Renesas provides the best MCU and solutions for the automotive electronics application market

Renesas' automotive MCU

Renesas has a history of over 25 years in automotive MCUs and has a market share of over 20% in the world. Renesas' automotive MCUs are used by major automotive electronics manufacturers in the world, such as Bosch, Continental, Delphi, TRW, Aisin, and Denso. The products of these automotive electronics manufacturers are adopted by many other car manufacturers in the world. Quality and performance are the most important for cars, and car manufacturers and automotive electronics manufacturers have given high praise to the high quality and high performance of Renesas' automotive MCUs. As a result of these achievements, Renesas has also obtained many trade contracts from automotive electronics manufacturers that did not use Renesas products at the time, and these automotive electronics manufacturers are using Renesas' automotive MCUs to develop automotive electronics products. The following will introduce solutions for new products applied to 32-bit MCUs.

Multi-core technology

Ultimately, it is the basic performance of MCU and MPU that determines the "intelligence" of the car. The power consumption of MPUs in PCs and servers increases and reaches its limit as the CPU speeds up. Although the vector of development towards multi-core has changed, this is still the same for high-end MCUs and MPUs for automobiles. The operating environment of automotive MCUs is very harsh and needs to work at high temperatures. For example, the engine ECU was originally placed in the car compartment, but now it is installed in the engine compartment and has to work in an environment with a temperature of 125 ℃. Therefore, its heat generation must be controlled to be much smaller than that of PCs. The frequency naturally has an upper limit, and the way to lower the frequency while improving performance is multi-core technology. Renesas uses two multi-core methods, SH-2A and SH-4A, for controllers and processors respectively to develop new products.

Figure 1 Application of Multi-Core in automotive electronics

Another difference from PCs is that in automotive MCUs and MPUs, symmetric multi-processing (SMP) like PCs cannot meet all the necessary conditions. Figure 1 shows the general application of multi-core technology in automotive electronics. The multi-core form and processing method required for engine and transmission control, brake and steering control, vehicle coordination, multimedia, etc. are different from those shown in Figure 1. For example, when the engine and transmission control adopts a dual-core method, asymmetric multi-processing (AMP) should be adopted to work as two real-time control systems that do not interfere with each other. Task allocation is program-specified. In addition, brake and steering control, which tends to be by-wire, requires that the two cores work exactly the same to ensure system redundancy. This requires a structure that can compare and monitor the working conditions of the two cores. For this reason, Renesas has added the Lock-Step Dual function to the SH-2A MCU for brake and steering control. This function, as shown in Figure 2, constantly compares the working conditions of the two CPUs while also comparing and monitoring the working conditions of the DMA controller and the peripheral bus bridge in duplex mode.

Figure 2 SH-2A Lock-Step Dual function

Engine and transmission controls

The exhaust gas emitted by automobiles is one of the causes of air pollution and global warming. Therefore, the automobile industry has been working hard to reduce and purify the exhaust gas emitted. The most important way to reduce exhaust gas emissions is to efficiently convert fuel into rotational power and transmit it to the wheels. Using less fuel to obtain greater rotational power can save fuel costs. In order to achieve this goal, a high-precision power system is necessary. The power system consists of an engine, clutch, transmission, differential gear, and drive shaft. The engine and transmission are electronically controlled by an ECU. In order to perform complex control, large-scale control algorithms need to be executed at high speed. The ECU must be able to work at high speed and have a microcomputer with a large-capacity fast-erase memory built in. In addition, recently, the ECU is required to be installed in a high-temperature engine compartment when used for engine control, and to be installed in high-temperature lubricating oil when used for transmission control. Both must be able to work stably at 125°C.

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The SH705x series with built-in SH-2E that Renesas previously supplied has been used by many automobile manufacturers.

The SH725xx series with built-in SH-2A (a higher-end core than SH-2E) is now available and is being used by many automotive electronics manufacturers for new product development. It is expected to be used in actual vehicles from this year to next year. The highest-end product is the SH72544R, which has an operating frequency of 200 MHZ and is equipped with 2.5 MB of Flash memory, a Flash memory with 128 KB data storage EEPROM function, 128 KB SRAM, a high-performance timer ATU-III for engine control, and 3-channel CAN. It can be used in future electronic control of engines and gearboxes. Flash MCU uses 90 nm technology for the first time, which increases the operating frequency and expands the capacity of built-in Flash memory.

In the future, the complexity of powertrain electronic control will increase rapidly. In order to adapt to this trend, the multi-core SH-2A-Dual with two SH-2As can be used to achieve high performance.

