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1、BRITISH STANDARD BS ISO 22896:2006 Road vehicles Deployment and sensor bus for occupant safety systems ICS 43.040.80 ? Licensed Copy: London South Bank University, London South Bank University, Sun Dec 24 04:27:35 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS ISO 22896:2006 This British Standard was
2、 published under the authority of the Standards Policy and Strategy Committee on 29 December 2006 BSI 2006 ISBN 0 580 49772 0 National foreword This British Standard was published by BSI. It is the UK implementation of ISO 22896:2006. The UK participation in its preparation was entrusted to Technica
3、l Committee AUE/16, Electrical and electronic equipment. 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 contract. Users are responsible for its correct application. Compliance w
4、ith a British Standard cannot confer immunity from legal obligations. Amendments issued since publication Amd. No. DateComments Licensed Copy: London South Bank University, London South Bank University, Sun Dec 24 04:27:35 GMT+00:00 2006, Uncontrolled Copy, (c) BSI Reference number ISO 22896:2006(E)
5、 INTERNATIONAL STANDARD ISO 22896 First edition 2006-11-15 Road vehicles Deployment and sensor bus for occupant safety systems Vhicules routiers Bus de dploiement et de capteurs pour les systmes de scurit des occupants BS ISO 22896:2006 Licensed Copy: London South Bank University, London South Bank
6、University, Sun Dec 24 04:27:35 GMT+00:00 2006, Uncontrolled Copy, (c) BSI ii Licensed Copy: London South Bank University, London South Bank University, Sun Dec 24 04:27:35 GMT+00:00 2006, Uncontrolled Copy, (c) BSI iii Contents Page Foreword iv 1 Scope . 1 2 Terms and definitions. 1 3 Abbreviations
7、 3 4 General. 4 5 System architecture 5 5.1 General. 5 5.2 Deployment bus 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
8、 deployment bus . 17 6.8 Bus signal parameters . 18 7 Data Link Layer. 22 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
9、 devices 42 8.5 Application Layer for sensor devices. 47 Annex A (informative) 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) Late
10、ncy time analysis for interrupts from smart sensors . 53 Annex E (informative) CRC examples 56 Annex F (informative) Deployable devices 57 Annex G (informative) Slave manufacturer identification codes. 60 BS ISO 22896:2006 Licensed Copy: London South Bank University, London South Bank University, Su
11、n Dec 24 04:27:35 GMT+00:00 2006, Uncontrolled Copy, (c) BSI iv Foreword ISO (the International Organization for Standardization) is a worldwide federation of national standards bodies (ISO member bodies). The work of preparing International Standards is normally carried out through ISO technical co
12、mmittees. 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-governmental, in liaison with ISO, also take part in the work. ISO collaborates closely with th
13、e 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 main task of technical committees is to prepare International Standards. Draft Internati
14、onal 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. Attention is drawn to the possibility that some of the elements of this document may be
15、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, Electrical and electronic equipment. BS ISO 22896:2006 Licensed Copy: London South Bank University
16、, London South Bank University, Sun Dec 24 04:27:35 GMT+00:00 2006, Uncontrolled Copy, (c) BSI 1 Road 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 system
17、s. It covers Physical Layer and Data Link Layer and 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
18、 deploy messages 2.2 bitmap addressing method of addressing 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 represe
19、ntation of a data bit during the Data Phase 2.4 command 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
20、 commands for control of deployable devices 2.9 deployable device irreversible actuator BS ISO 22896:2006 Licensed Copy: London South Bank University, London South Bank University, Sun Dec 24 04:27:35 GMT+00:00 2006, Uncontrolled Copy, (c) BSI 2 2.10 D-Frame type of frame primarily used for diagnost
21、ic 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 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
22、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 occurrence of an interrupt requesting event in the sensor and the actual start of an S-Frame polling message 2.17 LS0-
23、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 responsible for communication on the bus and for power distribution over the bus 2.21 Multi-Sharing mode used in S-F
24、rames 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 ISO 22896:2006 Licensed Copy: London South Bank University, London South Bank University, Sun Dec 24 04:27:35 GM
25、T+00:00 2006, Uncontrolled Copy, (c) BSI 3 2.24 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
26、 for half-rate mode 2.28 S-Frame 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
27、 slave address bitmap part of 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
28、of a frame, used to define the 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 22896:2006 Licensed Copy: London South Bank University, London South Bank University, Sun Dec
29、24 04:27:35 GMT+00:00 2006, Uncontrolled Copy, (c) BSI 4 HSD High Side Driver INT Interrupt LSB Least Significant Bit LSD Low Side Driver MSA Multi-Sharing Address MSB Most Significant Bit MTP Multi Time Programmable NVM Non Volatile Memory ORC Occupant Restraint Controller OTP One Time Programmable
30、 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 Automotive occupant restraint systems are controlled by a Sensing and Diagnostic Module (SDM), also called Airbag Control Unit (ACU
31、), Restraint Control Module (RCM) or Occupant Restraint Controller (ORC), which is connected to peripheral devices: dynamic sensors with high update rates, e.g. for remote front and side impact sensing; static sensors with low update rates, e.g. buckle switches, seat position and occupancy sensors;
32、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 a two-wire connection between the SDM and the peripheral devices and supplies power to the slaves. It offers bi-directional commun
33、ication. 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 communication by sending message frames on the bus. Slaves may transmit their data within these frames when requested by the maste
34、r. 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 reaction to the interrupt is application specific and typically lets the master stop diagnostic communication and start polling of im
35、pact data instead. BS ISO 22896:2006 Licensed Copy: London South Bank University, London South Bank University, Sun Dec 24 04:27:35 GMT+00:00 2006, Uncontrolled Copy, (c) BSI 5 The data is usually coded using differential bus voltage. On a bus, where several transmitters are sharing the same wiring,
36、 using voltage 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 dat
37、a like diagnostics, 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
38、 bus shall 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 cons
39、idered. NOTE 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 deploy
40、ment bus 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
41、range 0b000000 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 defa
42、ult address 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 S
43、ensor bus 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 bu
44、s. NOTE Raw-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 22896:2006 Licensed Copy: London South Bank University, London South Bank University, Sun Dec 24 04:27:35 GMT+00:00 2006, Uncontro
45、lled Copy, (c) BSI 6 EXAMPLE In the absence of an event, the master can poll diagnostic data and/or static sensor data from all slaves. When an event 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
46、bus bandwidth for exclusive communication of time-critical data from smart sensors to the master. The number of smart sensors that can be connected to the bus is usually limited by the ratio between the available bandwidth and the latency time requirements for this data transfer. Additional static s
47、ensors 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 Clause 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 inte
48、rrupt capability of smart sensors. Since raw-data sensors usually are not required to send bus interrupts, they may be implemented without this option. 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 in
49、terrupt 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 connected 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 the other hand for signalling bu
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