Connecting humans to technology: A look at Human-Machine Interference

July 1, 2017
So what to do about HMI? There are a lot of service opportunities that can be addressed because the radio in a vehicle isn’t operating correctly. Unless these vehicles are still under the factory warranty then there are plenty of service options available.

If you ever get the chance to see a good car movie, then check out the movie American Graffiti. Many of you who grew up in that era may remember what it was like to drive your car while listening to your human machine interface (HMI). Sometimes it’s referred to as an (HIM) or Human Interface Module. Ok, I know what you’re thinking. He must be talking about the radio or he’s gone off the deep end. So let’s have a brief history lesson so I can make some sense of this crazy nonsense.

The beginning

Back in 1930, the Galvin Brothers installed the first commercially successful car radio in the Model A for an expensive option of $540. It was the first product to wear the Motorola name. Since then, motor vehicles have evolved with the changes in technology as the years have progressed. In 1952 the FM radio was introduced, and in 1953 many manufacturers offered an upscale radio with both AM and FM.

In 1955, the first music “on demand” was offered by Chrysler in the form of a turntable installed in the vehicle. It played seven-inch records while driving down the road! Naturally it was a bust. In 1965 the first 8-track players were in production; 1970 saw the release of the cassette player, and finally in 1985 we saw the advent of the CD player. In 30 years the car radio has evolved into a sophisticated, computerized central intelligence module that the driver uses to incorporate his or her entertainment and/or infotainment choices while driving. The term HMI means the interaction of the human being to make a change or selection to the module that controls our entertainment.

Figure 1

Way back in the day, nobody referred to the car radio as an HMI or HIM, but we as humans did interact with the radio in the fact that when we wanted a change, we adjusted the knob to select another station or we changed that cassette tape if we wanted to hear a different song. It’s the same kind of principal today as it was back then, only today there are a lot more electronics and technological changes that take place that we as vehicle owners are not aware of. So let’s fast forward to 2017 and look at some of the electronics that play a part in our entertainment and our infotainment systems. We will focus on the 2017 Chevrolet Silverado (Fig. 1) as our vehicle in this discussion.

Entertainment vs. infotainment

Entertainment is designed to give pleasure like listening to music. Infotainment is the programming that gives information which then in turn gives entertainment. For example, a GPS system or Global Positioning System. Some of the electronics in a modern day entertainment or infotainment system consist of a stereo radio, a navigation system, a universal serial bus (USB) system, a cellular phone system, speech recognition system, Bluetooth systems and others (Figs. 2, 3). These different systems work on a data bus line known as the MOST (Media Oriented Systems Transport) network. It is a high-speed network that communicates with the GMLAN network. The radio in this system is considered the bus master or gateway as its sometimes referred to. Let’s take a closer look.

Figure 2 Figure 3

The HMI is the component that is responsible for the video in the display screen. It’s called an HMI because it is a video touch screen display screen that works as the interface between human and system (hence the name) (Fig. 4). The HMI works in conjunction with the instrument panel cluster (IPC) and the radio. The HMI module communicates with the infotainment display module via the Local Interconnect Network (LIN) bus network for control communications, touch communications and the dimming or brightness of the display itself. The LIN network is a single wire used to transmit information between a module master and other smart devices. Digital data that’s in the form of a video is sent on a dedicated video cable.

Figure 4
Figure 5

So, how does all this work? Your radio is in constant communication with your HMI module and is ready to interact with your touch commands, voice commands, Bluetooth communications and even a USB memory card reader — yes, the same as one that’s in your home PC. The HMI actually has three different networking systems that connect to it: the GMLAN, or GM local area network, the MOST network and the LIN bus network. That is why it’s called the bus master (Fig. 5).

When things go wrong
Go about your diagnosis just like you would any other network problem. The important thing to remember is to make sure you know what players are involved in the system you’re working on. There are a lot of different combinations that are offered for this vehicle and some of the options might not be there. A service information system along with a GM option code index are a couple of the essential tools you will need.

