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10 Mbps Ethernet Technology and the Challenges Facing

Automotive Microcontrollers

Vector Automotive Ethernet Symposium 2019

Harald Zweck, Expert Automotive Communication

Agenda

10Mbps Ethernet – Introduction

The technology behind 10Mbps Ethernet and PLCA

Examples and options for Hardware implementations

Relation to other Ethernet standards

The standardization ecosystem and the most recent status

Outlook: Integration into the Automotive communication world

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2 2019-04-02 Copyright © Infineon Technologies AG 2019. All rights reserved.

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Trend in In-Vehicle-Networking

Growing number of network technologies over time

0,01

0,1

1

10

100

1000

10000

1985 1990 1995 2000 2005 2010 2015 2020 2025

Bus

Point-to-Point

Ethernet

Discontinued

K-LINE

PWM

J1850 LIN

D2B

Byteflight MOST-25

MOST-50

USB 2.0

LVDS APIX

HDMI 1.2 USB 3.0

100BASE-T1

MOST-150 1000BASE-T1

CAN 2.0

CAN FD

USB 3.1

APIX-2

SENT

PSI-5

FlexRay

VAN

HDBaseT

CXPI

GPOF

Taken from: Dr. Matheus, BMW Automotive Ethernet Congress, Munich, February 2017


Trends in In-Vehicle-Networking

New Technologies are based on Ethernet

0,01

0,1

1

10

100

1000

10000

1985 1990 1995 2000 2005 2010 2015 2020 2025

Bus

Point-to-Point

Ethernet

New Technologies

PWM

LIN

MOST-25 MOST-50

USB 2.0

LVDS APIX

HDMI 1.2 USB 3.0

100BASE-T1


GPOF

CAN 2.0

CAN FD

USB 3.1

APIX-2

SENT

PSI-5

FlexRay

HDBaseT

CXPI

2.5..10G Ethernet



Trends in In-Vehicle-Networking

The Baud Rate Gap

0,01

0,1

1

10

100

1000

10000

1985 1990 1995 2000 2005 2010 2015 2020 2025

Bus

Point-to-Point

Ethernet

New Technologies

PWM

LIN

USB 2.0

LVDS APIX

HDMI 1.2 USB 3.0

100BASE-T1


GPOF

CAN 2.0

CAN FD

USB 3.1

APIX-2

SENT

PSI-5

HDBaseT

CXPI

2.5..10G Ethernet


2Mbps < gap < 100Mbps


Summary

Cost level close to CAN / FlexRay

Baud rates faster than CAN / FlexRay

Technology with smooth integration into Ethernet

› Targets of 10Mbps* Ethernet technology

10Mbps: 10 Megabits per second


Some Clarifications

› The new 10Mbps Ethernet technology is called in IEEE 802.3: 10Base-T1S

› 10Base => 10Mbps speed grade

› T1 => physical layer is single twisted pair (unshielded)

› S => short range (favorite solution for Automotive purposes)

› 10Base-T1S and PLCA (“Physical Layer Collision Avoidance”) and (old) 10Base-T are different

› The presentation covers 10Base-T1S multidrop version

› The multidrop physical layer supports bus architectures (similar to CAN)

› The presentation does not cover 10Base-T1L point to point version

› The P2P long range version targets industrial applications


Agenda







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The technology behind 10Mbps Ethernet and PLCA*

› 10BASE-T1S supports bus architectures similar to CAN

› PLCA* based networks have one special node which controls the traffic on the bus

-> Head Node

MCU

Ethernet 10Base-T1S

PHY

MCU

Ethernet 10Base-T1S

PHY

MCU

Ethernet 10Base-T1S

PHY

MCU

Ethernet 10Base-T1S

PHY

MCU

Ethernet 10Base-T1S

PHY

MCU

Ethernet 10Base-T1S

PHY

MCU

Ethernet 10Base-T1S

PHY

MCU*

Ethernet 10Base-T1S

PHY

Head Node

2500 cm

PLCA*: Physical Layer Collision Avoidance MCU*: Microcontroller Unit


10 cm


› 10BASE-T1S uses PLCA (“Physical Layer Collision Avoidance”) to resolve contentions

MCU*

Head Node

MCU

MCU

MCU

MCU

ID 0

ID 1

ID 2

ID 3

ID 4

› Each node gets an ID assigned

› The head node has always the ID 0

› There is no relation to MAC / IP / VLAN addresses of the node

MCU*: Microcontroller Unit



› The PLCA* technology (basic functionality)

MCU

Head Node

MCU

MCU

MCU

MCU

ID 0

ID 1

ID 2

ID 3

ID 4

› PLCA* runs “cycles” on the shared medium

0 0 1 2 .. N

› Within a cycle each node is assigned a transmit opportunity (TO)

› During its TO the node is allowed to transmit data

Shared medium

(twisted pair wires)

Cyclic repetition

Node ID

time

MCU*: Microcontroller Unit


PLCA*: Physical Layer Collision Avoidance


› PLCA* and half-duplex operation

› Each cycle starts with a “beacon” sent by the head node

› A node can skip its transmit opportunity by leaving the time slot untouched

› During the time window with its node ID the node can transmit data

› The transmitting node will typically enlarge the time window

› A node can insert “idle” in its time window to extend the time slot

to compensate MAC delays

› A node can burst high priority messages

0

2

2

4 4

N



0 0 1 2 .. N 0 1 2 3 4 5 .. N 0 4 0 0

0 0


› PLCA* and half-duplex operation

› Minimum size of a time slot: The client does not use its slot

› Maximum size of a time slot: The client sends idle and the maximum sized Ethernet frame

