Road vehicles -- Media Oriented Systems Transport (MOST)

This document specifies the conformance test plan for the 50-Mbit/s balanced media physical layer for MOST (MOST50 bPHY), a synchronous time-division-multiplexing network. This document specifies the basic conformance test measurement methods, relevant for verifying compatibility of networks, nodes, and MOST components with the requirements specified in ISOÂ 21806-12.

Véhicules routiers -- Système de transport axé sur les médias

General Information

Status
Published
Publication Date
27-May-2021
Current Stage
5060 - Close of voting Proof returned by Secretariat
Start Date
26-Apr-2021
Completion Date
26-Apr-2021
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INTERNATIONAL ISO
STANDARD 21806-13
First edition
2021-05
Road vehicles — Media Oriented
Systems Transport (MOST) —
Part 13:
50-Mbit/s balanced media physical
layer conformance test plan
Véhicules routiers — Système de transport axé sur les médias —
Partie 13: Plan d'essais de conformité de la couche physique en milieu
équilibré à 50-Mbit/s
Reference number
ISO 21806-13:2021(E)
ISO 2021
---------------------- Page: 1 ----------------------
ISO 21806-13:2021(E)
COPYRIGHT PROTECTED DOCUMENT
© ISO 2021

All rights reserved. Unless otherwise specified, or required in the context of its implementation, no part of this publication may

be reproduced or utilized otherwise in any form or by any means, electronic or mechanical, including photocopying, or posting

on the internet or an intranet, without prior written permission. Permission can be requested from either ISO at the address

below or ISO’s member body in the country of the requester.
ISO copyright office
CP 401 • Ch. de Blandonnet 8
CH-1214 Vernier, Geneva
Phone: +41 22 749 01 11
Email: copyright@iso.org
Website: www.iso.org
Published in Switzerland
ii © ISO 2021 – All rights reserved
---------------------- Page: 2 ----------------------
ISO 21806-13:2021(E)
Contents Page

Foreword ..........................................................................................................................................................................................................................................v

Introduction ................................................................................................................................................................................................................................vi

1 Scope ................................................................................................................................................................................................................................. 1

2 Normative references ...................................................................................................................................................................................... 1

3 Terms and definitions ..................................................................................................................................................................................... 1

4 Symbols and abbreviated terms ........................................................................................................................................................... 2

4.1 Symbols ......................................................................................................................................................................................................... 2

4.2 Abbreviated terms ............................................................................................................................................................................... 2

5 Conventions ............................................................................................................................................................................................................... 3

6 Operating conditions and measurement tools, requested accuracy ..............................................................3

6.1 Operating conditions ......................................................................................................................................................................... 3

6.2 Apparatus — Measurement tools, requested accuracy ....................................................................................... 3

7 Electrical characteristics .............................................................................................................................................................................. 4

8 Balanced media characteristics ............................................................................................................................................................ 4

8.1 Threshold for detection of alignment and transferred jitter ........................................................................... 4

8.2 RMS signal amplitude ......... ............................................................................................................................................................... 4

8.3 PSD of SP2 output signal ................................................................................................................................................................ 5

8.4 Attenuation of electrical interconnect ................................................................................................................................ 7

8.4.1 General...................................................................................................................................................................................... 7

8.4.2 Test procedure general ............................................................................................................................................... 8

8.4.3 Example set-up test procedure............................................................................................................................ 8

8.4.4 Test procedure for data acquisition................................................................................................................. 8

8.4.5 Impact of attenuation on the data signal .................................................................................................... 9

8.5 Characteristic impedance of balanced media ............................................................................................................10

8.6 RL of PCB interfaces ........................................................................................................................................................................13

8.7 Receive tolerance ...............................................................................................................................................................................15

8.7.1 General...................................................................................................................................................................................15

8.7.2 Pattern generator .........................................................................................................................................................15

8.7.3 Arbitrary signal generator ....................................................................................................................................16

8.7.4 Cable assembly or its analogue representation .................................................................................16

8.7.5 Stimulus creation for SP3 ......................................................................................................................................16

9 Measurement of phase variation ......................................................................................................................................................18

9.1 General ........................................................................................................................................................................................................18

9.2 Measuring alignment jitter ........................................................................................................................................................20

9.3 Measuring transferred jitter .....................................................................................................................................................23

10 Test set-ups..............................................................................................................................................................................................................26

10.1 General ........................................................................................................................................................................................................26

10.2 Set-ups for SP2 link quality .......................................................................................................................................................26

10.3 Set-ups for SP3 link quality .......................................................................................................................................................28

10.4 Set-ups for SP3 receive tolerance ........................................................................................................................................30

11 Power-on and power-off ............................................................................................................................................................................31

