1、 g49g50g3g38g50g51g60g44g49g42g3g58g44g55g43g50g56g55g3g37g54g44g3g51g40g53g48g44g54g54g44g50g49g3g40g59g38g40g51g55g3g36g54g3g51g40g53g48g44g55g55g40g39g3g37g60g3g38g50g51g60g53g44g42g43g55g3g47g36g58systemsICS 43.040.80Road vehicles Deployment and sensor bus for occupant safety BRITISH STANDARDBS
2、ISO 22896:2006BS ISO 22896:2006This British Standard was published under the authority of the Standards Policy and Strategy Committee on 29 December 2006 BSI 2006ISBN 0 580 49772 0Amendments issued since publicationAmd. No. Date Commentscontract. Users are responsible for its correct application.Com
3、pliance with a British Standard cannot confer immunity from legal obligations. National forewordThis British Standard was published by BSI. It is the UK implementation of ISO 22896:2006.The UK participation in its preparation was entrusted to Technical Committee AUE/16, Electrical and electronic equ
4、ipment.A list of organizations represented on AUE/16 can be obtained on request to its secretary.This publication does not purport to include all the necessary provisions of a Reference numberISO 22896:2006(E)INTERNATIONAL STANDARD ISO22896First edition2006-11-15Road vehicles Deployment and sensor b
5、us for occupant safety systems Vhicules routiers Bus de dploiement et de capteurs pour les systmes de scurit des occupants BS ISO 22896:2006ii iiiContents Page Foreword iv 1 Scope . 1 2 Terms and definitions. 1 3 Abbreviations 3 4 General. 4 5 System architecture 5 5.1 General. 5 5.2 Deployment bus
6、5 5.3 Sensor bus 5 5.4 Combined sensor and deployment bus . 6 6 Physical Layer. 6 6.1 Bus medium 6 6.2 Bus topology . 6 6.3 Bus load. 8 6.4 Bus signals 10 6.5 Bit coding 12 6.6 Fault tolerance 15 6.7 Use of analogue safing on a deployment bus . 17 6.8 Bus signal parameters . 18 7 Data Link Layer . 2
7、2 7.1 Bus Idle 22 7.2 Addresses 22 7.3 Message frames 24 7.4 Bit fields within a frame 32 8 Application Layer 35 8.1 General. 35 8.2 Common D-Frame commands. 36 8.3 Memory layout of slaves 37 8.4 Application Layer for deployable devices 42 8.5 Application Layer for sensor devices. 47 Annex A (inform
8、ative) In-car address programming for daisy-chain systems 50 Annex B (informative) Guideline for definition of deviations from standard parameters 51 Annex C (informative) Rationale of functionality 52 Annex D (informative) Latency time analysis for interrupts from smart sensors . 53 Annex E (inform
9、ative) CRC examples 56 Annex F (informative) Deployable devices 57 Annex G (informative) Slave manufacturer identification codes. 60 BS ISO 22896:2006iv Foreword ISO (the International Organization for Standardization) is a worldwide federation of national standards bodies (ISO member bodies). The w
10、ork of preparing International Standards is normally carried out through ISO technical committees. Each member body interested in a subject for which a technical committee has been established has the right to be represented on that committee. International organizations, governmental and non-govern
11、mental, in liaison with ISO, also take part in the work. ISO collaborates closely with the International Electrotechnical Commission (IEC) on all matters of electrotechnical standardization. International Standards are drafted in accordance with the rules given in the ISO/IEC Directives, Part 2. The
12、 main task of technical committees is to prepare International Standards. Draft International Standards adopted by the technical committees are circulated to the member bodies for voting. Publication as an International Standard requires approval by at least 75 % of the member bodies casting a vote.
