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Automo Electron Recent decades have seen dramatic improvements in the fuel efficiency, emissions and safety of cars, mostly bought about by electronic systems, along with improved structural design and materials. The number of parts involved in modern automotive electronics is mind-boggling, and the cost is becoming a significant proportion of the vehicle overall. 12 Silicon Chip Australia’s electronics magazine siliconchip.com.au otive nics Part 1– by Dr David Maddison Image courtesy: www.facebook/public/images/ 01-picture-library/ ChristophHammerschmidt/ 2016-03-16-delphi_automotive_ power_distribution.jpg Terminology V ehicle electronics can be separated into several categories including engine and transmission management, safety, driver assistance (eg, lane departure warnings and cruise control), chassis control (braking, stability and traction controls and four-wheel-drive systems), passenger comfort, navigation and entertainment. In this article, we will take a look at the history of these devices, how they are currently used and how they work. We have covered some aspects of these systems in past issues such as engine management (October & November 1993), anti-lock braking (November 1994), traction control (March 1996 & February 1999), adaptive cruise control (September 2005), cylinder deactivation (January 2009), airbags (November 2016), onboard diagnostics (February 2010) and advanced diagnostics (September 2020). We also recently described MEMS devices in detail, which are used as sensors for airbag activation and vehicle stability control. That was in the November 2020 issue (siliconchip.com. au/Article/14635), so we won’t look at those in too much extra detail. siliconchip.com.au Confusingly, ECU can stand for either Engine Control Unit or Electronic Control Unit, and ECM can stand for either Engine Control Module or Electronic Control Module. We will use Engine Control Unit (ECU) for the device that controls the engine and Electronic Control Module (ECM) for the many other devices distributed throughout a car that control various systems. An ECU that controls the transmission as well as the engine is known as a Powertrain Control Module (PCM). ECMs control particular subsystems on the vehicle, such as doors and windows, batteries, lights, steering, the sound system, navigation, stability control, braking etc. Individual manufacturers might also have their own unique names for these devices. A brief history of automotive electronics One of the motivations for electronic engine management was laws passed in California, USA that required cars from the 1966 model year to have reduced emissions of hydrocarbons and carbon monoxide. Early mechanical emission controls were inefficient and power-hungry. Controlling emissions became much easier and more efficient as electronics became more capable and cheaper. As time progressed, the laws became much more stringent and were also adopted worldwide. Vehicle emission controls were introduced into Australia in 1972 through ADR26, followed by ADR27 for gasoline vehicles and ADR30/00 for diesel vehicles in 1976. Australia’s electronics magazine December 2020  13 Fig.1 (above): the Bosch electronic controller for manual transmissions from 1965. It was way ahead of its time. Source: Bosch Media. Fig.2 (right): the main board of a Bosch D-Jetronic analog fuel injection system from around 1968. Source: https://members.rennlist.com/pbanders/ecu.htm Some selected milestones in ECU development can be summed up as follows. In the 1970s, it involved electronic control of carburettor mixtures, fuel injection and ignition timing. In the 1980s, more extensive fuel management was introduced due to the widespread introduction of fuel injection and closed-loop lambda control (air-fuel mixture setting). In the 1990s, ECUs started managing vehicle security functions, making theft much more difficult. ECUs were also introduced on diesel engines. In the 2000s, drive-by-wire throttle control and turbocharger control were introduced. Increasing numbers of sensors and controller functions were added. In the 2010s, almost all aspects of a car came under the management of the ECU or another computer system. All devices are connected by high-speed data buses, and many vehicles introduced driver assistance features. A more detailed history follows • 1965: Bosch developed an electronic control for manual transmissions, negating the need for the clutch to be depressed (see Fig.1). Several hundred of these systems were installed on the Glas 1700 car in 1965. The technology was regarded as way ahead of its time, but BMW acquired the Glas company, and they lost interest in it. • 1968: Volkswagen introduced electronically-controlled fuel injection (using the Bosch D-Jetronic system; Fig.2) on the VW Type 3. The controller was an analog device. See the video titled “Type3FISlideShow” at https://youtu. be/jIN1HZUrxL8 You can find quite a bit of documentation on the DJetronic system at siliconchip.com.au/link/ab4f and siliconchip.com.au/link/ab4g • 1969: Ford introduced the Sure-Track Braking System (anti-skid brakes) as an option on the Lincoln Continental Mark III and the Thunderbird. For more information on this, see siliconchip.com.au/link/ab4h • 1973: Chrysler introduced electronic engine control. The points in the distributor were replaced with a magnetic pickup coil, and the rotor with a reluctor (toothed wheel). Both were connected to an ECU (see Fig.4). The system was very basic but improved reliability due