1、BRITISH STANDARD BS EN 50157-2-3:1999 Domestic and similar electronic equipment interconnection requirements: AV link Part 2-3: System oriented application The European Standard EN50157-2-3:1998has the status of a British Standard ICS33.160.30; 33.160.40BSEN50157-2-3:1999 This British Standard, havi
2、ng been prepared under the directionof the Electrotechnical Sector Committee, was publishedunder the authority ofthe Standards Committee andcomes into effect on 15May1999 BSI 04-2000 ISBN 0 580 32038 3 National foreword This British Standard is the English language version of EN50157-2-3:1998. The U
3、K 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, video and audiovisual engineering, which has the responsibility to: aid enquirers to understand
4、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 developments and promulgate them in the UK. A list of organizations represented on this subcommittee ca
5、n 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 Catalogue under the section entitled “International Standards Correspondence Index”, or by using the
6、 “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 correct application. Compliance with a British Standard does not of itself confer immunity from
7、legal obligations. Summary of pages This document comprises a front cover, an inside front cover, pages i and ii, theEN title page, pages 2 to 8 and a back cover. This standard has been updated (see copyright date) and may have had amendments incorporated. This will be indicated in the amendment tab
8、le on the inside front cover. Amendments issued since publication Amd. No. Date CommentsBSEN50157-2-3:1999 BSI 04-2000 i Contents Page National foreword Inside front cover Foreword 2 Text of EN 50157-2-3 3ii blankEUROPEAN STANDARD NORME EUROPENNE EUROPISCHE NORM EN 50157-2-3 August 1998 ICS 33.160.3
9、0; 33.160.40 Descriptors: Television systems, peritelevision devices, appliance interconnection, data transmissions, message English version Domestic and similar electronic equipment interconnection requirements: AV link Part 2-3: System oriented application Spcification des interconnexions des quip
10、ements lectroniques domestiques et usage analogue: AV link Partie 2-3: Application oriente systme Kennwerte fr die Kleinsignalverbindung zwischen elektronischen Gerten fr den Heimgebrauch und hnliche Anwendungen:AV link Teil 2-3: Systemorientierte Anwendung This European Standard was approved by CEN
11、ELEC on 1998-08-01. CENELEC members are bound to comply with the CEN/CENELEC Internal Regulations 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 standa
12、rds may be obtained on application to the Central Secretariat or to any CENELEC member. This European 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 notif
13、ied to the Central Secretariat has the same status as the official versions. CENELEC members are the national electrotechnical standards bodies of Austria, Belgium, CzechRepublic, Denmark, Finland, France, Germany, Greece, Iceland, Ireland, Italy, Luxembourg, Netherlands, Norway, Portugal, Spain, Sw
14、eden, Switzerland and UnitedKingdom. CENELEC European Committee for Electrotechnical Standardization Comit Europen de Normalisation Electrotechnique Europisches Komitee fr Elektrotechnische Normung Central Secretariat: rue de Stassart 35, B-1050 Brussels 1998 CENELEC All rights of exploitation in an
15、y form and by any means reserved worldwide for CENELEC members. Ref. No. EN 50157-2-3:1998 EEN50157-2-3:1998 BSI 04-2000 2 Foreword This European Standard was prepared by the former Technical Committee CENELECTC203, Electronic entertainment and educational systems for household and similar use, (in
16、July1998TC203 has become part of TC206, Consumer equipment for entertainment and information and related sub- systems). The text of the draft was submitted to the formal vote and was approved by CENELEC as EN50157-2-3on1998-08-01. Contents Page Foreword 2 1 Scope 3 2 Normative references 3 3 The AV
17、link model 4 4 The physical medium 5 5 The mode 3 frame format 6 6 The frame communication 7 7 The mode 3 message structure 7 Figure 1 AV link model 4 Figure 2 Start bit pulse format 5 Figure 3 Data bit pulse format 5 Figure 4 Signal free time before a new “Initiator” may send a new message 6 Figure
18、 5 Signal free time before the same “Initiator” may send a new message 6 Figure 6 Signal free time before re-transmission of a frame 6 Figure 7 AV link mode 3 frame format 7 Figure 8 Mode 3 start sequence 7 Figure 9 Application identifier block 7 Figure 10 AV link mode 3 message 7 Figure 11 Applicat
19、ion identifier table 8 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 national standards conflicting with the EN have to be withdrawn (dow) 1999-08-01.EN50157-2-3:1998 B
20、SI 04-2000 3 1 Scope AV link mode 3 is an audio/video communication system AV link mode3devices communicate with each other by sending and receiving messages. The communication of AV link takes place via contact10of the peritelevision connector as specified in EN50049-1. This document specifies the
21、AV link mode3communication protocols. Within the protocol a 3-bit “Application identifier” is present. If a company wishes to use the mode3protocol for its own application an “Application identifier” code can be allocated by EACEM Secretariat. 2 Normative references This European Standard incorporat
22、es by dated or undated reference, provisions from other publications. These normative references are cited at the appropriate places in the text and the publications are listed hereafter. For dated references, subsequent amendments to or revisions of any of these publications apply to this European
23、Standard only when incorporated in it by amendment or revision. For undated references the latest edition of the publication referred to applies. EN 50049-1, Domestic and similar electronic equipment interconnection requirements:Peritelevision connector. EN 50157-1, Domestic and similar electronic e
24、quipment interconnection requirements: AV link Part 1: General. EN 50157-2-1, Part 2-1: Signal quality matching and automatic selection of source devices. EN 50157-2-2, Part 2-2: Basic system oriented commands. IEC 60807-9, Rectangular connectors for frequencies below3Mhz Part 9:Detail specification
25、 for a range of peritelevision connectors. EN 50157-2-3:1998 4 BSI 04-2000 3 The AV link model The figure below shows the AV link model by which AV link devices can communicate with each other. If a link mode 1 is used, the implementation of mode2or3is optional Audio/Video system Applications AV.lin
26、k Part 1 General Part 2-1 Part 2-2 Part 2-3 Part 2-8 Signal quality Basic System Oriented System oriented application Part 2-8 Selection of devices Commands Network layer Mode 1 Network layer Mode 2 Network layer Mode 3 Network layer Mode 8 Control signal format Application message format Command me
27、ssage format To be stated Mode 1 frame specification Mode 2 frame specification Mode 3 frame specification Mode 8 frame specification Specification of the Physical layer (EN 50049-1) Specification of the control signal line on Contact 10 of the peritelevision connector: Bit specification Electrical
28、specification Mechanical specification Specification of the peritelevision connector (EN 50049-1) Figure 1 AV link modelEN50157-2-3:1998 BSI 04-2000 5 4 The physical medium This section describes the physical medium through which basic AV link commands may be communicated from one device to another.
