The Development of Automotive Embedded Systems

1 Development History of Automotive Embedded Systems　　Embedded systems were born in the microcomputer era and have experienced a long independent development path of microcontrollers. The core of embedded systems is embedded microprocessors. Similar to the development of embedded microprocessors, automotive embedded systems can also be divided into three stages:　　The first stage: SCM (Single Chip Microcomputer) systems. Based on 4-bit and low-end 8-bit microprocessors, integrating the CPU and peripheral circuits onto a single chip, configuring external parallel buses, serial communication interfaces, SFR modules, and Boolean instruction systems. The hardware structure and functions are relatively simple, processing efficiency is low, storage is easy to be small, and the software structure is also relatively simple, not requiring an embedded operating system. This low-level automotive SCM system is mainly used in any relatively simple control scenarios with small data processing volume and low real-time requirements, such as wipers, headlights, instrument panels, and electric windows.Figure 1 Automotive Embedded SoC System Structure　　The second stage: MCU (Micro Controller Unit) systems. Based on high-end 8-bit and 16-bit processors, integrating more external interface function units, such as A/D conversion, PWM, PCA, Watchdog, high-speed I/O ports, etc., and configuring a serial bus between chips; the software structure is more complex, and the program data volume has significantly increased. The second-generation automotive embedded systems can complete simple real-time tasks and are currently widely used in automotive electronic control systems, such as ABS systems, intelligent airbags, active suspension, and engine management systems.　　The third stage: SoC (System of Chips) systems. Based on high-performance 32-bit or even 64-bit embedded processors, using DSP as a coprocessor in scenarios requiring fast processing of massive discrete-time signals. To meet the continuously expanding embedded application needs of automotive systems, the processing level is continuously improved, and storage capacity and integration are increased. Supported by embedded operating systems, they have real-time multi-task processing capabilities and tighter coupling with networks. Automotive SoC systems are high-end applications of embedded technology in automotive electronics, meeting the requirements of modern automotive electronic control systems for continuously expanding functions, increasingly complex logic, and increasing communication frequency between subsystems, representing the development trend of automotive electronic technology. Automotive embedded SoC systems are mainly applied in hybrid powertrains, chassis integrated control, automotive positioning and navigation, vehicle status recording and monitoring, etc.

2019-8-5 15:11:55 Comments

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Tan Xue

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2 Automotive Embedded SoC Systems　　2.1 Technical Characteristics　　Automotive embedded SoC systems are the product of the transition of embedded systems to high-end applications of real-time multi-task management, network coupling, and communication, greatly improving the real-time performance, reliability, and intelligence of automotive electronic systems. In addition to having the common characteristics of ordinary embedded systems, it also has the following advantages:　　(1) Strong support for real-time multi-task management, with an interrupt response time of 1-2μs;　　(2) Strong memory protection capabilities;(3) Capable of reasonable task scheduling under the support of embedded real-time operating systems, making full use of system resources;　　(4) Strong expansion capabilities in both hardware structure and software functions, significantly improving system integration and reducing costs;　　(5) Ultra-low power consumption, with the vehicle’s static power consumption at the level of hundreds of watts;　　(6) Enhanced anti-interference capability of system hardware, suitable for various working environments such as high temperature, humidity, vibration, and electromagnetic radiation;　　(7) Real-time operating system supports multi-threaded software structure, enhancing the software’s anti-interference capability;　　(8) Provides strong network communication capabilities, with interfaces such as IEEE1394, USB, CAN, Bluetooth, or IrDA, supporting corresponding communication networking protocol software and physical layer driver software, providing fault-tolerant data transmission capabilities and greater communication bandwidth.　　2.2 System Structure　　Automotive embedded SoC systems consist of two main parts: hardware and software. Hardware includes embedded processing and peripheral devices, while software includes application software and operating systems. Software implements automotive electronic control strategies through data structures, algorithms, and communication protocols, while hardware provides a platform for software to run and execute specific control.　　The integration of embedded SoC hardware systems is increasing, generally in a modular structure, as shown in Figure 1(a). In addition to the high-performance CPU core, real-time clock modules, SRAM (Static Random Access Memory), and large-capacity FLASH are expanded through the IP bus, configuring CAN bus and USB communication modules, seamlessly integrating PWM output, multi-channel serial ports, A/D conversion interfaces, and unified high-speed buffers, supporting RISC technology, multi-level pipeline technology, and on-chip debugging technology. The system’s real-time processing capability, reliability, and network communication capability are greatly enhanced.　　Modern automotive electronic systems have gradually evolved from single control to multi-variable multi-task coordinated control, with increasingly large and complex software, requiring embedded systems to seek new software solutions. Figure 1(b) describes the typical structure of automotive embedded SoC system software. It adopts modular software design based on standardized interfaces and communication protocols, with internal communication completed directly by the interaction layer, ensuring information transfer between applications. The network layer has data flow processing capabilities and serves as an intermediary interface for information exchange between different system levels, maximizing system resource integration. The embedded real-time operating system abandons the traditional front-and-back mode of operating systems, using a bus driver layer and hardware abstraction layer to manage I/O ports, reasonably allocating CPU resources, adopting a priority-based event management strategy, and calling applications through APIs (Application Programming Interfaces), managing interrupts, system behaviors, and tasks comprehensively through mailbox, message queue, and semaphore mechanisms.　　2.3 Common SoC System Platforms　　To adapt to the development trend of automotive electronic systems, semiconductor and software manufacturers from various countries have launched corresponding embedded SoC products.　　Notable SoC hardware platforms include: Intel’s StrongArm core processor, which has a 32-bit RISC data bus, 512KB of FLASH, 256KB of SRAM, and a 16-bit THUMB instruction set, supporting on-chip debugging, three-level pipeline technology, and LCD control; Motorola’s Dragonball core processor, a 32-bit RISC processor with a clock frequency of 16.85MHz and a processing speed of 2.7MIPS, seamlessly integrating SRAM, EPROM, FLASH, LCD controllers, and PWM output, supporting 16-bit port DRAM; NEC’s VR core processor, a 64-bit RISC chip with a clock speed of 300MHz and a processing level of 603MIPS, integrating a unified L2 cache, DRAM controller, PCI-X bridge, and 10/100 MAC device. Notable SoC software platforms, namely real-time operating systems, include QNX’s QNX, Wind River’s Vxworks, and Integrated System’s PSOSystem. They are real-time, microkernel, priority-based, message-passing, preemptive multi-tasking, multi-user distributed network operating systems, with modular structures, high-speed and stable core operations, strong communication capabilities, and scalability.　　Among the above platforms, the StrongArm core processor, Dragonball core processor, and VxWorks operating system have good application prospects in automotive SoC systems.