Graphical dashboard

The dashboard of a car is equipped with various instruments and displays, as well as warning lights and alarm buzzers to warn the driver. In the past, mechanical speedometers, fuel level meters and odometers were used, but now dashboards are mostly made of stepper motors and LCDs. Recently, mid-range and high-end cars have been equipped with dashboards that display car diagnostic information, safety information, etc. on large LCDs.

Now people are paying attention to graphic instrument panels that can display more information. Graphic instrument panels can be divided into two categories: one is a panel that adds TFT-LCD graphic display to the original instrument driven by a stepper motor, and the other is a large TFT-LCD graphic instrument panel that does not use movable parts like instruments, but displays all content.

Graphic instrument panels that use both instruments and TFT-LCDs should choose medium-sized QVGA or WQVGA TFT-LCDs that are not too expensive. While the TFT-LCD displays the car's diagnostic information and safety information that are easy for the driver to see, it can also use software to switch to display the rear image taken when the car is backing up, and can also use arrows to indicate the direction of the destination, providing a simple navigation function, so it can improve the driver's ability to distinguish and significantly improve safety. In Europe, various car manufacturers have made plans to use this instrument panel not only for high-end cars, but also for mid-range cars. To manufacture this instrument panel, high-speed processing technology must be used, using a 32-bit microcomputer with a speed of more than 100 MHz. Renesas provides 32-bit microcomputers SH7262 and SH7264 for this application, and samples are now being supplied, and production will begin in May this year. Since it has a built-in 144 MHz 32-bit SH-2A CPU, a video display controller and video input port for graphics and video display, and a 1 MB SRAM that can hold a frame buffer for WVGA (480×240 pixels) TFT-LCD on both sides, it can greatly reduce external components. Although the SH7262 does not have a built-in PWM timer for controlling stepper motors, it can be combined with a cheap instrument panel MCU that drives stepper motors to form a variety of instrument panels with different functions. The SH7264 has four built-in PWM timers for controlling stepper motors, so a complete instrument panel can be formed with just one.

An idea of ​​a graphical instrument panel using the SH7264 is shown in Figure 3, where you can see that it has very few external components. There is also an instrument panel demonstration system using the SH7264, which provides instrument panel demonstration software, image database, and converter for converting bitmap data to RGB output to facilitate user development.

Figure 3: An idea for a graphical dashboard using the SH7264

The TFT-LCD and control circuitry for a complete graphical instrument panel are expensive, and it will probably be some time before more cars have them installed.

Gateway

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Today's cars have body control, safety (airbags), powertrain, multimedia subsystems and multiple networks for fault diagnosis. Currently, these subsystems mainly use CAN connections. In addition, as the amount of communication continues to increase in the future, it is necessary to adopt a method that can both increase the baud rate of CAN and increase the number of channels.

Therefore, the evolution to the higher speed 10 Mb/s FlexRay is the main development direction of the automotive network in the future. However, in order for the automotive network to have extremely high reliability, various technical evaluations must be carried out. At present, the actual application in automobiles is still very limited. Therefore, before FlexRay becomes popular, CAN will play a leading role. The current problem is how to increase its channel number to meet the needs. In fact, the CAN used in high-end cars has about 5 channels. On the other hand, if we look at CAN from a topological point of view, the main bottleneck lies in the processing capacity of the network connectors at the intersections of each channel.

To adapt to this situation, Renesas provides the R32C/145 group as an MCU for the CAN gateway. As shown in Figure 4, the R32C/145 hardwareizes the receiving part and performs routing selection for the 6-channel CAN. 1-2 channel CAN usually uses software to handle the gateway, but once the communication volume increases, it cannot be handled by software and must be handled by hardware. The use of hardware methods can achieve message relay within 20 μs, and at the same time, the software burden can be reduced by more than 70%. The R32C/145 also meets the software specifications for the gateway specified by AUTOSAR, the automotive standard software development alliance.

Figure 4 CAN network microcontroller using R32C/145

In the future, Renesas also plans to develop MCUs for network connectors that are compatible with FlexRay and MOST.

Digital Car Audio

The multi-core SH-2A-Dual is being gradually promoted and applied to high-end digital car audio. The SH7265 is equipped with two SH-2As with an operating frequency of 200 MHz, and has a processing capacity of 480MIPS×2. As shown in Figure 5, one of the CPUs is used to process the hard disk, while the other CPU is used to process the media system, which is the envisioned asymmetric parallel processing (AMP). In addition to installing a USB2.0 (high-speed) host, the SH7265 also has a built-in sound software library and AAC encoder that can adapt to various formats. The encoder is completed by software because the specifications and contents used include variable parts; from the perspective of work efficiency, it is better to use hardware to construct the encoder.

Figure 5 SH726 Function Overview

As mentioned above, Renesas can provide ideal MCUs and technical support for many aspects of automotive electronics.