ISO 20794-4:2020

Road vehicles — Clock extension peripheral interface (CXPI) — Part 4: Data link layer and physical layer

This document specifies the CXPI data link layer and the CXPI physical layer. The DLL is based on: — priority-based CXPI network access; — non-destructive content-based arbitration; — broadcast frame transfer and acceptance filtering; and — node related error detection and error signalling. The CXPI physical layer (PHY) requirements comprise of: — physical signalling (PS) sub-layer, which specifies the requirements of the clock generation function, the encoding and decoding of CXPI frames, and bit-wise collision resolution logic; — physical media attachment (PMA) sub-layer, which specifies the requirements of the signal shaping waveform logic; — physical media dependent (PMD) sub-layer, which specifies the requirements of the CXPI network termination, electrostatic discharge protection, etc., and device connector requirements; and — physical media (PM), which specifies the requirements of the CXPI network cable/wiring harness.

Véhicules routiers — Interface du périphérique d'extension d'horloge (CXPI) — Partie 4: Couches de liaison de données et physique

General Information

• Status: Published
• Publication Date: 04-Feb-2020
• ICS: 43.040.15 - Car informatics. On board computer systems
• Technical Committee: ISO/TC 22/SC 31 - Data communication
• Drafting Committee: ISO/TC 22/SC 31/WG 3 - In-vehicle networks
• Current Stage: 9020 - International Standard under periodical review
• Start Date: 15-Jan-2025
• Due Date: 15-Jan-2025
• Completion Date: 15-Jan-2025

Relations

• Consolidated By: ISO 3262-6:2022 - Extenders — Specifications and methods of test — Part 6: Precipitated calcium carbonate
• Effective Date: 06-Jun-2022

Standards Content (Sample)

INTERNATIONAL ISO
STANDARD 20794-4
First edition
2020-02
Road vehicles — Clock extension
peripheral interface (CXPI) —
Part 4:
Data link layer and physical layer
Véhicules routiers — Interface du périphérique d'extension d'horloge
(CXPI) —
Partie 4: Couches de liaison de données et physique
Reference number
©
ISO 2020
© ISO 2020
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: [phone]
Fax: [phone]
Email: [e-mail]
Website: www.iso.org
Published in Switzerland
ii © ISO 2020 – All rights reserved

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 . 3
5 Conventions . 4
6 Introduction to data link layer and physical layer . 5
6.1 Frames . 5
6.2 Frame collision avoidance . 5
6.3 Error detection and indication . 5
6.4 Clock transmission and detection . 5
7 Service interface parameters (SIP) . 5
7.1 SIP — General . 5
7.2 SIP — Data type definitions . 5
7.3 SIP — Ftype, frame type . 6
7.4 SIP — ReqId, request identifier . 6
7.5 SIP — ReqTypeId, request type identifier . 6
7.6 SIP — PDU, protocol data unit . 6
7.7 SIP — Length, length of PDU . 7
7.8 SIP — ev_wakeup_ind, event wake-up indication (optional) . 7
7.9 SIP — cmd_wakeup_req, command wake-up request . 7
7.10 SIP — NMInfo, network management information . . 8
7.11 SIP — SCT, sequence count . 8
7.12 SIP — Result, result . 8
8 Data link layer (DLL) . 8
8.1 SI — L_Data.req and L_Data.ind service interface . 8
8.2 SI — L_Data.req and L_Data.ind service interface parameter mapping . 9
8.3 DLL — Service interface with L_Ftype parameter mapping .10
8.3.1 DLL — L_Data.req and L_Data.ind with L_Ftype = NormalCom (L_
Length = NULL) .10
8.3.2 DLL — L_Data.req and L_Data.ind with L_Ftype = NormalCom (L_
Length ≥ 0016) . .11
8.3.3 DLL — L_Data.req and L_Data.ind interface with L_Ftype = DiagNodeCfg .12
8.4 DLL — Frame fields .13
8.4.1 DLL — Frame field definition .13
8.4.2 DLL — Request type identifier and request identifier fields.14
8.4.3 DLL — L_FI (frame information) field .15
8.4.4 DLL — L_DATA (data field) .16
8.4.5 DLL — L_CRC field .17
8.5 DLL — Internal operation .19
8.6 DLL — Timing parameters .20
8.6.1 DLL — IBS timing handling .20
8.6.2 DLL — IFS timing handling .20
8.6.3 DLL — Beginning condition of frame .21
8.6.4 DLL — Start of frame .22
8.6.5 DLL — Frame transmission time .22
8.7 DLL — Completion of frame .23
8.7.1 DLL — General .23
8.7.2 DLL — Completing condition of L_PTYPE field .23
8.7.3 DLL — Completing condition of L_PID field .23
8.7.4 DLL — Completing condition of frame .24
8.8 DLL — Byte arbitration .24
8.9 DLL — Function models .24
8.9.1 DLL — Transmission logic .24
8.9.2 DLL — Reception logic .25
8.10 DLL — Error detection .26
8.10.1 DLL — General .26
8.10.2 DLL — Byte error (Err_DLL_Byte) .26
8.10.3 DLL — CRC error (Err_DLL_CRC) .27
8.10.4 DLL — Parity error (Err_DLL_Parity) .27
8.10.5 DLL — Data length code error (Err_DLL_DLC) .27
8.10.6 DLL — Data length code extension error (Err_DLL_DLCext) .27
8.10.7 DLL — Framing error (Err_DLL_Framing) .28
8.10.8 DLL — Exception handling for L_FI_DLC = '1111 ' detection .28
9 Physical layer (PHY) .28
9.1 PHY — Overview .28
9.2 PHY — Concept of waveform generation .29
9.3 PHY — Physical signalling (PS) requirements .30
9.3.1 PHY — PS general .30
9.3.2 PHY — PS physical interface configuration .31
9.3.3 PHY — PS bit rate .31
9.3.4 PHY — PS bit sample timing .31
9.3.5 PHY — PS encoding and decoding logic .32
9.3.6 PHY — PS clock generation .35
9.3.7 PHY — PS node clock synchronization and bit synchronization .36
9.3.8 PHY — PS detection of clock existence .36
9.3.9 PHY — PS bit-wise collision resolution .37
9.3.10 PHY — PS AC parameters.
...

