Road vehicles - Controller area network(CAN) - Part 2: High-speed medium access unit
1 Scope
This document specifies the high-speed physical media attachment (HS-PMA) of the controller area network (CAN), a serial communication protocol that supports distributed real-time control and multiplexing for use within road vehicles.
This includes HS-PMA without and with low-power mode capability as well as with selective wake-up functionality. The physical media dependant sublayer is not in the scope of this document.
2 Normative references
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.
GB/T 41588.1-2022 Road vehicles - Controller area network (CAN) - Part 1: Data link layer and physical signalling
ISO 11898-1 Road vehicles - Controller area network(CAN) - Part: 1 Data link layer and physical signalling
GB/T 41588.1-2022 Road vehicles - Controller area network (CAN) - Part 1: Data link layer and physical signalling
ISO 16845-2 Road vehicles - Controller area network (CAN) conformance test plan - Part 2: High-speed medium access unit - Conformance test plan
3 Terms and definitions
For the purposes of this document, the terms and definitions given in ISO 11898-1 and the following apply.
3.1
attachment unit interface; AUI
interface between the PCS that is specified in ISO 11898-1 and the PMA that is specified in this document
3.2
ground; GND
electrical signal ground
3.3
legacy implementation
HS-PMA implementation that has been released prior to the publication of this document
3.4
low-power mode
mode in which the transceiver is not capable of transmitting or receiving messages, except for the purposes of determining if a WUP or WUF is being received
3.5
medium attachment unit; MAU
unit that comprises the physical media attachment and the media dependent interface
3.6
media dependent interface; MDI
interface that ensures proper signal transfer between the media and the physical media attachment
3.7
normal-power mode
mode in which the transceiver is fully capable of transmitting and receiving messages
3.8
physical coding sublayer; PCS
sublayer that performs bit encoding/decoding and synchronization
3.9
physical media attachment; PMA
sublayer that converts physical signals into logical signals and vice versa
3.10
transceiver
implementation that comprises one or more physical media attachments
4 Symbols and abbreviated terms
For the purposes of this document, the symbols and abbreviated terms given in ISO 11898-1 and the following apply. Some of these abbreviations are also defined in ISO 11898-1. If the definition of the term in this document is different from the definition in ISO 11898-1, this definition applies.
AUI: attachment unit interface
DLC: data length code
EMC: electromagnetic compatibility
ESD: electro static discharge
GND: ground
HS-PMA: high-speed PMA
MAU: medium attachment unit
MDI: media dependent interface
PCS: physical coding sublayer
PMA: physical media attachment
PMD: physical media dependent
WUF: wake-up frame
WUP: wake up pattern
5 Functional description of the HS-PMA
5.1 General
The HS-PMA comprises one transmitter and one receiving entity. It shall be able to bias the connected physical media, an electric two-wire cable, relative to a common ground. The transmitter entity shall drive a differential voltage between the CAN_H and CAN_L signals to signal a logical 0 (dominant) or shall not drive a differential voltage to signal a logical 1 (recessive) to be received by other nodes connected to the very same media. These two signals are the interface to the physical media dependent sublayer.
The HS-PMA shall provide an AUI to the physical coding sublayer as specified in ISO 11898-1. It comprises the TXD and RXD signals as well as the GND signal. The TXD signal receives from the physical coding sublayer the bit-stream to be transmitted on the MDI. The RXD signal transmits to the physical coding sublayer the bit-stream received from the MDI.
Implementations that comprise one or more HS-PMAs shall at least support the normal-power mode of operation. Optionally, a low-power mode may be implemented.
Some of the items specified in the following depend on the operation mode of the (part of the) implementation, in which the HS-PMA is included.
Table 1 shows the possible combinations of HS-PMA operating modes and expected behaviour.
Table 1 HS-PMA operating modes and expected behaviour
Operation mode Bus biasing behaviour Transmitter be haviour
Normal Bus biasing active Dominant or recessivea
Low power Bus biasing active or inactive recessive
a Depends on input conditions as described in this document.
All parameters given in this subclause shall be fufilled throughout the operating temperature range and supply voltage range (if not explicitly specified for unpowered) as specified individually for every HS-PMA implementation.
5.2 HS-PMA test circuit
The outputs of the HS-PMA implementation to the CAN signals are called CAN_H and CAN_L, TXD is the transmit data input and RXD is the receive data output. Figure 2 shows the external circuit that defines the measurement conditions for all required voltage and current parameters. RL represents the effective resistive load (bus load) for an HS-PMA implementation, when used in a network, and C1 represents an optional split-termination capacitor, C2 represents a filter capacitor. The values of RL and C1 vary for different parameters that the HS-PMA implementation needs to meet and are given as condition in Tables 2 to 20.