to the elimination of the points and rotor, provided better timing accuracy, a stronger spark and a higher RPM limit. The development of the internal combustion engine isn’t yet over. . . New engine technology such as Mazda’s SkyActiv-X, variable As an example of what is now possible, the Audi SQ7 has an valve timing, variable compression ratios and engines without electric supercharger as well as traditional turbochargers. camshafts would be impossiThe electric supercharger Passive turbocharger ble without computerised engine is used to eliminate turbo Active turbocharger management. lag and can spool up from Air recirculation valve (See the separate panel on camidle to 70,000rpm in oneIntake manifold collector Compressor activation valve less engines.) quarter of a second (while with swirl control If engine ‘accessories’ are powthe turbos are still spooling EPC bypass valve ered electrically rather than meup), after which it is disenchanically, they become easier gaged. Electric powered to control. It requires significant compressor (EPC) Electric accessories can also power, just as an engineimprove fuel economy as they driven supercharger does. have virtually no parasitic loss It is powered by a 3kW Charge air cooler Charge air X-shaped when switched off (just that of the alternator which charges a manifold alternator, which will be present re- Electric supercharger 470Wh 48V battery which gardless, although many vehicles (compressor) on the Audi SQ8. Charge air cooler powers, via a DC-DC conthese days disconnect the alterna- This device would not have been possible verter, a 7kW 12V electric without sophisticated engine management. tor much of the time too). motor on the supercharger. 14 Silicon Chip Australia’s electronics magazine siliconchip.com.au Fig.3: an Australian advertisement for the Chrysler Electronic Lean Burn system from Time magazine, November 1978. • 1973: Japan Electrical Control Systems Co Ltd, now JECS Corporation, formed as a joint venture between Robert Bosch GmbH (Germany), Nissan Motor Co (Japan) and Diesel Kiki Co Ltd (Japan; now named Zexel Corp). This gave Nissan access to Bosch electronic fuel injection systems, which were manufactured in Japan. The original systems they used were Bosch L-Jetronic with Japanese electronics, (usually) German sensors and fuel pumps and regulators made under license to Bosch by Denso. JECS produced 16-bit ECUs for the Nissan 300ZX from 1993 onward. • 1975: Ford USA introduced the EEC1 electronic engine control system. It used a Toshiba TLCS-12 12-bit purpose-designed microprocessor. The system had 2800 logic gates, 512 bits of RAM and 2kb of EPROM. The 12-bit processor arose from a requirement for a measurement resolution of 0.1% or better (8-bit resolution would give 0.39%, 12-bit resolution gives 0.024%). It appears that the system was experimental, as it wasn’t introduced into vehicles until 1978. • 1976: GM and Motorola teamed up to develop a custom CPU for engine management. This was incorporated in the Computer Command Control System or CCC for emissions control, released in 1981. You can view a PDF with details about CCC at siliconchip.com.au/link/ab4i • 1976-89: Chrysler USA introduced its Electronic Lean Burn system. In Australia, some models of the CL Valiant Fig.4: an early Chrysler (USA) electronic ignition system scheme from around 1973. Based on an image from fourforty.com. siliconchip.com.au Fig.5: the GM MISAR electronic ignition timing system from around 1977. Source: www.delcoremyhistory.com Australia’s electronics magazine December 2020  15 Fig.6: the GM Computer Command Control System (CCC), introduced in 1981. Fig.7: typical engine torque output (black) and power (blue) as a function of engine RPM at full throttle. Despite torque falling from its peak at Ntmax RPM, power continues to climb until Npmax RPM as power is the product of torque and RPM, and RPM is increasing faster than the torque is decreasing to that point. Source: x-engineer.org (including the Charger) had it, and it was widely advertised (see Fig.3). • 1977: Oldsmobile introduced MISAR (MIcroprocessor Sensing and Automatic Regulation), a microprocessorcontrolled ignition timing system on the Toronado model (see Fig.5). It comprises two LSIs with a total of 20,000 transistors. It improved fuel economy by one mile per US gallon and made the engine more responsive and smoother running. It also helped to meet emissions targets. • 1977: Motorola released the 35,000 transistor MC6801 microprocessor, and in 1978, GM became the main customer for this device as it was used in the TripMaster digital trip meter for the 1978 Cadillac Seville. • 1978: The Ford EEC-1 (Electronic Engine Control) was introduced into some US models. It controlled ignition timing, the EGR (exhaust gas recirculation) valve and the ‘smog pump’. These were the 1979 model year cars, mainly the LTD and Mercury Grand Marquis with the 351 Windsor V8 motors sold into the California market (which had stricter emission laws than elsewhere in the USA). Fig.8: power curves for one engine as a function of throttle position and RPM. This sort of data is incorporated into engine maps. Source: x-engineer.org 16 Silicon Chip • 1979: Ford USA introduced the EEC-2, which controlled an electronic carburettor with oxygen feedback and a fuel supply stepper motor, ignition timing, the EGR valve and the ‘smog pump’. It used the Intel 80A49H processor. • 1980: Ford USA introduced the EEC-3, with fuel injection control. • 1981: GM introduced CCC, which (as described above), started development