Why do we use multiplexing on cars ? EVOLUTION DU CABLAGE METRES - - PowerPoint PPT Presentation

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Why do we use multiplexing on cars ? EVOLUTION DU CABLAGE METRES - - PowerPoint PPT Presentation

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Automotive Engineering Section, UniKLMFI - Autotronic 2 (multiplexing) Why do we use multiplexing on cars ? EVOLUTION DU CABLAGE METRES (longueur de cablage) NOMBRE DINTERCONNEXIONS 2000 1800 1800 1600 1600 1400 1400 1200 1200 1000

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SLIDE 1

Why do we use multiplexing on cars ?

Automotive Engineering Section, UniKLMFI - Autotronic 2 (multiplexing)

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SLIDE 2

After 1995, the target for car builders was to reduce the size of harness.

MCN001

LA DIMINUTION DU VOLUME DU CABLAGE : ENJEU MAJEUR 95 -2000

EVOLUTION DU CABLAGE

1960 1985 1995 200 400 600 800 1000 1200 1400 1600 1800 1960 1985 1995

NOMBRE D’INTERCONNEXIONS

1960 1985 1995 200 400 600 800 1000 1200 1400 1600 1800 2000 1960 1985 1995

METRES (longueur de cablage)

Automotive Engineering Section, UniKLMFI - Autotronic 2 (multiplexing)

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SLIDE 3

One way of communication ( the bus) is shared between several users ( the stations). In concrete terms :  More simple harness.

  • réduce the cost,
  • réduce the volume of the harness,
  • réduce the number of connectors.

 Possibility to exchange data between all the ECU in the car.

  • increase driving pleasure,
  • reduce the number of sensors.

Définition :

Automotive Engineering Section, UniKLMFI - Autotronic 2 (multiplexing)

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SLIDE 4
  • The data exchange between all the stations in the car are

sent on the bus in « numeric form ». What is MULTIPLEXING ?

Station A Station C Station B

Automotive Engineering Section, UniKLMFI - Autotronic 2 (multiplexing)

slide-5
SLIDE 5

Data gives information coded in binary system, that means with 0 or 1 . 0 or 1 is called « a bit ». A group of 8 bits is called « a BYTE ». It is possible to translate decimal numbers in binary code. example : 8 => 00001000. THE BINARY NOTATION

Automotive Engineering Section, UniKLMFI - Autotronic 2 (multiplexing)

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SLIDE 6

For example : O or 1 are corresponding to a certain level of voltage on a wire.

1 Bit 1 Bit 1 Bit 1 Bit 1 Bit 1 Bit 1 Bit 1 Bit 1 Bit 1 Bit

« 01010110 » : 8 Bits = 1 BYTE

« 0 » « 1 » « 0 » « 1 » « 0 » « 1 » « 1 » « 0 » « 0 » « 1 »

THE BINARY NOTATION

Automotive Engineering Section, UniKLMFI - Autotronic 2 (multiplexing)

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SLIDE 7

THE BINARY NOTATION

DATA are converted in a series of BITS called « A FRAME » on the BUS.

Automotive Engineering Section, UniKLMFI - Autotronic 2 (multiplexing)

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SLIDE 8

The serial transmission

01001011 FRAME

Station B

BYTE to transmit: 01001011

Station A

On cars, the FRAME is transmitted in SERIAL MODE

  • n the BUS.

Automotive Engineering Section, UniKLMFI - Autotronic 2 (multiplexing)

slide-9
SLIDE 9

Station A Station D Station C Station B Station E

The BUS

The role of the bus is to allow the exchange of data between all the stations ( ECU in the car) Like that, the bus links all the ECU together.

  • THE BUS

Automotive Engineering Section, UniKLMFI - Autotronic 2 (multiplexing)

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SLIDE 10
  • The wired bus.