Key
VDiff ——differential voltage between CAN_H and CAN_L wires
VCAN_H—— single ended voltage on CAN_H wire
VCAN_L ——single ended voltage on CAN_L wire
CRXD ——capacitive load on RXD
Figure 2 HS-PMA test circuit
Road vehicles - Controller area network(CAN) - Part 2: High-speed medium access unit
1 Scope
This document specifies the high-speed physical media attachment (HS-PMA) of the controller area network (CAN), a serial communication protocol that supports distributed real-time control and multiplexing for use within road vehicles.
This includes HS-PMA without and with low-power mode capability as well as with selective wake-up functionality. The physical media dependant sublayer is not in the scope of this document.
2 Normative references
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.
GB/T 41588.1-2022 Road vehicles - Controller area network (CAN) - Part 1: Data link layer and physical signalling
ISO 11898-1 Road vehicles - Controller area network(CAN) - Part: 1 Data link layer and physical signalling
GB/T 41588.1-2022 Road vehicles - Controller area network (CAN) - Part 1: Data link layer and physical signalling
ISO 16845-2 Road vehicles - Controller area network (CAN) conformance test plan - Part 2: High-speed medium access unit - Conformance test plan
3 Terms and definitions
For the purposes of this document, the terms and definitions given in ISO 11898-1 and the following apply.
3.1
attachment unit interface; AUI
interface between the PCS that is specified in ISO 11898-1 and the PMA that is specified in this document
3.2
ground; GND
electrical signal ground
3.3
legacy implementation
HS-PMA implementation that has been released prior to the publication of this document
3.4
low-power mode
mode in which the transceiver is not capable of transmitting or receiving messages, except for the purposes of determining if a WUP or WUF is being received
3.5
medium attachment unit; MAU
unit that comprises the physical media attachment and the media dependent interface
3.6
media dependent interface; MDI
interface that ensures proper signal transfer between the media and the physical media attachment
3.7
normal-power mode
mode in which the transceiver is fully capable of transmitting and receiving messages
3.8
physical coding sublayer; PCS
sublayer that performs bit encoding/decoding and synchronization
3.9
physical media attachment; PMA
sublayer that converts physical signals into logical signals and vice versa
3.10
transceiver
implementation that comprises one or more physical media attachments
4 Symbols and abbreviated terms
For the purposes of this document, the symbols and abbreviated terms given in ISO 11898-1 and the following apply. Some of these abbreviations are also defined in ISO 11898-1. If the definition of the term in this document is different from the definition in ISO 11898-1, this definition applies.
AUI: attachment unit interface
DLC: data length code
EMC: electromagnetic compatibility
ESD: electro static discharge
GND: ground
HS-PMA: high-speed PMA
MAU: medium attachment unit
MDI: media dependent interface
PCS: physical coding sublayer
PMA: physical media attachment
PMD: physical media dependent
WUF: wake-up frame
WUP: wake up pattern
5 Functional description of the HS-PMA
5.1 General
The HS-PMA comprises one transmitter and one receiving entity. It shall be able to bias the connected physical media, an electric two-wire cable, relative to a common ground. The transmitter entity shall drive a differential voltage between the CAN_H and CAN_L signals to signal a logical 0 (dominant) or shall not drive a differential voltage to signal a logical 1 (recessive) to be received by other nodes connected to the very same media. These two signals are the interface to the physical media dependent sublayer.
The HS-PMA shall provide an AUI to the physical coding sublayer as specified in ISO 11898-1. It comprises the TXD and RXD signals as well as the GND signal. The TXD signal receives from the physical coding sublayer the bit-stream to be transmitted on the MDI. The RXD signal transmits to the physical coding sublayer the bit-stream received from the MDI.
Implementations that comprise one or more HS-PMAs shall at least support the normal-power mode of operation. Optionally, a low-power mode may be implemented.
Some of the items specified in the following depend on the operation mode of the (part of the) implementation, in which the HS-PMA is included.
Table 1 shows the possible combinations of HS-PMA operating modes and expected behaviour.
Table 1 HS-PMA operating modes and expected behaviour
Operation mode Bus biasing behaviour Transmitter be haviour
Normal Bus biasing active Dominant or recessivea
Low power Bus biasing active or inactive recessive
a Depends on input conditions as described in this document.
All parameters given in this subclause shall be fufilled throughout the operating temperature range and supply voltage range (if not explicitly specified for unpowered) as specified individually for every HS-PMA implementation.
5.2 HS-PMA test circuit
The outputs of the HS-PMA implementation to the CAN signals are called CAN_H and CAN_L, TXD is the transmit data input and RXD is the receive data output. Figure 2 shows the external circuit that defines the measurement conditions for all required voltage and current parameters. RL represents the effective resistive load (bus load) for an HS-PMA implementation, when used in a network, and C1 represents an optional split-termination capacitor, C2 represents a filter capacitor. The values of RL and C1 vary for different parameters that the HS-PMA implementation needs to meet and are given as condition in Tables 2 to 20.
Key
VDiff ——differential voltage between CAN_H and CAN_L wires
VCAN_H—— single ended voltage on CAN_H wire
VCAN_L ——single ended voltage on CAN_L wire
CRXD ——capacitive load on RXD
Figure 2 HS-PMA test circuit
