Vehicle Communication

Component Location

Networks

• Etherloop

Controllers

• Autopilot Computer
• HVBATT: HV Battery controller
• Infotainment Computer
• VCLEFT: Left vehicle controller
• VCREAR: Rear vehicle controller
• VCRIGHT: Right vehicle controller

Harnesses

• All

Communication Networks

Cybertruck Communication Architecture Overview

In Cybertruck, there are numerous distributed computers that cooperate to control the vehicle's behavior. These controllers communicate locally with each other through many small communication networks. For messages to be shared throughout the vehicle, the small networks are connected to one large, high-speed Ethernet network called Etherloop. This new central Ethernet design replaces numerous main CAN networks (Body, Vehicle, Party, Chassis, Powertrain, etc.,).

Etherloop connects Infotainment, Autopilot, High Voltage (HV) battery, Left Vehicle Controller (VCLEFT), Right Vehicle Controller (VCRIGHT), and Rear Vehicle Controller (VCREAR). Developed to simplify and strengthen the vehicle communication network by reducing the amount of cross-vehicle CAN wires, Etherloop also adds message redundancy and increased logging capability. Each node connected to Etherloop has a specialized gateway to manage traffic flow, referred to as an Etherloop Generalized Gateway (EGG).

Bus Abbreviation	Bus Name	Bus Type
BP	Battery Pack	CAN
DIPF	DI Private Front	CAN
DIPR	DI Private Rear	CAN
ETH	Infotainment Ethernet	CANETH bus
HVS	High Voltage System	CAN
LC	Left Bus	CAN
LEFTBODY	Left Body Bus	CAN
RC	Right Bus	CAN
RCM PRIV	Restraints Control Module Private Bus	CAN
REARSTEER	Rear Steering Bus	CAN
RIGHTBODY	Right Body Bus	CAN
THERMAL	Thermal Bus	CAN

Etherloop

Etherloop Physical Network

Etherloop consists of six main Etherloop nodes connected in a loop formation by a shielded, twisted two wire Ethernet network between each node. The main nodes are the Gateway, Autopilot, HV Battery, right vehicle controller, rear vehicle controller, and left vehicle controller. The Media Contol Unit (MCU) and the Autopilot computer each use eight port Ethernet switches to connect to Etherloop. The vehicle controllers use a multicore (four 400 MHz cores) microprocessor with an integrated three port gigabit Ethernet switch. Two ports on the switch are connected outside the chip to Etherloop, and one port is connected internally. One of the cores of the multicore microprocessor is dedicated to managing Etherloop traffic, called the Etherloop Generalized Gateway (EGG). The other cores on vehicle microcontrollers run dedicated applications, like the Drive Inverter (DI) and Pedal Monitor (PM) in VCLEFT.

The Infotainment and Autopilot computers are connected by a board to board connector inside the car computer. The Etherloop connections between them travel through this connector.

Etherloop can be thought of as standard Ethernet with a custom Tesla-designed protocol built on top.

Layer	Layer Description
Application	Vehicle payload
Presentation	Security payload
Data link	Ethernet
Physical	Automotive-grade Ethernet cable

Etherloop Generalized Gateway (EGG)

Each node on the Etherloop has a switch to manage Ethernet traffic flow. On the vehicle controllers, the switch is controlled by an EGG. The EGG allows the node to talk bi-directionally around the Etherloop communicating to the next EGG using Ethernet protocol. Attached to the EGGs are numerous CAN networks and interior networks to communicate to other cores. The EGG is responsible for monitoring traffic as a gateway and ensuring a message is routed to where it needs to go. The EGG also acts as a translator that can convert frames between Ethernet and CAN. The EGGs also handle message security and constantly monitor network conditions. Data is sent between controllers using the CAN frames.

Example Etherloop flow:

1. An Etherloop frame travels on the Etherloop and comes into the EGG switch.
2. The EGG checks the Ethertype of the frame. Unknown Ethertypes are dropped.
3. The EGG holds that frame and waits for the other duplicated frame to come in. Once it arrives the second frame is dropped.
4. The EGG validates that the frame is secure.
5. The EGG extracts the payload from inside the frame.
6. The EGG then sends the messages from the payload to the appropriate destinations.  

Duplicated Messages

On the Etherloop, critical vehicle traffic is duplicated and then sent in opposite directions around the Etherloop: clockwise and counter-clockwise. Each node is then responsible for dropping the second copy of a message it has already received. If a node receives only one message, it will suspect there is a problem with part of the network and set an alert.

Battery Pack (BP) CAN

• Description: Battery Pack CAN bus between vehicle and the High Voltage (HV) Ancillary Bay.
• Baud rate: 1Mbps

Node	Node Name	Network Connections
EGGREAR	Rear Etherloop Gateway (EGGREAR, EGGREAR1, EGGREAR2, EGGREAR3)	DIPR, EGGREARPRIV, LOOP
HVBATT	High Voltage Battery (HVBATTCON, HVBATTMON, HVBATTPROC, HVBIG)

Drive Inverter Front (DIPF) CAN

• Description: Private CAN bus between the front drive unit and the DI/PM application in the left vehicle controller.

Node	Node Name	Network Connections
DIF/PMF	Front drive inverter / pedal monitor
DFLKF	Front differential locker
EGGLEFT	Left Etherloop Gateway
SDCF	Front motor secondary disconnect controller

Drive Inverter Rear (DIPR) CAN

• Description: Private CAN bus between the rear drive unit and the DI/PM application in the left vehicle controller.

