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

Automotive Engineering Section, UniKLMFI - Autotronic 2 (multiplexing) Why do we use multiplexing on cars ?

EVOLUTION DU CABLAGE METRES (longueur de cablage) NOMBRE D’INTERCONNEXIONS 2000 1800 1800 1600 1600 1400 1400 1200 1200 1000 1000 800 800 600 600 400 400 200 200 0 0 1960 1960 1985 1985 1995 1995 1960 1960 1985 1985 1995 1995 LA DIMINUTION DU VOLUME DU CABLAGE : ENJEU MAJEUR 95 -2000 MCN001 After 1995, the target for car builders was to reduce the size of harness. Automotive Engineering Section, UniKLMFI - Autotronic 2 (multiplexing)

Définition : 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. Automotive Engineering Section, UniKLMFI - Autotronic 2 (multiplexing)

What is MULTIPLEXING ? Station A Station C Station B • The data exchange between all the stations in the car are sent on the bus in « numeric form ». Automotive Engineering Section, UniKLMFI - Autotronic 2 (multiplexing)

THE BINARY NOTATION 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. Automotive Engineering Section, UniKLMFI - Autotronic 2 (multiplexing)

THE BINARY NOTATION For example : O or 1 are corresponding to a certain level of voltage on a wire. « 01010110 » : 8 Bits = 1 BYTE 1 Bit 1 Bit 1 Bit 1 Bit 1 Bit 1 Bit 1 Bit 1 Bit 1 Bit 1 Bit « 0 » « 1 » « 0 » « 1 » « 0 » « 1 » « 1 » « 0 » « 0 » « 1 » 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)

On cars, the FRAME is transmitted in SERIAL MODE on the BUS. The serial transmission Station A Station B FRAME BYTE to 01001011 transmit: 01001011 Automotive Engineering Section, UniKLMFI - Autotronic 2 (multiplexing)

- THE BUS Station A Station B Station C Station D 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. 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)

- The multiplexing interface in each ECU connected to the bus : ECU Multiplexing interface Inputs ECU BUS of the Translator Sender system outputs Reads information Translates information from Send orders 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 40 bits = 5 bytes The frame is composed with several parts called « FIELDS » Automotive Engineering Section, UniKLMFI - Autotronic 2 (multiplexing)

THE FRAME Station C Station A Station B A1, A2,A3,A4;B1,B2,B3;C1,C2 Example of frame language ( with 7 fields) on the bus sof Ident. Com. data control ack eof 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 Automotive Engineering Section, UniKLMFI - Autotronic 2 (multiplexing)

- The Frame. SOF IDENT. COM. DATA CTRL ACK. EOF Permits to inform the stations connected to the bus on the length of the following field ( data). Permits to synchronize The ECU clocks. Permits to fix the priority level and to identify the sender of the frame. Automotive Engineering Section, UniKLMFI - Autotronic 2 (multiplexing)

-The frame. SOF IDENT. COM. DATA CTRL ACK. EOF Permits the receptor to check if the frame has been received completely. 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. Automotive Engineering Section, UniKLMFI - Autotronic 2 (multiplexing)

- THE PRIORITY LEVEL 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 0001 0001 1111 Com. DATA station A CTRL Ack. EOF station A SOF 0001 0000 0101 Com. DATA station B CTRL Ack. EOF station B SOF 0001 0000 0000 Com. DATA station C CTRL Ack. EOF station C SOF Com. DATA station C CTRL Ack. EOF 0001 0000 On the Bus Automotive Engineering Section, UniKLMFI - Autotronic 2 (multiplexing)

- priority level. Début 0001 0001 1111 Com. Informations de A Contrôle Ack. Fin Station A SOF 0001 0000 0101 Com. DATA station B CTRL Ack. EOF Station B SOF 0001 0000 0000 Com. DATA station C CTRL Ack. EOF Station C SOF Com. DATA station C CTRL Ack. EOF 0001 0000 00 On the Bus Automotive Engineering Section, UniKLMFI - Autotronic 2 (multiplexing)

- priority level Début 0001 0001 1111 Com. Informations de A Contrôle Ack. Fin station A Début 0001 0000 0101 Com. Informations de B Contrôle Ack. Fin Station B Début 0001 0000 0000 Com. DATA station C CTRL Ack. EOF Station C Début Com. DATA station C CTRL Ack. EOF 0001 0000 0000 Station C has the highest priority level on the bus 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)

- EXCHANGE OF DATA ON THE SAME BUS. 1320 Injection ECU 1313 Engine speed encoding 1010 1100 0100 1010 Engine speed sensor INTERFACE BUS CAN I/S 7000 INTERFACE 7005 (x tops par tour) 1010 1100 0100 1010 ABS wheel sensor 7800 ESP Automotive Engineering Section, UniKLMFI - Autotronic 2 (multiplexing)

1320 Injection ECU 1313 Engine speed encoding 1010 1100 0100 1010 Engine speed sensor INTERFACE BUS CAN I/S 7000 INTERFACE 7005 0100 1111 0101 0011 Codage de la vitesse 1010 1100 0100 1010 ABS wheel sensor 7800 ESP Automotive Engineering Section, UniKLMFI - Autotronic 2 (multiplexing)

1320 - DATA is shared. injection ECU 1313 Engine speed encoding 1010 1100 0100 1010 0100 1111 0101 0011 Engine speed sensor INTERFACE BUS CAN I/S 7000 INTERFACE 7005 0100 1111 0101 0011 Codage de la vitesse 1010 1100 0100 1010 ABS wheel sensor 7800 ESP Automotive Engineering Section, UniKLMFI - Autotronic 2 (multiplexing)

1320 Injection ECU 1313 Engine speed encoding 1010 1100 0100 1010 0100 1111 0101 0011 Engine speed sensor INTERFACE BUS CAN I/S 7000 INTERFACE INTERFACE 7005 0100 1111 0101 0011 1010 1100 0100 1010 Codage de la vitesse 1010 1100 0100 1010 ABS wheel sensor 1630 BVA 7800 ESP Automotive Engineering Section, UniKLMFI - Autotronic 2 (multiplexing)

1320 BSI injection ECU 1313 Engine speed 1010 1100 0100 1010 encoding 1010 1100 0100 1010 0100 1111 0101 0011 0100 1111 0101 0011 Engine speed sensor INTERFACE INTERFACE BUS CAN I/S 7000 INTERFACE INTERFACE 7005 0100 1111 0101 0011 1010 1100 0100 1010 Codage de la vitesse 1010 1100 0100 1010 ABS wheel sensor 1630 automatic 7800 gear box ESP Automotive Engineering Section, UniKLMFI - Autotronic 2 (multiplexing)

- EXCHANGE OF DATA ON TWO DIFFERENT BUSES. (BSI is a bridge between the buses) 1320 BSI Engine ECU 1313 Engine speed 1010 1100 0100 1010 encoding 1010 1100 0100 1010 0100 1111 0101 0011 0100 1111 0101 0011 Engine speed sensor INTERFACE INTERFACE INTERFACE BUS CAN I/S 7000 INTERFACE INTERFACE INTERFACE 7005 0100 1111 0101 0011 0100 1111 0101 0011 1010 1100 0100 1010 Codage de la vitesse 1010 1100 0100 1010 1010 1100 0100 1010 ABS wheel sensor 1630 0004 Automatic gear 7800 Instrument box BUS VAN COMFORT ESP panel Automotive Engineering Section, UniKLMFI - Autotronic 2 (multiplexing)