單片機(jī)外文文獻(xiàn)翻譯

1、<p><b>　　外文文獻(xiàn)</b></p><p><b>　　一單片機(jī)簡(jiǎn)介</b></p><p>　　單片機(jī)是一種集成在電路芯片，是采用超大規(guī)模集成電路技術(shù)把具有數(shù)據(jù)處理能力的中央處理器CPU隨機(jī)存儲(chǔ)器RAM、只讀存儲(chǔ)器ROM、多種I/O口和中斷系統(tǒng)、定時(shí)器/計(jì)時(shí)器等功能（可能還包括顯示驅(qū)動(dòng)電路、脈寬調(diào)制電路、模擬多路轉(zhuǎn)換器、A/

2、D轉(zhuǎn)換器等電路）集成到一塊硅片上構(gòu)成的一個(gè)小而完善的計(jì)算機(jī)系統(tǒng)。</p><p>　　單片機(jī)也被稱為微控制器（Microcontroller），是因?yàn)樗钤绫挥迷诠I(yè)控制領(lǐng)域。單片機(jī)由芯片內(nèi)僅有CPU的專用處理器發(fā)展而來(lái)。最早的設(shè)計(jì)理念是通過(guò)將大量外圍設(shè)備和CPU集成在一個(gè)芯片中，使計(jì)算機(jī)系統(tǒng)更小，更容易集成進(jìn)復(fù)雜的而對(duì)體積要求嚴(yán)格的控制設(shè)備當(dāng)中。INTEL的Z80是最早按照這種思想設(shè)計(jì)出的處理器，從此以后，單片

3、機(jī)和專用處理器的發(fā)展便分道揚(yáng)鑣。</p><p>　　二、單片機(jī)的發(fā)展趨勢(shì)</p><p>　　現(xiàn)在可以說(shuō)單片機(jī)是百花齊放，百家爭(zhēng)鳴的時(shí)期，世界上各大芯片制造公司都推出了自己的單片機(jī)，從8位、16位到32位，數(shù)不勝數(shù)，應(yīng)有盡有，有與主流C51系列兼容的，也有不兼容的，但它們各具特色，互成互補(bǔ)，為單片機(jī)的應(yīng)用提供廣闊的天地。 </p><p>　　縱觀單片機(jī)的發(fā)展過(guò)

4、程，可以預(yù)示單片機(jī)的發(fā)展趨勢(shì)，大致有： </p><p>　　1.低功耗CMOS 　　</p><p>　　MCS-51系列的8031推出時(shí)的功耗達(dá)630mW，而現(xiàn)在的單片機(jī)普遍都在100mW左右，隨著對(duì)單片機(jī)功耗要求越來(lái)越低，現(xiàn)在的各個(gè)單片機(jī)制造商基本都采用了CMOS(互補(bǔ)金屬氧化物半導(dǎo)體工藝)。象80C51就采用了HMOS(即高密度金屬氧化物半導(dǎo)體工藝)和CHMOS(互補(bǔ)高密度金屬氧化

5、物半導(dǎo)體工藝)。CMOS雖然功耗較低，但由于其物理特征決定其工作速度不夠高，而CHMOS則具備了高速和低功耗的特點(diǎn)，這些特征，更適合于在要求低功耗象電池供電的應(yīng)用場(chǎng)合。所以這種工藝將是今后一段時(shí)期單片機(jī)發(fā)展的主要途徑。 </p><p><b>　　2.微型單片化 </b></p><p>　　現(xiàn)在常規(guī)的單片機(jī)普遍都是將中央處理器(CPU)、隨機(jī)存取數(shù)據(jù)存儲(chǔ)(RAM)

6、、只讀程序存儲(chǔ)器(ROM)、并行和串行通信接口，中斷系統(tǒng)、定時(shí)電路、時(shí)鐘電路集成在一塊單一的芯片上，增強(qiáng)型的單片機(jī)集成了如A/D轉(zhuǎn)換器、PMW(脈寬調(diào)制電路)、WDT(看門狗)、有些單片機(jī)將LCD(液晶)驅(qū)動(dòng)電路都集成在單一的芯片上，這樣單片機(jī)包含的單元電路就更多，功能就越強(qiáng)大。甚至單片機(jī)廠商還可以根據(jù)用戶的要求量身定做，制造出具有自己特色的單片機(jī)芯片。 此外，現(xiàn)在的產(chǎn)品普遍要求體積小、重量輕，這就要求單片機(jī)除了功能強(qiáng)和功耗低外，還要求

