GB/T 41588.1-2022 英文版 Road vehicles - Controller area network(CAN) - Part 1: Data link layer and physical signalling

GB/T 41588.1-2022 英文版 道路車輛 控制器局域網(wǎng)（CAN） 第1部分：數(shù)據(jù)鏈路層和物理信令

標(biāo)準(zhǔn)翻譯網(wǎng)提供更多標(biāo)準(zhǔn)英文版。

1 范圍

本文件規(guī)定了一些用于建立CAN數(shù)據(jù)鏈路層模塊間的數(shù)字信息交互的特性?？刂破骶钟蚓W(wǎng)是一

種串行通信協(xié)議,支持分布式實(shí)時(shí)控制和多路復(fù)用,用于道路車輛和其他控制應(yīng)用。

本文件規(guī)定了傳統(tǒng)CAN和可變數(shù)據(jù)速率CAN幀格式。傳統(tǒng)CAN幀格式比特率可達(dá)1Mbit/s,

每幀有效負(fù)載可達(dá)8字節(jié),可變數(shù)據(jù)速率幀格式比特率高于1Mbit/s,每幀有效負(fù)載超過(guò)8字節(jié)。

本文件根據(jù)ISO/IEC 7498-1開(kāi)放系統(tǒng)互連(OSI)的ISO 參考模型,從分層的角度描述了CAN的

2 規(guī)范性引用文件

下列文件中的內(nèi)容通過(guò)文中的規(guī)范性引用而構(gòu)成本文件必不可少的條款。其中,注日期的引用文

件,僅該日期對(duì)應(yīng)的版本適用于本文件;不注日期的引用文件,其最新版本(包括所有的修改單)適用于

本文件。

ISO/IEC 7498-1 信息處理系統(tǒng) 開(kāi)放系統(tǒng)互連 第1部分:基本參考模式

注:GB/T 9387.1-1998 信息技術(shù) 開(kāi)放系統(tǒng)互連 基本參考模型 第1部分:基本模型

ISO/IEC 8802-2 信息技術(shù) 系統(tǒng)間遠(yuǎn)程通信和信息交換 局域網(wǎng)和城域網(wǎng) 特定要求 第2部

分:邏輯鏈路控制

3 術(shù)語(yǔ)和定義

下列術(shù)語(yǔ)和定義適用于本文件。

3.1

仲裁段

使用標(biāo)稱位時(shí)間的段。

3.2

位填充

當(dāng)使用NRZ位表示時(shí),為定期重新同步提供總線狀態(tài)改變的一種幀編碼方法。

注:每當(dāng)發(fā)送邏輯在數(shù)據(jù)中發(fā)現(xiàn)一定數(shù)量(填充寬度)連續(xù)相同的位值,它會(huì)在輸出位流中自動(dòng)填充一個(gè)值相反的位,即填充位。接收方將數(shù)據(jù)幀和遠(yuǎn)程幀中的填充位去掉,即執(zhí)行相反的進(jìn)程。

3.3

總線

所有節(jié)點(diǎn)都是被動(dòng)連接并允許雙向傳輸?shù)耐ㄐ啪W(wǎng)絡(luò)的拓?fù)洹?/p>

3.4

總線比較器

將來(lái)自通信媒介的物理信號(hào)轉(zhuǎn)換成邏輯信息或者數(shù)據(jù)信號(hào)的電路。

3.5

總線驅(qū)動(dòng)

將信息或者數(shù)據(jù)信號(hào)轉(zhuǎn)換成可以在通信媒介上傳輸?shù)奈锢硇盘?hào)的電路。

3.6

總線狀態(tài)

兩種互補(bǔ)的邏輯狀態(tài)中的一種:顯性或隱性。

注:顯性位相當(dāng)于邏輯0,隱性位相當(dāng)于邏輯1。如果同時(shí)傳輸顯性和隱性位,最終總線狀態(tài)為顯性。當(dāng)沒(méi)有傳輸時(shí),總線為空閑。處于空閑時(shí)間時(shí),總線為隱性狀態(tài)。

