to.“zer

o”

.leve

.by.a.tran

sistor,

.whil

.the.“one

”

.leve

.is.

rais

.by.a.pul

l-up

.resi

stor.

When

.the.baud.rate.is.adju

sted

.on.a.stan

dard

.SCI.devi

ce,

.it.must.be.ensu

red

.that.it.does.not.devi

ate

by.mor

.tha

.the.all

owed

.2%.fro

.the.mas

ter

.clo

ck.

45.5.3 Identier

LIN.uses.a.message.ID.in.the.third.and.nal.byte.of.the.header.. is.byte.consists.of.6.bits.for.the.ID.and.

two.par

ity

.bit

.and.thu

.it.is.desi

gnated

.as.the.PID

. e.64.pos

sible

.IDs.are.sho

.in.Tab

.45.

.unti

.versi

.1.3.of.the.LIN.spec

ication,

.bits.four.and.ve.of.the.ID.had.a.spec

ial

.mean

ing.

.When.

the.IDs.0–59.were.used.for.the.tran

smission

.of.signa

ls,

.bit.four.and.ve.den

.the.numbe

.of.data.

byte

.as.see

.in.Tab

.45.

. is.tab

.doe

.not.exi

.for.LIN.ver

sion

.2.0.and.lat

er.

.impl

icit

.codi

.of.the.data.leng

.in.the.iden

tier

.is.no.long

.obli

gatory

.since.LIN.versi

.1.2..

Now.a.eld.leng

.of.one.to.eigh

.data.byte

.is.possi

ble

.for.ever

.ID.. e.eld.leng

.must.be.indi

cated

at.the.mes

sage

.de

nition

.in.the.sec

tion

.“Fr

ames”

.of.the.LDF

TABLE 45.1 Partitioning.of.the.Range.ofValues.

ofthe.“Prot

ected

.Ide

ntiers”

Identier Meaning

0x0–0x3B

.(0–59) Tra

nsmission

.of.signa

0x3C

.(60) Ma

ster

.req

uest

.fram

.(MRF).for.the.

conguratio

.and.diag

nostics

0x3D

.(61) Sl

ave

.resp

onse

.fram

.(SRF).to.ID.0x3C

0x3E/0x3F

62/63

Reser

ved

.for.fut

ure

.expan

sions

.of.the.

prot

ocol

TABLE 45.2 Meaning.of.Bit.4.and.5.of.

the.Ide

ntiers

.(Ma

ndatory

.unt

Vers

ion1.2;

.Opt

ional

.fro

.Ver

sion

.1.3

;

Inva

lid

.fro

.Ver

sion

.2.0

)

ID5 ID4 Number.of.Data.Bytes

0 0 2

0 1 2

1 0 4

1 1 8