in 1976 (see Fig.6). • 1983: the ZF 4HP22 EH automatic transmission was introduced in the BMW 745i. It had electronic control over the pressure regulator, torque converter lockup and shift valves (previous automatic transmissions used hydraulic control). Fig.9: petrol engine emissions of various combustion byproducts as a function of the air/fuel ratio. The ratios for best power and best fuel economy are shown in red and blue respectively, along with the ‘compromise’ target range (green) to give good torque, power, economy and emissions. Deviations from the ideal stoichiometric air-fuel ratio of 14.7 are permitted under certain circumstances such as acceleration, maximum power, best economy or start-up, among others. Source: Toyota Motor sales literature. Australia’s electronics magazine siliconchip.com.au Fig.10: a graph showing how torque, fuel consumption and pollutants change with ignition timing. TDC stands for “top dead centre”, the point at which a piston is at its upper limit of travel; advanced timing is where the spark occurs before TDC during the compression stroke while retarded timing is where it happens afterwards. Based on a graph from what-when-how.com • 1984: Ford USA introduced the EEC-4 with OBD-1 support. It used the Intel 8061 microprocessor. The EEC-4 is a favourite among Ford performance engine enthusiasts, and it can run nearly any engine. It apparently has engine control features just as advanced as modern controllers. Extensive documentation for modification is available, for example, see www.tiperformance.com.au/Reference/ eectch98.pdf (we do not endorse modification; modify ECUs at your own risk). This gives a good insight into how these devices work at a highly detailed level. • 1986: Carnegie Mellon University developed a selfdriving car, the Nav lab-1. See the video titled “NavLab 1 (1986): Carnegie Mellon” at https://youtu.be/ntIczNQKfjQ and www.ri.cmu.edu/robotics-groups/navlab/ • 1986: Chrysler introduced multiplexed wired communication modules. These provide weight, space and l l l Fig.11: an engine map or ‘fuel map’ showing manifold absolute pressure (MAP) as a percentage vs engine RPM, with each point in the table indicating the volumetric efficiency. This is the amount of air flowing into an engine compared to its theoretical maximum (it can exceed 100% in some circumstances). This tells the ECU how much fuel to inject for a particular MAP and RPM. Live ECU data is shown above. Source: Summit Racing Equipment. • • • • • cost saving as much less wire has to be used, since communications can be over a single wire rather than multiple wires. 1987: the standards for the CAN (controller area network) bus were introduced. 1991: the first car with a CAN bus goes on sale, the Mercedes Benz W140 series which included the 300 SD, CL 500, CL 600, S 320, S 420 and S 500 sedans. 1991: the CAN 2.0 bus specification was published by Bosch. 1991: a partnership was formed between Ford and Motorola to develop a PTEC (powertrain and transmission electronics controller) using a Motorola PowerPC chip. This replaced Ford’s EEC-IV in 1994, which used an Intel chip. 1993: the CAN bus physical layer and data link standards were published by the ISO. The physical layer standards are not part of CAN 2.0. Repairing your ECU or ECMs Fig.12: the output voltage of a typical narrowband lambda sensor as a function of air-fuel ratio. This is often referred to as an ‘S-curve’. Low voltages indicate rich operation while higher voltages indicate lean; stoichiometric operation is around 500mV. siliconchip.com.au Dealers or independent mechanics may be able to repair or replace your car’s electronic modules. But also, in Australia, several companies specialise in repairing these devices. You can find them by Googling “car module repair”. If you want to do it yourself, there are also numerous YouTube videos and other online resources on the topic. Here is an example of a US video that shows how to reprogram a used ‘junkyard’ module to give it the identity of your current car. See the video titled “Save Money Using a Junkyard Engine Control Module” at https://youtu.be/Hhk7Wg0i3KE The dealer said it was impossible and needed an extremely expensive replacement module! Such a technique may or may not work for you or any diagnostic tools or modules you have. Australia’s electronics magazine December 2020  17 EXHAUST GAS HIGH-PRESSURE SEAL OUTSIDE AIR SLITS – V + INTERIOR PLATINUM ELECTRODE HOUSING ZIRCONIA SENSOR SENSOR SHIELD EXTERIOR PLATINUM ELECTRODE EXHAUST MANIFOLD Fig.13: a narrowband lambda sensor is usually a solid-state electrochemical cell made with zirconia ceramic material. These are cheaper than wideband but only really tell the ECU whether the engine is running rich or lean. • 1994: Ford USA introduced EEC-5 with OBD-2. This is also a favourite among Ford engine modification enthusiasts. • 1996: OBD-II onboard diagnostics became mandatory for all cars and light trucks in the USA. • 2001: EOBD, the European equivalent of OBD-II, became mandatory for petrol cars in the EU. • 2003 Ford US introduced the EEC-6. • 2004: EOBD became mandatory for diesel vehicles in the EU. • 2009: Google started their self-driving car project. • 2012: Bosch published further extensions to CAN called CAN FD (flexible data rate). This provides a faster bit rate, but is compatible with CAN 2.0, so CAN FD devices can coexist on the same network as CAN 2.0 devices. • 2014: the first commercial self-driving vehicle, the Navya, was launched. See https://navya.tech/en/ • 2016: the Tesla “Autopilot 8.0” system