29、 The physical layer is described in EN50049-1and EN50157-2-1. Contact 10 forms a control signal line connecting all devices within the AV link chain. 4.1 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 cl
30、ause5. It consists of a start bit followed by a number of data bits. The figures below show the format of the bits. The format and timing of those bits is described in EN50157-2-1. 4.2 Control signal line arbitration Control signal line arbitration ensures that only one “Initiator” gains control of
31、the control signal line. This guarantees that an “Initiator” will never be interrupted 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 sign
32、al line have to ensure that the control signal line has been inactive for a duration equal to or greater than the signal free time (see4.3). Control signal line arbitration on system level commences with the leading edge or the start bit. Control signal line arbitration continues with the applicatio
33、n identifier field. The control signal line arbitration continues in the application field. It is recommended therefore that the application block starts with a unique address field,e.g.the source address, similar to the method as used for mode2 (see EN50157-2-2). If a device transmits a “1” bit and
34、 detects a “0” bit then it shall assume that it has lost the arbitration to a second “Initiator”. A device that has lost the arbitration shall discontinue transmitting the current frame and switch to the “Follower” state. Then the device has to wait for the control signal line to be inactive for the
35、 duration equal to the signal free time period (see4.3) before attempting to gain control of the control signal line by a frame re-transmission as specified in4.3. If the device fails to gain control of the control signal line then it shall abandon the transmission of the message. 4.3 Signal free ti
36、me Before attempting to transmit or to re-transmit a frame a device shall ensure that the control signal has been inactive for a number of bit periods. This is the signal free time. The length of the required signal free time depends on the current status of the control signal line and the initiatin
37、g device. Figure 2 Start bit pulse format Figure 3 Data bit pulse formatEN50157-2-3:1998 6 BSI 04-2000 4.3.1 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 the first frame
38、of that new message the “Initiator” shall ensure that the control signal line has been inactive for at least seven bit periods. 4.3.2 New message by the present “Initiator” An “Initiator” wants to transmit a new message, after it occupied the control signal line by transmitting a previous message. B
39、efore 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. 4.3.3 Frame re-transmission of the same message The “Initiator” may decide to attempt to transmit subsequent frames with the sam
40、e message. Before attempting to re-transmit the frame, the transmitting device shall ensure that the control signal line has been inactive for at least five bit periods. The maximum number of re-tries is five. 5 The mode 3 frame format AV link mode 3 communication is based on AV link mode3messages o
41、f variable length. An AV link mode3message is conveyed over the physical medium using AV link mode3frames. An AV link mode3frame is a self contained unit that consists of the following data units: a start sequence block with a start bit and three mode bits; an application identifier block; an applic
42、ation block containing one or more data fields. The maximum number of bits in one frame shall not exceed100bits. Figure 4 Signal free time before a new “Initiator” may send a new message Figure 5 Signal free time before the same “Initiator” may send a new message Figure 6 Signal free time before re-
43、transmission of a frameEN50157-2-3:1998 BSI 04-2000 7 5.1 Start sequence Each frame commences with a start sequence. Any frame not adhering to this sequence shall be ignored by the AV link communication layer. The sequence consists of a start bit and three mode bits. The start bit indicates the begi
44、nning of a new frame. The bit prevents other devices from gaining control of the control signal line and readies them for reception of a frame. The mode bits determine the format and nature or the frame. A number of “1” bits are followed by one“0” bit. The number of “1” bits designates the mode of t
45、he frame. Mode 1: represented by a single “0” bit is used for signal quality matching and automatic selection of source devices as described in AV link mode1, EN50157-2-1. Mode 2: represented by one “1” bit followed by a“0”bit is used for basic system oriented commands as described in AV link mode2,
46、 EN50157-2-2. Mode 3: represented by two “1” bits followed by a“0”bit is used for system application messages as described in this document. 5.2 The application identifier block The application identifier is used to identify the application area of the current frame. The field consists of three bits
47、, most significant bit first. 5.3 Application block The application block contains a variable number of bits, describing the application information as specified by the application. The application block may be subdivided into one or more data fields as specified by the application. It is recommende
48、d that the application block starts with a unique address field,e.g.the source address, which takes part in the line arbitration (see4.2). 6 The frame communication Mechanisms to improve reliable communications for the transfer of mode3commands, such as frame re-transmissions of flow control, may be
49、 used by the application as appropriate. 7 The mode 3 message structure AV link mode 3 communication is based on AV link mode3messages. An AV link mode3message is conveyed from a transmitting device (the “Initiator”) to one or more receiving devices the “Follower(s)”. An AV link mode3message consists of the application identifier block and the application block. An AV link mode3message details the system application. Each application identifier indicates another application area, in which a numbe
