Introduction.
In the automotive industry, today, electronic systems and mainly semiconductor technologies have really helped improve vehicle performance and harness numerous capabilities that were not present years ago. Key among these technologies are microcontroller chips which are involved in a wide array of functionalities ranging from braking, engine control, air bags, chassis control, entertainment, lighting and even infotainment among other functions that are now part of modern “smart cars”. In modern microcontroller chips, new functionalities can be implemented using software by leveraging the improved performance and memory features seen in modern designs. On the other hand, technology standardization and the drive towards new software architectures are now driving automotive electronics towards more and more powerful devices, and consequently enabling vehicle design enhancements that make them faster, smarter, green and most importantly, fun.
This paper will investigate 10 automotive applications of microcontroller technology and their major features. However, since it is hard to have a microcontroller suited to just one function in a vehicle, this paper will categorize the applications into major categories where in most cases, a single microcontroller can be used for several applications. For example, communication microcontrollers can also perform audio processing, infotainment, networking, etc. This is due to the fact that there does not exist a single communications protocol that could effectively address all automotive applications and thus a single microcontroller module can be used to integrate communications between several vehicle subsystems.
Communications (Ethernet-AVB networking, Infotainment, Controller Area Networks (CAN), Audio processing):
Microcontrollers have numerous applications in enhancing communications between ECU’s (electronic control units) such that vehicular systems are able to share real-time data between different ECU’s (Bannatyne, 2009). A good example is the ATMEL SMART ARM-based microcontroller that is used in vehicle entertainment systems to enhance connectivity for audio systems, head units, and telematics. The ARM Cortex-M7 microcontroller series by Atmel christened SAM V has a combination of connectivity interfaces such as Media LB, USB, CAN (Controller Area Network) and Ethernet AVB used to enhance communication (Atmel.com, 2016; Microchip Inc., 2016). Some of the highest performing chips in this series deliver up to 1500 Core-Marks (Atmel.com, 2016).
Handling Complex Algorithms:
Over the years, automotive electronics have become quite complex, and this has a significant impact on peripheral integration and throughput requirements on automotive microcontrollers. Complex algorithms are now required to help in switching and handling inputs from various communication systems and sensors, actuator control outputs and execute vehicle control cycles in real-time. However, microcontrollers have become quite powerful and advanced in term of CPU throughput, cache memory, program memories and a number of transistors per chip. For example, 32-bit RISC processors are now used for new generations of anti-lock braking system (ABS), differential gear systems and Airbags. The growing complexity of algorithms has led to the emergence of vehicular operating systems which are mainly developed in-house, but there are expectations of an industry migration to operating system standardization and efficient network management. For example, the OSEK/VDX (Offene Systeme und deren Schnittstellen fur die Elektronik im Kraftfahzeug) operating systems has been adopted by many industry players as an open standard to help decouple algorithms (application code) from network management processes thus helping avoid incompatibility issues between software and hardware. OSEK has a standardized API, protocol, and behavior and this helps facilitate software portability and reusability and ensuring predictable systems behavior (Bannatyne, 2009).
Safety, Failure/Fault Tolerance and High-Temperature environment applications.
Microcontrollers are used in safety critical vehicle systems to provide fail-safe functionality while future implementations these will include fault-tolerant microcontrollers. Modern ABS systems are fail-safe, and if electrical faults occur, the vehicle switches from the faulty ABS to the foundation hydraulic brakes. However, fault-tolerant systems should recognize that a fault has occurred and still continue to operate safely even when the fault persists. Some safety oriented controllers include the 8-bit controllers by Atmel that are used to deliver performance, power, safety and flexibility, and have high-temperature ratings to ensure they operate in extreme conditions without failure thus ensuring failure critical systems such as ABS stay online (Atmel.com, 2016).
Lighting, Capacitive Touch Sensing, Wheel and Button Slider Applications.
Most automotive microcontrollers offer lighting control which mainly involves controlling vehicle lights such as indicators, brake lights, head light brightness, interior lighting and vehicle status indicators, and other integrated lighting systems such as dashboard LEDs. Microcontrollers are used to detect output from braking systems thus signaling the lights to go on/off. On the other hand, smart indicators that automatically turn on when the vehicle detects an oncoming turn from GPS navigation systems is an application of microcontrollers. On the same note, modern vehicles come with an onboard touch-based control panel for infotainment, navigation and also to show various vehicle status indicators. A classic example is the Mercedes S-class sedan where a series of indicators comes up when one backs into a parking space to show how much room is left without touching other parked vehicles or obstructions such as walls. As such, modern microcontrollers to offer support for capacitive touch screen sensing to allow for user input, and also view status such as wheel positions, etc.
Vehicle Control, Engine Control and Driver Information:
These applications mainly employ 16-bit microcontrollers to enhance vehicle control and powertrain and in such chips, the key decision factor is their computational performance (Agarwal, 2014). Modern luxury sedans and SUVs such as Jaguar use microcontrollers for cruise control to keep the distance from vehicles driving ahead in traffic. In modern Volvos, the ignition keys use flash memory to hold driver personal information and personalized settings such as mirror and seat positions, radio presets and music settings. DSP processors are used to for voice recognition and also to control echo cancellation in hands-free devices (Turley, 2003).
Finally, the most crucial application of microcontrollers is in the ECM (engine control module) that uses up the most expensive and powerful microcontroller in a typical automotive. The microcontroller in the ECM controls where the throttle should be set, the amount of fuel to be injected into the cylinders (Fleming, 2011), and also when to fire spark plugs, etc. This controller also provides onboard vehicle diagnostics, power distribution to various electronic components, and communicates with onboard microcontrollers and other automotive systems to share data obtained from various sensors/actuators. The microcontroller collects data from various analog sensors, digitizes it, and then uses it to calculate the required engine settings. The calculated results are then converted into actuator settings. The analog and digital outputs from the ECM module are also used to operate these actuators. In some vehicles, the driver can decide to make various trade-offs between fuel economy and power by simply activating a switch that makes the ECM microcontroller run different engine subroutines, and also provide car enthusiasts with great control over engine performance in various situations (CVEL, 2012).
References:
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Atmel.com, (2016). Automotive Microcontrollers: Intelligence and Control for Demanding Environments. [online] Atmel.com. Available at: http://www.atmel.com/products/automotive/automotive_microcontrollers/ [Accessed 11 Aug. 2016].
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