› Minimum size of a bus cycle: beacon + (minimum time slot * number of clients)

› Maximum size of a bus cycle: All clients (incl. the head node) send maximum sized packet

0 0 1 2 .. N 0 0 1 2 3 4 5 .. N 0 4

Minimum bus cycle Minimum time slot Maximum time slot



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› Example implementation 10Base-T1S Analog PHY

(“Transceiver”)

› PLCA is integrated into the microcontroller MAC

› Cost efficient PHY with analog circuits only

› Low pin count interface to MCU

› New interface between MAC and PHY required

Microcontroller

Ethernet PLCA-MAC

Interface

To / from Bus



Analog circuit

10Base-T1S

Interface

Analog PHY

“Transceiver”


› Example implementation 10Base-T1S MAC-PHY

› MAC-PHY: PLCA function plus PHY

› The MAC-PHY contains digital plus analog functionality

› The interface between MC and PHY is an Automotive SPI

To / from Bus

SPI

SPI Interface

Microcontroller



Ethernet PLCA-MAC

SPI Interface

10Base-T1S

Analog circuit


› Example implementation 10Base-T1S MAC-PHY

› MAC-PHY: PLCA function plus PHY (“Transceiver”)

› The MAC-PHY contains digital plus analog functionality

› MC and PHY communicate via a standard MII interface

To / from Bus



Microcontroller

Ethernet MAC

MII

Ethernet PLCA-MAC

MII

10Base-T1S

Analog circuit

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Relation to other IEEE Standards

› Carrier Sense Multiple Access with Collision Detection (CSMA/CD)

› PLCA* is an extension of CSMA/CD

› CSMA/CD can be used to manage special exceptions

like e.g. SW or HW failures

Microcontroller

Ethernet MAC

Head Node

Microcontroller

Ethernet MAC

Microcontroller

Ethernet MAC

Microcontroller

Ethernet MAC




› 802.1AS Time Synchronization Microcontroller

Ethernet MAC

Time Master

Microcontroller

Ethernet MAC

Time Slave

Head Node

Microcontroller

Ethernet MAC

Time Slave

› PLCA* is not compatible to parts of the 802.1AS standard

=> not a technical issue

=> issue of how the 802.1AS standard works

› Several solutions currently in discussion (status as of today)




› 802.1Qbv (Time Aware Shaper - TAS)

› 802.1Qav (Credit Based Shaper - CBS)

› Shapers are independent of PLCA*

› But: PLCA* will have an impact on shaper effects

Microcontroller

Ethernet MAC

Transmit Queue

CBS

TAS

Transmit Queue

CBS

TAS

PLCA



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10Base-T1S related Standardization Eco System

IEEE 802.3cg

Ethernet 10Base-T1S PHY

10Base-T1S

Interface

To / from Bus

IEEE 802.3cg

OPEN TC6 / TC14

OPEN TC14

Microcontroller

Ethernet PLCA-MAC

Interface

Ethernet Driver & Stack AutoSAR ?

IEEE 802.3cg

› New SW components for PLCA: AutoSAR ?

› PLCA: IEEE 802.3cg, Clause 148

› SPI interface MAC to PHY: OPEN TC6/TC14 JWG

› Analog PHY interface MAC to PHY: OPEN TC14

› MII interface: Standard available

› Standardization activities for 10Mbps Ethernet

› 10Base-T1S: IEEE 802.3cg, Clause 147

› Test suite 10Base-T1S: OPEN TC14

› EPL*: IEEE 802.3cg, Clause 147

EPL*: Electrical Physical Layer



Timeline of Standardization Eco System (Assumptions)

Planned:

IEEE 802.3cg

Release to Revcom

2019

H1 H2

2020

H1

We are here

Planned:

IEEE 802.3cg

Board approval


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Integration into Automotive Microcontroller Ecosystem

› PLCA* compatible driver stacks – “Transceiver Interface”

› TSN drivers may have to be adapted to PLCA

› PLCA needs a driver set

› Transceiver Interface needs a new driver set

Microcontroller

Driver for Native Interface

Ethernet MAC

Transmit Queue

CBS

TAS

Transmit Queue

CBS

TAS

PLCA

Transceiver Interface

Driver for PLCA

Driver for TSN

Ethernet Stack



Integration into Automotive Microcontroller Ecosystem

› PLCA* compatible driver stacks – SPI Interface

› Stack and MAC-PHY will communicate via SPI using a

special protocol

› The protocol will provide access to MAC-PHY control

› The protocol will provide access to MAC-PHY data

› A new driver stack is required for MAC-PHY the protocol

Microcontroller

Driver for SPI Interface

SPI HW Unit

SPI Interface

Driver for MAC-PHY Control

Driver for Protocol Conversion

Ethernet Stack



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10Mbps Ethernet Technology and the Challenges Facing ... · › The new 10Mbps Ethernet technology...

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