11.1 General ........................................................................................................................................................................................................31

11.2 Measuring EBC parameters ......................................................................................................................................................32

11.2.1 Measuring EBC parameters – Test set-up ...............................................................................................32

11.2.2 Measuring EBC parameters – Signal charts ...........................................................................................33

11.2.3 Measuring EBC parameters – Test sequences .....................................................................................33

11.3 Measuring BEC parameters ......................................................................................................................................................35

11.3.1 Measuring BEC parameters – Test set-up ...............................................................................................35

11.3.2 Measuring BEC parameters – Signal chart .............................................................................................37

11.3.3 Measuring BEC parameters – Test sequences .....................................................................................37

© ISO 2021 – All rights reserved iii
---------------------- Page: 3 ----------------------
ISO 21806-13:2021(E)

12 Detecting bit rate (frequency reference) .................................................................................................................................40

13 System performance ......................................................................................................................................................................................41

13.1 General ........................................................................................................................................................................................................41

13.2 SP3 receiver tolerance ...................................................................................................................................................................41

13.3 TimingMaster delay tolerance ................................................................................................................................................41

14 Conformance test of 50-Mbit/s balanced media physical layer .......................................................................44

14.1 Location of interfaces .....................................................................................................................................................................44

14.2 Control signals ......................................................................................................................................................................................44

14.3 Limited access to specification points .............................................................................................................................45

14.4 Parameter overview ........................................................................................................................................................................45

15 Limited physical layer conformance .............................................................................................................................................45

15.1 Overview ...................................................................................................................................................................................................45

15.2 Test set-up ................................................................................................................................................................................................46

15.3 Generating test signals for the IUT input section SP3 ........................................................................................47

15.4 Analysis of test results ...................................................................................................................................................................47

15.5 Test flow overview ............................................................................................................................................................................47

15.6 Measurement of SP3 input signal of the IUT ..............................................................................................................48

15.7 Measurement of SP2 output signal of the IUT ..........................................................................................................49

15.8 Measurement of RL ..........................................................................................................................................................................49

15.9 Functional test of wake-up and shutdown ...................................................................................................................49

16 Direct physical measuring accuracy..............................................................................................................................................50

Annex A (informative) Limited physical layer conformance for development tools .......................................51

Annex B (normative) SP3 stress conditions ...............................................................................................................................................52

Annex C (informative) Test fixture .......................................................................................................................................................................53

Annex D (informative) Overview on test modes ....................................................................................................................................56

Bibliography .............................................................................................................................................................................................................................57

iv © ISO 2021 – All rights reserved
---------------------- Page: 4 ----------------------
ISO 21806-13:2021(E)
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 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 with ISO, also take part in the work.

ISO collaborates closely with the International Electrotechnical Commission (IEC) on all matters of

electrotechnical standardization.

The procedures used to develop this document and those intended for its further maintenance are

described in the ISO/IEC Directives, Part 1. In particular, the different approval criteria needed for the

different types of ISO documents should be noted. This document was drafted in accordance with the

editorial rules of the ISO/IEC Directives, Part 2 (see www .iso .org/ directives).

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. Details of

any patent rights identified during the development of the document will be in the Introduction and/or

on the ISO list of patent declarations received (see www .iso .org/ patents).

Any trade name used in this document is information given for the convenience of users and does not

constitute an endorsement.

For an explanation of the voluntary nature of standards, the meaning of ISO specific terms and

expressions related to conformity assessment, as well as information about ISO's adherence to the

World Trade Organization (WTO) principles in the Technical Barriers to Trade (TBT), see www .iso .org/

iso/ foreword .html.

This document was prepared by Technical Committee ISO/TC 22, Road vehicles, Subcommittee SC 31,

Data communication.
A list of all parts in the ISO 21806 series can be found on the ISO website.

Any feedback or questions on this document should be directed to the user’s national standards body. A

complete listing of these bodies can be found at www .iso .org/ members .html.
© ISO 2021 – All rights reserved v
---------------------- Page: 5 ----------------------
ISO 21806-13:2021(E)
Introduction

The Media Oriented Systems Transport (MOST) communication technology was initially developed at

the end of the 1990s in order to support complex audio applications in cars. The MOST Cooperation was

founded in 1998 with the goal to develop and enable the technology for the automotive industry. Today,

MOST enables the transport of high Quality of Service (QoS) audio and video together with packet

data and real-time control to support modern automotive multimedia and similar applications. MOST is

a function-oriented communication technology to network a variety of multimedia devices comprising

one or more MOST nodes.
Figure 1 shows a MOST network example.
Figure 1 — MOST network example
The MOST communication technology provides:
— synchronous and isochronous streaming,
— small overhead for administrative communication control,
— a functional and hierarchical system model,
— API standardization through a function block (FBlock) framework,
— free partitioning of functionality to real devices,
— service discovery and notification, and
[2]

— flexibly scalable automotive-ready Ethernet communication according to ISO/IEC/IEEE 8802-3 .