3.7

傳統(tǒng)標(biāo)準(zhǔn)幀格式

使用11位ID,傳輸時(shí)只用1種位速率,一幀最多包含8個(gè)數(shù)據(jù)字節(jié)的數(shù)據(jù)幀或者遠(yuǎn)程幀格式。

4 符號(hào)和縮略語(yǔ)

下列符號(hào)和縮略語(yǔ)適用于本文件。

ACK:應(yīng)答

AUI:連接單元接口

BCH:BCH碼

BRS:位速率轉(zhuǎn)換

CAN:控制器局域網(wǎng)絡(luò)

CBFF:傳統(tǒng)標(biāo)準(zhǔn)幀格式

CEFF:傳統(tǒng)擴(kuò)展幀格式

CRC:循環(huán)冗余校驗(yàn)

CSMA:載波偵聽(tīng)多路訪問(wèn)

DF:數(shù)據(jù)幀

5 CAN基本概念

5.1 CAN特性

CAN有如下特性:

---基于優(yōu)先級(jí)的多主總線訪問(wèn);

---基于內(nèi)容的非破壞性仲裁;

---所有幀都是廣播;

---幀多播傳輸,由接收方過(guò)濾;

---遠(yuǎn)程數(shù)據(jù)請(qǐng)求;

---配置靈活;

---網(wǎng)絡(luò)范圍的數(shù)據(jù)一致性;

---錯(cuò)誤檢測(cè)和錯(cuò)誤標(biāo)識(shí);

---失去仲裁的、或者未被應(yīng)答的、或傳輸過(guò)程中被錯(cuò)誤干擾的幀自動(dòng)重發(fā);

---區(qū)分臨時(shí)錯(cuò)誤和永久故障節(jié)點(diǎn),且自動(dòng)關(guān)閉失效節(jié)點(diǎn)。

5.2 幀

發(fā)送到總線上的信息,有固定格式的幀,數(shù)據(jù)長(zhǎng)度可能不同,但是最大長(zhǎng)度有限制。當(dāng)總線空閑時(shí),

任何已連接的節(jié)點(diǎn)都允許啟動(dòng)DF或者RF的發(fā)送。當(dāng)總線上沒(méi)有幀發(fā)送時(shí),總線為空閑。此外,任何

已連接的節(jié)點(diǎn)都可能通過(guò)特定幀指示錯(cuò)誤或者過(guò)載情形(EF和OF)。

5.3 總線訪問(wèn)方法

如果兩個(gè)或以上的節(jié)點(diǎn)同時(shí)開(kāi)始發(fā)送DF或者RF,總線訪問(wèn)沖突通過(guò)對(duì)其ID標(biāo)識(shí)符進(jìn)行基于內(nèi)

容的仲裁來(lái)解決。該仲裁機(jī)制保證了不會(huì)丟失信息或者造成時(shí)間的丟失。DF或者RF為高優(yōu)先級(jí)的

發(fā)送方獲得總線訪問(wèn)權(quán)。DF和RF擁有同樣ID時(shí),DF贏得總線仲裁。

6 CAN的層級(jí)架構(gòu)

6.1 參考OSI模型

根據(jù)OSI參考模型(見(jiàn)ISO/IEC 7498-1),本文件的CAN架構(gòu)分為兩層(見(jiàn)圖2):

6.2 協(xié)議定義

兩個(gè)同級(jí)協(xié)議實(shí)體,通過(guò)交換幀或者PDU來(lái)相互通信。

7 LLC子層描述

7.1 概述

根據(jù)ISO/IEC 8802-2,LLC子層描述了DLL的上層部分,它與獨(dú)立于媒介訪問(wèn)方法類型的協(xié)議事

件相關(guān)聯(lián)。

7.2 LLC子層的服務(wù)

7.2.1 無(wú)連接模式傳輸服務(wù)的類型

7.2.2 服務(wù)原語(yǔ)定義

7.2.2.1 概述

此條描述了LLC服務(wù)的服務(wù)原語(yǔ)和其相關(guān)參數(shù),LLC服務(wù)原語(yǔ)的完整列表見(jiàn)表3。

8 LLC和 MAC間的接口

8.1 服務(wù)

MAC子層為本地LLC子層提供以下服務(wù):

