Inside Connections: How Your Car’s Components Communicate Inside Connections: How Your Car’s Components Communicate

Inside Connections: How Your Car’s Components Communicate

From dashboards to databases, a lot goes on inside the cockpit – the passenger area of an automobile.

by Jenny Donelan

IT’S strange to consider how the focal point of a car’s interior is something that was originally designed to protect the vehicle’s occupants from dirt and mud “dashed” up from the road. Today’s car dashboards are filled with gauges, buttons, knobs, and of course, displays. And they are now called cockpits, nerve centers, product differentiators – whatever companies want to call them. But they all began as simple barriers made of wood, metal, or leather that protected passengers in horse-drawn carriages, and later on, in automobiles like the one in Fig. 1. Early cars generally had the engine under the vehicle instead of in front – so there was no need for a nose or hood.

Fig. 1:  “Horseless carriage” was not a misnomer for the earliest automobiles. This Präsident model, built in 1897 by the Austro-Hungarian company Nesselsdorfer Wagenbau (now Tatra in the Czech Republic) would not look out of place with horse in harness attached to it. Note the dashboard on the right – future home to speedometers, nav systems, backup cameras, and more. Source: KapitanT, Wikimedia Commons.

Today’s dashboards look more like the one on the left in Fig. 2, or, if your wallet is a little thicker, the one on the right.

Fig. 2:  On the left, Visteon’s instrument cluster for the Ford Mustang includes circular displays embedded into the dashboard in a look mimicking “traditional” analog gauges. On the right, the company’s cluster for the Range Rover Velar looks more futuristic, combining displays with different functions (camera, tachometer, navigation system) into one large, flat area. Source: Visteon.

Underneath It All

The functionality of today’s dashboard is something we take for granted. We push the pedal toward the metal, and the arrow on the speedometer moves clockwise as the car goes faster. When we forget to replace the oil, the dashboard – and sometimes a disembodied voice – warns us that we are endangering our investment through neglect.

Some of this functionality has moved beyond the dashboard; to the center stack, for example, or to the steering wheel, or to the windshield, in the case of a head-up display. We are heading toward the holistic concept of the “connected car,” in which everything in our car communicates with pretty much everything else, both inside and outside the vehicle.

In fact, our cars have been connected for a long time – just not connected in the way we are considering them now, with cameras and electronic signals and automatic updates. For most of automotive history, they have been mechanically connected with cables and levers and gears. When you depressed the gas pedal, a cable connected to the pedal pulled a lever at the throttle to inject more gas into the engine, so your car could accelerate. Another cable moved the needle on your speedometer. Cables are used in cars to this day, for various functions.


Between the years of purely mechanical systems and the new, exciting world of connected cars, there was a gradual increase in computerized systems used in vehicles, starting in the 1970s. By the mid-1980s, Bosch had developed a controller area network (CAN) bus that allowed microcomputers and devices to communicate with each other (Fig. 3).

Fig. 3:  This diagram from a 2013 update announcement issued by Bosch for CAN FD (CAN with a flexible data rate), depicts some of the vehicle safety and efficiency systems (such as the GPS) connected through the network. Source: Bosch.

CAN became the defacto standard for cars, and is the legacy system in most cars today, according to Upton Bowden, new technology planning director for Visteon Corporation, a Tier 1 automotive supplier specializing in cockpit electronics. (It should be noted that there are sometimes other networking systems in the car, such as the lower-cost local-interconnect network (LIN) bus standard, which is sometimes used to complement CAN by networking less critical subsystems.)

“CAN runs around your vehicle as a wire system,” says Bowden. “It allows discrete components such as instrument clusters, radio infotainment displays, and so forth to send messages back and forth. For instance, when turn-by-turn information is coming from your navigation system, that [via CAN] gets pushed out to your instrument cluster so it can be displayed.” CAN’s standard transfer rate is 1 Mbit per second with data messages 8 bytes long. Starting around 2013, Bosch introduced a flexible data rate version, CAN FD, in which the transfer rate can at times exceed 1 Mbit/s and the data messages can be up to 64 bytes long.

Additional device connections might include what the industry calls a “silver box control,” mounted behind a display, for example, to offer additional functionality. Many vehicles today also have TCUs (telematics control units) that do software updates via a cellular pipeline. “Before TCUs, updates and upgrades were challenging and difficult unless you went to the dealership,” says Bowden.