was introduced. It is intended for driver assistance, not for self-driving which some people inappropriately use it for (perhaps confused by the name). From 2009 to the present, there have been many innovations on self-driving vehicles, but they are beyond the scope of this article. Fig.14: this is how the more expensive and complicated wide-band oxygen sensors work. They provide a useful output over a lambda range of about 0.7 to over 2.0. That corresponds to air/fuel ratios from 10:1 to over 30:1 for petrol (ie, with the stoichiometric ratio of 14.7:1 being a lambda of 1.0). This allows for much more precise tuning of engine conditions for a particular target lambda value. Combustion optimisation with the ECU The most fundamental role of the ECU is to control the amount of fuel injected into the engine to give the right airfuel ratio, and to control the timing and duration of the ignition spark in non-diesel engines. A crankshaft position sensor indicates the position of the pistons in the cylinders, so that the correct injection timing and spark timing can be determined. The effect of varying air-fuel ratio and ignition timing on various parameters is shown in the figures above. Beyond those fundamentals, many other parameters are taken into account by the ECU. These includes: • the amount of air inducted into the engine • the throttle position • intake air temperature and pressure • engine load • camshaft position (when variable valve timing is used) • engine temperature • exhaust oxygen content • air filter restriction • vehicle speed • current gear • engine knock (if any is detected) • and more. CAN bus LIN bus Fig.15: this shows how the LIN bus complements CAN bus. It is simpler, cheaper and suitable for non-critical, low data rate applications. Source: CSS Electronics. 18 Silicon Chip Fig.16: SafeSPI is an automotive serial protocol for safetycritical devices like airbag controllers. Source: Synopsys, Inc Australia’s electronics magazine siliconchip.com.au The camless engine Fig.17: some of the functions provided by Advanced Driver Assistance Systems (ADAS) by Servotech. It uses a variety of electronic control modules (ECMs) with embedded software and sensors such as radar, cameras, ultrasonic and lidar to control steering, engine, transmission and brake systems. Source: Servotech, Inc. The main objectives in running a street car engine are to optimise power, fuel economy and emissions. Unfortunately, all these objectives tend to conflict with each other. Fortunately, the ECU can adjust engine parameters hundreds or thousands of times per second to find the best compromise between these three goals, depending on what the driver is doing. The stoichiometric air-fuel ratio is the ratio where all the fuel and oxygen will be consumed during full combustion. For perfect “test” petrol, 14.7g of air is required to burn 1.0g of fuel. If there is more air than required then the mixture is “lean”, and if there is less, it is “rich”. But the ideal ratio varies with things like the exact blend of fuel used. Most cars with an ECU use an oxygen sensor that measures the oxygen and hydrocarbons in the exhaust, providing feedback to the ECU to optimise the air-fuel ratio. This is known as lambda control (see Figs.12-14). In reality, a stoichiometric ratio is avoided except under light loads because it burns too hot, and it carries an increased risk of premature detonation or knocking, which can cause engine damage. For acceleration and other high loads, a richer (cooler burning) ratio is used, but emissions of unburnt hydrocarbons increase as a result. Fuel-injected, ECU-controlled engines (nearly all of them today) can operate in ‘open-loop’ or ‘closed-loop’ mode. In closed-loop mode, the amount of fuel injected is determined by the amount of air entering the cylinders and feedback from the oxygen sensor(s). In open-loop mode, the amount of fuel injected is an ‘educated guess’ by the ECU based on numerous tables and calculations that were generated during the engine’s development. Open-loop might be used constantly on racing engines, where fuel economy and emissions are not so critical. Still, closed-loop mode is required for street cars at least some of the time, and represents a compromise between best fuel economy and minimal emissions. Nevertheless, open-loop mode is used on street cars in circumstances such as: siliconchip.com.au There are significant advantages for an internal combustion engine without a traditional camshaft, with the valves instead operated electromechanically or hydraulically. It would be more compact, lighter, have reduced rotating mass, reduced internal friction and possibly a much higher RPM limit. Such a motor could also be started with only a small starter motor, as it could be started on one cylinder initially, and it could also be run in either direction, possibly obviating the need for a reverse gear. ECU-operated electromechanical valves would mean complete and precise control over the combustion cycle, which is extremely difficult with mechanically-operated valves, even with variable valve timing or lift. That would lead to much-increased power, improved fuel economy and lower emissions. Such an engine could use a variety of fuels, run lean fuel ratios, have ‘free’ cylinder deactivation. It could even allow brief bursts of two-stroke operation or the “five-stroke” Miller or Atkinson cycles, or homogenous charge compression ignition (HCCI), where gasoline is ignited by compression, similarly to diesel. Such an engine could continuously cycle between