2019-8-5 15:12:10 Comments

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Ma Shuyuan

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3 Typical Applications of SoC Systems　　Automotive embedded SoC systems fully adapt to the working environment and technical requirements of automobiles and are widely applied in automotive electronic technology. Among them, the integrated control system for ABS/ASR/ACC being researched by Beijing Institute of Technology is representative.　　The ABS/ASR/ACC integrated system is a new active safety system for automobiles that integrates the anti-lock braking function (ABS), anti-slip driving function (ASR), and adaptive cruise function (ACC). The system structure is shown in Figure 2. It fully utilizes existing components of each subsystem, such as wheel speed sensors, engine speed sensors, throttle position sensors, accelerator pedal sensors, and detection radars to form a sensor network, sharing controllers and actuators. On the software side, it applies information fusion and centralized control technology to achieve anti-lock braking, anti-slip driving, and adaptive cruise functions through comprehensive adjustment of braking torque and engine output power. The control process fully considers the interrelationships among the three logical modules, achieving information fusion sharing; for example, the wheel slip rate calculation for ABS and ASR can be unified, and the vehicle speed information obtained by the ACC detection radar can be used to correct the ABS reference speed.　　The system selects a 32-bit SoC hardware platform such as the Dragonball core MC68E328 to replace the original 16-bit ABS controller, improving hardware processing speed and anti-interference capability, with richer port resources. The onboard radar uses the AC110 type 77GHz millimeter-wave onboard radar produced by France’s AutoCruise company, with radar signal processing using DSP processors, communicating with the ABS/ASR/ACC integrated system controller via CAN bus. CAN bus transmission has capabilities for differential data transmission, fault tolerance, and non-destructive arbitration, with transmission rates up to Mbps. The use of CAN communication improves the real-time performance of the control system and facilitates functional expansion and information sharing of the vehicle’s sensor data. The CAN communication topology is shown in Figure 3.The difficulty of software integration for the automotive ABS/ASR/ACC system is: how to manage interrupts and coordinate the priority of various tasks while ensuring control real-time performance, thus introducing embedded real-time operating systems is essential in this system. Real-time operating systems can reasonably allocate software and hardware resources, perform real-time parallel processing of multiple tasks, and provide conditions for functional expansion such as HAC (Hill Start Assist) and EBD (Electronic Brakeforce Distribution), while supporting a multi-threaded software structure, enhancing software anti-interference capability. The operating system selected is VxWorks, and task scheduling adopts a priority-based preemptive strategy. Based on the operating system and task priority settings, the specific ABS, ASR, and ACC control functions are implemented by calling application programs through APIs.　　The integrated ABS/ASR/ACC system uses a new generation of embedded technology to improve the system’s real-time performance, reliability, maintainability, and scalability.

2019-8-5 15:12:14 Comments

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Li Lei

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4 Development Trends of SoC Systems　　Automotive embedded SoC systems have excellent performance, and their superiority is gradually recognized by the automotive industry. In the future, automotive embedded SoC systems will present the following development trends:　　(1) Automotive embedded SoC systems will develop towards FPGA/CPLD (Field Programmable Gate Arrays/Complex Programmable Logic Devices), with systems composed of fractional programmable interconnect logic units, allowing units to exchange information, with a large number of calculations completed directly by hardware, resulting in a more flexible architecture and higher integration;　　(2) In system development, it will follow a universal open platform and unified standards for automotive electronic systems. To improve the universality of software and hardware, accelerate development speed, and reduce costs, SoC systems urgently need to establish unified standards and development platforms. The MODISTARC specification based on the OSEK/VDX standard issued by Europe will be the development trend of automotive embedded system development platforms;　　(3) With the development of automotive local area network technology and intelligent transportation technology, embedded SoC systems will form vehicle distributed control systems based on C-class or D-class networks and remote high-frequency communication systems based on wireless communication;　　(4) The application scope of embedded SoC systems will gradually expand from high-end cars and imported cars to low-end cars and domestically produced cars.　　Automotive embedded systems have developed rapidly in recent years. With the arrival of the post-PC era, embedded high-end applications based on network communication and real-time multi-task parallel processing will become increasingly widespread. Automotive embedded SoC systems use 32-bit or 64-bit high-performance processors in hardware and embed real-time operating systems in software, featuring diverse functions, high integration, network communication, rapid development, and low costs, with broad applications in automotive electronic control and onboard network communication systems, making them the best solution for future automotive electronics.

2019-8-5 15:12:14 Comments

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Li Lei

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5 Conclusion　　In summary, automotive embedded systems are evolving rapidly, with significant advancements in technology and applications. The future of automotive embedded systems looks promising, with continued innovation and development expected to enhance vehicle performance, safety, and connectivity.