INTERNATIONAL ISO
STANDARD 20794-4
First edition
2020-02
Road vehicles — Clock extension
peripheral interface (CXPI) —
Part 4:
Data link layer and physical layer
Véhicules routiers — Interface du périphérique d'extension d'horloge
(CXPI) —
Partie 4: Couches de liaison de données et physique
Reference number
©
ISO 2020
© ISO 2020
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: [phone]
Fax: [phone]
Email: [e-mail]
Website: www.iso.org
Published in Switzerland
ii © ISO 2020 – All rights reserved

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 . 3
5 Conventions . 4
6 Introduction to data link layer and physical layer . 5
6.1 Frames . 5
6.2 Frame collision avoidance . 5
6.3 Error detection and indication . 5
6.4 Clock transmission and detection . 5
7 Service interface parameters (SIP) . 5
7.1 SIP — General . 5
7.2 SIP — Data type definitions . 5
7.3 SIP — Ftype, frame type . 6
7.4 SIP — ReqId, request identifier . 6
7.5 SIP — ReqTypeId, request type identifier . 6
7.6 SIP — PDU, protocol data unit . 6
7.7 SIP — Length, length of PDU . 7
7.8 SIP — ev_wakeup_ind, event wake-up indication (optional) . 7
7.9 SIP — cmd_wakeup_req, command wake-up request . 7
7.10 SIP — NMInfo, network management information . . 8
7.11 SIP — SCT, sequence count . 8
7.12 SIP — Result, result . 8
8 Data link layer (DLL) . 8
8.1 SI — L_Data.req and L_Data.ind service interface . 8
8.2 SI — L_Data.req and L_Data.ind service interface parameter mapping . 9
8.3 DLL — Service interface with L_Ftype parameter mapping .10
8.3.1 DLL — L_Data.req and L_Data.ind with L_Ftype = NormalCom (L_
Length = NULL) .10
8.3.2 DLL — L_Data.req and L_Data.ind with L_Ftype = NormalCom (L_
Length ≥ 0016) . .11
8.3.3 DLL — L_Data.req and L_Data.ind interface with L_Ftype = DiagNodeCfg .12
8.4 DLL — Frame fields .13
8.4.1 DLL — Frame field definition .13
8.4.2 DLL — Request type identifier and request identifier fields.14
8.4.3 DLL — L_FI (frame information) field .15
8.4.4 DLL — L_DATA (data field) .16
8.4.5 DLL — L_CRC field .17
8.5 DLL — Internal operation .19
8.6 DLL — Timing parameters .20
8.6.1 DLL — IBS timing handling .20
8.6.2 DLL — IFS timing handling .20
8.6.3 DLL — Beginning condition of frame .21
8.6.4 DLL — Start of frame .22
8.6.5 DLL — Frame transmission time .22
8.7 DLL — Completion of frame .23
8.7.1 DLL — General .23
8.7.2 DLL — Completing condition of L_PTYPE field .23
8.7.3 DLL — Completing condition of L_PID field .23
8.7.4 DLL — Completing condition of frame .24
8.8 DLL — Byte arbitration .24
8.9 DLL — Function models .24
8.9.1 DLL — Transmission logic .24
8.9.2 DLL — Reception logic .25
8.10 DLL — Error detection .26
8.10.1 DLL — General .26
8.10.2 DLL — Byte error (Err_DLL_Byte) .26
8.10.3 DLL — CRC error (Err_DLL_CRC) .27
8.10.4 DLL — Parity error (Err_DLL_Parity) .27
8.10.5 DLL — Data length code error (Err_DLL_DLC) .27
8.10.6 DLL — Data length code extension error (Err_DLL_DLCext) .27
8.10.7 DLL — Framing error (Err_DLL_Framing) .28
8.10.8 DLL — Exception handling for L_FI_DLC = '1111 ' detection .28
9 Physical layer (PHY) .28
9.1 PHY — Overview .28
9.2 PHY — Concept of waveform generation .29
9.3 PHY — Physical signalling (PS) requirements .30
9.3.1 PHY — PS general .30
9.3.2 PHY — PS physical interface configuration .31
9.3.3 PHY — PS bit rate .31
9.3.4 PHY — PS bit sample timing .31
9.3.5 PHY — PS encoding and decoding logic .32
9.3.6 PHY — PS clock generation .35
9.3.7 PHY — PS node clock synchronization and bit synchronization .36
9.3.8 PHY — PS detection of clock existence .36
9.3.9 PHY — PS bit-wise collision resolution .37
9.3.10 PHY — PS AC parameters.
...