 The bus is composed of 2 isolated copper wires ( small section ( 0,6mm²).  For safety, the frame is driven by one wire and the

  • pposite of the frame is

driven by the other wire. The 2 wires of the bus are twisted ( to avoid electromagnetic problems)

Automotive Engineering Section, UniKLMFI - Autotronic 2 (multiplexing)

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SLIDE 11

For some applications, the bus is composed of :

 One wire only ( economic solution).  Optical fiber ( high speed of transfer).  Radio signal ( easy to fit)

Automotive Engineering Section, UniKLMFI - Autotronic 2 (multiplexing)

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SLIDE 12

BUS ECU

Inputs

  • utputs

ECU

  • f the

system Multiplexing interface

Translator

  • The multiplexing interface in each ECU connected to

the bus :

Sender

Reads information Send orders Translates information from ECU to multiplexing language Emits or receive the frames.

Automotive Engineering Section, UniKLMFI - Autotronic 2 (multiplexing)

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SLIDE 13

The frames are sent one by one on the bus. The space between two frames is called « INTER FRAME SPACE »

Automotive Engineering Section, UniKLMFI - Autotronic 2 (multiplexing)

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SLIDE 14
  • THE FRAME STRUCTURE
  • The frame structure is defined by the communication procedure.

DATA DATA

01101100 00101100 01001100 01101110 11101100

The frame is composed with several parts called « FIELDS »

40 bits = 5 bytes

Automotive Engineering Section, UniKLMFI - Autotronic 2 (multiplexing)

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SLIDE 15

SOF

: start of frame (envelope)

IDENT

: identification (12 bits) (address)

Com.

: command field (4 bits) (recorded delivery

DATA : information field

(letter)

Control

: control field (15 bits) (signing)

Ack

: acknowledgement (recorded delivery response)

EOF

: end of frame

Station A Station B Station C A1, A2,A3,A4;B1,B2,B3;C1,C2

Example of frame language ( with 7 fields) on the bus

sof Ident. Com. data control eof ack

THE FRAME

Automotive Engineering Section, UniKLMFI - Autotronic 2 (multiplexing)

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SLIDE 16
  • The Frame.

SOF IDENT. COM. DATA CTRL ACK. EOF

Permits to fix the priority level and to identify the sender of the frame. Permits to inform the stations connected to the bus on the length

  • f the following field ( data).

Permits to synchronize The ECU clocks.

Automotive Engineering Section, UniKLMFI - Autotronic 2 (multiplexing)

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SLIDE 17
  • The frame.

SOF IDENT. COM. DATA CTRL ACK. EOF

The transmitter waits in this field for the response

  • f the receptor ( to know if the frame has been

correctly received). Indicates the end

  • f the frame.

Permits the receptor to check if the frame has been received completely.

Automotive Engineering Section, UniKLMFI - Autotronic 2 (multiplexing)

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SLIDE 18

SOF 0001 0001 1111 Com. DATA station A CTRL Ack. EOF SOF 0001 0000 0101 Com. DATA station B CTRL Ack. EOF SOF 0001 0000 0000 Com. DATA station C CTRL Ack. EOF

station C station B station A

The bus can accept only one frame at a same time. So each frame is given by a priority level to avoid « bugs » 0 is DOMINANT 1 is RECESSIVE SOF Com. DATA station C CTRL Ack. EOF

On the Bus

0001 0000

  • THE PRIORITY LEVEL

Automotive Engineering Section, UniKLMFI - Autotronic 2 (multiplexing)

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SLIDE 19

Début 0001 0001 1111

  • Com. Informations de A Contrôle Ack.

Fin SOF 0001 0000 0101 Com. DATA station B CTRL Ack. EOF SOF 0001 0000 0000 Com. DATA station C CTRL Ack. EOF

Station C Station B Station A

SOF Com. DATA station C CTRL Ack. EOF

On the Bus

0001 0000 00

  • priority level.

Automotive Engineering Section, UniKLMFI - Autotronic 2 (multiplexing)

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SLIDE 20

Début 0001 0001 1111

  • Com. Informations de A Contrôle Ack.

Fin Début 0001 0000 0101

  • Com. Informations de B Contrôle Ack.

Fin Début 0001 0000 0000 Com. DATA station C CTRL Ack. EOF

Station C Station B station A

Début Com. DATA station C CTRL Ack. EOF

Station C has the highest priority level on the bus

0001 0000 0000

  • priority level

Automotive Engineering Section, UniKLMFI - Autotronic 2 (multiplexing)

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SLIDE 21

A car is fitted with several different buses.