MOST is a synchronous time-division-multiplexing (TDM) network that transports different data types

on separate channels at low latency. MOST supports different bit rates and physical layers. The network

clock is provided with a continuous data signal.

1) MOST® is the registered trademark of Microchip Technology Inc. This information is given for the convenience

of users of this document and does not constitute an endorsement by ISO.
vi © ISO 2021 – All rights reserved
---------------------- Page: 6 ----------------------
ISO 21806-13:2021(E)

Within the synchronous base data signal, the content of multiple streaming connections and control

data is transported. For streaming data connections, bandwidth is reserved to avoid interruptions,

collisions, or delays in the transport of the data stream.

MOST specifies mechanisms for sending anisochronous, packet-based data in addition to control data

and streaming data. The transmission of packet-based data is separated from the transmission of

control data and streaming data. None of them interfere with each other.

A MOST network consists of devices that are connected to one common control channel and packet

channel.

In summary, MOST is a network that has mechanisms to transport the various signals and data streams

that occur in multimedia and infotainment systems.

The ISO standards maintenance portal (https:// standards .iso .org/ iso/ ) provides references to MOST

specifications implemented in today's road vehicles because easy access via hyperlinks to these

specifications is necessary. It references documents that are normative or informative for the MOST

versions 4V0, 3V1, 3V0, and 2V5.

The ISO 21806 series has been established in order to specify requirements and recommendations

for implementing the MOST communication technology into multimedia devices and to provide

conformance test plans for implementing related test tools and test procedures.

To achieve this, the ISO 21806 series is based on the open systems interconnection (OSI) basic reference

[1] [3]

model in accordance with ISO/IEC 7498-1 and ISO/IEC 10731 , which structures communication

systems into seven layers as shown in Figure 2. Stream transmission applications use a direct stream

data interface (transparent) to the data link layer.
© ISO 2021 – All rights reserved vii
---------------------- Page: 7 ----------------------
ISO 21806-13:2021(E)
Figure 2 — The ISO 21806 series reference according to the OSI model

The International Organization for Standardization (ISO) draws attention to the fact that it is claimed

that compliance with this document may involve the use of a patent.

ISO takes no position concerning the evidence, validity and scope of this patent right.

The holder of this patent right has assured ISO that he/she is willing to negotiate licences under

reasonable and non-discriminatory terms and conditions with applicants throughout the world. In

this respect, the statement of the holder of this patent right is registered with ISO. Information may be

obtained from the patent database available at www .iso .org/ patents.

Attention is drawn to the possibility that some of the elements of this document may be the subject of

patent rights other than those in the patent database. ISO shall not be held responsible for identifying

any or all such patent rights.
viii © ISO 2021 – All rights reserved
---------------------- Page: 8 ----------------------
INTERNATIONAL STANDARD ISO 21806-13:2021(E)
Road vehicles — Media Oriented Systems Transport
(MOST) —
Part 13:
50-Mbit/s balanced media physical layer conformance test
plan
1 Scope

This document specifies the conformance test plan for the 50-Mbit/s balanced media physical layer for

MOST (MOST50 bPHY), a synchronous time-division-multiplexing network.

This document specifies the basic conformance test measurement methods, relevant for verifying

compatibility of networks, nodes, and MOST components with the requirements specified in

ISO 21806-12.
2 Normative references

The following documents are referred to in the text in such a way that some or all of their content

constitutes requirements 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 21806-1, Road vehicles — Media Oriented Systems Transport (MOST) — Part 1: General information

and definitions

ISO 21806-12, Road vehicles — Media Oriented Systems Transport (MOST) — Part 12: 50-Mbit/s balanced

media physical layer

EN 50289-1-8, Communication cables — Specifications for lest methods — Part 1-8: Electrical test

methods — Attenuation

EN 50289-1-11, Communication cables — Specifications for lest methods — Part 1-11: Electrical test

methods — Characteristic impedance, input impedance, return loss

No JEDEC JESD8C.01, interface Standard for Nominal 3 V/3.3 V Supply Digital Integrated Circuits

3 Terms and definitions

For the purposes of this document, the terms and definitions given in ISO 21806-1, ISO 21806-12 and

the following apply.

