College】 【weak SCM system expansion and configuration of some principles!.】..

<br> a microcomputer application system hardware design consists of two parts: First, system expansion, that is, the internal MCU function unit, such as ROM, RAM, I / O, timer / counter, interrupt systems, application systems can not .meet. requirements, must be extended in the chip, select the appropriate chip, design appropriate circuits.. Second, the system configuration, the configuration according to functional requirements of the system peripherals such as keyboards, monitors, printers, A / D, D ./ A converter, to design the appropriate interface circuit.. <BR> System expansion and configuration should follow the following principles: <BR> 1, selected as a typical circuit, and in line with conventional usage of single chip.. The .standardization of the hardware systems, modular and lay a good foundation.. <BR> 2, system expansion and peripheral equipment, staffing levels should be sufficient to meet the functional requirements of application systems, and leave appropriate room for secondary development.. < .; BR> 3, the hardware structure should be considered in conjunction with application software solutions.. Hardware and software solutions will have a mutual influence, consider the following principles: the function of the software to achieve real calamity by the software as much as possible .in order to simplify the hardware structure.. It must be noted, by the software to the hardware features, the general response time is longer than the hardware and CPU-time.. <BR> 4, the system performance of related devices to .be matched as possible.. Constitute a CMOS chip microcontroller, such as selection of low-power system, the system should be as much as possible of all the chip select low-power products.. <BR> 5, reliability and anti- .jamming design is an integral part of hardware design, which includes chips, device selection, decoupling filter, printed circuit board layout, channel isolation.. <BR> 6, MCU peripheral circuit is higher, must take into account the drive capability.. .Drive capacity, the system does not work reliably, additional lines can be enhanced driving ability or drive to reduce chip power consumption to reduce the bus load.. <BR> 7, as far as possible towards the "monolithic" design direction of .the hardware system.. The more system components, devices and the stronger the mutual interference between the power consumption also increases, but also inevitably reduces the stability of the system.. With the integration of microcontroller chip more powerful, the real system on chip SoC .has been met, such as ST's newly launched μPSD32 × × series of products on a single chip integrated 80C32 core, large capacity FLASH memory, SRAM, A. / D, I / O, two serial ports, watchdog, power-on reset circuit .and so on ...