(ECU with the same level of performance are grouped on the same bus).  More performant.  More reliable.

Automotive Engineering Section, UniKLMFI - Autotronic 2 (multiplexing)

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SLIDE 22

BUS CAN I/S

ABS wheel sensor

7000 7005

(x tops par tour) 1010 1100 0100 1010

Engine speed sensor

1010 1100 0100 1010

Engine speed encoding

INTERFACE INTERFACE

1313 7800

ESP

1320

Injection ECU

  • EXCHANGE OF DATA ON THE SAME BUS.

Automotive Engineering Section, UniKLMFI - Autotronic 2 (multiplexing)

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SLIDE 23

BUS CAN I/S

ABS wheel sensor

7000 7005

0100 1111 0101 0011 1010 1100 0100 1010 Codage de la vitesse

Engine speed sensor

1010 1100 0100 1010

Engine speed encoding

INTERFACE INTERFACE

1313 7800

ESP

1320

Injection ECU

Automotive Engineering Section, UniKLMFI - Autotronic 2 (multiplexing)

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SLIDE 24

BUS CAN I/S

ABS wheel sensor

7000 7005

0100 1111 0101 0011 1010 1100 0100 1010 Codage de la vitesse

Engine speed sensor

0100 1111 0101 0011 1010 1100 0100 1010

Engine speed encoding

INTERFACE INTERFACE

1313 7800

ESP

1320

injection ECU

  • DATA is shared.

Automotive Engineering Section, UniKLMFI - Autotronic 2 (multiplexing)

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SLIDE 25

INTERFACE 1010 1100 0100 1010

BUS CAN I/S

1630

BVA

ABS wheel sensor

7000 7005

0100 1111 0101 0011 1010 1100 0100 1010 Codage de la vitesse

Engine speed sensor

0100 1111 0101 0011 1010 1100 0100 1010

Engine speed encoding

INTERFACE INTERFACE

1313 7800

ESP

1320

Injection ECU

Automotive Engineering Section, UniKLMFI - Autotronic 2 (multiplexing)

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SLIDE 26

INTERFACE 1010 1100 0100 1010

BUS CAN I/S

1630 automatic gear box

ABS wheel sensor

7000 7005

0100 1111 0101 0011 1010 1100 0100 1010 Codage de la vitesse

Engine speed sensor

0100 1111 0101 0011 1010 1100 0100 1010

Engine speed encoding

INTERFACE INTERFACE

1313 7800

ESP

1320

injection ECU

INTERFACE

0100 1111 0101 0011 1010 1100 0100 1010

BSI

Automotive Engineering Section, UniKLMFI - Autotronic 2 (multiplexing)

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SLIDE 27

INTERFACE 1010 1100 0100 1010

BUS CAN I/S

1630

Automatic gear box

ABS wheel sensor

7000 7005

0100 1111 0101 0011 1010 1100 0100 1010 Codage de la vitesse

Engine speed sensor

0100 1111 0101 0011 1010 1100 0100 1010

Engine speed encoding

INTERFACE INTERFACE

1313 7800

ESP

1320

Engine ECU

INTERFACE

0100 1111 0101 0011 1010 1100 0100 1010

BSI 0004

Instrument panel

INTERFACE 0100 1111 0101 0011 1010 1100 0100 1010

BUS VAN COMFORT

INTERFACE

  • EXCHANGE OF DATA ON TWO DIFFERENT BUSES.