all types of operational modes, depending on what is required for the circumstances. The principle is simple; making something sufficiently robust to work in an engine is not. These engines are under development by a variety of manufacturers such as Camcon Auto Ltd and FreeValve (www.freevalve.com – a company related to hypercar manufacturer Koenigsegg).See the video titled “Intelligent Valve Technology - Petrol engine, diesel efficiency” at https://youtu. be/XdEhg9JDuEw Camcon Auto Ltd’s iVT, intelligent Valve Technology concept (https://camcon-automotive.com/). Valves are operated via a digital signal from the ECU rather than mechanical means giving enormous flexibility in engine operation. Video: “Intelligent Valve Technology - Petrol engine, diesel efficiency” https://youtu.be/XdEhg9JDuEw • starting and warm-up (like a choke on older engines, where more fuel needs to be injected); • at higher loads and during acceleration (where fuel economy is less critical; similar to the accelerator pump on carburetted engines); • and during deceleration and engine braking, or when the engine speed is rapidly varying. When engine RPM and the throttle position are stable, such as at idle or constant speed driving, the engine will operate in closed-loop mode for maximum fuel economy and minimum emissions. Australia’s electronics magazine December 2020  19 In some cases, the engine will run lean, which reduces fuel consumption, but not too lean as that could lead to the creation of too many oxides of nitrogen. In open-loop mode, the ECU controls the engine according to an “engine map” stored in the ECU, which sets engine parameters according to engine load, RPM etc. It receives no direct feedback from the oxygen (lambda) sensor, although long-term averaged data from the lambda sensor may be used to adjust the maps. An engine map is produced by a series of dynamometer tests that measure the engine performance against a range of variables such as engine speed (RPM), load, throttle setting, ignition timing, air-fuel ratio and engine and ambient temperatures. Maps are generated for such combined variables as torque and power as a function of engine speed; fuel consumption as a function of torque; emissions of CO, HC and NOx as a function of air-fuel ratio; and torque, fuel consumption and Types of fuel injection • Dual injection is another variation. One version is like port or sequential injection but with two injectors per cylinder, possibly spraying on two intake valves (in a three- or four-valve-percylinder engine). One injector may be smaller than the other, to give finer control over the amount of fuel injected. • Another variation is a combination of port and direct injection, with two injectors per cylinder, one internal and one external (see below). Toyota introduced this system on the 2006 Lexus IS350 and called it D-4S. Both port injection (PI) and direct injection (DI) have advantages and disadvantages. As fuel is injected, cooling of the surrounding intake air-fuel charge occurs either in the port (PI) or cylinder (DI). PI is good for naturally aspirated (non-turbo or non-supercharged) engines as it cools the incoming charge, which increases its density and allows more charge to enter the combustion chamber. It’s also mechanically simpler to locate the injectors in the port (PI) rather than the combustion chamber (DI). With PI, there is also more time for fuel vapourisation to occur. A disadvantage of PI is sometimes the fuel condenses on the port walls, affecting the fuel ratio. With DI, there is less chance of premature detonation (knock) because the charge and cylinder wall surfaces are cooled during the compression stroke, just before ignition. DI also allows for a higher compression ratio due to the cooling effect and therefore, more power. DI also gives the possibility of stratified charge ignition (SCI), with multiple fuel injections timed over a single compression stroke. A DI system is more expensive, and also allows carbon deposits to accumulate on the back of the intake valves. In PI, the valves are cleaned naturally by the fuel vapour passing over them. Dual injection systems with both PI and DI can have the advantages of both the PI and DI systems. LOW TORQUE HIGH Fuel injection is vital for modern engine management, as it gives superior fuel delivery accuracy to carburation. Several different types of fuel injection are in use, as follows: • Single-point or throttle-body injection is the simplest type of fuel injection and replaces the carburettor with a throttle body and one or more injectors. This is the easiest system to retrofit to an existing carburetted engine. • Port or multiport injection is where fuel is injected outside each cylinder’s intake port, making for more accurate and customisable injection than single-point. No fuel can condense in the intake manifold, plus there is less delay in it reaching the cylinder. • In conventional multiport injection, fuel for all cylinders is dispensed at the same time, so fuel must remain in the intake port waiting for a valve to open. During this time, engine running conditions may have changed. • Sequential fuel injection addresses this by injecting fuel for each individual cylinder before its intake valve opens. • Direct injection takes the sequential concept further and injects fuel directly into the cylinder, bypassing intake valves and providing the most accurate fuel metering. A high-pressure fuel pump (HPFP) is required, often driven off a camshaft. The low-pressure in-tank fuel pump remains, with its role being to