13、 Attention is drawn to the possibility that some of the elements of this document may be the subject of patent rights. ISO shall not be held responsible for identifying any or all such patent rights. ISO 22896 was prepared by Technical Committee ISO/TC 22, Road vehicles, Subcommittee SC 3, Electrica
14、l and electronic equipment. BS ISO 22896:20061Road vehicles Deployment and sensor bus for occupant safety systems 1 Scope This International Standard is a specification of a serial communications bus protocol for automotive occupant restraint systems. It covers Physical Layer and Data Link Layer and
15、 those parts of the Application Layer that are not supplier-specific. 2 Terms and definitions For the purposes of this document, the following terms and definitions apply. 2.1 analogue safing using a special bus level (LS0-level) for confirmation of deploy messages 2.2 bitmap addressing method of ad
16、dressing one or several slaves at a time by assigning each bit of the address field to a different slave 2.3 bus level one out of four levels of the differential bus voltage, whereof one forms the Power Phase and the other three are used for representation of a data bit during the Data Phase 2.4 com
17、mand part of a D-Frame, transmitted by the master, defining the purpose of the frame 2.5 CRC field part of a D-Frame or S-Frame 2.6 data field part of a D-Frame 2.7 Data Phase part of a data bit providing the bit value 2.8 deploy command family four commands for control of deployable devices 2.9 dep
18、loyable device irreversible actuator BS ISO 22896:20062 2.10 D-Frame type of frame primarily used for diagnostic communication and actuation of deployable devices 2.11 differential bus voltage differential voltage between the two bus wires 2.12 duty cycle percentage of a bit time that is assigned to
19、 the Power Phase 2.13 E-bit bit in a D-Frame indicating an error or a “read” command 2.14 half-rate mode used for sensors that shall not reply in every S-Frame 2.15 hold-up capacitor capacitor supplying power to a slave during the Data Phase 2.16 latency time worst-case duration between the occurren
20、ce of an interrupt requesting event in the sensor and the actual start of an S-Frame polling message 2.17 LS0-level bus level indicating an error, a bus interrupt or a “0” with analogue safing 2.18 L0-level bus level indicating a “0” 2.19 L1-level bus level indicating a “1” 2.20 master device respon
21、sible for communication on the bus and for power distribution over the bus 2.21 Multi-Sharing mode used in S-Frames for dynamic assignment of slave data to the first slot 2.22 node master or slave 2.23 point-to-point addressing addressing used for communication between the master and one slave BS IS
22、O 22896:200632.24 power level bus level forming the Power Phase 2.25 Power Phase part of a data bit during which the master transmits the power level 2.26 R-bit reserved bit in D-frames for future definition 2.27 SEL-bit bit used in S-Frames to control slaves configured for half-rate mode 2.28 S-Fra
23、me type of frame used by the master to collect dynamic data from slaves periodically 2.29 signal address address assigned to peculiar signals provided by slaves, used in S-Frames for Multi-Sharing 2.30 slave device that is connected to the bus and is not the master 2.31 slave address bitmap part of
24、a D-Frame in which each bit corresponds to one slave 2.32 slot part of an S-Frame assigned to a certain slave to be filled with its data 2.33 Slot Length determines the number of data bits that a slot consists of 2.34 Sub-Slot sub-section of a slot 2.35 T-bit first bit of a frame, used to define the
25、 frame type (S- or D-Frame) 3 Abbreviations ACU Airbag Control Unit ASIC Application-Specific Integrated Circuit CRC Cyclic Redundancy Check ECU Electronic Control Unit BS ISO 22896:20064 HSD High Side Driver INT Interrupt LSB Least Significant Bit LSD Low Side Driver MSA Multi-Sharing Address MSB M
26、ost Significant Bit MTP Multi Time Programmable NVM Non Volatile Memory ORC Occupant Restraint Controller OTP One Time Programmable RAM Random Access Memory RCM Restraint Control Module ROM Read Only Memory SDM Sensing and Diagnostic Module SEL Select SOF Start Of Frame SSB Slot Start Bit 4 General
27、Automotive occupant restraint systems are controlled by a Sensing and Diagnostic Module (SDM), also called Airbag Control Unit (ACU), Restraint Control Module (RCM) or Occupant Restraint Controller (ORC), which is connected to peripheral devices: dynamic sensors with high update rates, e.g. for remo
28、te front and side impact sensing; static sensors with low update rates, e.g. buckle switches, seat position and occupancy sensors; actuators, especially deployable devices, e.g. squibs. The SDM is also referred to as “master”; the peripheral devices are also referred to as “slaves”. The bus provides
29、 a two-wire connection between the SDM and the peripheral devices and supplies power to the slaves. It offers bi-directional communication. The masters bus interface sends energy into the bus, the slaves bus interface extracts power from the bus. The master determines the bus speed and initiates all
30、 communication by sending message frames on the bus. Slaves may transmit their data within these frames when requested by the master. Smart dynamic sensors (defined in 5.3) may send an interrupt to the master while the bus is idle or while there is diagnostic communication on the bus. The masters re
31、action to the interrupt is application specific and typically lets the master stop diagnostic communication and start polling of impact data instead. BS ISO 22896:20065The data is usually coded using differential bus voltage. On a bus, where several transmitters are sharing the same wiring, using vo
