Serial bus: faster than a car-EDN

2021-12-13 19:20:59 By : Ms. vivian he

In some of my previous articles, I talked about the integration of more wireless connections with vehicles, and the evolution of radio frequency connectors used in vehicles. This time, let's take a look at in-car data connections other than RF.

TE Connectivity has developed a 4-wire connection system that can support two pairs of twisted pairs and a data speed of gigabit per second. Figure 1 shows an example of the HSD connector.

The TE HSD catalog lists right-angle and right-angle cable versions, as well as boards installed in various orientations. (Note: This particular catalog has a good introduction to the signal integrity of high-speed data; it is worth a look.) TE stated that these connectors are compatible with the USCAR specification I mentioned in the previous article. In addition, similar to the RF Fakra connector I discussed earlier, the HSD connector has keying and color coding. Figure 2 shows TE's solution for these connectors.

A different road Molex has taken another road that supports high-speed data in cars by repacking consumer-grade 5-pin shielded connectors into what they call HSAutoLink. This data bus is also called USCAR USB, which complies with the automotive requirements of USB 2.0.

MOST is connected in an article published by Masahiko Otake of Mitsubishi in Laser Focus World last year. He introduced the history of MOST cooperation (not a company). MOST was established in 1998 by partners Audi, BMW, Daimler, Harman and Microchip Technology, in response to Mercedes-Benz's successful use of POF (plastic optical fiber) in cars in its D2B network. The partner organization hopes to standardize high-speed data architecture and utilize lightweight solutions that are not affected by EMI.

The MOST network is used to interconnect various electronic modules in vehicles to provide driver information, safety systems, and entertainment. In addition to the five partners, MOST Collaboration also lists 16 integrators (including many other OEMs) and more than 60 suppliers certified by the program on its website. MOST150 is the latest standard; it specifies a data transmission rate of up to 150Mb/s, using PMMA (polymethyl methacrylate) plastic optical fiber. Mitsubishi Rayon Corporation is a supplier of PMMA fiber to this market through its ESKA brand. Figure 4 shows some examples of how to use MOST.

LVDS LVDS is a twisted pair technology in which information is transmitted by the voltage difference between two wires (differential pairs) of constant current. On the Future Electronics website, they provide a brief overview of LVDS and explain that it has been used for high-speed bus calculations since the mid-1990s. However, due to its design with high immunity to electromagnetic interference and low power consumption, it has a wider range of applications, including automobiles.

The LVDS implementation can support data rates up to 3Gb/s and, as mentioned earlier, can be implemented in various connector interfaces. Figure 5 shows the basic idea of ​​the LVDS signal pair.

As more and more electronic systems are integrated into cars, including broadband Internet and in-vehicle video, solutions are already in place that can provide performance over 1Gb/s and provide fiber optics when needed. Interestingly, there are so many coexisting standards and unique OEM products in automotive connectivity. Although some people may be surprised, connectivity in cars is an evolving technology area that is now beginning to catch up with consumer electronics.

Does your car have a high-speed serial bus? Is it effective?

You must log in or register to post comments.