Node	Node Name	Network Connections
DIR/PMR	Rear drive inverter / pedal monitor
DFLKR	Rear differential locker
EGGLEFT	Left Etherloop Gateway
SDCR	Rear motor secondary disconnect controller
TLC	Trailer controller
VCLEFT	Left vehicle controller
VCREAR	Rear vehicle controller

Infotainment Ethernet Bus

• Description: Infotainment Ethernet
• Baud rate: 500kbps

Node	Node Name	Network Connections
ADSP	Audio Digital Signal Processor
AP A	Autopilot A Processor
GTW	Vehicle Gateway	LOOP
INFO	Infotainment System on a Chip (SOC)
TCU	Telematic Control Unit
OBD	On-board Diagnostic port

High Voltage System Bus

• Description: High Voltage (HV) system bus
• Baud rate: 1Mbps

Node	Node Name	Network Connections
CP	Charge Port controller
HVBATT	High Voltage Battery Interface Gateway	BP
PCS2	Power Conversion System - Gen 2 controller

Left CAN

• Description: Left domain communication bus connecting steering and airbag controllers.
• Baud rate: 500kbps

Node	Node Name	Network Connections
DI	Drive Inverter application
EGGLEFT	Left Etherloop gateway (EGGLEFT, PM, DI)	DIPF, EGGLEFTPRIV, LOOP
ESP	Stability controller
PEPS	Primary Electric Power Steering controller (PEPS, PEPSM)
PSFA	Primary Steering Feedback Actuator (PSFA, PSFAM)
RCM	Restraint Control Module
SCCM	Steering Console Control Module

Left Body Bus

• Description: Left body communication network that connects the Vehicle Security (VCSEC) module and the Left Vehicle Controller (VCLEFT) to the left-side door handles.
• Baud rate: 500kbps

Node	Node Name
EGGLEFT	Left Etherloop gateway (EGGLEFT, EGGLEFTVC, DI)
VCDOORFL	Front-Left door controller
VCDOORRL	Rear-Left door controller
VCLEFT	Left vehicle body controller
VCSEC	Security controller

RCM Private Bus

Node	Node Name
EGGRIGHT	Right Etherloop gateway
GTW	Vehicle Gateway
ICR	In-Cabin Radar
RCM	Restraint Control Module

Right Bus

• Description: Right domain communication bus connecting brake and steering controllers.
• Baud rate: 500kbps

Node	Node Name	Network Connections
EGGRIGHT	Right Etherloop gateway (EGGRIGHT, EGGRIGHT1, EGGRIGHT2, EGGRIGHT3)	LOOP, THERMAL
IBST	Brake booster controller
SEPS	Secondary Power Steering controller (SEPS, SEPSM)
SSFA	Secondary Steering Feedback Actuator controller (SSFA, SSFAM)

Rearsteer Bus

• Description: Rear Steer CAN
• Baud rate: 500kbps

Node	Node Name	Network Connections
EGGREAR	Rear Etherloop gateway (EGGREAR, EGGREAR1, EGGREAR2)	EGGREARPRIV, LOOP
RSA	Rear Steering Actuator controller (RSA, RSAM)

Right Body Bus

• Description: Right Body CAN
• Baud rate: 500kbps

Node	Node Name	Network Connections
VCDOORFR	Front-Right Door Controller
VCDORRR	Rear-Right Door Controller
VCRIGHT	Vehicle Controller Right	EGGRIGHTPRIV

Thermal Bus

• Description: Thermal CAN
• Baud rate: 500kbps

Node	Node Name	Network Connections
CMPT	Thermal Compressor
EGGRIGHT	Right Etherloop gateway (EGGRIGHT, EGGRIGHT1, EGGRIGHT2, EGGRIGHT3)	EGGRIGHTPRIV, LOOP, RC
VCRIGHT	Right Vehicle Controller
VCSUPER	Supermanifold Vehicle Controller

Serviceability

The EGGs are able to detect numerous communication issues, both with Etherloop and with connected CAN networks. Diagnosis is based on vehicle alerts, mainly reported from the separate EGGs. Start any diagnosis with checking for the presence of a052_EtherloopError.

a052_EtherloopError

Type of Error	Error Description	Payload Examples
Power Domain Issue (most severe)	One of the two power domains on Cybertruck has been detected to be down.	LEFT_POWER_DOMAIN_OR_ECU - If this is reported by EGGREAR or EGGRIGHT, then it means that the EGGLEFT is down since its the only ecu on left power domain. RIGHT_POWER_DOMAIN - If this is reported by EGGLEFT, then it means that APP, EGGRIGHT, and EGGREAR are all down.
ECU Issue	There is a node missing and link errors on both sides of that node	appEcu eggleftEcu eggrearEcu eggrightEcu gtwEcu
Node Issue	There were no link errors detected, but the identified node is missing.	appNode eggleftNode eggrearNode eggrightNode gtwNode
Etherloop Link Down (least severe)	The Etherloop link between two nodes has been determined to be down.	appCCW appCW eggleftCCW eggleftCW eggrearCCW eggrearCW eggrightCCW eggrightCW gtwCCW gtwCW

Measuring Network Resistance

1. Power down the vehicle.
2. Measure the "total resistance" of the CAN network. This should be close to 60 Ω.
   • If total resistance equals 120 Ω, then there is an open circuit in one part of the circuit.
   • If total resistance is less than 60 Ω, then there is most likely a short in the circuit from CAN+ to CAN- or to another circuit.
3. Measure "CAN+ resistance to GND" to determine if there is a short to chassis ground.
4. Measure "CAN- resistance to GND" to determine if there is a short to chassis ground.

Measuring a CAN Waveform

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