(BSI is a bridge between the buses)

Automotive Engineering Section, UniKLMFI - Autotronic 2 (multiplexing)

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SLIDE 28

0004

Instrument panel

INTERFACE 0100 1111 0101 0011 1010 1100 0100 1010 INTERFACE

BUS VAN COMFORT

ABS wheel sensor

7000 7005

0100 1111 0101 0011 1010 1100 0100 1010 Codage de la vitesse

Engine speed sensor

0100 1111 0101 0011 1010 1100 0100 1010

Engine speed encoding

INTERFACE INTERFACE INTERFACE INTERFACE

0100 1111 0101 0011

1010 1100 0100 1010

1010 1100 0100 1010

1313 7800

ESP

1630

automatic gear box

BSI 1320

Injection ECU

BUS CAN I/S BUS VAN BODY

INTERFACE 0100 1111 0101 0011 1010 1100 0100 1010 INTERFACE

Automotive Engineering Section, UniKLMFI - Autotronic 2 (multiplexing)

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SLIDE 29

B.S.I

Automotive Engineering Section, UniKLMFI - Autotronic 2 (multiplexing)

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SLIDE 30

MAIN NETWORKS USED ON CITROËN CARS

CODE NAME CAR MODELS VAN Vehicle Area Network Xsara, xsara picasso, C3, C2,C5… CAN HS (I/S) Control Area Network High Speed ( Inter / Systems) Xsara, xsara picasso, C3, C2,C5… CAN LS (FT) Control Area Network Low Speed ( Fault Tolerant) C3 II,C4,C4 picasso,C5 II, C6 … LIN Local Interconnect Network C3 II,C4,C4 picasso,C5 II, C6 …

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SLIDE 31

THE VAN NETWORK

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SLIDE 32

VAN (Vehicle Area Network).

  • Historical.
  • 1985/86 Born of VAN,
  • 1994 Test one model of car (XM),
  • (…) Mass production
  • 2004 End of production

Automotive Engineering Section, UniKLMFI - Autotronic 2 (multiplexing)

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SLIDE 33
  • Example of architecture VAN CAN, (C3)

ECM BVA Combiné Climatisation Changeur de CD Calculateur de navigation Afficheur multifonctions Autoradio

Calculateur d’additivation

carburant Capteur angle volant ESP ABS Platines de portes AVG et AVD Calculateur Air- bag BSM COM 2000 Boîtier Alarme anti- effraction

Automotive Engineering Section, UniKLMFI - Autotronic 2 (multiplexing)

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SLIDE 34

VAN very well adapted to car environment. M E E E E M M M M

Maximum 16 ECU on the same bus.

Automotive Engineering Section, UniKLMFI - Autotronic 2 (multiplexing)

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SLIDE 35

Architecture CAN / VAN (C8) 1

+ VAN

Automotive Engineering Section, UniKLMFI - Autotronic 2 (multiplexing)

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SLIDE 36
  • Synoptic diagram (C8)

Automotive Engineering Section, UniKLMFI - Autotronic 2 (multiplexing)

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SLIDE 37
  • Supply of the stations (C8) (+VAN).

Automotive Engineering Section, UniKLMFI - Autotronic 2 (multiplexing)

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SLIDE 38
  • Electric signals on the bus VAN

2 wires on the bus called DATA and DATA/.

5 V 4.5 V max 2.8 V 0.5 V min

t

DATA DATA /

DATA : 1 1 t

Udiff

Udiff = V DATA – V DATA/ if Udiff > 0 the bit is 1 ( recessive) if Udiff < 0 the bit is 0 ( dominant)

Automotive Engineering Section, UniKLMFI - Autotronic 2 (multiplexing)

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SLIDE 39
  • Advantages of the differential reading :
  • The data is not modified by electromagnetic perturbations

5 V 4.5 V max 2.8 V 0.5 V min

t

DATA DATA /

Udiff

Automotive Engineering Section, UniKLMFI - Autotronic 2 (multiplexing)

slide-40
SLIDE 40
  • FAULT TOLERANCE:

Short circuit to earth Short circuit to + supply Wire cut

 With these faults, the VAN still works ( in downgraded mode).

Automotive Engineering Section, UniKLMFI - Autotronic 2 (multiplexing)

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SLIDE 41
  • Characteristics of the VAN NETWORK :

 Transfer speed : 250 KTs (Kilo time slot / second) maximum

  • 125 KTs for VAN Comfort,
  • 62.5 KTs for VAN Body.

 Length of the data field 28 Bytes maximum.  Maximum 16 ECU on the same bus.  Downgraded mode possible.  Very well adapted for car applications.

