Automotive Ethernet in the Vehicle

Figure 1 Block diagram of a typical ADAS system
showing the in-vehicle networks used.

As all Automotive Ethernet technologies utilize a single twisted-pair cable (T1) and a point-to-point network topology, they differ primarily in their data rates and encoding methods. For the most part, the data rate determines the applications for which a particular Automotive Ethernet standard can be used. If we take the case of an automatic driver assistance system (ADAS), we can see where each Automotive Ethernet variant might best be used to replace existing automotive protocols. 

(Click on any figure to enlarge the image.)

Distinguishing BroadR-Reach and 100Base-T1

Figure 1: BroadR-Reach provides full-duplex operation
over a single twisted pair of wires

The world of Automotive Ethernet can be a little confusing in that there are two dominant specifications that serve the application space: BroadR-Reach and 100Base-T1. Both are explicitly intended for automotive use and there's quite a bit of overlap between them. In this installment, we'll look a little more closely at BroadR-Reach applications and also explain the differences between it and 100Base-T1.

Back to Basics: Automotive Ethernet

Figure 1: Automotive Ethernet handles

a wealth of functionality

Today's vehicles are as networked, if not more so, than our homes, offices, and factories. According to one estimate, the wiring harness for a multiplexed bus in a high-end luxury vehicle can weigh as much as 110 lbs. Hence the rise of standards for automotive networking such as Automotive Ethernet (Figure 1). Let's begin a survey of the basics of Automotive Ethernet: What is it, where did it come from, where is it going, and what are the testing requirements?