Introdu ction of SCM SCM is a semiconductor wafer integration: the central processing unit (CPU), memory (RAM and ROM), parallel I/O, serial I/O, timer/counters, interrupt system, the system clock circuit and the system bus microcomputer. With miniature computer properties, thus called the single chip computer, abbreviation microcontroller. Mainly used in measurement and control field. When using single chip, are usually of the measure and control system in the core status and Embedded them so often called on international chip Embedded controller (EMCU MicroController, Embedded security unit.and), or micro controller (MCU, MicroController unit.and). Our country used to use "one-chip computer" this name. MCU is computer technology an important milestone in the history of computer, marks formal formation of the general computer systems and embedded computer system two branches. SCM small volume, low cost, embedded in industrial control unit, robot, intelligent instrumentation, automotive electronic system, the weapon system, home appliances, office automation equipment, financial electronic system, toys, personal information terminals and communication products. According to its use can be divided into general type and special two kinds big. (1) universal single-chip microcomputer is the internal development resources (such as the memory and I/O, etc. Various kinds of peripheral function parts) can all to give users. Users according to the needs, design a single-chip microcomputer chip on general as the core, match again with peripheral interface circuit and other peripheral equipment, and write the corresponding software to meet the various different need of measurement and control system. Usually said and book introduc...