ISO and IEC maintain terminological databases for use in standardization at the following addresses:

— ISO Online browsing platform: available at https:// www .iso .org/ obp
— IEC Electropedia: available at http:// www .electropedia .org/
2) Available at https:// www .jedec .org/ .
© ISO 2021 – All rights reserved 1
---------------------- Page: 9 ----------------------
ISO 21806-13:2021(E)
3.1
intersymbol interference

disturbance due to the overflowing into the signal element representing a wanted digit of signal

elements representing preceding or following digits
[SOURCE: IEC Electropedia, 702-08-33]
4 Symbols and abbreviated terms
4.1 Symbols
--- empty table cell or feature undefined
ε relative permittivity
F frequency
ρ bit rate
ρ network frame rate
t time
T temperature
T ambient temperature
T typical temperature
Typ
4.2 Abbreviated terms
AFE analogue frontend
AJ alignment jitter
BALUN balanced-unbalanced
BEC balanced media to electrical converter
BR bitrate
BTR balanced media transceiver
BW bandwidth
Cfg configuration
CH channel
DC direct current
DSO digital sampling oscilloscope
EBC electrical to balanced media converter
FFT fast Fourier transformation
IUT implementation under test
2 © ISO 2021 – All rights reserved
---------------------- Page: 10 ----------------------
ISO 21806-13:2021(E)
MNC MOST network controller
PG pattern generator
PLL phase lock loop
PSD power spectral density
RBW resolution bandwidth
RMS root mean square
SP specification point
TDR time-domain reflectometer
TJ transferred jitter
UI unit interval
VNA vector network analyser
5 Conventions
[3]

This document is based on OSI service conventions as specified in ISO/IEC 10731 .

6 Operating conditions and measurement tools, requested accuracy
6.1 Operating conditions

Temperature range for MOST components: T = -40 °C to +105 °C according to ISO 21806-12:2021, 11.3.

Voltage range for MOST components: V and V , with an operating range of 3,3 V ± 0,165 V

CCCN CCSW
according to ISO 21806-12:2021, Clause 10.

NOTE There are functional requirements for the EBC within an extended voltage supply range according to

ISO 21806-12.
6.2 Apparatus — Measurement tools, requested accuracy

Apart from the measurement tools listed in this subclause, depending on the chosen test method and

method to generate stimuli for the test, further equipment is necessary (e.g. electrical attenuator,

discrete filter module to emulate cable transfer function). Performance requirements of such equipment

depend on the use case.
The following list provides the measurement tools.
6.2.1 Oscilloscope
— digital sampling oscilloscope;
— sampling rate ≥5 gigasample/s;
— bandwidth ≥1 GHz;
— sampling memory ≥10 megasample;
— active probe (single-ended, differential).
© ISO 2021 – All rights reserved 3
---------------------- Page: 11 ----------------------
ISO 21806-13:2021(E)
6.2.2 VNA or TDR (TDR bandwidth ≥3,5 GHz).
6.2.3 Ampere meter
— accuracy ≤2 µA;
— trigger input (for timing measurements).
6.2.4 Pattern generator for generating MOST50 bPHY stress pattern
— bandwidth 100 Mbit/s;
— trigger output (for timing measurements).
7 Electrical characteristics

LVTTL testing of MOST devices or MOST components shall be performed according to JEDEC No.

JESD8C.01.
8 Balanced media characteristics
8.1 Threshold for detection of alignment and transferred jitter

All jitter measurements are based on detection of edges in the data stream. The threshold for detecting

edges is set to 0 V of the differential signal (zero-crossing). DC offset in the measurements shall be

minimized as it may indirectly compromise timing-parameter results, see 10.2 and 10.3.

8.2 RMS signal amplitude

In ISO 21806-12:2021, 9.2, output signal power boundaries for SP2 and minimum input signal power at

SP3 are defined as RMS voltage.

A waveform, signal voltage over time, is acquired on an oscilloscope. The RMS voltage V is calculated

RMS
according to Formula (1).
V = Vi (1)
RMS ∑
i=1
where
V is the root-mean-square signal voltage;
RMS
N is the number of time steps with equidistant time interval;
V is the voltage amplitude at a specific time step;
i is the index of summation.

RMS signal voltage amplitude gives a representation of the average signal power P as specified in

Formula (2).
RMS
P = (2)
where
4 © ISO 2021 – All rights reserved
---------------------- Page: 12 ----------------------
ISO 21806-13:2021(E)
P is the average signal power in [W];
V is the root-mean-square signal voltage.
RMS
R resistance of 100 Ω.

In order to get to a representative average value, it requires a long-term observation. Depending

on the chosen SP2 and applied channel losses, intersymbol interference impact affects the signal to

be measured. It may lead to locally distributed RMS minima and maxima when choosing only short

snippets of the signal. The acquired waveform shall have a minimum length of 125 µs (125 µs equals six

frames with a frame rate of 48 kHz).

