Embedded control systems vary from temporary data acquisition and control systems running experiments to “brains” for standard mass-market products. Embedded control systems also range in complexity from telecommunications switching systems to alarm clocks. Different applications have different requirements, with several form factors available to meet them. Which will meet your needs best depends not only on the ultimate use控制工程网版权所有, but where the system is in its life cycle.
　　Three CPU form factors

are especially well suited for embedded applications: microcontrollerswww.cechina.cn, field programmable gate arrays (FPGAs), and application-specific integrated circuits (ASICs).
　　Microcontrollers’ biggest advantage is that they are highly adaptable by being programmable in human-readable languages, such as C and C++. Many microcontroller applications are complex enough to require use of an operating system, such as Linux or Microsoft Windows Embedded as well.
　　Microcontrollers’ biggest disadvantage is also that they are highly adaptablewww.cechina.cn, often requiring high-level programming and resource-intensive operating systems. For many applications, microcontrollers are overkill of sometimes monumental proportions.
　　ASIC, FPGA characteristics
　　Two compute-engine technologies stand out as microcontroller alternatives: field programmable gate arrays (FPGAs) and application-specific integrated circuits (ASICs). Both implement Boolean-logic algorithms in hardware. Both are highly adaptablewww.cechina.cn, being capable of addressing a wide range of logical functions from simple on-off controls to entire microprocessors. Both are programmed using standard hardware description language (HDL), such as VHDL and Verilog, rather than software written in third-generation and higher programming languages.
　　They differ in non-recurring engineering (NRE) cost levels and variable costs, as well as re-programmability, scalabilitywww.cechina.cn, and development time associated with volume production.

　　FPGA characteristics include being re