Comparing Automotive Protocols

October 25, 2024 · [rt_reading_time label="" postfix="min" postfix_singular="min"] read
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LIN vs CAN vs Ethernet

FACTOR
LIN
CAN
ETHERNET
COMMUNICATION CHARACTERISTICS
Access Control
Medium Access Control
Master-slave (single master, multiple slaves)
Multi-Master
CSMA/CA (Carrier Sense Multiple Access/Collision Avoidance)
Multi-Master
CSMA/CA (Carrier Sense Multiple Access/Collision Avoidance)
Bus Conflicts
Master uses arbitration process to resolve bus conflict
Resolved by arbitration on message ID
Resolved by collision detection and backoff
Transmission
Communication Type
Serial, synchronous
Serial, asynchronous
Serial, asynchronous
Message Transmission
Deterministic
Deterministic
Non-deterministic, packet-switched
Triggered Technique (event / time triggered)
Time-triggered
Time-triggered
Event-triggered
Message Transmission Latency
Low, predictable
Low, predictable
Low
Latency Jitter
Constant
Load dependent
Typically low
Efficiency
Bus Utilization Efficiency (excluding idle time)
Typically low (10-40%) due to simple protocol
High (up to 100% for critical messages)
High
Quality of Service
Limited
Higher due to prioritization of messages
Supports QoS features in higher layers
Error detection and correction methods
Basic parity checks
CRC (Cyclic Redundancy Check)
CRC and additional methods in higher layers
PERFORMANCE
Speed
Speed
Slow
Medium
Fast
Typical Bus Speed (bit/sec)
Up to 20Kbps
33Kbps – 1 Mbps
10 Mbps – 100 Gbps
Capacity
Data and Frame Size
1 – 8 bytes payload
44 bits overhead
0 – 8 bytes payload
47 bits overhead (std ID)
67 bits overhead (ext iD)
Large (up to 1500 bytes standard, jumbo frames possible)
PHYSICAL LAYER & MEDIA
Connection Details
Cable Type
Unshielded twisted pair
Shielded twisted pair
UTP, STP, fiber optic
Cable core
Copper
Copper
Copper, fiber optics
No. of Lines Required
1
2
2, 4, or 8 depending on Ethernet variant
Max. Cable Length
40 meters (theoretically) – typically 10 – 20 meters
40 meters (at 1 Mbps)
100 meters (Ethernet over copper), kilometers over fiber
Energy
Power Consumption
Very low
Low
Varies, higher than CAN/LIN for high speeds
Nodes
Number of Nodes
Up to 16 nodes
64 to 128 nodes
Thousands of nodes (depends on Ethernet switches)
Possible Topologies
Linear (bus)
Linear (bus), star
Bus, star, ring
SCALABILITY & EXTENSIBILITY
Growth Potential
Extensibility
Limited
Moderate
High
Scalability
Limited
Good
High
Reliability
Basic
High
High
Interoperability
Low
Medium
High
Security
Basic
Basic
Basic
COST & COMPLEXITY
Cost Factors
Overall Cost
Low
Moderate
High
Implementation
Implementation Complexity
Low
Moderate
Complex
Implementation Cost
Low
Moderate
High
USAGE
Applications
Use Cases
Sensor / actuator interface to a master ECU
(doors, mirrors, windows, motors, ABS)
Automotive control networks, industrial automation
(Electric seats, mirrors, tailgate, wiper control)
General-purpose networking, IoT, industrial automation

J1939 vs UDS

FACTOR
J1939
UDS
COMMUNICATION CHARACTERISTICS
Transmission
Communication Type
Serial, asynchronous (over CAN)
Serial, asynchronous (over CAN or other transport layers)
Message Transmission
Deterministic message priority
Non-deterministic
Triggered Technique (event / time triggered)
Event-triggered
Event-triggered (on request)
Message Transmission Latency
Low, predictable
Varies, typically low (depends on transport layer)
Latency Jitter
Low (due to CAN message priority)
Low to medium (depends on transport layer)
Efficiency
Bus Utilization Efficiency (excluding idle time)
High, especially for critical messages
Moderate (diagnostic traffic can be infrequent but potentially high)
Quality of Service
Higher due to message prioritization
Limited (depends on underlying transport)
Bit Coding
NRZ w/ bit stuffing (CAN-based)
NRZ (based on underlying transport protocol, e.g., CAN)
Error detection and correction methods
CRC, with error detection on CAN layer
Error detection depends on transport layer (e.g., CAN’s CRC)
SCALABILITY & EXTENSIBILITY
Growth Potential
Extensibility
High (supports complex vehicle networks)
Moderate (extends with new diagnostic services)
Scalability
High (due to its support for multiple segments)
Limited by transport and protocol overhead
Reliability
High
High (depends on underlying protocol like CAN)
Interoperability
Medium
Low (specific to diagnostics)
COST & COMPLEXITY
Cost Factors
Overall Cost
Moderate to high (depending on network size and complexity)
Moderate (due to diagnostic focus)
Implementation
Implementation Complexity
Complex (due to broader network control needs)
Moderate (requires handling diagnostic routines)
Implementation Cost
Moderate to high
Moderate (diagnostic equipment needed)
INDUSTRY SUPPORT & STANDARDIZATION
Acceptance
Industry Acceptance
Widely accepted in commercial trucks and heavy machinery
Widely used for vehicle diagnostics
USAGE
Applications
Use Cases
Heavy-duty vehicle communication, fleet management, engine control
Vehicle diagnostics
(OBD-II, ECU diagnostics)