DC offset in the measurements shall be minimized as it may indirectly compromise RMS signal voltage

amplitude results, see 10.2 and 10.3.
8.3 PSD of SP2 output signal

PSD as specified in ISO 21806-12:2021, 9.2 is used as a link quality criterion at SP2. The main purpose is

to limit pulse shape variations and inherently limit the transmitted signal bandwidth.

Several measurement options are available to perform spectral signal analysis. A method using time-

domain data acquisition followed by FFT post-processing is given for reference. Other measurement

methods are permitted. In the case of discrepancies, the reference method shall be used.

PSD shall be measured with an RMS detector and using an effective RBW of 500 kHz. Besides directly

measuring PSD with 500 kHz resolution bandwidth, this can be achieved
...

INTERNATIONAL ISO
STANDARD 21806-13
First edition
Road vehicles — Media Oriented
Systems Transport (MOST) —
Part 13:
50-Mbit/s balanced media physical
layer conformance test plan
Véhicules routiers — Système de transport axé sur les médias —
Partie 13: Plan d'essais de conformité de la couche physique en milieu
équilibré à 50-Mbit/s
PROOF/ÉPREUVE
Reference number
ISO 21806-13:2021(E)
ISO 2021
---------------------- Page: 1 ----------------------
ISO 21806-13:2021(E)
COPYRIGHT PROTECTED DOCUMENT
© ISO 2021

All rights reserved. Unless otherwise specified, or required in the context of its implementation, no part of this publication may

be reproduced or utilized otherwise in any form or by any means, electronic or mechanical, including photocopying, or posting

on the internet or an intranet, without prior written permission. Permission can be requested from either ISO at the address

below or ISO’s member body in the country of the requester.
ISO copyright office
CP 401 • Ch. de Blandonnet 8
CH-1214 Vernier, Geneva
Phone: +41 22 749 01 11
Email: copyright@iso.org
Website: www.iso.org
Published in Switzerland
ii PROOF/ÉPREUVE © ISO 2021 – All rights reserved
---------------------- Page: 2 ----------------------
ISO 21806-13:2021(E)
Contents Page

Foreword ..........................................................................................................................................................................................................................................v

Introduction ................................................................................................................................................................................................................................vi

1 Scope ................................................................................................................................................................................................................................. 1

2 Normative references ...................................................................................................................................................................................... 1

3 Terms and definitions ..................................................................................................................................................................................... 1

4 Symbols and abbreviated terms ........................................................................................................................................................... 2

4.1 Symbols ......................................................................................................................................................................................................... 2

4.2 Abbreviated terms ............................................................................................................................................................................... 2

5 Conventions ............................................................................................................................................................................................................... 3

6 Operating conditions and measurement tools, requested accuracy ..............................................................3

6.1 Operating conditions ......................................................................................................................................................................... 3

6.2 Apparatus — Measurement tools, requested accuracy ....................................................................................... 3

7 Electrical characteristics .............................................................................................................................................................................. 4

8 Balanced media characteristics ............................................................................................................................................................ 4

8.1 Threshold for detection of alignment and transferred jitter ........................................................................... 4

8.2 RMS signal amplitude ......... ............................................................................................................................................................... 4

8.3 PSD of SP2 output signal ................................................................................................................................................................ 5

8.4 Attenuation of electrical interconnect ................................................................................................................................ 7

8.4.1 General...................................................................................................................................................................................... 7

8.4.2 Test procedure general ............................................................................................................................................... 8

8.4.3 Example set-up test procedure............................................................................................................................ 8

8.4.4 Test procedure for data acquisition................................................................................................................. 8

8.4.5 Impact of attenuation on the data signal .................................................................................................... 9

8.5 Characteristic impedance of balanced media ............................................................................................................10

8.6 RL of PCB interfaces ........................................................................................................................................................................13

8.7 Receive tolerance ...............................................................................................................................................................................15

8.7.1 General...................................................................................................................................................................................15

8.7.2 Pattern generator .........................................................................................................................................................15

8.7.3 Arbitrary signal generator ....................................................................................................................................16

8.7.4 Cable assembly or its analogue representation .................................................................................16

8.7.5 Stimulus creation for SP3 ......................................................................................................................................16

9 Measurement of phase variation ......................................................................................................................................................18

9.1 General ........................................................................................................................................................................................................18

9.2 Measuring alignment jitter ........................................................................................................................................................20

9.3 Measuring transferred jitter .....................................................................................................................................................23

10 Test set-ups..............................................................................................................................................................................................................26

10.1 General ........................................................................................................................................................................................................26

10.2 Set-ups for SP2 link quality .......................................................................................................................................................26

10.3 Set-ups for SP3 link quality .......................................................................................................................................................28

10.4 Set-ups for SP3 receive tolerance ........................................................................................................................................30

11 Power-on and power-off ............................................................................................................................................................................31

