Automotive ETHERNET Description

AUTOMOTIVE ETHERNET 

The Automotive Ethernet network in this vehicle is being used for communications between the Radio and Instrument Panel Cluster (IPC) video related ECUs. The Radio is responsible for sending streams to the IPC for music album art, phone contacts, and navigation map if equipped. Only two ECUs are ever connected to a Automotive Ethernet network. The Automotive Ethernet voltages represent symbols that an ECU sender encodes based on a desired bit stream and an ECU receiver uses the resulting symbol stream to decode. There are several methods used for the encoding and decoding the different voltages generated. Information can be transferred bidirectionally on Automotive Ethernet at 100Mbit/s. Two interconnected ECUs can send and receive simultaneously (full duplex). As a sender, an ECU adds its own differential voltage to the two wires; while as a receiver, it subtracts its own voltage from the applied total voltage. The result of the subtraction corresponds to the voltage that was sent by the opposite ECU. This mechanism is a component of the echo cancellation method that is used in other Ethernet systems. For differential voltages to be added or subtracted, the two ECUs must know when a new symbol begins. This means that both ECUs must be synchronized to the symbol stream. This is done with the help of a Master (Sender) ECU and Slave (Receiver) ECU. The Master (Sender) ECU generates a continuous symbol stream to which the Slave (Receiver) ECU is synchronized.

For a complete AUTOMOTIVE ETHERNET BUS SYSTEM wiring diagram.