supply fuel to the HPFP. A dual port injection system with one injector discharging directly into the cylinder (as in direct injection) and the other injector discharging into the port. Video: “Why New Cars Are Using Both Direct & Port Fuel Injection” https://youtu.be/66C4YIiwRbM 20 Silicon Chip LOW RPM At lower RPM both direct and port injection may be used depending on the torque requirement, while at higher RPM, only direct injection is used. Australia’s electronics magazine HIGH siliconchip.com.au Open-source ECUs There are several open-source ECU projects, as follows: • SECU-3 (https://secu-3.org/en/), originally of Russian origin, is described as an “open source ignition and fuel injection control system”. A variety of prebuilt units or kit components can be purchased from the website. Fig.18: an example of an automotive night vision system on an Audi S8. From the video titled “Audi S8: Night Vision with pedestrian detection” at https://youtu.be/-38NlE4KWZ8 emissions as a function of spark timing at specific RPM. Many different types of fuel maps are possible, optimising for various requirements such as maximum power, economy or minimum emissions. Note that in the case of emissions, some can be treated outside of the engine in the catalytic converter (we’ll cover catalytic converters next month in more detail). The objective of the fuel map is to indicate to the ECU the amount of fuel to be injected to satisfy particular operating conditions. These operating conditions are generally engine speed and load, where the load is typically indicated by either throttle position or intake manifold pressure or both (see Figs.7-11). Most ECUs support a “limp home” mode in the event of ECU or sensor malfunction. It provides the bare minimum of functionality to get the engine running. In some GM vehicles, there is a “Calpac” chip that is used in case the ECU PROM data becomes unreadable, or there are sensor malfunctions. It is a resistor network that contains preset base values to provide typical values that should be given by various engine sensors, but which are not present or ignored in a limp-home situation. Sensors are ignored, and the engine operates much like earlier generations. Data buses Individual electronic modules in a vehicle need to communicate with each other, and several data buses have been developed for the purpose. Ethernet is not commonly used Fig.19: the Australian-made Haltech Elite 950 aftermarket ECU, suitable for basic four, six and eight-cylinder engines, including carburettor conversions. See the video “Elite 950 Explained” at https://youtu.be/hGuAneUd2_4 siliconchip.com.au • Speeduino (https://speeduino.com/home/) is an Australian Arduino Mega 2560 R3 based project. A variety of prebuilt modules and kit components can be purchased from their website. See the video titled “Making an insanely fast Speeduino ECU” at https://youtu.be/xgNpUEs6CWE • RusEFI (https://rusefi.com/) is an open-source project for race cars and off-road vehicles. It is not intended for emissioncontrolled vehicles or those with integrated safety systems. The website has a shop for purchasing related components. See the video “rusEfi open source standalone ECU runs M73 BMW v12 engine” at https://youtu.be/TGf8IMwRuIY • Rabbit ECU (https://mdac.com.au/rabbit-ecu-project/) is a low-cost Arduino-compatible DIY ECU which has been fitted to vehicles including a Commodore SS, Holden Astra and Holden Corsa. • OpenECU (www.pi-innovo.com/product/openecu/) is software that allows manufacturers to develop applications for ECMs. See the video “Pi Innovo OpenECU Demonstration” at https://youtu.be/SbsCdAC0l7E • RomRaider (https://romraider.com/) is an “open source tuning suite created for viewing, logging and tuning of modern Subaru Engine Control Units and some older BMW M3 (MS41/42/43) DME”. • DIYEFI.org (www.diyefi.org) is “a truly open source engine management system, one that you can build for the cost of the components alone”. • Kvaser offers some open source software to support their hardware, in addition to purchased software. See www. kvaser.com/support/open-source-software/ in automotive applications. There have been many, but here are some current automotive data bus protocols; we will not include those for aircraft. • CAN bus (Controller Area Network) is one of the most popular vehicular data buses and operates at 5V over shielded, twisted pair wires. The ISO 11898-2 standard is for high-speed CAN bus at 1Mbit/s or 5Mbit/s, while ISO 11898-3 or fault-tolerant CAN bus runs at 125kbit/s. There are other variations. It has a high fault tolerance in electrically noisy environments. It is complementary with LIN (see below). Incidentally, it is used in areas other than motor vehicles such as the Shimano DI2 gear shifter on bicycles, automated environments, prosthetic limbs, passenger lifts, medical equipment and model railroads. • FlexRay is faster, more reliable and more expensive than CAN bus and has safety-critical features plus data rates up to 10Mbit/s. It is used on some Audi, Bentley, BMW, Lamborghini, Mercedes Benz, Rolls Royce, Land Rover and Volvo vehicles. • OBD-II onboard diagnostics supports five different communications protocols via the standard Data Link Australia’s electronics magazine December 2020  21 Fig.20: the Haltech iC-7 Display Dash that connects to a Haltech ECU via CAN bus. It can also be connected to most vehicles via the OBD2 port, which also carries CAN. See the video: “iC-7 Display Dash | PRODUCT OVERVIEW” at https://youtu.be/IDqIIXl2z2Q Fig.21: the optional Haltech CAN