Automotive Engineering Section, UniKLMFI - Autotronic 2 (multiplexing)

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SLIDE 42

THE CAN High Speed ( Inter/Systems) NETWORK

Automotive Engineering Section, UniKLMFI - Autotronic 2 (multiplexing)

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SLIDE 43

CAN (Controller Area Network).

  • Historical.
  • 1980 : Born of CAN.
  • 1992 : First vehicle fitted with CAN network
  • 1993 : CAN High-Speed is standardized

(transfert speed 1 Mbit/s)

  • 2000 : CAN Low-Speed Fault Tolerant is

standardized (transfert speed 125 Kbits/s)

  • 2004 : CAN Low-Speed Fault Tolerant replace the

VAN network on CITROËN cars.

Automotive Engineering Section, UniKLMFI - Autotronic 2 (multiplexing)

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SLIDE 44
  • Since 2004 all CITROËN carshave been FULL CAN
  • The transfert speed of the VAN NETWORK was not

enough for high performance ECU.

  • CAN became a standard for all car builders.
  • CAN LS (FR) has the same qualities than the VAN.

Automotive Engineering Section, UniKLMFI - Autotronic 2 (multiplexing)

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SLIDE 45
  • Electric signals on the bus CAN.

2 wires on the bus called CAN High and CAN Low.

5 V 3.5 V max 2.5 V 1.5 V min

t CAN H CAN L

DATA : 1 1 t

Udiff

Udiff = V CAN H – V CAN L if Udiff ≥ 2 the bit is 0 ( dominant) if Udiff = 0 the bit is 1 (recessive)

Automotive Engineering Section, UniKLMFI - Autotronic 2 (multiplexing)

slide-46
SLIDE 46
  • - Advantages of the differential reading :
  • The data is not affected by electromagnetic perturbations

5 V 3.5 V max 2.5 V 1.5 V min

t CAN H CAN L Udiff

Automotive Engineering Section, UniKLMFI - Autotronic 2 (multiplexing)

slide-47
SLIDE 47
  • FAULT TOLERANCE:

With these faults, the CAN cannot work. (no downgraded mode)

Short circuit to earth

CAN H CAN L

Short circuit to + supply

CAN H CAN L

Wire cut

CAN L CAN H

Short circuit in the bus

CAN H CAN L

Automotive Engineering Section, UniKLMFI - Autotronic 2 (multiplexing)

slide-48
SLIDE 48
  • Architecture of the bus CAN.

40 m maxi 10 cm mini

1320 BSI 1630 7800 7715

  • Maximum 8 ECU on the same BUS,
  • 2 resistances at each end of the bus.

Automotive Engineering Section, UniKLMFI - Autotronic 2 (multiplexing)

slide-49
SLIDE 49
  • Network Architecture.

The resistances are located in the BSI and in the injection ECU on CITROËN cars.

BSI 1320

T T

Automotive Engineering Section, UniKLMFI - Autotronic 2 (multiplexing)

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SLIDE 50

Two possibilities to connect ECU on the CAN bus. 7600 7800 Daisy Chain ( serial) parallel

Automotive Engineering Section, UniKLMFI - Autotronic 2 (multiplexing)

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SLIDE 51
  • Characteristics of the CAN High Speed (Inter

System) NETWORK:  2 resistances at the end of the bus.  Transfer speed :  1 MBit/s (Mega Bit / second) maxi  250 Kbits/s for CITROËN cars (Full MUX)  Length of the data field 8 Bytes maximum.  Maximum 8 ECU on the same bus. The bus can not « wake up » the ECUs with a frame. No downgraded mode.

Automotive Engineering Section, UniKLMFI - Autotronic 2 (multiplexing)

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SLIDE 52

THE « FULL CAN » ARCHITECTURE

Automotive Engineering Section, UniKLMFI - Autotronic 2 (multiplexing)

slide-53
SLIDE 53

1 network CAN HS I/S 2 networks CAN LS.

