This paper introduces the structure and characteristics of Motorola 16 bit MCU MC9S12DP256 and its advantages over other single chip microcomputers. Through the application example of mc0s12dp256 in automotive electronic system, the application method of MC9S12DP256 in automotive electronic field is introduced.

China’s automobile industry has shown a good momentum of development since 2002. According to the latest data of the State Planning Commission, the production and sales volume of cars in 2002 broke through the one million mark for the first time, reaching 1.09 million and 1.126 million respectively, up 55% and 56% year on year. The production and sales situation of the whole automobile industry is also very good. Both the production and sales of automobiles have broken through the 3 million mark, reaching 3.25 million and 3.248 million respectively, with an increase of nearly 40%. In 2002, the auto industry surpassed the electronic industry for the first time and became the most important driving force for industrial growth. As the perfect combination of automotive industry and electronic industry, the development of automotive electronics industry will be more rapid. It is estimated that in recent years, the annual growth rate of the industry has exceeded 50%, which has become an important factor in promoting the development of the automobile industry. As the world’s largest supplier of automotive electronic semiconductor devices, Motorola’s microcontroller is widely used in automotive electronic control unit, and Motorola’s 16 bit microcontroller MC9S12DP256 is more and more popular with its powerful functions and excellent performance.

Motorola MC9S12DP256 single chip microcomputer structure, functional characteristics and application analysis in automobile field

The structure of 1 MC9S12DP256

Mc9s12dp25616 bit microcontroller is a mid-range chip of high-speed and high-performance 5.0vflash memory products based on 16 bit hcs12cpu and 0.25 μ m microelectronics technology. Its high performance price ratio makes it very suitable for some middle and high grade automobile electronic control system. At the same time, its simple background development mode (BDM) (as shown in Figure 1) will further reduce the development cost and make the field development and system upgrade 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 module, 1 8-channel pulse width modulation module and 49 independent digits 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; 256Kb flash EEPROM  12KB ram and 4KB EEPROM are on-chip. Fig. 1 shows the block diagram of the chip structure.

Function features of 2 MC9S12DP256

Mc9s series single chip microcomputer has three main characteristics

(1) 256Kb flash memory (flash) is integrated in the chip. In recent years, with the application of flash memory (flash) in microcontroller chip to mature, the development and application of microcontroller ushered in a new leap. Flash is a kind of nonvolatile storage medium. It is as convenient to read its contents as RAM, but its writing operation is faster than EPROM. At the same time, after the system power down, the content in flash can still be reliably kept unchanged. The main advantages of flash are simple structure, high integration density and low cost. Because flash can be partially erased, and the number of times of writing and erasing can reach tens of thousands of times, the development of microcontroller does not need expensive emulator.

(2) The application of PLL technology improves the electromagnetic compatibility of the system. In the past, in the application system of microcontroller without PLL, the crystal oscillator circuit becomes a big interference source because of its high working frequency (usually from several MHz to tens of MHz). This problem brings a lot of inconvenience to the system design and circuit board layout. The clock generator system of MC9S12 uses phase-locked loop technology skillfully, so it can generate several megabit system clock through software programming under the condition of external crystal oscillator with tens of kilohertz, so as to reduce the external radiation interference and improve the stability of the system.

(3) The simple background development mode (BDM) (as shown in Figure 2) further reduces the development cost and makes the field development and system upgrade more convenient.

In addition, although it has 16 bit bus structure, the external bus of MC9S12 can work in 8-bit and 16 bit modes according to different system requirements, so it can greatly adapt to the system requirements of different price levels.

Application of 3mc9s12dp256 in automotive electronics

This paper takes a typical automotive electronic door control system 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, MC9S12DP256 is selected as the central microcontroller, and mc33389a, mc33884 and mc33887 are shown in the figure MC33486 and so on are Motorola’s intelligent simulators. Mc33389a can directly convert the vehicle battery voltage into the 5V voltage required by the system. It can also connect the ignition switch signal, door switch signal and panel switch signal to the microcontroller for wake-up, reset and interruption by SPI. At the same time, the device also has a fault-tolerant can physical layer driver. 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 mirror position motor, rearview mirror folding motor and door lock motor (such as requiring a higher current to drive the window glass up and down, etc.). In fact, MC33486 can also be selected to work with independent MOS driver; mc33290 is mainly used to diagnose the whole system.

4 Summary

According to the above introduction, we can see that MC9S12DP256 is very powerful. Because of its abundant resources on chip, it only needs a single chip microcomputer and a small number of peripheral circuits for general simple applications. For complex system, it is convenient to expand the external circuit of MC9S12DP256. Especially in the field of automotive electronics, MC9S12DP256 has abundant on-chip memory, powerful timer and integrated can module, all of which bring great convenience to hardware design and software programming. Therefore, it can be predicted that the rapid development of automotive electronics industry will bring more extensive application and development space for this kind of high cost performance microcontroller.

Editor in charge: GT

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