keypad that integrates with a Haltech ECU. See the video “Haltech CAN Keypads | PRODUCT OVERVIEW” at https://youtu.be/CaT1kT3hW4g Connector (DLC) that all modern cars have. The protocols are: (a) SAE J1850 pulse width modulation at 41.6kbps, used mostly by Ford. (b) SAE J1850 variable pulse width at 10.4kbps, used mostly by GM. (c) ISO 9141-2 asynchronous serial at 10.4kbps, used chiefly by Chrysler, European and Asian vehicles. d) ISO 14230 Keyword Protocol 2000 asynchronous serial at 10.4kbps, also used by Chrysler, European and Asian vehicles. (e) ISO 15765 CAN bus (up to 1Mbps), mandatory in the USA after 2008 and possibly found on European cars after 2003. • LIN (Local Interconnect Network) is an inexpensive single-wire protocol for serial communications between devices in a vehicle. It is complementary with, but not a replacement for, CAN bus (see Fig.15). LIN is used for low data rate, non-critical applications in a vehicle such as controlling a sunroof, interior lighting, steering wheel cluster, climate control, seat adjustment and other motors etc. It supports data rates of 1-20kbits/s, uses 12V signalling and can serve as a gateway to a CAN bus. 22 Silicon Chip See the video titled “LIN Bus Explained - A Simple Intro (2020)” at https://youtu.be/TresvW4dxlc • MOST (media-oriented systems transfer) is a fibre-optic network used to integrate multimedia devices such as navigation systems, CD players, video screens, digital radios, mobile phones and in-car PCs. It saves the manufacturers of such devices having to develop custom interfaces for each vehicle. Up to 64 devices can share one bus, and adding a new device is as simple as plugging it in. It is used in preference to other automotive buses such as CAN because they are not fast enough to carry video. • SafeSPI (serial peripheral interface for automotive safety) is a protocol for the MEMS devices (described in our November issue), as used in active and passive safety system sensors. A SafeSPI safety system controller queries them – see Fig.16 and siliconchip.com.au/ link/ab4j (PDF). Programming ECUs and ECMs SAE J2534 is a PC-to-vehicle communications standard developed by the Society of Automotive Engineers to enable manufacturers and independent repairers (the “independent aftermarket”) to use standard tools to repair or modify vehicles by recalibrating, reflashing or installing updates to onboard electronics. This includes ECUs, TCMs, PCMs, throttle controllers and optionally other controllers. Can jump-starting damage an ECU? There is much discussion online about whether jumpstarting a car can damage the ECU. It seems that, as long as it is done correctly and with the right polarity, it is safe. However, we recommend you go by the advice of your car’s manufacturer. In some cases, such as with BMW, a new battery fitted to the vehicle needs “registration”. A scan tool is needed to reset the vehicle’s intelligent charging system and erase previous battery charging history. Failure to register may result in a fault indication and can also damage the new battery. Australia’s electronics magazine siliconchip.com.au Remapping or rechipping your ECU or TCU There are many aftermarket options to rechip or remap your ECU (and also automatic transmission TCU) with the claimed advantages of more power, torque or fuel economy, or better transmission change points. These things are certainly possible, but in most if not all cases it will void your powertrain warranty (even if any fault developed is seemingly unrelated to the ECU or TCU modifications). We have heard stories of $15,000 engine repair bills which were not covered by warranty because the owner had altered the ECU. So such modifications should be made with caution. It means that a repairer can use one device for programming a variety of different brands of vehicles. It is legally required in the USA for all vehicles produced since 2004, and each vehicle manufacturer must make their ECU reprogramming application software and calibrations available, for which they may charge a fee. It is also widely supported on vehicles outside the USA. OBD diagnostics (see our September 2020 article; siliconchip.com.au/Article/14576) are typically read using ELM327 or STN1110 interpreter ICs via a dongle and are read-only (except for clearing certain fault codes). But some top-end diagnostic scanners use J2534 and can write data as well, as was mentioned in that article. The requirement for non-dealer mechanics to be able to interface to the vehicle’s electronic systems relates to the “right to repair”. If your car is out of warranty, you are a motoring enthusiast and don’t mind the possibility of exceeding the manufacturer’s design specifications, and risking expensive repairs, you could consider modifying your engine and/or ECU. Just make sure that it continues to meet statutory requirements for emissions, noise etc. The legality of such modifications varies by state and territory; some are much stricter than others. So you need to do your research beforehand, or you could potentially be fined and forced to return the vehicle to its original condition. The open-source project OpenXC (http://openxcplatform.com/overview/) is “a combination of open source hardware and software that lets you extend your vehicle with custom applications and pluggable modules. It uses standard, well-known tools to open up a wealth of data from the vehicle to developers.” “… by installing a small hardware module to read and translate metrics from a car’s internal network, the data becomes accessible from most