11.1 General ........................................................................................................................................................................................................31

11.2 Measuring EBC parameters ......................................................................................................................................................32

11.2.1 Measuring EBC parameters – Test set-up ...............................................................................................32

11.2.2 Measuring EBC parameters – Signal charts ...........................................................................................33

11.2.3 Measuring EBC parameters – Test sequences .....................................................................................33

11.3 Measuring BEC parameters ......................................................................................................................................................35

11.3.1 Measuring BEC parameters – Test set-up ...............................................................................................35

11.3.2 Measuring BEC parameters – Signal chart .............................................................................................37

11.3.3 Measuring BEC parameters – Test sequences .....................................................................................37

© ISO 2021 – All rights reserved PROOF/ÉPREUVE iii
---------------------- Page: 3 ----------------------
ISO 21806-13:2021(E)

12 Detecting bit rate (frequency reference) .................................................................................................................................40

13 System performance ......................................................................................................................................................................................40

13.1 General ........................................................................................................................................................................................................40

13.2 SP3 receiver tolerance ...................................................................................................................................................................41

13.3 TimingMaster delay tolerance ................................................................................................................................................41

14 Conformance test of 50-Mbit/s balanced media physical layer .......................................................................44

14.1 Location of interfaces .....................................................................................................................................................................44

14.2 Control signals ......................................................................................................................................................................................44

14.3 Limited access to specification points .............................................................................................................................45

14.4 Parameter overview ........................................................................................................................................................................45

15 Limited physical layer conformance .............................................................................................................................................46

15.1 Overview ...................................................................................................................................................................................................46

15.2 Test set-up ................................................................................................................................................................................................46

15.3 Generating test signals for the IUT input section SP3 ........................................................................................47

15.4 Analysis of test results ...................................................................................................................................................................47

15.5 Test flow overview ............................................................................................................................................................................47

15.6 Measurement of SP3 input signal of the IUT ..............................................................................................................48

15.7 Measurement of SP2 output signal of the IUT ..........................................................................................................49

15.8 Measurement of RL ..........................................................................................................................................................................50

15.9 Functional test of wake-up and shutdown ...................................................................................................................50

16 Direct physical measuring accuracy..............................................................................................................................................50

Annex A (informative) Limited physical layer conformance for development tools .......................................52

Annex B (normative) SP3 stress conditions ...............................................................................................................................................53

Annex C (informative) Test fixture .......................................................................................................................................................................54

Annex D (informative) Overview on test modes ....................................................................................................................................57

Bibliography .............................................................................................................................................................................................................................58

iv PROOF/ÉPREUVE © ISO 2021 – All rights reserved
---------------------- Page: 4 ----------------------
ISO 21806-13:2021(E)
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 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 with ISO, also take part in the work.

ISO collaborates closely with the International Electrotechnical Commission (IEC) on all matters of

electrotechnical standardization.

The procedures used to develop this document and those intended for its further maintenance are

described in the ISO/IEC Directives, Part 1. In particular, the different approval criteria needed for the

different types of ISO documents should be noted. This document was drafted in accordance with the

editorial rules of the ISO/IEC Directives, Part 2 (see www .iso .org/ directives).

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. Details of

any patent rights identified during the development of the document will be in the Introduction and/or

on the ISO list of patent declarations received (see www .iso .org/ patents).

Any trade name used in this document is information given for the convenience of users and does not

constitute an endorsement.

For an explanation of the voluntary nature of standards, the meaning of ISO specific terms and

expressions related to conformity assessment, as well as information about ISO's adherence to the

World Trade Organization (WTO) principles in the Technical Barriers to Trade (TBT), see www .iso .org/

iso/ foreword .html.

This document was prepared by Technical Committee ISO/TC 22, Road vehicles, Subcommittee SC 31,

Data communication.
A list of all parts in the ISO 21806 series can be found on the ISO website.

Any feedback or questions on this document should be directed to the user’s national standards body. A

complete listing of these bodies can be found at www .iso .org/ members .html.
© ISO 2021 – All rights reserved PROOF/ÉPREUVE v
---------------------- Page: 5 ----------------------
ISO 21806-13:2021(E)
Introduction

The Media Oriented Systems Transport (MOST) communication technology was initially developed at

the end of the 1990s in order to support complex audio applications in cars. The MOST Cooperation was

founded in 1998 with the goal to develop and enable the technology for the automotive industry. Today,

MOST enables the transport of high Quality of Service (QoS) audio and video together with packet

data and real-time control to support modern automotive multimedia and similar applications. MOST is

a function-oriented communication technology to network a variety of multimedia devices comprising

one or more MOST nodes.
Figure 1 shows a MOST network example.
Figure 1 — MOST network example
The MOST communication technology provides:
— synchronous and isochronous streaming,
— small overhead for administrative communication control,
— a functional and hierarchical system model,
— API standardization through a function block (FBlock) framework,
— free partitioning of functionality to real devices,
— service discovery and notification, and
[2]

— flexibly scalable automotive-ready Ethernet communication according to ISO/IEC/IEEE 8802-3 .

