Multi-core embedded processing technology drives automotive technology development

        Over the past 40 years, the semiconductor industry has made tremendous progress in integration. Last year was the 40th anniversary of Moore's Law. For the most part, Moore's Law also applies to other areas that are trying to achieve rapid expansion in a short period of time through technology. An example from the 2005 SIA Annual Report is a good example of the impact of the semiconductor industry model on daily life: "In 1978, a commercial flight from New York to Paris took 7 hours and the ticket cost $900. If Moore's Law were applied to the airline industry, the ticket would now cost only about 1 penny and the flight time would not exceed 1 second." Obviously, the airline industry is reluctant to adopt Moore's Law, but many other industries are trying to apply it. The

        automotive industry has benefited greatly from the development of embedded processing technology, and some vehicles now use up to 60 processors. The demand for new automotive functions is increasing, which in turn further drives the demand for higher system performance and reliability. The development of engine technology and the ultimate "green vehicle" requires new ways to solve many of the current technical problems. Semiconductors will play an increasingly important role in solving many electrical technical problems with more powerful semiconductors, new memory technologies, and greater embedded processor performance and timing control functions.

        New semiconductor technologies will create new opportunities to solve existing technical challenges in the automotive electronics industry. The 32-bit microcontrollers currently used in the automotive industry contain more than 30 million transistors, and this number may quickly increase to more than 60 million in the next few years. As system integration continues to increase in the next few years, new technologies will need to be developed to fully utilize the full capabilities of semiconductors in increasingly complex systems. Advances in semiconductor technology have now enabled new functions that were unimaginable 10 years ago, and a new type of real-time multi-core debugging, calibration and loop hardware interface is meeting the special requirements of advanced engine powertrain systems.

        In the past 30 years, some people have tried to use cylinder deactivation technology. With the rise in fuel prices and the emergence of powerful embedded processors, automakers and end users are beginning to look at cylinder deactivation technology in a new light. Embedded processors are used to control engine timing to achieve a balance between torque and fuel economy of the powertrain system.

        Clean and environmentally friendly engines will be used in various powertrain applications from light vehicles to heavy trucks. Government regulations in some regions will make engines even cleaner and more environmentally friendly. Methods to clean exhaust using direct fuel injection into the cylinder and particulate matter traps will require extremely advanced timing control of the injectors and sensors that detect the status of the particulate matter trap.

        To address these challenges, new approaches are needed to enable engineering design teams to adopt new features with faster time to market, lower cost, higher reliability and increasing quantity. In the automotive market, embedded control for engine management has a very complex set of electromechanical system requirements. Changes in customer expectations and government regulations are driving the continuous changes in engine management. The evolution of engine technology toward lean-burn engines, camless engines and electronic hybrid vehicles will have a direct impact on the powertrain electronics of future vehicles. Continuously variable transmission will play an important role in future powertrain systems, and new microcontroller technology and semiconductor solutions will be the main driving force to make new technologies a reality.

        Figure 1 shows the complexity of engine management. The block diagram shows a common engine control system with multiple input and multiple output devices. These inputs can generate different levels of interrupts and exceptions depending on the impact on the system. The output devices can be pulse width modulation (PWM), general purpose input/output, or timed input/output.

Figure 1 Engine control system block diagram

        Real-time debugging is critical when debugging and calibrating mechatronic systems, which typically do not allow the performance of embedded processors to be modified or interrupted for interrogation by development tools. Today, system engineers can take advantage of more advanced development tools that were unthinkable just a few years ago.

        To address the problem of how to trace data and instructions in real time across multiple processor core types, the IEEE-ISTO Nexus 5001 Consortium or Nexus Forum was formed. The Nexus Forum first published a specification in 1999 and updated it in 2003. The

        Nexus 5001 specification includes standard features for setting breakpoints and watchpoints on data and instructions using non-intrusive debugging techniques. The specification will deploy several unique features to track down the most severe software and hardware faults. Some of the new features include: responsibility tracking information handling, data tracking, memory replacement, port replacement, program tracking, timeouts, and error message handling. Although many of these features have been implemented in microprocessors for many years, no processor has implemented all of the features and real-time debug interfaces.

