Automotive Engineering Section, UniKLMFI - Autotronic 2 · Codage de la vitesse Engine speed sensor...
Transcript of Automotive Engineering Section, UniKLMFI - Autotronic 2 · Codage de la vitesse Engine speed sensor...
Why do we use multiplexing on cars ?
Automotive Engineering Section, UniKLMFI - Autotronic 2
(multiplexing)
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
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1960 1985 1995
NOMBRE D’INTERCONNEXIONS
1960 1985 1995
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METRES (longueur de cablage)
Automotive Engineering Section, UniKLMFI - Autotronic 2 (multiplexing)
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)
• 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)
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)
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)
THE BINARY NOTATION
DATA are converted in a series of BITS called « A FRAME » on the
BUS.
Automotive Engineering Section, UniKLMFI - Autotronic 2 (multiplexing)
The serial transmission
01001011
FRAME
Station B
BYTE to
transmit:
01001011
Station A
On cars, the FRAME is transmitted in SERIAL MODE
on the BUS.
Automotive Engineering Section, UniKLMFI - Autotronic 2 (multiplexing)
Station A Station DStation CStation 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)
- 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
opposite 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)
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)
BUS
ECU
Inputs
outputs
ECU
of 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)
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)
- 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)
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 eofack
THE FRAME
Automotive Engineering Section, UniKLMFI - Autotronic 2 (multiplexing)
- 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
of the following field ( data).
Permits to synchronize
The ECU clocks.
Automotive Engineering Section, UniKLMFI - Autotronic 2 (multiplexing)
-The frame.
SOF IDENT. COM. DATA CTRL ACK. EOF
The transmitter waits in this field for the response
of the receptor ( to know if the frame has been
correctly received).
Indicates the end
of the frame.
Permits the receptor to
check if the frame has
been received completely.
Automotive Engineering Section, UniKLMFI - Autotronic 2 (multiplexing)
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)
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)
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)
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)
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
7800ESP
1320Injection ECU
- EXCHANGE OF DATA ON THE SAME BUS.
Automotive Engineering Section, UniKLMFI - Autotronic 2 (multiplexing)
BUS CAN
I/S
ABS wheel sensor
7000
70050100 1111 0101 0011
1010 1100 0100 1010
Codage de la vitesse
Engine speed sensor
1010 1100 0100 1010
Engine speed
encoding
INTERFACE
INTERFACE
1313
7800ESP
1320Injection ECU
Automotive Engineering Section, UniKLMFI - Autotronic 2 (multiplexing)
BUS CAN
I/S
ABS wheel sensor
7000
70050100 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
7800ESP
1320injection ECU - DATA is shared.
Automotive Engineering Section, UniKLMFI - Autotronic 2 (multiplexing)
INTERFACE
1010 1100 0100 1010
BUS CAN
I/S
1630BVA
ABS wheel sensor
7000
70050100 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
7800ESP
1320Injection ECU
Automotive Engineering Section, UniKLMFI - Autotronic 2 (multiplexing)
INTERFACE
1010 1100 0100 1010
BUS CAN
I/S
1630
automatic
gear box
ABS wheel sensor
7000
70050100 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
7800ESP
1320injection ECU
INTERFACE
0100 1111 0101 0011
1010 1100 0100 1010
BSI
Automotive Engineering Section, UniKLMFI - Autotronic 2 (multiplexing)
INTERFACE
1010 1100 0100 1010
BUS CAN
I/S
1630Automatic gear
box
ABS wheel sensor
7000
70050100 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
7800ESP
1320Engine ECU
INTERFACE
0100 1111 0101 0011
1010 1100 0100 1010
BSI
0004Instrument
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)
0004Instrument
panel
INTERFACE
0100 1111 0101 0011
1010 1100 0100 1010
INTERFACE
BUS VAN COMFORT
ABS wheel sensor
7000
70050100 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
7800ESP
1630automatic gear
box
BSI1320Injection ECU
BUS CAN
I/S
BUS VAN
BODY
INTERFACE
0100 1111 0101 0011
1010 1100 0100 1010INTERFACE
Automotive Engineering Section, UniKLMFI - Autotronic 2 (multiplexing)
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 …
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)
- 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)
VAN very well adapted to car environment.
ME
E
E
E
MM
M M
Maximum 16 ECU on the same bus.
Automotive Engineering Section, UniKLMFI - Autotronic 2 (multiplexing)
Architecture CAN / VAN (C8)1
+ VAN
Automotive Engineering Section, UniKLMFI - Autotronic 2 (multiplexing)
- Supply of the stations (C8) (+VAN).
Automotive Engineering Section, UniKLMFI - Autotronic 2 (multiplexing)
- Electric signals on the bus VAN
2 wires on the bus called DATA and DATA/.
5 V4.5 V max
2.8 V
0.5 V mint
DATA
DATA /
DATA : 1 10t
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)
- Advantages of the differential reading :
- The data is not modified by electromagnetic perturbations
5 V4.5 V max
2.8 V
0.5 V mint
DATA
DATA /
Udiff
Automotive Engineering Section, UniKLMFI - Autotronic 2 (multiplexing)
- 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)
- 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)
THE CAN
High Speed ( Inter/Systems)
NETWORK
Automotive Engineering Section, UniKLMFI - Autotronic 2 (multiplexing)
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)
- 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)
-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 10t
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)
- - 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)
- 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)
- 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)
- 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)
Two possibilities to connect ECU on the CAN bus.
7600 7800
Daisy Chain ( serial)parallel
Automotive Engineering Section, UniKLMFI - Autotronic 2 (multiplexing)
- 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)
THE « FULL CAN »
ARCHITECTURE
Automotive Engineering Section, UniKLMFI - Autotronic 2 (multiplexing)
1 network
CAN HS I/S
2 networks
CAN LS.
-Example C4
Automotive Engineering Section, UniKLMFI - Autotronic 2 (multiplexing)
THE CAN
Low Speed
(Fault Tolerant)
NETWORKAutomotive Engineering Section, UniKLMFI - Autotronic 2 (multiplexing)
- Electric signals on the bus CAN LS.
5 V4.8 V min
3.6 V max
2.5 V
1.4 V max
0.2 V maxt
DATA: 1 10t
CAN L
CAN H
Automotive Engineering Section, UniKLMFI - Autotronic 2 (multiplexing)
- 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)
- 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)
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 slaveQuestion 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)
- THE FRAME STRUCTURE.
DataSOF CTRLSynchro 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)
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)
Front Windscreen-wipers C4 picasso
Automotive Engineering Section, UniKLMFI - Autotronic 2 (multiplexing)
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)
- 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)
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)