CAN data buses are already used in several control circuits. The basic principle of CAN is that instead of a separate wire for each type of data, in general, two wires are used. Through these wires, data is exchanged on engine speed, fuel consumption, throttle position, engine interference and switching processes.
The principle of operation of CAN is based on the fact that each control device transmits its data to the network to which all other control devices are connected. If any device registers data important for its operation, then these data are also taken into account by other devices.
However, due to the fact that in a car a large amount of data received from networked electronic systems must be transmitted reliably and in real time, Audi intends to soon abandon the inefficient CAN bus system. Instead of CAN, it is supposed to use a data bus system built using the Time Triggered Architecture technique (TTA) - a synchronized optical or electronic bus system for systems that control the operation of the transmission and chassis.
In current models, various controllers are installed to control the chassis: ESP electronic stability control system, EDS electronic differential lock, ASR traction control and air suspension. If it is possible to combine separate systems in such a way that they interact in real time, then this will allow for distributed regulation. To do this, the recipient of the data must know in advance the moment of receipt of information, in addition, all systems must be synchronized in time. In TTA, all this is provided thanks to a specifically set timeout. TTA technology allows the development, use and maintenance of fault-tolerant, redundant systems. This technique uses principles that have proven themselves in aviation.
CAN structure
The CAN system consists of the following components:
- CAN controller. The controller receives the data to be transmitted from the computing device, which is part of the control device. The controller performs primary data processing and transfers them to the CAN transceiver. In addition, the controller receives data from the transceiver, processes them and transfers them to the control unit's VU.
- CAN transceiver. The transceiver transmits and receives data. It converts the data received from the CAN controller into electrical signals and transfers them to the data bus.
- Bus termination. Resistance that prevents transmitted data from bouncing back as a reflected signal and distorting the original information.
- Bus lines. The bidirectional CAN-Low and CAN-' High lines are used for data transmission.
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