for CAN-FD/PN Transceivers iCC 2017 1 Content Standards and their - - PowerPoint PPT Presentation

1

Interoperability challenges for CAN-FD/PN Transceivers

iCC 2017

www.cs-group.de communication & systems group

Content

• Standards and their problems
• Consequences for multi-supplier-solutions
• Ways to achieve interoperability
• Interoperability test specification for

CAN & CAN-FD transceiver devices

• Conclusion

2

www.cs-group.de communication & systems group

Standards and their problems

Why are the standards created?

• To improve quality
• To facilitate innovation
• To increase speed-to-market
• To share development costs

What is the main problem that often arises from standards?

• The specification can be ambiguous
• Specification is not clear enough
• Leads to different interpretations

3

Might it be a problem for my system?

www.cs-group.de communication & systems group

Consequences for multi-supplier-solutions

It might be a problem for multi-supplier-solutions!

• Different suppliers create products according to the same standard

 The products shall interact in the same system

• But! One single standard can be interpreted differently

 Human language itself is ambiguous  A specified standard might contain coverage holes or missing details  The implementer might get something wrong or make a mistake

4

www.cs-group.de communication & systems group

System functionality with multi-supplier-solutions

How to achieve system functionality in systems using multi-supplier-solutions?

5

www.cs-group.de communication & systems group

Ways to achieve interoperability

a) Build up the intended system out of desired components and test it for a proper functionality

 Sole appraisal: the desired components are working as expected within the certain system in a certain environment  Benefit: quite easy set up, by a simple mock-up  Disadvantage: each system, each option needs to be tested

b)Check once the ability to interact with all combinations of devices

 Disadvantage: Number of combinations increases rapidly with available implementations

c) Run at first the conformance test and afterwards the general interoperability test (IOPT) for each implementation

 Benefit: one conformance test + one interoperability test per device, each device usable in all systems

6

www.cs-group.de communication & systems group

Fundamentals of conformance testing

“Conformance testing is testing to determine whether a product or system meets some specified standard that has been developed for efficiency or interoperability.” – to be like specified – Fundamentals of conformance testing

• To apply conformance testing, a specified standard must exist

 This could be an international, national or company-specific standard

• Different implementations of a standard are existing or planned
• Conformance testing verifies whether an implementation

represents the standard or not

• The conformance test is the minimum requirement to guarantee

interoperability

7

www.cs-group.de communication & systems group

Fundamentals of interoperability testing

“Interoperability is a property referring to the ability of diverse products or systems to work together (inter-operate).” – to be able to interact, to communicate – Fundamentals of interoperability

• Interoperability is a property that is based on intended functional

behaviour

 Interoperability is relevant, if multiple entities shall inter-operate  Specified standards shall describe interoperable products and systems, i.e. the intended functional behaviour

• Consequently, interoperability is the result of adherence of

implementations to their specified standard

8

www.cs-group.de communication & systems group

IOPT – Test specification – Scope and aim

Scope

• Definition of test cases and test

requirements to realize a test plan for the verification of CAN transceiver devices regarding their interoperability, even if provided by different manufacturers. Aim

• Increase the probability of collaboration
• f CAN transceivers within a CAN system

and increase the confidence level. Contrary to conformance tests, interoperability tests are based on a predefined reference environment. Single device measurements are not in focus of the interoperability tests.

9

www.cs-group.de communication & systems group

IOPT – Test specification – Addressed transceiver

High-speed CAN transceiver types addressed by the test

• Transceiver with and without bus wake-up capability
• Transceiver with selective wake-up functionality
• Transceiver with selective wake-up functionality

tolerant to CAN-FD frames Bit rates in focus of the tests Reference environment

2 Mbit/s ≤ 1 Mbit/s 5 Mbit/s 5 Mbit/s reference environment 2 Mbit/s reference environment 500 kbit/s reference environment

10

www.cs-group.de communication & systems group

IOPT – Test specification – Network

Standard net test topology

11

Bus failure injection Ground shift

[one node at a time]

Ring communication Tests executed once in a homogeneous and once in a heterogeneous network with dedicated reference devices

www.cs-group.de communication & systems group

IOPT – Test specification – Focus of the tests

Transceiver behaviour can be represented by a state machine

• Transitions from one transceiver state to another represent

reactions to certain events e.g. mode change, bus failures, ground shifts (or their combinations)  IOPT tests focus on the dynamical sequential behaviour

• The interoperability tests verify the sequential behaviour of the

transceiver in reference to the specified sequential behaviour

 Observed and controlled at external points  Consideration of interoperability relevant phenomena

• The verification happens on operation mode variation

in combination with ground shift and bus failures

12

www.cs-group.de communication & systems group

IOPT – Test specification – Test cases

• The test cases are based on operation mode transition

from normal to low-power and the way back, which have to be ensured under all circumstances

• Realized in 7 different test flows,

with different logical bus failures injection point

• Stress conditions covered by test cases

 8 different bus failures

» open wire on CAN high » open wire on CAN low » short circuit between CAN high and battery voltage » short circuit between CAN low and battery voltage » short circuit between CAN high and Ground » short circuit between CAN low and Ground » disconnection of one terminating node

 Ground shift of ±1V applied at each node (one node at a time)  Local wake-up  Wake-up via bus initialized by each node once

13

www.cs-group.de communication & systems group

IOPT – Test specification – Example test flow

14

www.cs-group.de communication & systems group

IOPT – Test specification – Overview of all views

7 test flows of the interoperability test system

15

5 flows with 16 sources for bus wake-up, 3 ground shift values applied at each node (one node at a time  33 scenarios) and 8 bus failures result in 21,120 test cases 2 flows with local wake-up only, 3 ground shift values applied at each node (one node at a time  33 scenarios) and 8 bus failures result in 528 test cases Furthermore the tests need to be executed twice, once in a homogeneous and

• nce in a heterogeneous network with dedicated reference devices

 43,296 single test cases with several verdict points each

www.cs-group.de communication & systems group

Conclusion

• It is a fact that standardized specifications can be interpreted in

different ways

• This fact leads to having applications with similar but not equal

behaviour

 They must be interoperable!  How could this be prevented?  How to guarantee that different solutions will work together?  How could designers and customers ensure interoperable behaviour?

Conformance + interoperability testing is the answer!

16

C & S group GmbH Am Exer 19b Sebastianstrasse 1a 38302 Wolfenbüttel 85049 Ingolstadt Germany Germany Tel +49 53 31 ∙ 90 555 0 Fax +49 53 31 ∙ 90 555 110 info@cs-group.de www.cs-group.de

Thanks for your attention!