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1、 Reference number ISO 11898-5:2007(E) ISO 2007 INTERNATIONAL STANDARD ISO 11898-5 First edition 2007-06-15 Road vehicles Controller area network (CAN) Part 5: High-speed medium access unit with low-power mode Vhicules routiers Gestionnaire de rseau de communication (CAN) Partie 5: Unit daccs au mdiu
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5、 inform the Central Secretariat at the address given below. COPYRIGHT PROTECTED DOCUMENT ISO 2007 All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized in any form or by any means, electronic or mechanical, including photocopying and microfilm, wi
6、thout permission in writing from either ISO at the address below or ISOs member body in the country of the requester. ISO copyright office Case postale 56 CH-1211 Geneva 20 Tel. + 41 22 749 01 11 Fax + 41 22 749 09 47 E-mail copyrightiso.org Web www.iso.org Published in Switzerland ii ISO 2007 All r
7、ights reserved ISO 11898-5:2007(E) ISO 2007 All rights reserved iii Contents Page Foreword iv Introduction v 1 Scope . 1 2 Normative references. 1 3 Terms and definitions. 1 4 Symbols and abbreviated terms . 2 5 Functional description of medium access unit (MAU) with low-power mode 2 5.1 General. 2
8、5.2 Physical medium attachment sub layer specification 2 6 Conformance tests . 5 6.1 General. 5 6.2 VSplit output function. 5 6.3 Output voltage during low-power mode. 6 6.4 Internal resistance during low-power mode 6 6.5 Propagation delay during normal mode. 7 6.6 Wake-up filter time during low-pow
9、er mode 7 6.7 Bus driver symmetry during normal mode 7 6.8 Input leakage current, unpowered device 8 7 Electrical specification of high-speed medium access unit (HS-MAU). 8 7.1 Physical medium attachment sub layer specification 8 7.2 CAN node. 10 7.3 Medium dependent interface (MDI) specification, c
10、onnector parameters 18 7.4 Physical medium specification . 18 Bibliography. 20 ISO 11898-5:2007(E) iv ISO 2007 All rights reserved Foreword ISO (the International Organization for Standardization) is a worldwide federation of national standards bodies (ISO member bodies). The work of preparing Inter
11、national 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-governmental, in liaison wit
12、h 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 main task of technica
13、l 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. Attention is drawn to
14、 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 11898-5 was prepared by Technical Committee ISO/TC 22, Road vehicles, Subcommittee SC 3, Electrical and electronic equ
15、ipment. ISO 11898 consists of the following parts, under the general title Road vehicles Controller area network (CAN): Part 1: Data link layer and physical signalling Part 2: High-speed medium access unit Part 3: Low-speed, fault-tolerant, medium-dependent interface Part 4: Time-triggered communica
16、tion Part 5: High-speed medium access unit with low-power mode -,-,- ISO 11898-5:2007(E) ISO 2007 All rights reserved v Introduction ISO 11898 was first published as one document in 1993. It covered the CAN data link layer as well as the high-speed physical layer. In the reviewed and restructured IS
17、O 11898 series: Part 1 describes the data link layer including the logical link control (LLC) sub layer and the medium access control (MAC) sub layer as well as the physical signalling (PLS) sub layer; Part 2 defines the high-speed medium access unit (MAU); Part 3 defines the low-speed fault-toleran
18、t medium access unit (MAU); Part 4 defines the time-triggered communication; Part 5 defines the power modes of the high-speed medium access unit (MAU). ISO 11898-1 and ISO 11898-2 have been cancelled and replaced ISO 11898:1993. -,-,- INTERNATIONAL STANDARD ISO 11898-5:2007(E) ISO 2007 All rights re
19、served 1 Road vehicles Controller area network (CAN) Part 5: High-speed medium access unit with low-power mode 1 Scope This part of ISO 11898 specifies the CAN physical layer for transmission rates up to 1 Mbit/s for use within road vehicles. It describes the medium access unit functions as well as
20、some medium dependent interface features according to ISO/IEC 8802-2. This part of ISO 11898 represents an extension of ISO 11898-2, dealing with new functionality for systems requiring low-power consumption features while there is no active bus communication. Physical layer implementations accordin
21、g to this part of ISO 11898 are compliant with all parameters of ISO 11898-2, but are defined differently within this part of ISO 11898. Implementations according to this part of ISO 11898 and ISO 11898-2 are interoperable and can be used at the same time within one network. 2 Normative references T
22、he following referenced documents are indispensable for the application of this document. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies. ISO 7637-3, Road vehicles Electrical disturbances
23、from conduction and coupling Part 3: Electrical transient transmission by capacitive and inductive coupling via lines other than supply lines ISO 11898-2:2003, Road vehicles Controller area network (CAN) Part 2: High-speed medium access unit 3 Terms and definitions For the purposes of this document,
24、 the terms and definitions given in ISO 11898-2 and the following apply. 3.1 VCC CAN node supply voltage of the physical layer used for the bus receiver, transmitter and optional split termination voltage VSplit during normal mode NOTE Typical voltage of VCC is 5 V. 3.2 split termination voltage VSp
25、lit CAN node output voltage of split termination support output relative to ground signal of the module (GND) -,-,- ISO 11898-5:2007(E) 2 ISO 2007 All rights reserved 3.3 propagation time tProp CAN node signal propagation time measured from an edge at transmit data (TXD) input to the corresponding e
26、dge on receive data (RXD) output of the MAU 3.4 wake-up filter time tWake CAN node duration of a dominant signal on the bus lines CAN_H and CAN_L for forcing a wake-up to the CAN NODE 3.5 wake-up pattern CAN node one or multiple consecutive dominant bus levels for at least tWake, each separated by a
27、 recessive bus level NOTE Figures within this part of ISO 11898 are using arrows as following: voltages + ? ; currents flowing from the positive to the negative pole. 4 Symbols and abbreviated terms For the purposes of this document, the symbols and abbreviated terms given in ISO 11898-2 apply. 5 Fu