---對(duì)LLC幀的 MAC應(yīng)答;

---發(fā)送 MACOF。

發(fā)給LLC子層、或者來(lái)自LLC子層的接口服務(wù)數(shù)據(jù)應(yīng)按7.3定義。

8.2 時(shí)間和時(shí)間觸發(fā)

8.2.1 描述

CAN可以設(shè)計(jì)成支持網(wǎng)絡(luò)范圍的時(shí)鐘同步,基于此,可以額外支持時(shí)間觸發(fā)通信。時(shí)鐘同步選項(xiàng)

描述了網(wǎng)絡(luò)中節(jié)點(diǎn)時(shí)鐘校準(zhǔn)的前提條件。為了讓網(wǎng)絡(luò)中的節(jié)點(diǎn)時(shí)鐘同步,需要一個(gè)共同的參考點(diǎn)。應(yīng)

采用SOF位、或者任意報(bào)文的EOF最后一位的采樣點(diǎn)作為參考點(diǎn)。節(jié)點(diǎn)時(shí)鐘同步便于在更高層協(xié)議

建立網(wǎng)絡(luò)范圍內(nèi)的時(shí)基。如果實(shí)現(xiàn)的話,時(shí)間觸發(fā)通信選項(xiàng)可以使得幀在定義的時(shí)間間隙發(fā)送。

用于建立全網(wǎng)時(shí)基的硬件應(yīng)包含在LLC和 MAC中。

8.2.2 時(shí)基

任何支持時(shí)間和時(shí)間觸發(fā)選項(xiàng)的節(jié)點(diǎn)應(yīng)提供時(shí)基。時(shí)基是一個(gè)至少長(zhǎng)16位的循環(huán)計(jì)數(shù)器,通過(guò)內(nèi)

部或外部產(chǎn)生的滴答計(jì)時(shí)發(fā)生器來(lái)產(chǎn)生時(shí)鐘刻度。

8.2.3 時(shí)間參考點(diǎn)

任何接收或者發(fā)送的報(bào)文都應(yīng)調(diào)用所捕獲的時(shí)基,時(shí)基取自各自報(bào)文的SOF或者EOF最后一位

的采樣點(diǎn)。在成功接收?qǐng)?bào)文后,抓取值應(yīng)被提供給CPU,至少保持一個(gè)報(bào)文,且在接收到下一個(gè)報(bào)文前

仍可讀。

8.2.4 事件產(chǎn)生

從上述的時(shí)基中,應(yīng)至少能產(chǎn)生一個(gè)可編程的事件觸發(fā)。該觸發(fā)應(yīng)能被CPU在0至(216-1)個(gè)時(shí)

間刻度范圍內(nèi)自由編程。

8.3 禁止自動(dòng)重發(fā)

可以禁止自動(dòng)重發(fā)(見(jiàn)5.11)。

8.4 報(bào)文的時(shí)間戳

可選的,支持CANFD的實(shí)現(xiàn)或者不支持CANFD的實(shí)現(xiàn),可以為接收和發(fā)送的數(shù)據(jù)幀提供報(bào)文

時(shí)間戳。

時(shí)間戳長(zhǎng)度為8位、16位或者32位。時(shí)基的時(shí)鐘源應(yīng)由節(jié)點(diǎn)內(nèi)部產(chǎn)生,或者應(yīng)由LLC用戶提供。

時(shí)基計(jì)數(shù)器應(yīng)遞增,且超限后歸0。

時(shí)基計(jì)數(shù)器對(duì)LLC用戶在任意時(shí)間可讀。時(shí)基的值應(yīng)在每一個(gè)數(shù)據(jù)幀的參考點(diǎn)獲取。對(duì)于傳統(tǒng)

幀,參考點(diǎn)是各自幀SOF的采樣點(diǎn),或者是幀被認(rèn)為是有效時(shí)的時(shí)間點(diǎn)(根據(jù)9.7)。對(duì)于FD幀,當(dāng)

FDF為隱性,且隨后的res位為顯性,則參考點(diǎn)是SOF的采樣點(diǎn),或者res位的采樣點(diǎn),或者是幀被認(rèn)