MOST is a synchronous time-division-multiplexing (TDM) network that transports different data types

on separate channels at low latency. MOST supports different bit rates and physical layers. The network

clock is provided with a continuous data signal.

1) MOST® is the registered trademark of Microchip Technology Inc. This information is given for the convenience

of users of this document and does not constitute an endorsement by ISO.
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ISO 21806-13:2021(E)

Within the synchronous base data signal, the content of multiple streaming connections and control

data is transported. For streaming data connections, bandwidth is reserved to avoid interruptions,

collisions, or delays in the transport of the data stream.

MOST specifies mechanisms for sending anisochronous, packet-based data in addition to control data

and streaming data. The transmission of packet-based data is separated from the transmission of

control data and streaming data. None of them interfere with each other.

A MOST network consists of devices that are connected to one common control channel and packet

channel.

In summary, MOST is a network that has mechanisms to transport the various signals and data streams

that occur in multimedia and infotainment systems.

The ISO standards maintenance portal (https:// standards .iso .org/ iso/ ) provides references to MOST

specifications implemented in today's road vehicles because easy access via hyperlinks to these

specifications is necessary. It references documents that are normative or informative for the MOST

versions 4V0, 3V1, 3V0, and 2V5.

The ISO 21806 series has been established in order to specify requirements and recommendations

for implementing the MOST communication technology into multimedia devices and to provide

conformance test plans for implementing related test tools and test procedures.

To achieve this, the ISO 21806 series is based on the open systems interconnection (OSI) basic reference

[1] [3]

model in accordance with ISO/IEC 7498-1 and ISO/IEC 10731 , which structures communication

systems into seven layers as shown in Figure 2. Stream transmission applications use a direct stream

data interface (transparent) to the data link layer.
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ISO 21806-13:2021(E)
Figure 2 — The ISO 21806 series reference according to the OSI model

The International Organization for Standardization (ISO) draws attention to the fact that it is claimed

that compliance with this document may involve the use of a patent.

ISO takes no position concerning the evidence, validity and scope of this patent right.

The holder of this patent right has assured ISO that he/she is willing to negotiate licences under

reasonable and non-discriminatory terms and conditions with applicants throughout the world. In

this respect, the statement of the holder of this patent right is registered with ISO. Information may be

obtained from the patent database available at www .iso .org/ patents.

Attention is drawn to the possibility that some of the elements of this document may be the subject of

patent rights other than those in the patent database. ISO shall not be held responsible for identifying

any or all such patent rights.
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INTERNATIONAL STANDARD ISO 21806-13:2021(E)
Road vehicles — Media Oriented Systems Transport
(MOST) —
Part 13:
50-Mbit/s balanced media physical layer conformance
test plan
1 Scope

This document specifies the conformance test plan for the 50-Mbit/s balanced media physical layer for

MOST (MOST50 bPHY), a synchronous time-division-multiplexing network.

This document specifies the basic conformance test measurement methods, relevant for verifying

compatibility of networks, nodes, and MOST components with the requirements specified in

ISO 21806-12.
2 Normative references

The following documents are referred to in the text in such a way that some or all of their content

constitutes requirements 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 21806-1, Road vehicles — Media Oriented Systems Transport (MOST) — Part 1: General information

and definitions

ISO 21806-12, Road vehicles — Media Oriented Systems Transport (MOST) — Part 12: 50-Mbit/s balanced

media physical layer

EN 50289-1-8, Communication cables — Specifications for lest methods — Part 1-8: Electrical test

methods — Attenuation

EN 50289-1-11, Communication cables — Specifications for lest methods — Part 1-11: Electrical test

methods — Characteristic impedance, input impedance, return loss

No JEDEC JESD8C.01, interface Standard for Nominal 3 V/3.3 V Supply Digital Integrated Circuits

3 Terms and definitions

For the purposes of this document, the terms and definitions given in ISO 21806-1, ISO 21806-12 and

the following apply.