28、nctional description of medium access unit (MAU) with low-power mode 5.1 General The following description is valid for a two-wire differential bus. The values of the voltage levels, the resistances and the capacitances as well as the termination network are described in Clause 7. 5.2 Physical mediu
29、m attachment sub layer specification 5.2.1 General As shown in Figure 1 the bus line is terminated by termination network A and termination network B. These terminations are intended to suppress reflections. Besides this reflection-optimized termination structure, centralized single terminations are
30、 possible at limited bit rates and topologies. Figure 1 Suggested electrical interconnection ISO 11898-5:2007(E) ISO 2007 All rights reserved 3 Two different termination models are recommended within the high-speed medium access unit according to Figures 1 and 2: termination with a single resistor b
31、etween CAN_H and CAN_L, and split termination dividing the single resistor into two resistors with the same value in series connection, while the centre tap is connected to a grounding capacitor and optionally to a dedicated split supply. Key 1 physical layer Figure 2 Termination variants, single re
32、sistor termination and split termination In order to support low-power functionality, two different modes of operation are defined as follows. Normal mode: The behaviour during normal mode is described within ISO 11898-2. Low-power mode: Described within this part of ISO 11898. 5.2.2 Bus levels duri
33、ng normal mode The bus can have one of the two logical states: recessive or dominant (see Figure 3). The bus is in the recessive state if the bus drivers of all CAN nodes are switched off. In this case, the mean bus voltage is generated by the termination and by the high internal resistance of each
34、CAN nodes receiving circuitry. In the recessive state, VCAN_H and VCAN_L are fixed to a mean voltage level, determined by the bus termination. Vdiff is less than a maximum threshold. The recessive state is transmitted during bus idle or a recessive bit. Figure 3 illustrates the maximum allowed diffe
35、rential recessive bus voltage. Typically, the differential voltage is about zero volts. Optionally the recessive bus state may become stabilized making use of a dedicated split termination voltage (VSplit). This optional output voltage of physical layer implementations according to this part of ISO
36、11898 may be optionally connected to the centre tap of the split termination resistors. Whenever the receiver of a physical layer is not actively biasing towards 2,5 V, the optional VSplit shall become floating. A dominant bit is sent to the bus if the bus driver of at least one unit is switched on.
37、 This induces a current flow through the terminating resistors, and consequently a differential voltage between the two wires of the bus. A differential voltage greater than a minimum threshold represents the dominant state. The dominant state overwrites the recessive state, and is transmitted durin
38、g a dominant bit. The dominant and recessive states are detected by transforming the differential voltages of the bus to the corresponding recessive and dominant voltage levels within the receive comparator. During arbitration, various CAN nodes may simultaneously transmit a dominant bit. In this ca
39、se, Vdiff exceeds the Vdiff seen during a single operation. Single operations means that the bus is driven by one CAN node only. -,-,- ISO 11898-5:2007(E) 4 ISO 2007 All rights reserved 5.2.3 Bus levels during low-power mode During low-power mode, the bus drivers are entirely disabled. It is not pos
40、sible to actively drive a differential level to the bus lines using a physical layer within low-power mode. In contrast to the normal mode behaviour, the bus wires shall be pulled to the ground signal of the module (GND) via the high-ohmic internal input resistors Rin of the receiver. Thus, there is
41、 no active VCC supply required defining the bus levels during low- power operation. The optional split termination voltage (VSplit) is disabled here and shall behave high-ohmic (floating) in order not to pull the bus into a certain direction. From a physical point of view, there are only the two def
42、ined operating conditions possible. The normal mode with VCC/2 biasing whenever normal bus communication takes place and low-power mode with GND biasing whenever the system becomes shutdown. Key 1 normal mode 2 low-power mode 3 simplified transceiver bias implementation Figure 3 Physical bit represe
43、ntation and simplified bias implementation 5.2.4 Wake-up out of low-power mode During low-power operation, a physical layer optionally shall monitor the bus lines CAN_H and CAN_L for wake-up events. Implementations supporting this feature shall make use of a differential bus comparator monitoring th
44、e bus line. A bus wake-up shall be performed if the bus shows one or multiple consecutive dominant bus levels for at least tWake, each separated by a recessive bus level. 5.2.5 Systems with unpowered nodes In order to allow undisturbed CAN communication in systems, which have a couple of nodes inten
45、tionally unpowered (e.g. ignition key controlled modules), while other nodes continue to communicate normally, it is important that these unpowered nodes affect the bus levels as little as possible. This requires that transceivers, which are temporarily unpowered, show a lowest possible leakage curr
46、ent to the bus lines inside the still communicating system. The lower the leakage current in the unpowered case, the better the system performance in the permanently supplied part of the network. Depending on the target application (permanently supplied or temporarily unsupplied) the maximum leakage
47、 parameter according to Table 4 can be tolerated (permanently supplied nodes) or should be reduced as far as possible (temporarily unsupplied nodes). -,-,- ISO 11898-5:2007(E) ISO 2007 All rights reserved 5 NOTE In contrast to a low-power mode, where the device is still supplied, unpowered means a p
48、hysical disconnection from the power supply. 6 Conformance tests 6.1 General All conformance tests for normal mode of operation are specified in ISO 11898-2. Besides these tests, some tests are added dealing with the optional VSplit functionality and the low-power mode behaviour. The figures and the formulae shown within this clause indicate the principles of how the electrical parameters specified in Clause 7 should be verified. 6.2 VSplit output function 6.2.1 General VSplit is an optional output voltage supporting recessive bus stabilization. When this funct