1、| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | BRITISH STANDARD BS EN 50157-2-2:1999 The
2、European Standard EN 50157-2-2:1998 has the status of a British Standard ICS 33.160.30 NO COPYING WITHOUT BSI PERMISSION EXCEPT AS PERMITTED BY COPYRIGHT LAW Domestic and similar electronic equipment interconnection requirements: AV link Part 2-2: Basic system oriented commandsThis British Standard,
3、 having been prepared under the direction of the Electrotechnical Sector Committee, was published under the authority of the Standards Committee and comes into effect on 15 May 1999 BSI 05-1999 ISBN 0 580 32041 3 BS EN 50157-2-2:1999 Amendments issued since publication Amd. No. Date Text affected Na
4、tional foreword This British Standard is the English language version of EN 50157-2-2:1998. The UK participation in its preparation was entrusted by Technical Committee EPL/100, Audio, video and multimedia systems and equipment, to Subcommittee EPL/100/3, Equipment and systems in the field of audio,
5、 video and audiovisual engineering, which has the responsibility to: aid enquirers to understand the text; present to the responsible European committee any enquiries on the interpretation, or proposals for change, and keep the UK interests informed; monitor related international and European develo
6、pments and promulgate them in the UK. A list of organizations represented on this subcommittee can be obtained on request to its secretary. Cross-references The British Standards which implement international or European publications referred to in this document may be found in the BSI Standards Cat
7、alogue under the section entitled “International Standards Correspondence Index”, or by using the “Find” facility of the BSI Standards Electronic Catalogue. A British Standard does not purport to include all the necessary provisions of a contract. Users of British Standards are responsible for their
8、 correct application. Compliance with a British Standard does not of itself confer immunity from legal obligations. Summary of pages This document comprises a front cover, an inside front cover, the EN title page, pages 2 to 13 and a back cover.CENELEC European Committee for Electrotechnical Standar
9、dization Comite Europe en de Normalisation Electrotechnique Europa isches Komitee fu r Elektrotechnische Normung Central Secretariat: rue de Stassart 35, B-1050 Brussels 1998 CENELEC All rights of exploitation in any form any by any means reserved worldwide for CENELEC national Members. Ref. No. EN
10、50157-2-2:1998 E EUROPEAN STANDARD EN 50157-2-2 NORME EUROPE ENNE EUROPA ISCHE NORM August 1998 ICS 33.160.30; 33.160.40 Descriptors: television systems, peritelevision devices, appliance interconnection, control systems, connectors, datatransmissions, message, frame check sequence, protocol English
11、 version Domestic and similar electronic equipment interconnection requirements: AV link Part 2-2: Basic system oriented commands Spe cification des interconnexions des e quipements e lectroniques domestiques et a usage analogue: AV link Partie 2-2: Commandes de base du syste me Kennwerte fu r die K
12、leinsignalverbindung zwischen elektronischen Gera ten fu r den Heimgebrauch und a hnliche Anwendungen: AV link Teil 2-2: Grundlegende systemorientierte Befehle This European Standard was approved by CENELEC on 1998-08-01. CENELEC members are bound to comply with the CEN/CENELEC Internal Regulations
13、which stipulate the conditions for giving this European Standard the status of a national standard without any alteration. Up-to-date lists and bibliographical references concerning such national standards may be obtained on application to the Central Secretariat or to any CENELEC member. This Europ
14、ean Standard exists in three official versions (English, French, German). A version in any other language made by translation under the responsibility of a CENELEC member into its own language and notified to the Central Secretariat has the same status as the official versions. CENELEC members are t
15、he national electrotechnical committees of Austria, Belgium, Czech Republic, Denmark, Finland, France, Germany, Greece, Iceland, Ireland, Italy, Luxembourg, Netherlands, Norway, Portugal, Spain, Sweden, Switzerland and United Kingdom.Page 2 EN 50157-2-2:1998 BSI 05-1999 Foreword This European Standa
16、rd was prepared by the former Technical Committee CENELEC TC 203, Electronic entertainment and educational systems for household and similar use (in July 1998 TC 203 has become part of TC 206, Consumer equipment for entertainment and information and related sub-systems). The text of the draft was su
17、bmitted to the formal vote and was approved by CENELEC as EN 50157-2-2 on 1998-08-01. The following dates were fixed: latest date by which the EN has to be implemented at national level by publication of an identical national standard or by endorsement (dop) 1999-08-01; latest date by which the nati