  • Example C4

Automotive Engineering Section, UniKLMFI - Autotronic 2 (multiplexing)

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SLIDE 54

2 Example new C5

Automotive Engineering Section, UniKLMFI - Autotronic 2 (multiplexing)

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SLIDE 55

THE CAN Low Speed (Fault Tolerant) NETWORK

Automotive Engineering Section, UniKLMFI - Autotronic 2 (multiplexing)

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SLIDE 56
  • Electric signals on the bus CAN LS.

5 V 4.8 V min 3.6 V max 2.5 V 1.4 V max 0.2 V max

t

DATA: 1 1 t CAN L CAN H

Automotive Engineering Section, UniKLMFI - Autotronic 2 (multiplexing)

slide-57
SLIDE 57
  • FAULT TOLERANCE:

With these faults, the CAN LS still works ( downgraded mode)

Short circuit to earth

CAN H CAN L

Short circuit to + supply

CAN H CAN L

Wire cut

CAN L CAN H

Short circuit in the bus

CAN H CAN L

Automotive Engineering Section, UniKLMFI - Autotronic 2 (multiplexing)

slide-58
SLIDE 58
  • Characteristics of the CAN LS NETWORK :

 No resistance at the end of the bus.  Maximum 20 ECU on the same bus.  Downgraded mode possible.  Transfer speed, 125 Kbits/s.  The bus CAN LS can wake up the ECUs with a

frame.

Automotive Engineering Section, UniKLMFI - Autotronic 2 (multiplexing)

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SLIDE 59

THE LIN NETWORK

Automotive Engineering Section, UniKLMFI - Autotronic 2 (multiplexing)

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SLIDE 60

Characteristics of the LIN NETWORK:

  • The bus is made of only 1 wire.
  • Maximum 17 ECU on the same bus.

1 Master, 16 slaves

Response of the slave Question of the master

  • The response is in the same frame than the question.

5025 5030 PSF1

1 wire for the bus

Automotive Engineering Section, UniKLMFI - Autotronic 2 (multiplexing)

slide-61
SLIDE 61
  • THE FRAME STRUCTURE.

Data SOF CTRL Synchro Identification

Sent by the master Sent by the slave 9 dominant bits(0) 10 bits 1010101010 8 bits 8 octets 8 bits

Automotive Engineering Section, UniKLMFI - Autotronic 2 (multiplexing)

slide-62
SLIDE 62

The LIN FRAME

Automotive Engineering Section, UniKLMFI - Autotronic 2 (multiplexing)

slide-63
SLIDE 63

BSI BSM master wiper (slave 1) CAN LS/Car LIN wiper (slave 2)

+ CAN + LIN

Example of LIN network

Automotive Engineering Section, UniKLMFI - Autotronic 2 (multiplexing)

slide-64
SLIDE 64

Front Windscreen-wipers C4 picasso

Automotive Engineering Section, UniKLMFI - Autotronic 2 (multiplexing)

slide-65
SLIDE 65

CAN I/S LIN

UC

Brakes CMM BSI (master)

Tank tap sensor + fuel gauge Interface MUX Pump (slave) Pump

additive

sensor pump

C4 HDI FULL CAN

Example of LIN network

Automotive Engineering Section, UniKLMFI - Autotronic 2 (multiplexing)

slide-66
SLIDE 66
  • Characteristics of the LIN NETWORK :

 No Downgraded mode possible.  LIN network is used for many functions ( directionnal

head lamps, alternator remote control, …)

 Transfert speed, 19,2 Kbits/s.

Automotive Engineering Section, UniKLMFI - Autotronic 2 (multiplexing)

slide-67
SLIDE 67

LEXICAL

Automotive Engineering Section, UniKLMFI - Autotronic 2 (multiplexing)

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SLIDE 68

Glossary.

VAN : Vehicle Area Network. CAN : Controler Area Network. LIN : Local Interconnect Network. MOST : Media Oriented Systems Transport. Bit : elementary Information in the binary language (1 or 0). BYTE : Group of 8 bits. Récessive : Bit = 1. Dominant : Bit = 0 Frame : Information composed with a package of fields. Transfer speed : number of bits transmitted in one second(Kb/s or Kts/s).

Automotive Engineering Section, UniKLMFI - Autotronic 2 (multiplexing)