Application of Motorola 16-bit MCU MC9S12DP256 in automotive electronics

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Application of Motorola 16-bit MCU MC9S12DP256 in automotive electronics [Copy link]

Abstract : This paper introduces the structure, characteristics and advantages of Motorola's 16-bit MCU MC9S12DP256 compared with other MCUs. Through the application example of MC9S12DP256 in automotive electronic gating system, this paper briefly introduces the application method of MC9S12DP256 MCU in the field of automotive electronics. Keywords : MC9S12DP256; automotive electronic gating system; automotive electronics 　　China's automobile industry has shown a good development momentum since 2002. According to the latest data from the State Planning Commission, the production and sales of cars in China exceeded one million for the first time in 2002, reaching 1.09 million and 1.126 million respectively, an increase of 55% and 56% year-on-year. The production and sales situation of the entire automobile industry is also very good. The production and sales of automobiles have both exceeded the 3 million mark, reaching 3.25 million and 3.248 million respectively, an increase of nearly 40%. The abnormally prosperous car market in 2002 made the automobile industry surpass the electronics industry for the first time and become the most important driving force for industrial growth. As a perfect combination of the automobile industry and the electronics industry, the development of the automotive electronics industry will be more rapid. It is estimated that the annual growth rate of the industry in recent years has exceeded 50%, becoming an important factor in driving the development of the automobile industry. As the world's largest supplier of automotive electronic semiconductor devices, Motorola's microcontrollers are widely used in automotive electronic control units, and Motorola's 16-bit microcontroller MC9S12DP256 is increasingly favored by people for its powerful functions and excellent performance. 1 Structure of MC9S12DP256 The MC9S12DP256 16-bit microcontroller is a mid-range chip based on the 16-bit HCS12 CPU and 0.25μm microelectronic technology, high-speed, high-performance 5.0V FLASH memory products. Its high performance-price ratio makes it very suitable for some mid-to-high-end automotive electronic control systems. At the same time, its simpler background development mode (BDM) (as shown in Figure 1) will further reduce development costs and make on-site development and system upgrades more convenient. 　　The main frequency of MC9S12DP256 is as high as 25MHz. At the same time, many standard modules are integrated on the chip, including 2 asynchronous serial communication ports SCI, 3 synchronous serial communication ports SPI, 8-channel input capture/output comparison timer, 2 10-bit 8-channel A/D conversion modules, 1 8-channel pulse width modulation module, 49 independent digital I/O ports (20 of which have external interrupt and wake-up functions), 5 CAN modules compatible with CAN2.0A/B protocol and an internal IC bus module; the chip has 256kB Flash EEPROM, 12kB RAM, and 4kB EEPROM. Figure 1 shows the chip structure block diagram. 2 Functional features of MC9S12DP256 The MC9S series microcontrollers have three main features: 　　(1) 256kB of flash memory (Flash) integrated on the chip. In recent years, with the maturity of the application of flash memory (Flash) in microcontroller chips, the development and application of microcontrollers have ushered in a new leap. Flash is a non-volatile storage medium. Reading its contents is as easy as reading RAM, and writing to it is faster than EPROM. At the same time, after the system loses power, the contents can still remain unchanged. The main advantages of Flash are simple structure, high integration density and low cost. Since Flash can be partially erased and the number of write and erase times can reach tens of thousands of times, it no longer requires expensive emulators to develop microcontrollers. 　　(2) The application of phase-locked loop technology improves the electromagnetic compatibility of the system. In the past, in microcontroller application systems that did not use phase-locked loops, the crystal oscillator circuit became a major interference source due to its relatively high operating frequency (usually several megahertz to tens of megahertz). This problem brought a lot of inconvenience to system design and circuit board layout. The MC9S12 clock generation system cleverly uses phase-locked loop technology, so that when an external crystal oscillator of tens of kilohertz is connected, a system clock of several megahertz can be generated through software programming, thereby reducing external radiation interference and improving system stability. 　　(3) The simple background development mode (BDM) (as shown in Figure 2) further reduces development costs and makes on-site development and system upgrades more convenient. 　　In addition, although it has a 16-bit bus structure, the external bus of the MC9S12 can work in 8-bit and 16-bit modes according to different system requirements, so it can greatly adapt to system requirements at different price points. 3 Application of MC9S12DP256 in Automotive Electronics Now, a typical automotive electronic door control system is used as an example to illustrate the application of MC9S12DP256 in automotive electronics. Figure 3 shows the schematic diagram of the door control system. In the figure, the central microcontroller uses MC9S12DP256, and the MC33389A, MC33884, MC33887, MC33486, etc. in the figure are all Motorola's intelligent analog devices. Among them, MC33389A can directly convert the car battery voltage into the 5V voltage required by the system, and can also connect the ignition switch signal, door switch signal and panel switch signal to the microcontroller through SPI for wake-up, reset and interruption. At the same time, the device also has a CAN physical layer driver with fault-tolerant function. In addition, it can also connect the system to the vehicle network; the main function of MC33884 is to monitor the status of the panel switch in real time and drive the panel lighting; MC33887 can be used to drive the rearview mirror position motor, rearview mirror folding motor and door lock motor (such as requiring a large current to drive the lifting of the window glass, etc.). In fact, this function can also use MC33486 to work with an independent MOS driver tube; MC33290 is mainly used for diagnosis of the entire system. 4 Summary According to the above introduction, it can be seen that the functions of MC9S12DP256 are very powerful. Due to its extremely rich on-chip resources, for general simple applications, only one single-chip microcomputer plus a small amount of peripheral circuits are needed. For complex systems, it is also convenient to expand the external circuit of MC9S12DP256. Especially in the field of automotive electronics, the rich on-chip memory, powerful timer and integrated CAN module of MC9S12DP256 all bring great convenience to hardware design and software programming. Therefore, it can be predicted that the rapid development of the automotive electronics industry will inevitably bring more extensive applications and development space to this cost-effective microcontroller.