為是有效時(shí)的時(shí)間點(diǎn)(根據(jù)9.7)。

在EOF后,獲取的時(shí)間戳的值應(yīng)對(duì)LLC用戶可讀。

9 MAC子層

9.1 概述

MAC子層描述了 OSIDLL的低層部分。它為L(zhǎng)LC子層和PL層提供服務(wù)接口,有以下功能

組成:

---發(fā)送/接收數(shù)據(jù)的封裝/解封;

---錯(cuò)誤檢測(cè)和標(biāo)識(shí);

---發(fā)送/接收媒介訪問(wèn)管理。

9.2 MAC子層服務(wù)

9.2.1 服務(wù)描述

MAC子層提供的服務(wù)應(yīng)允許本地LLC子層實(shí)體和同級(jí)LLC子層實(shí)體間交換 MSDU,其服務(wù)

如下。

a) 帶應(yīng)答的數(shù)據(jù)傳送

該服務(wù)可以讓LLC實(shí)體間無(wú)需建立數(shù)據(jù)鏈路連接就能交換 MSDU。其數(shù)據(jù)傳送可以是點(diǎn)對(duì)

點(diǎn)、多播或者廣播式的。

b) 帶應(yīng)答的遠(yuǎn)程數(shù)據(jù)請(qǐng)求

該服務(wù)允許LLC實(shí)體向另一個(gè)遠(yuǎn)程節(jié)點(diǎn)請(qǐng)求發(fā)送LSDU,兩者無(wú)需建立數(shù)據(jù)鏈路連接。遠(yuǎn)程

LLC實(shí)體應(yīng)用其 MAC層“帶應(yīng)答的數(shù)據(jù)傳送”服務(wù)發(fā)送被請(qǐng)求的數(shù)據(jù)。由遠(yuǎn)程節(jié)點(diǎn)的 MAC

子層產(chǎn)生服務(wù)的ACK。ACK不應(yīng)包含遠(yuǎn)程節(jié)點(diǎn)用戶的任何數(shù)據(jù)。

c) OF傳送

該服務(wù)允許LLC實(shí)體請(qǐng)求發(fā)送OF。OF是特殊固定格式的LPDU,可用于延遲下一個(gè)DF或

者RF。

1 Scope

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This document specifies the characteristics of setting up an interchange of digital information between modules implementing the CAN data link layer. Controller area network is a serial communication protocol, which supports distributed real-time control and multiplexing for use within road vehicles and other control applications.

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This document specifies the Classical CAN frame format and the newly introduced CAN Flexible Data Rate Frame format. The Classical CAN frame format allows bit rates up to 1 Mbit/s and payloads up to 8 byte per frame. The Flexible Data Rate frame format allows bit rates higher than 1 Mbit/s and payloads longer than 8 byte per frame.

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This document describes the general architecture of CAN in terms of hierarchical layers according to the ISO reference model for open systems interconnection (OSI) according to ISO/IEC 7498-1. The CAN data link layer is specified according to ISO/IEC 8802-2 and ISO/IEC 8802-3.

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This document contains detailed specifications of the following (see Figure 2):

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——logical link control sub-layer;

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——medium access control sub-layer;

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——physical coding sub-layer.

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There are three implementation options. They are the following:

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——support of the Classical CAN frame format only, not tolerating the Flexible Data Rate frame format;

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——support of the Classical CAN frame format and tolerating the Flexible Data Rate frame format;

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——support of the Classical CAN frame format and the Flexible Data Rate frame format.

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The last option is recommended to be implemented for new designs.

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Note: Implementations of the first option can communicate with implementations of the third option only as long as the Flexible Data Rate frame format is not used; otherwise, Error Frames are generated. There are opportunities to run implementations of the first option also in CAN networks using the Flexible Data Rate frame format, but these are not in the scope of this document.

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2 Normative references

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The following referenced documents are indispensable for the application 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.