        Calibration and debugging methods used over the past decade have used a “must see every cycle” mindset when debugging and calibrating powertrain systems. The Nexus 5001 approach avoids the “must see every cycle” approach by making the following four assumptions about the debugging situation.

● Both source and object code are available in the development tool. This allows host-based tools to trace or calculate program flow without direct address or data bus visibility.
● Only streaming instruction changes are required from the target system to the development tool. Once the host calibration/debug tool has access to the target code, synchronization between the embedded processor and the host tool is maintained by simply modifying the streaming instruction address transmitted over the debug interface. The Nexus 5001 specification sends synchronization information if the streaming change does not implement a synchronization address within 255 instructions.
● Only a limited number of data locations must be displayed in real time, while most data values ​​can be examined during interrupts or updated when special events occur. The ability of the Nexus 5001 interface to trace data values ​​is new to many engineers. Traditionally, this process has been accomplished with a powerful logic analyzer. The analyzer is responsible for tracking the address bus and triggering the data bus to write data to a specific memory location. This is a very difficult task, and the emergence of large data caches and on-chip system SRAM makes it almost impossible.
● Finally, if an error occurs, the user must be notified from the debug environment. The Nexus 5001 specification provides a FIFO buffer of variable size in the transmitter section. If the FIFO overflows, the interface will send an error message. The user can choose when the overflow error occurs to implement an obsolete embedded processor or continue operation by sending a new synchronization message. The

        Nexus 5001 port can be configured to capture the amount of information required by development, loop hardware, or calibration tools. Several IC manufacturers have adopted the Nexus 5001 specification in multiple CPU architectures to support a variety of applications from mobile phones, automobiles, hard disk drive controllers to video processors.

        A multi-core real-time interface recently developed for compatible PowerPC architectures provides real-time debug, calibration, rapid prototyping, and loop hardware functions on a single interface. Figure 2 shows a block diagram of the four processing units in a multi-core debug architecture based on the Nexus 5001 standard. The first version provides real-time interfaces to four data processing units. These four processing units are the e200z Power architecture-compatible core, two enhanced timing processing units (E-TPUs), and a direct memory access (DMA). Through a single connection on the Class 3 Nexus 5001 interface, host tools can collect data from any or all of the processing units simultaneously. In addition, debugging and calibration tools can establish breakpoints/watchpoints for data and instructions on any or all of the processing units. An example of using this application is an engineer tracing a problem between timing events on the E-TPU and code running on the PowerPC e200 ISA-compatible Book-e processing core.

Figure 2 Nexus multi-processor implementation block diagram

        A floating point and/or single instruction multiple data (SIMD) device can be implemented on a 32-bit embedded processor to support complex algorithms. SIMD allows one instruction to be implemented on multiple data sets, which is very useful in filtering and array algorithms. The Nexus debug port allows monitoring of floating point and SIMD data and instructions.

       The latest embedded automotive processors in the MPC5500 product family are driving new engine technologies. The integration of DSP functions with the MPC5500 SIMD device can drive powertrain development in multiple areas, including advanced engine impact detection, CVT improvements and 6-speed automatic shifting. In addition, DSP functions are also being used in hybrid electric vehicle power converter modules to control large electric engines.

        The emergence of new microcontrollers, input/output systems, development tools, communication methods and advanced algorithms will enable new automotive applications. Embedded processors with real-time multicore debugging capabilities will make traditional run-control debugging methods obsolete.

        Embedded processors have become an integral part of modern daily life. Most embedded processors are not noticed by users who occasionally use this technology. Semiconductor technology will greatly increase integration, performance and reduce costs in future products. Design engineers must deploy new technologies to fully exploit the advantages of complex semiconductor technologies, while semiconductor suppliers must ensure a balance between system requirements, performance, and system cost.