7、其體積要小。現(xiàn)在的許多單片機(jī)都具有多種封裝形式，其中SMD(表面封裝)越來(lái)越受歡迎，使得由單片機(jī)構(gòu)成的系統(tǒng)正朝微型化方向發(fā)展。 </p><p>　　3.主流與多品種共存 　　</p><p>　　現(xiàn)在雖然單片機(jī)的品種繁多，各具特色，但仍以80C51為核心的單片機(jī)占主流，兼容其結(jié)構(gòu)和指令系統(tǒng)的有PHILIPS公司的產(chǎn)品，ATMEL公司的產(chǎn)品和中國(guó)臺(tái)灣的Winbond系列單片機(jī)。所以C805

8、1為核心的單片機(jī)占據(jù)了半壁江山。而Microchip公司的PIC精簡(jiǎn)指令集(RISC)也有著強(qiáng)勁的發(fā)展勢(shì)頭，中國(guó)臺(tái)灣的HOLTEK公司近年的單片機(jī)產(chǎn)量與日俱增，與其低價(jià)質(zhì)優(yōu)的優(yōu)勢(shì)，占據(jù)一定的市場(chǎng)分額。此外還有MOTOROLA公司的產(chǎn)品，日本幾大公司的專用單片機(jī)。在一定的時(shí)期內(nèi)，這種情形將得以延續(xù)，將不存在某個(gè)單片機(jī)一統(tǒng)天下的壟斷局面，走的是依存互補(bǔ)，相輔相成、共同發(fā)展的道路。</p><p><b>　

9、　三、仿真器的發(fā)展</b></p><p>　　縱觀國(guó)內(nèi)近二十年的仿真技術(shù)發(fā)展歷程，根據(jù)仿真器使用的技術(shù)來(lái)劃分，國(guó)內(nèi)仿真器的設(shè)計(jì)大約可以分成以下幾個(gè)時(shí)期：</p><p>　　(1) 70年代末期-80年代中期</p><p>　　這個(gè)時(shí)期采用的技術(shù)主要是仿真開(kāi)發(fā)系統(tǒng)，現(xiàn)在看來(lái)技術(shù)含量不高，用戶要求也不高。</p><p>　　(

10、2) 80年代末期-90年代末期</p><p>　　這個(gè)時(shí)期主要使用華邦一顆帶有仿真功能的芯片制作，采用的技術(shù)叫做Bondout。采用這顆芯片能大大簡(jiǎn)化仿真器的設(shè)計(jì)，因此國(guó)內(nèi)仿真器的水準(zhǔn)有了大的提高，基本上可以不占用用戶資源。</p><p>　　正是由于仿真性能的提高，國(guó)內(nèi)的仿真器制作在將近10年的時(shí)間內(nèi)沒(méi)有進(jìn)步，一直采用這種制作模式。雖然個(gè)別廠商也嘗試過(guò)別的技術(shù)來(lái)提高仿真水準(zhǔn)，例如H

11、OOKS技術(shù)，但是由于本身技術(shù)的限制沒(méi)有成功。相反國(guó)外的仿真器較早地使用了HOOKS技術(shù)，在初期由于HOOKS技術(shù)本身的復(fù)雜性，仿真性能和價(jià)格不如國(guó)內(nèi)采用Bondout的仿真器。</p><p>　　隨著IC技術(shù)的發(fā)展，國(guó)內(nèi)制作HOOKS技術(shù)的條件已經(jīng)成熟，但是國(guó)內(nèi)的幾家主要的生產(chǎn)廠商還陶醉于Bondout技術(shù)之中。</p><p>　　(3) 2000年開(kāi)始</p><