CAN has done a good job for a long time, but cars, or rather the features in cars, have started to outgrow it. “CAN is a cost-effective, proven automotive-grade solution, but it doesn’t have high bandwidth,” says Bowden. “What it’s designed for is to pass messages back and forth and it works quite well for that, but not when you are trying to pass high amounts of video-resolution graphics around the car.” With functionalities like rear and sideview display mirrors, head-up displays, enhanced infotainment panels, and vehicle information, combined with the need for everything to look good (200-ppi resolution, wide color gamut, etc. vs. the green, segmented displays of yore), the sheer amount of data flowing in and out of a car is requiring ever more computer and network power.

Ethernet Evolution

A lot of this data is being and will continue to be taken over by Ethernet, says Bowden. “That doesn’t mean there aren’t alternatives out there,” he says “but most companies are looking at Ethernet, partly because it is very common in the consumer space today. It’s a cost adder over the CAN architecture, but it also has improved performance capabilities.”

Another, related trend, according to Bowden, is the integration of systems in the cockpit. “Instead of standalone components of instrument clusters, infotainment/radio, etc., we are seeing a move to integrate those components into a single automotive electronic control module – what we call a domain controller.”  This is typically a multi-core controller with a powerful processor that runs several different applications as well as the vehicle networking. “The benefit there is that now you have a single box to update,” he says. “And a real benefit on the display side is that all the human-machine interface graphics are controlled from a single unit, as opposed to separate units that do their own thing, passing messages back and forth.” This can be done with a GPU that enables faster, better imagery.

Such consolidation is being done industry wide, says Bowden, adding that Visteon is launching a controller product called SmartCore later this year, which he says will be the industry’s first consolidated cockpit controller (Fig. 4). “We think it will be a tipping point in the automotive industry from an integration standpoint. Everything controlled by one device as opposed to a distributed system,” he says.

SmartCore will work with CAN as well as Ethernet. “In general, a controller needs to have the ability to work with both networks, as many vehicles today still have legacy CAN modules,” says Bowden. High-end vehicles today often have between 60 and 70 electronic modules in them, but even basic and mid-range models have 20 to 50.1 Some of these modules might be a simple seat controller running on CAN. It could make sense to leave those kinds of traditional operations to CAN and to operate the higher end data traffic via Ethernet. So we may see two or more types of networking systems in a car. 

Fig. 4:  On the left is the “silver box” for Visteon’s SmartCore controller and on the right, a demo of the interface for an upcoming generation of SmartCore. Source: Visteon.

Then You Add Autonomous….

Where all of this becomes even more complicated is in semi-autonomous and autonomous cars. The “handoff” in a semi-autonomous scenario is but one example. Let’s say you get in your car to go to work. You get on the highway and the car goes into autonomous mode. You are answering emails when the car becomes aware of a situation – a traffic jam or bad weather, perhaps – that you need to deal with, immediately. The car will notify you by shaking your seat or steering wheel or via an audible notification, or by a combination of all three. You need to be able to understand what the situation is and take control immediately. This is where a very rich user experience will be needed – one that will recognize threats, make it obvious what they are, recommend activity, and allow the driver to take over – very quickly and accurately. It’s all got to work, every time.

“One of the things we know from consumer research as well as testing systems ourselves is that the success and acceptance of autonomous driving is going to be largely based on consumer trust,” says Bowden. “Trust in the system, trust that the car can do the driving. One of the things that builds trust is visual feedback, so as a passenger, you see that the car is aware of its surroundings. You can look up at any time and see that it’s tracking lanes and following road signs.” Such a system will not come cheap in terms of computing power or display quantity and quality. An Ethernet connection between the systems and the domain controller would be a must, says Bowden.

Our Future Is Someone Else’s Past

As quaint as the car at the beginning of this article appears to be, it is only 120 years old and was state of the art in its time. Years from now, an “antique” 2018 Honda Odyssey minivan with its multitude of display and communication systems and its 15 cupholders might amuse future generations, for reasons we can’t even imagine yet.  •

1Mertl, Steve, “How Cars Have Become Rolling Computers,” The Globe and Mail, May 2018.

Jenny Donelan is the editor in chief of Information Display Magazine.  She can be reached at