Other essential requirements are needed to properly repair this system. As I mentioned earlier, the entertainment/infotainment systems in this vehicle offers a USB receptacle(s), memory card reader, speech recognition for voice-actuated commands and the use of Bluetooth for all Bluetooth devices. These features are all part of this system, and they are programmable. The way this system is programmed is very similar to the way you program a normal ECM or BCM in a GM vehicle. The service programming system (SPS) is a subscription-based service offered by GM. However, here’s the difference. Some components are programmed through SPS and some are programmed using a USB flash drive. Some require both. Programming the infotainment systems involves using the SPS system to download the latest calibration files for the particular make and model you’re working on. The calibrations that are downloaded are used to upgrade the vehicle’s firmware to accommodate the types of infotainment components that are used in that specific vehicle. This is done just like any of the other systems on a GM vehicle. The other type of programming also involves using the SPS procedure, but the difference is that you will be downloading the calibration files to a USB flash drive. The flash drive has to be a 2.0 compatible drive or higher to accommodate the transfer speeds of the data. The minimum size requirement for flashing with a USB drive is 4GB. Flashing using a USB drive is for updating the infotainment systems software that’s programmed in the various components of the entertainment system in the vehicle. One thing to note, if the wrong software is used to program the system, the HMI unit could be damaged. Be sure to select Human Machine Interface control module USB copy/USB file transfer in the SPS programming program. This is VIN specific and using an incorrect VIN is where the HMI could be damaged.

When programming this system, performing a USB flash event is done before the typical SPS procedure is carried out. When programming some radios, the vehicle’s modules must go to sleep for five minutes after programming. If not, the vehicle might not have sound, could have a blank screen or it could not have any touch screen response. It could also have an incorrect screen as well. If any of these symptoms appear, then turn off the vehicle and wait the required five minutes before trying to attempt the programming sequence again. Anytime you have to do a programming repair on one of these systems it is usually done do to a component failure and the component needs replacement or a calibration update as instructed by a technical service bulletin (TSB). It works the same as any other computer problem that you are probably already familiar with.

Evolution

Figure 6

The HMI has evolved along with technology, just like any other component on today’s automobile. It started out with version 1.0 in 2013 to version 2.5 in 2017. The processor speeds have changed considerably to be able to handle the increased data and memory that is needed in today’s media requirements. Most people today have a smartphone that’s either an Apple or an Android device. Both companies have developed software that is compatible with the GM My Link software (Fig. 6) that’s used in GM vehicles today. By downloading the Apple app “Apple Car Play” or the Android app “Android Auto,” and connecting the phone to the vehicle by using a USB cable will allow the phone to be displayed on the touch screen of the vehicles digital display. So using the Google Maps app on the phone will allow the use of a navigational map being displayed on the display of the vehicle (Fig. 7). Pretty cool right? This surely beats using the old navigation method of having to update the software in the older systems as it constantly seemed like it was inaccurate and out of date. This system is a lot less expensive as well, and the program is free on your cell phone.

As far as diagnostics on these vehicles, the use of a compatible scan tool is necessary to be able to properly repair this system. The GM Global Diagnostic System, or GDS2, is required to do some of the bidirectional steps in testing the HMI system. One thing that I have noticed is when a new vehicle has had the entertainment system altered with a non-factory component, all sorts of problems can crop up if a component is installed that really shouldn’t be there or if the installation is done incorrectly. These newer entertainment systems are pretty sophisticated and a lot could and can go wrong. Besides, who wants the malfunction indicator lamp to be on because something is on the network that shouldn’t be there or is missing and should be there?

Figure 7

So what to do about HIM? There are a lot of service opportunities that can be addressed because the radio in a vehicle isn’t operating correctly. Unless these vehicles are still under the factory warranty then there are plenty of service options available. No need to send the vehicle away. Just understand how the system works and who the players are. It is my understanding that other than the color of the vehicle, the two most important features on a vehicle to the majority of most customers is the air conditioning system and the entertainment system. People like to stay comfortable, and most will pay to stay that way.

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