ISO and IEC maintain terminological databases for use in standardization at the following addresses:

— ISO Online browsing platform: available at https:// www .iso .org/ obp
— IEC Electropedia: available at http:// www .electropedia .org/
2) Available at https:// www .jedec .org/ .
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ISO 21806-13:2021(E)
3.1
intersymbol interference

disturbance due to the overflowing into the signal element representing a wanted digit of signal

elements representing preceding or following digits
[SOURCE: IEC Electropedia, 702-08-33]
4 Symbols and abbreviated terms
4.1 Symbols
--- empty table cell or feature undefined
a amplitude
ε relative permittivity
F frequency
ρ bit rate
ρ network frame rate
t time
T temperature
T ambient temperature
T typical temperature
Typ
4.2 Abbreviated terms
AFE analogue frontend
AJ alignment jitter
BALUN balanced-unbalanced
BEC balanced media to electrical converter
BR bitrate
BTR balanced media transceiver
BW bandwidth
Cfg configuration
CH channel
DC direct current
DSO digital sampling oscilloscope
EBC electrical to balanced media converter
FFT fast Fourier transformation
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ISO 21806-13:2021(E)
IUT implementation under test
MNC MOST network controller
PG pattern generator
PLL phase lock loop
PSD power spectral density
RBW resolution bandwidth
RMS root mean square
SP specification point
TDR time-domain reflectometer
TJ transferred jitter
UI unit interval
VNA vector network analyser
5 Conventions
[3]

This document is based on OSI service conventions as specified in ISO/IEC 10731 .

6 Operating conditions and measurement tools, requested accuracy
6.1 Operating conditions

Temperature range for MOST components: T = -40 °C to +95 °C according to ISO 21806-12:2021, 11.3.

Voltage range for MOST components: V and V , with an operating range of 3,3 V ± 0,165 V

CCCN CCSW
according to ISO 21806-12:2021, Clause 10.

NOTE There are functional requirements for the EBC within an extended voltage supply range according to

ISO 21806-12.
6.2 Apparatus — Measurement tools, requested accuracy

Apart from the measurement tools listed in this subclause, depending on the chosen test method and

method to generate stimuli for the test, further equipment is necessary (e.g. electrical attenuator,

discrete filter module to emulate cable transfer function). Performance requirements of such equipment

depend on the use case.
The following list provides the measurement tools.
6.2.1 Oscilloscope
— digital sampling oscilloscope;
— sampling rate ≥5 gigasample/s;
— bandwidth ≥1 GHz;
— sampling memory ≥10 megasample;
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ISO 21806-13:2021(E)
— active probe (single-ended, differential).
6.2.2 VNA or TDR (TDR bandwidth ≥3,5 GHz).
6.2.3 Ampere meter
— accuracy ≤2 µA;
— trigger input (for timing measurements).
6.2.4 Pattern generator for generating MOST50 bPHY stress pattern
— bandwidth 100 Mbit/s;
— trigger output (for timing measurements).
7 Electrical characteristics

LVTTL testing of MOST devices or MOST components shall be performed according to JEDEC No.

JESD8C.01.
8 Balanced media characteristics
8.1 Threshold for detection of alignment and transferred jitter

All jitter measurements are based on detection of edges in the data stream. The threshold for detecting

edges is set to 0 V of the differential signal (zero-crossing). DC offset in the measurements shall be

minimized as it may indirectly compromise timing-parameter results, see 10.2 and 10.3.

8.2 RMS signal amplitude

In ISO 21806-12:2021, 9.2, output signal power boundaries for SP2 and minimum input signal power at

SP3 are defined as RMS voltage.

A waveform, signal voltage over time, is acquired on an oscilloscope. The RMS voltage V is calculated

RMS
according to Formula (1).
V = Vi (1)
RMS
i=1
where
V is the root-mean-square signal voltage;
RMS
N is the number of time steps with equidistant time interval;
V is the voltage amplitude at a specific time step;
i is the index of summation.

RMS signal voltage amplitude gives a representation of the average signal power P as specified in

Formula (2).
RMS
P = (2)
where
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ISO 21806-13:2021(E)
P is the average signal power in [W];
V is the root-mean-square signal voltage.
RMS
R resistance of 100 Ω.

In order to get to a representative average value, it requires a long-term observation. Depending

on the chosen SP2 and applied channel losses, intersymbol interference impact affects the signal to

be measured. It may lead to locally distributed RMS minima and maxima when choosing only short

snippets of the signal. The acquired waveform shall have a minimum length of >125 µs (125 µs equals

six frames with a frame rate of 48 kHz).

DC offset in the measurements shall be minimized as it may indirectly compromise RMS signal voltage

amplitude results, see 10.2 and 10.3.
8.3 PSD of SP2 output signal

PSD as specified in ISO 21806-12:2021, 9.2 is used as a link quality criterion at SP2. The main purpose is

to limit pulse shape variations and inherently limit the transmitted signal bandwidth.

Several measurement options are available to perform spectral signal analysis. A method using time-

domain data acquisition followed by FFT post-processing is given for reference. The following method

is provided as a reference procedure. Other measurement methods are permitted. In the case of

...

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