18、onal standards conflicting with the EN have to be withdrawn (dow) 1999-08-01. Contents Page Foreword 2 1 Scope 3 2 Normative references 3 3 The AV link model 4 4 Abbreviations and definitions 5 5 The AV link interconnection chain 5 6 The physical medium 8 7 The mode 2 frame format 9 8 The frame comm
19、unication 11 9 The mode 2 message structure 11 10 The mode 2 “Opcode” table 12Page 3 EN 50157-2-2:1998 BSI 05-1999 1 Scope AV link devices may communicate with each other in AV link mode 2 by sending and receiving basic system oriented commands. The AV link mode 2 communication takes place via the A
20、V link on contact 10 of the peritelevision connector as specified in EN 50049-1. By sending AV link system oriented commands a device may control some basic functions of other devices. For instance an AV link television may control some functions of an AV link video cassette recorder. This document
21、specifies the AV link communication protocols and the basic AV link commands within mode 2. 2 Normative references This European Standard incorporates by dated or undated reference, provisions from other publications. These normative references are cited at the appropriate places in the text and the
22、 publications are listed hereafter. For dated references, subsequent amendments to or revisions of any of these publications apply to this European Standard only when incorporated in it by amendment or revision. For undated references the latest edition of the publication referred to applies. EN 500
23、49-1, Domestic and similar electronic equipment interconnection requirements: Peritelevision connector. EN 50157-1, Domestic and similar electronic equipment interconnection requirements: AV link Part 1: General. EN 50157-2-1, Part 2-1: Signal quality matching and automatic selection of source devic
24、es IEC 60807-9, Rectangular connectors for frequencies below 3 MHz Part 9: Detail specification for a range of peritelevision connectors. BSI 05-1999 Page 4 EN 50157-2-2:1998 3 The AV link Audio/Video system applications AV link Part 1 General Part 2-1 Part 2-2 Part 2-8 Signal quality Basic system o
25、riented commands For future extension Selection of devices Network layer Mode 1 Network layer Mode 2 Network layer Mode 8 Control signal format Command message format To be stated Mode 1 frame specification Mode 2 frame specification Specification of the physical layer (EN 50049-1) Specification of
26、the control signal line on contact 10 of the peritelevision connector: Bit specification Electrical specification Mechanical specification Specification of the peritelevision connector (EN 50049-1) Figure 1 AV link model Figure 1 shows the AV link model by which AV link devices can communicate with
27、each other.Page 5 EN 50157-2-2:1998 BSI 05-1999 4 Abbreviations and definitions ACK ACKnowledge AV link connector 21-pin peritelevision connector for audio/video systems as specified in the AV link document EN 50157-1 broadcast message a message addressed to all devices, using the general call desti
28、nation address block a number of bits that are clustered command data unit of bits that specify the addressed device what action to perform directly addressed message a message transmitted to an individual device address downstream signal path the signal path away from the display unit. For the defi
29、nition see EN 50157-2-1 ECT extended command table. Bit in the command block of a frame. For future use EOM end of message. Bit in the header block of a frame. This bit indicates the presence or absence of a command block follower the device that responds to a message which is initiated by the initi
30、ator. See EN 50157-2-1 frame a self contained unit in which a message is conveyed over the physical layer and that consists of a start block, a header block and a command block initiator the device that starts a message exchange. See EN 50157-2-1 message data block structure, through which a command
31、 may be sent from one device to another. It includes the address block and the command block SAT satellite tuner upstream signal path the signal path towards the display unit. For the definition see EN 50157-2-1 VCR1 video cassette recorder with address 1 VCR2 video cassette recorder with address 2
32、5 The AV link interconnection chain The signal path interconnection chain of AV link devices is an interconnection system with the chain principle as described in clause 3 of EN 50157-2-1. Some examples of configurations are given below. 5.1 Example 1 Minimum supported combination of devices This mi
33、nimum configuration only consists of a TV and a VCR. 5.2 Example 2 Extended combination of devices This configuration consists of a TV, a SAT, a VCR2, a VCR1 and NON-AV link devices. In a configuration with more than one VCR, VCR1 is always the lowest device in the chain.Page 6 EN 50157-2-2:1998 BSI