Android applications using the OpenXC library.” Another relevant open source project is Nobdy (Linux) at https://elinux.org/Nobdy Its goal is to “implement a featureful, stable middleware suite that provides an extensible and flexible interface to automotive sensor and actuator buses for the purpose of enabling car manufacturers, owners and developers the Fig.22: an example of an aftermarket EFI conversion kit, the Holley “Sniper” with an ECU built into the throttle body. There is a digital readout in the car. It is “self-tuning”, so no complicated programming is required, although it can be customised. siliconchip.com.au Australia’s electronics magazine December 2020  23 power to create new software that enhances the safety, economy and enjoyment of the driving experience.” Converting a legacy engine It is possible to convert a variety of legacy engines, such as in classic cars, to use more modern technologies. One of the simplest conversions is to replace the points in a Kettering ignition system with an electronic ignition system. This gives better reliability, better performance and there is no longer any need to adjust points or ignition timing. The points are replaced with an angular sensor that typically uses the Hall effect, with a rotating magnet on the distributor shaft, and a sensor where the points used to be mounted. A small computer monitors this sensor and switches the ignition coil to generate sparks at the appropriate time. SILICON CHIP and its predecessors have published several such projects over the years. A carburettor can also be replaced with an electronic throttle body that provides single-point fuel injection. This then injects a precise dose of fuel into the intake manifold. There are several aftermarket conversion kits available for a variety of engines. Some have the ECU built directly into the throttle body, to simplify wiring. They also typically require the addition of an oxygen sensor to the exhaust stream. Throttle position, air temperature and manifold absolute pressure (MAP) may also be monitored within the EFI conversion throttle body. Naturally, the more sensors are used, the more engine control there will be. There are carburettor conversion kits available from Holley (Fig.22), FiTech, MSD and Howell. More sophisticated kits such as from Edelbrock are also available to retrofit multipoint fuel injection onto certain engines, but are much more expensive. Haltech (www.haltech.com) is an Australian company with a worldwide reputation that makes a wide variety of aftermarket ECUs to suit many vehicles and applications. They also have a comprehensive YouTube channel (see Figs.19-21). MegaSquirt (http://megasquirt.info/) is another popular engine controller for the enthusiast or professional. It is said to be able to run every engine from a single piston lawnmower engine to an alcohol-fuelled dragster. They have a variety of products, including one which you put together yourself. Advanced driver assistance systems (ADAS) ADAS is designed to assist drivers in operating the vehicle. These systems include many sensors such as radar and lidar, whose data is combined in a process called sensor fusion to control steering, engine, transmission and brake systems (see Fig.17). There may be many individual electronic control modules providing distributed ADAS functions, but there is a trend toward having a centralised ADAS module as the ‘brain’ of the car. These systems include: • adaptive cruise control, to keep a constant distance to the vehicle in front regardless of their speed • anti-lock brakes (ABS) • automatic high-beam headlights or even glare-free “laser” high-beam systems • automatic parking • blind spot monitor or camera • collision avoidance system, which detects a rapidly approaching object and sounds an alarm or applies the brakes • crosswind stabilisation, which measures yaw rate, steering angle, etc to keep the vehicle on the desired path • cruise control • driver drowsiness detection (eg, by analysing the driver’s facial expression or steering inputs) • electronic stability control (ESC) • emergency brake assist (BAS), which detects panic braking and applies maximum braking effort • head-up display, to project vehicle information on the windscreen • hill descent control (helps to stabilise offroad vehicles during steep descents) • hill start assist, which holds the brakes on a hill until the accelerator is depressed • lane-centring system (also known as steering assist) • lane departure warning • night vision, to assist in avoiding obstacles such as pedestrians (Fig.18) • pedestrian protection system, which lifts the car bonnet when a pedestrian is struck • pre-crash system, which takes actions like pre-tensioning seatbelts prior to impact • rain sensor for automatic wiper activation and speed control • rear cross-traffic assistance, which detects traffic in a road being reversed into which the driver cannot see • reversing camera or 360° camera • satellite navigation • terrain response system (adjusts a four-wheel-drive system to suit terrain) • traction control (TC) • traffic sign recognition (eg, to warn if the speed limit is exceeded) • tyre pressure monitoring (TPMS) Next month An entry-level MegaSquirt product you put together yourself, but most of the MegaSquirt range is prebuilt. 24 Silicon Chip As we have run out of space in this issue, the followup article in the next issue will describe, in more detail, the most interesting and important types of ECMs found in modern vehicles. SC Australia’s electronics magazine siliconchip.com.au