12、;p>　　2000年是中國(guó)仿真器市場(chǎng)變化最大的時(shí)期，其中最引人注目的變化是華邦仿真芯片W78958的停產(chǎn)。</p><p>　　華邦公司在設(shè)計(jì)W78958芯片時(shí)，其內(nèi)部的仿真功能只是為了仿真器廠商能制作仿真器以便更好的推廣W78958。但是經(jīng)過(guò)幾年的變化，W78958演變成為一顆仿真器上使用的仿真專用芯片而不是用戶使用的標(biāo)準(zhǔn)芯片，使用的范圍也僅限于國(guó)內(nèi)，一年不到20000只的用量也促使華邦公司在進(jìn)入2002

13、年后宣布將停產(chǎn)該芯片。</p><p>　　W78958停產(chǎn)以后，國(guó)內(nèi)仿真器廠商處于一個(gè)非常尷尬的局面。由于W78958在國(guó)內(nèi)使用了將近10年，國(guó)內(nèi)的用戶群非常龐大，這些用戶將無(wú)法得到持續(xù)的支持特別是維修方面。另外，國(guó)內(nèi)圍繞在W78958上所做的技術(shù)工作也無(wú)法得到延續(xù)和提高，很多業(yè)界人士認(rèn)為仿真器行業(yè)將面臨另起爐灶或重新洗牌的局面。</p><p>　　HOOKS技術(shù)無(wú)疑是仿真器廠商在失去

14、W78958后的替代品，但是由于沒(méi)有長(zhǎng)期跟蹤和關(guān)注，短期內(nèi)多數(shù)廠家無(wú)法將復(fù)雜的HOOKS技術(shù)應(yīng)用于成熟的產(chǎn)品中。專家們認(rèn)為仿真器廠家的整體轉(zhuǎn)型可能需要2－3年的周期，并且有相當(dāng)?shù)姆抡嫫鲝S家將會(huì)被淘汰，市場(chǎng)擁有量將主要集中在少數(shù)幾個(gè)仿真器廠家。</p><p>　　隨著芯片廠家越來(lái)越多、資源越來(lái)越強(qiáng)，用甲廠芯片去仿真乙廠芯片的兼容仿真模式，存在資源覆蓋不全(如附加端口、附加外部中斷)、地址分布不同(如P4口)、操作

15、方式不同(如EXTRAM、WTD)等缺點(diǎn)。 用專用仿真芯片或Philips芯片去仿真20多個(gè)廠家的400多種芯片，所需的仿真頭越來(lái)越多，因此有了新一代專利技術(shù)的仿真器。</p><p>　　但是新一代專利技術(shù)的仿真器卻使沒(méi)有什么經(jīng)濟(jì)能力的初學(xué)者無(wú)力購(gòu)買。</p><p>　　四、以單片機(jī)為核心的嵌入式系統(tǒng)</p><p>　　單片機(jī)的另外一個(gè)名稱就是嵌入式微控制器，

16、原因在于它可以嵌入到任何微型或小型儀器或設(shè)備中。目前，把單片機(jī)嵌入式系統(tǒng)和Internet連接已是一種趨勢(shì)。但是，Internet一向是一種采用肥服務(wù)器，瘦用戶機(jī)的技術(shù)。這種技術(shù)在互聯(lián)上存儲(chǔ)及訪問(wèn)大量數(shù)據(jù)是合適的，但對(duì)于控制嵌入式器件就成了"殺雞用牛刀"了。要實(shí)現(xiàn)嵌入式設(shè)備和Int ernet連接，就需要把傳統(tǒng)的Internet理論和嵌入式設(shè)備的實(shí)踐都顛倒過(guò)來(lái)。為了使復(fù)雜的或簡(jiǎn)單的嵌入式設(shè)備，例如單片機(jī)控制的機(jī)床、單

