1.10 Car Onboard Network
1、 Overview of the plan:
With the increasing complexity of the electronic control system, as well as the increasing requirements for the communication capability between the electronic control units of the internal control function of the vehicle, the use of point-to-point links will increase the number of wiring harnesses in the vehicle, which brings great trouble to the design and manufacture of Automotive design in terms of the reliability, safety and weight of the internal communication. Therefore, in order to reduce the sharing and fast exchange of data through in-car connections, while improving reliability, we are implementing automotive electronic network systems based on the rapidly developing computer network, such as CAN, LAN, LIN, and MOSTs, that is, in car networks.
Currently, various countries and companies have multiple in vehicle network standards. The Society of Automotive Engineers (SAE) categorizes automotive networks into different levels based on their performance, namely Class A, Class B, Class C, Class D, and Class E.
2、 Structure and Principle
（1） CAN (Controller Area Network)
CAN bus is a serial data communication protocol developed by German BOSCH Company in the early 1980s to solve the data exchange between numerous control and test instruments in Hyundai Motor Company. It is a multi master bus, and the communication medium can be twisted pair, coaxial cable or Optical fiber. The communication speed can reach up to 1Mbps.
Characteristics of CAN bus: 1. There is no distinction between master and slave in data communication. Any node can initiate data communication with any other (one or more) nodes, and the communication order is determined by the priority order of each node's information. The information of high priority nodes is in 134 μ S communication; When multiple nodes initiate communication at the same time, those with lower priority will avoid those with higher priority, and will not cause congestion to the communication line; 3. The communication distance can reach up to 10KM (with a speed lower than 5Kbps) and the speed can reach 1Mbps (with a communication distance less than 40M); 4. The CAN bus transmission medium can be twisted pair or coaxial cable. CAN bus is applicable to Big data short distance communication or long distance small data. It has high real-time requirements, and can be used in the field where there are multiple masters and slaves or all nodes are equal.
(2)LIN (Local Interconnect Networks)
LIN Association was founded at the end of 1998, initially sponsored by BMW, Volvo, Audi, VW, DaimlerChrysler, Motorola and VCT, five automobile manufacturers, one semiconductor manufacturer and one software tool manufacturer. The association will primarily focus on defining an open standard for low-cost internal interconnect networks (LIN) in vehicles, where the use of CAN networks is not necessary in terms of bandwidth or complexity.
The LIN standard includes the definition of transmission protocols, transmission media, interfaces between development tools, and interfaces with software applications. LIN enhances the flexibility of the system architecture and provides interoperability for nodes in the network from both hardware and software perspectives, with better EMC (electromagnetic compatibility) characteristics foreseeable.
LIN supplements the current multiple networks within the vehicle and provides conditions for the classification of the internal network, which can help the vehicle achieve better performance and reduce costs. LIN protocol is committed to meeting the rapidly growing requirements for software complexity, Realizability and maintainability in distributed systems. It will meet this requirement by providing a series of highly automated Toolchain.
（3） Media Oriented Systems Transport (MOST)
Media Oriented Systems Transport (MOST) is an increasingly popular network standard among automotive manufacturers and suppliers. The MOST network uses optical fibers as the carrier, usually in a ring topology. MOSTs can provide a collective bandwidth of up to 25Mbps, much higher than traditional automotive networks. That is to say, 15 different audio streams can be played simultaneously. Therefore, it is mainly applied in automotive information and entertainment systems.
Developing car networks generally requires simulation development tools, such as CANOE, PFautoCAN, etc. Car networks are a very complex system where multiple communication networks exist simultaneously. A common type of CAN bus is the CAN bus, and even the CAN bus is divided into different speed CAN buses. For example, the engine control and transmission control of the power system will use a high-speed 500K CAN bus control. For comfort systems, such as the control of doors, lights, and windows, a low-speed 125K CAN bus control will be used.
3. Car network brand recommendation
|
Factory |
Model |
Category |
|
RENESAS |
RH850/F1K |
CAN microcontroller |
|
TOSHIBA |
TC9560、TC9560XBG |
bridge chip |
|
TE Connectivity |
— |
Car antenna Rail connectors M12 cable assembly |
|
Tyco Electronics |
— |
Dynamic connector AMPMODU connector AMPCT series connectors RAST connectors Circular connectors Motor connectors High speed line connectors Fiber optic connectors |
|
Rosenberger |
— |
Vehicle radio frequency connection system, high-speed data connection system, Vehicle mounted high-speed transmission system |
|
Electrical connection technology |
— |
Fakra board end&line end HSD board end&line end HD Camera connector Car USB |