34、 05-1999 Figure 2 Example of minimum combination of devicesPage 7 EN 50157-2-2:1998 BSI 05-1999 Figure 3 Example of more than two devicesPage 8 EN 50157-2-2:1998 BSI 05-1999 Figure 4 Start bit pulse format 6 The physical medium This clause describes the physical medium through which basic AV link co
35、mmands may be communicated from one device to another device. The physical medium over which basic AV link communication takes place, is contact 10 of the AV link connector. This contact forms a control signal line which connects all devices within the AV link chain. For the specification of the phy
36、sical medium and the electrical specification see EN 50049-1. 6.1 Bit format and timing A message is conveyed over the physical medium using one or more frames. A frame is a self contained unit as described in clause 7. It consists of a start bit followed by a number of data bits. The figures below
37、show the format of the bits. The format and timing of those bits are specified in EN 50157-2-1. 6.2 Control signal line arbitration Control signal line arbitration ensures that only one “Initiator” gains control of the control signal line. This guarantees that an “Initiator” will never be interrupte
38、d by another “Initiator” and if more than one “Initiator” starts simultaneously then only one will retain the control of the control signal line. All those devices that wish to transmit a frame onto the control signal line have to ensure that the control signal line has been inactive for a duration
39、equal to or greater than the signal free time. See 6.3. Control signal line arbitration commences with the leading edge of the start bit. Control signal line arbitration finishes with the terminating edge of the source address field within the header block. If a device transmits a “1” bit and detect
40、s a “0” bit then it shall assume that it has lost the arbitration and that a second “Initiator” is operating. If a device detects a second “Initiator” then it shall discontinue transmitting the current frame and shall switch to the “Follower” state. Then the device has to wait for the control signal
41、 line to be inactive for the duration equal to the signal free period as specified in 6.3, before it may attempt to gain control of the control signal line by a frame retransmission as specified in 8.1. If the device fails to gain control of the control signal line then it shall abandon the transmis
42、sion of the message. 6.3 Signal free time Before attempting to transmit or to retransmit a frame a device shall ensure that the control signal line has been inactive for a number of bit periods. This inactivity is the signal free time. The length of the required signal free time depends on the curre
43、nt status of the control signal line and the initiating device, and defines the access priority, of each message type. 6.3.1 New message by a new “Initiator” An “Initiator” wants to transmit a new message, but the control signal line is occupied by another “Initiator”. Before attempting to transmit
44、the first frame of that new message the “Initiator” shall ensure that the control signal line has been inactive for at least seven bit periods. 6.3.2 New message by the present “Initiator” An “Initiator” will transmit a new message, after it occupied the control signal line by transmitting a previou
45、s message. Before attempting to transmit the first frame of that new message the “Initiator” shall ensure that the control signal line has been inactive for at least nine bit periods. 6.3.3 Frame retransmission of the same message If a frame is not acknowledged by the receiving device, then the “Ini
46、tiator” will attempt to transmit subsequent frames with the same message. Before attempting to retransmit the frame, the transmitting device shall ensure that the control signal line has been inactive for at least five bit periods. The number of retries is specified in 8.1.Page 9 EN 50157-2-2:1998 B
47、SI 05-1999 Figure 5 Data bit pulse format Figure 6 Signal free time before a new “Initiator” may send a new message Figure 7 Signal free time before the same “Initiator” may send a new message Figure 8 Signal free time before retransmission of a frame START SEQUENCE HEADER BLOCK COMMAND BLOCK Start
48、“1” “0” Source Dest. EOM ACK Opcode Field ECK ACK Figure 9 Mode 2 frame format 7 The mode 2 frame format AV link mode 2 communication is based on messages of fixed length. A message is conveyed over the physical medium using mode 2 frames. A mode 2 frame is a self-contained unit that consists of a s
49、tart sequence, a header block, and a command block.Page 10 EN 50157-2-2:1998 BSI 05-1999 The “Initiator” sends the message using a frame. A follower may request that the current frame be terminated and that a message transfer be resumed later using a new frame. The “Follower” does so by NOT_ACKnowledging the command block. A message is, therefore, not necessarily conveyed using a single frame. The “Initiator” shall attempt to retransmit that message a number of times with the specified maximum as describe