32、ltage as the data signal has a significant advantage over current, because it enables the transmitter to verify the data that it sent on the bus. This is the most reliable way to detect bus collisions, e.g. when two sensors are transmitting their data at the same time. For less critical data like di
33、agnostics, reply data from slaves can be coded using current, which allows connection of deployable slaves to the bus via isolation resistors (see 6.6.4.2). 5 System architecture 5.1 General The specification covers sensor busses, deployment busses and combined sensor/deployment busses. The bus shal
34、l support 64 slave addresses, of which three shall be reserved for special purposes. The actual number of slaves that can be connected to one bus is limited by the supply current for the slaves and by the pin capacitance of the slaves (see also Clause 6). Bandwidth limits shall also be considered. N
35、OTE A single slave can incorporate the functionality of several slave addresses. 5.2 Deployment bus The deployment bus shall support deployable devices and static sensors. The bus shall provide point-to-point messages for diagnostic communications between master and slaves. Since the deployment bus
36、shall support fast selective deployment of several deployable devices, the bus shall also provide a special deploy message, which allows individual deployment control of up to 12 devices at a time. There shall be four deploy messages available, each controlling 12 device addresses: address range 0b0
37、00000 0b001011; address range 0b010000 0b011011; address range 0b100000 0b101011; address range 0b110000 0b111011. In this way, up to 4 12 = 48 deployable devices can be controlled by one bus. The address 0b000000 should not be used as a slave address, because this address shall be the default addre
38、ss of all slaves that have not been programmed yet. See also 7.2.1, 7.3.2 and 7.4.8. The deployment bus shall provide communication with and without a special “safing” signal, which may be used for additional differentiation between diagnostic communication and actual deploy commands. 5.3 Sensor bus
39、 The sensor bus shall support static and dynamic sensors. There may be two types of dynamic sensors. Raw-data sensors send time-critical data periodically to the SDM. Smart sensors send time-critical data event-driven only. Smart sensors can easily coexist with static sensors on the same bus. NOTE R
40、aw-data sensors usually occupy the bus bandwidth all the time, while smart sensors usually need the full bandwidth only for a short time during an event. BS ISO 22896:20066 EXAMPLE In the absence of an event, the master can poll diagnostic data and/or static sensor data from all slaves. When an even
41、t occurs, a smart sensor can stop this communication by sending an interrupt to the master and to the other slaves. The master can then assign the full bus bandwidth for exclusive communication of time-critical data from smart sensors to the master. The number of smart sensors that can be connected
42、to the bus is usually limited by the ratio between the available bandwidth and the latency time requirements for this data transfer. Additional static sensors on the bus do not contribute to the latency time, but they contribute to the physical bus load, which also limits the number of slaves (see C
43、lause 6) on the bus. On a sensor bus, the “safing” signal, known from the deployment bus, shall be used for error indication and optionally for the interrupt capability of smart sensors. Since raw-data sensors usually are not required to send bus interrupts, they may be implemented without this opti
44、on. Devices (master and slaves) made for raw-data sensor busses should either not have bus interrupt capability or provide a means to disable the bus interrupt function in a reliable way. 5.4 Combined sensor and deployment bus On a combined sensor and deployment bus, all types of slaves that are con
45、nected to the same bus would have to share the available bandwidth and the available bus power. This shall be taken into account when designing such a mixed system. The “safing”-level LS0 shall be used on the one hand for confirmation of deploy messages (i.e. LS0 transmitted by the master), and on t
46、he other hand for signalling bus collisions (i.e. LS0 transmitted by a dynamic sensor during an S-Frame) or for interrupting communication (i.e. LS0 transmitted by a smart sensor during a D-Frame). The deployment and sensor bus protocol shall ensure that the relevant function of the LS0-level can be
47、 clearly identified by all nodes (see 8.5.4). 6 Physical Layer 6.1 Bus medium The bus can use unshielded twisted pair or untwisted cable (see Table 3). The maximum bus length depends on the bus topology (see 6.2). 6.2 Bus topology 6.2.1 Parallel configuration For a parallel bus configuration, each s
48、lave shall be directly connected to the two bus wires Bus-A and Bus-B (see Figure 1). Figure 1 Parallel connection of slaves to the bus BS ISO 22896:20067In parallel configuration, the wires may be routed in a bus, tree or ring structure (see Figure 2) or combinations of these. A ring may be impleme
49、nted either by connecting both ends of the bus cable to a single bus output of the master, or by connecting each end of the cable to a separate output of the master (see also 6.6.3.2). Parallel squibs can be implemented as polarized or non-polarized devices. For non-polarized devices, it does not matter which pin is connected to which bus wire. Dynamic sensors shall be polarized. Key M = master S = slave Figure 2 Bus topologies for parallel configuration BS ISO 22896:20068 6.2.2 Daisy-chain configuration Fi
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