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ISO/IEC 7498-1 Information technology - Open systems interconnection - Basic reference model: The basic model

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GB/T 9387.1-1998 Information technology-Open Systems Interconnection-Basic Reference Mode l- Part 1: The Basic Model (ISO/IEC 7498-1: 1994, IDT)

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ISO/IEC 8802-2 Information technology - Telecommunications and information exchange between systems - Local and metropolitan area networks - Specific requirements - Part 2: Logical link control

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Note: GB/T 15629.2-2008 Information technology - Telecommunications and information exchange between systems - Local and metropolitan area networks - Specific requirements - Part 2: Logical link control (ISO/IEC 8802-2:1998, IDT)

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ISO/IEC 8802-3 Information technology - Telecommunications and information exchange between systems - Local and metropolitan area networks - Specific requirements - Part 3: Standard for Ethernet

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Note: GB/T 15629.3-2014 Information technology - Telecommunications and information exchange between systems - Local and metropolitan area networks - Specific requirements - Part 3: Carrier sense multiple access with collision detection(CSMA/CD)access method and physical layer specif (ISO/IEC 8802-3: 2000, MOD)

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3 Terms and definitions

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For the purpose of this document, the following terms and definitions apply.

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3.1

arbitration phase

phase where the nominal bit time is used

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3.2

bit stuffing

frame coding method providing bus state changes required for periodic resynchronization when using an NRZ bit representation

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Note: Whenever the transmitting logic encounters a certain number (stuff width) of consecutive bits of equal value in the data, it automatically stuffs a bit of complementary value - a stuff bit - into the outgoing bit stream. Receivers de-stuff the Data Frames and the Remote Frames, ie. the inverse procedure is carried out.

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3.3

bus

topology of a communication network, where all nodes are reached by passive links which allow transmission in both directions

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3.4

bus comparator

electronic circuit converting physical signals used for transfer across the communication medium back into logical information or data signals

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3.5

bus driver

electronic circuit converting information or data signals into physical signals so that these signals can be transferred across the communication medium

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3.6

bus state

one of two complementary logical states: dominant or recessive

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Note: The dominant state represents the logical 0, and the recessive state represents the logical 1. During simultaneous transmission of dominant and recessive bits, the resulting bus state is dominant. When no transmission is in progress, the bus is idle. During idle time, it is in recessive state

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3.7

classical base frame format

format for Data Frames or Remote Frames using an 11-bit identifier, which are transmitted with one single bit rate and up to and including 8 data bytes

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3.8

classical extended frame format

format for Data Frames or Remote Frames using a 29-bit identifier, which are transmitted with one single bit rate and up to and including 8 data bytes

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3.9

classical frame

Data Frame or Remote Frame using the Classical Base Frame Format or the Classical Extended Frame Format

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3.10

content-based arbitration

CSMA arbitration procedure resolving bus- contention when multiple nodes simultaneously access the bus

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3.11

data bit rate

number of bits per time during data phase, independent of bit encoding/decoding

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3.12

data bit time

duration of one bit in data phase

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3.13

data frame

frame containing user data (e.g. one or more signals or one or more suspect parameters of one or more process data)

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3.14

data phase

phase where the data bit time is used

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3.15

edge

difference in bus-states between two consecutive time quanta

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3.16

error frame

frame indicating the detection of an error condition

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3.17

FD enabled

able to receive and to transmit FD Frames, as well as Classical Frames

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3.18

FD base frame format

format for Data Frames using an 11-bit identifier, which are transmitted with a flexible bit rate and up to and including 64 data bytes

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3.19

FD extended frame format

format for Data Frames using a 29-bit identifier, which are transmitted with a flexible bit rate and up to and including 64 data bytes

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3.20

FD frame

data Frame using the FD Base Frame Format or FD Extended Frame Format

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3.21

FD intolerant

only able to receive or to transmit Classical Frames, disturbing FD Frames

?

3.22

FD tolerant

not able to receive or to transmit FD Frames but not disturbing them

?

3.23

frame

protocol Data Unit of the data link layer specifying the arrangement and meaning of bits or bit fields in the sequence of transfer across the transmission medium

?

3.24

handle

hardware object label of one or multiple LLC frames (LPDU)

?

3.25

higher-layer protocol

protocol above the Data Link Layer protocol according to the Open System Interconnection model

?

[SOURCE: ISO/IEC 7498-1]