【正文】 制器的功能微控制器通常包含幾個到幾十個通用輸入/輸出引腳（GPIO的）。微控制器一個不常見的功能，是數(shù)模轉(zhuǎn)換器（DAC），允許控制器輸出模擬信號或電壓等級。一個專用的脈寬調(diào)制（PWM）模塊使得CPU可以控制電源轉(zhuǎn)換器，阻性負載，電機等，而不需要在計時循環(huán)上浪費大量的CPU資源。C，串行外圍接口和控制器區(qū)域網(wǎng)絡(luò)互聯(lián)定時器，計數(shù)器，PWM發(fā)生器和看門狗等外設(shè)時鐘發(fā)生器，往往是一個石英振蕩器計時晶體諧振器或RC電路許多包括模擬到數(shù)字轉(zhuǎn)換器，一些包括數(shù)字至模擬轉(zhuǎn)換器在線編程和調(diào)試支持這種集成大大降低了芯片的數(shù)量和電路板布線和空間，可以使用單獨的芯片生產(chǎn)等效系統(tǒng)。制造商必須平衡的需要，盡量減少芯片尺寸而不是增加更多功能。一個典型的發(fā)達國家家庭很可能只有四個通用微控制器，卻有約三十幾個微控制器?？删幊檀鎯ζ饕矞p少了新產(chǎn)品的部署所需的時間。許多微控制器是如此奇特，它們有效地要求自己非標準的C，如8051的 SDCC，它阻止使用標準的工具（如代碼庫或靜態(tài)分析工具）防止代碼和硬件功能不相關(guān)。一個模擬器將顯示控制器內(nèi)部狀態(tài)和輸出，以及允許輸入信號的產(chǎn)生。s budget over 25%.Most microcontrollers at this time had two variants. One had an erasable EPROM program memory, which was significantly more expensive than the PROM variant which was only programmable once. Erasing the EPROM required exposure to ultraviolet light through a transparent quartz lid. Onetime parts could be made in lowercost opaque plastic packages.In 1993, the introduction of EEPROM memory allowed microcontrollers (beginning with the Microchip PIC16x84) to be electrically erased quickly without an expensive package as required for EPROM, allowing both rapid prototyping, and In System Programming. The same year, Atmel introduced the first microcontroller using Flash memory. Other panies rapidly followed suit, with both memory types.Cost has plummeted over time, with the cheapest 8bit microcontrollers being available for under $ in quantity (thousands) in 2009, and some 32bit microcontrollers around $1 for similar quantities.Nowadays microcontrollers are cheap and readily available for hobbyists, with large online munities around certain processors.In the future, MRAM could potentially be used in microcontrollers as it has infinite endurance and its incremental semiconductor wafer process cost is relatively low.VolumesAbout 55% of all CPUs sold in the world are 8bit microcontrollers and microprocessors. According to Semico, over four billion 8bit microcontrollers were sold in 2006.A typical home in a developed country is likely to have only four generalpurpose microprocessors but around three dozen microcontrollers. A typical midrange automobile has as many as 30 or more microcontrollers. They can also be found in many electrical devices such as washing machines, microwave ovens, and telephones.Embedded designA microcontroller can be considered a selfcontained system with a processor, memory and peripherals and can be used as an embedded system.[1] The majority of microcontrollers in use today are embedded in other machinery, such as automobiles, telephones, appliances, and peripherals for puter systems. These are called embedded systems. While some embedded systems are very sophisticated, many have minimal requirements for memory and program length, with no operating system, and low software plexity. Typical input and output devices include switches, relays, solenoids, LEDs, small or custom LCD displays, radio frequency devices, and sensors for data such as temperature, humidity, light level etc. Embedded systems usually have no keyboard, screen, disks, printers, or other recognizable I/O devices of a personal puter, and may lack human interaction devices of any kind.InterruptsMicrocontrollers must provide real time (predictable, though not necessarily fast) response to events in the embedded system they are controlling. When certain events occur, an interrupt system can signal the processor to suspend processing the current instruction sequence and to begin an interrupt service routine (ISR, or interrupt handler). The ISR will perform any processing required based on the source of the interrupt before returning to the original instruction sequence. Possible interrupt sources are device dependent, and often include events such as an internal timer overflow, pleting an analog to digital conversion, a logic level change on an input such as from a button being pressed, and data received on a munication link. Where power consumption is important as in battery operated devices, interrupts may also wake a microcontroller from a low power sleep state where the processor is halted until required to do something by a peripheral event.[ProgramsMicrocontroller programs must fit in the available onchip program memory, since it would be costly to provide a system with external, expandable, memory. Compilers and assemblers are used to convert highlevel language and assembler language codes into a pact machine code for storage in the microcontroller39。C, Serial Peripheral Interface and Controller Area Network for syste