17、片機(jī)控制的門鎖，能切實(shí)可行地和Internet連接，就要求專門為嵌入式微控制器設(shè)備設(shè)計(jì)網(wǎng)絡(luò)服務(wù)器，使嵌入式設(shè)備可以和Internet相連，并通過(guò)標(biāo)準(zhǔn)網(wǎng)絡(luò)瀏覽器進(jìn)行過(guò)程控制。 </p><p>　　目前，為了把單片機(jī)為核心的嵌入式系統(tǒng)和Internet相連，已有多家公司在進(jìn)行這方面的較多研究。這方面較為典型的有emWare公司和TASKING公司。 EmWare公司提出嵌入式系統(tǒng)入網(wǎng)的方案--EMIT技術(shù)。這個(gè)技術(shù)

18、包括三個(gè)主要部分：即emMicro， emGateway和網(wǎng)絡(luò)瀏覽器。目前，單片機(jī)應(yīng)用中提出了一個(gè)新的問(wèn)題：這就是如何使8位、16位單片機(jī)控制的產(chǎn)品，也即嵌入式產(chǎn)品或設(shè)備能實(shí)現(xiàn)和互聯(lián)網(wǎng)互連？ TASKING公司目前正在為解決這個(gè)問(wèn)題提供了途徑。該公司已把emWare的EMIT軟件包和有關(guān)的軟件配套集成，形成一個(gè)集成開(kāi)發(fā)環(huán)境，向用戶提供開(kāi)發(fā)方便。</p><p>　　五 單片機(jī)應(yīng)用的可靠性技術(shù)發(fā)展 </p&g

19、t;<p>　　在單片機(jī)應(yīng)用中，可靠性是首要因素為了擴(kuò)大單片機(jī)的應(yīng)用范圍和領(lǐng)域，提高單片機(jī)自身的可靠性是一種有效方法。近年來(lái)，單片機(jī)的生產(chǎn)廠家在單片機(jī)設(shè)計(jì)上采用了各種提高可靠性的新技術(shù)，這些新技術(shù)表現(xiàn)在如下幾點(diǎn)： </p><p>　　1、EFT（Ellectrical Fast Transient）技術(shù) </p><p>　　EFT技術(shù)是一種抗干擾技術(shù)，它是指在振蕩電路的正

20、弦信號(hào)受到外界干擾時(shí)，其波形上會(huì)迭加各種毛刺信號(hào)，如果使用施密特電路對(duì)其整形，則毛刺會(huì)成為觸發(fā)信號(hào)干擾正常的時(shí)鐘，在交替使用施密特電路和RC濾波電路時(shí)，就可以消除這些毛否則令其作用失效，從而保證系統(tǒng)的時(shí)鐘信號(hào)正常工作。這樣，就提高了單片機(jī)工作的可靠性。Motorola公司的 MC68HC08系列單片機(jī)就采用了這種技術(shù)。 低噪聲布線技術(shù)及驅(qū)動(dòng)技術(shù) </p><p>　　在傳統(tǒng)的單片機(jī)中，電源及地線是在集成電路外殼的

21、對(duì)稱引腳上，一般是在左上、右下或右上、左下的兩對(duì)對(duì)稱點(diǎn)上。這樣，就使電源噪聲穿過(guò)整塊芯片，對(duì)單片機(jī)的內(nèi)部電路造成干擾?，F(xiàn)在，很多單片機(jī)都把地和電源引腳安排在兩條相鄰的引腳上。這樣，不僅降低了穿過(guò)整個(gè)芯片的電流，另外還在印制電路板上容易布置去耦電容，從而降低系統(tǒng)的噪聲。 現(xiàn)在為了適應(yīng)各種應(yīng)用的需要，很多單片機(jī)的輸出能力都有了很大提高，Motorola公司的單片機(jī)I/O口的灌拉電流可達(dá)8mA以上，而Microchip公司的單片機(jī)可達(dá)25mA

22、。其它公司：AMD，F(xiàn)ujitsu，NEC ，Infineon，Hitachi，Ateml，Tosbiba等基本上可達(dá)8～20mA的水平。這些電流較大的驅(qū)動(dòng)電路集成到芯片內(nèi)部在工作時(shí)帶來(lái)了各種噪聲，為了減少這種影響，現(xiàn)在單片機(jī)采用多個(gè)小管子并聯(lián)等效一個(gè)大管子的方法，并在每個(gè)小管子的輸出端串上不同等效阻值的電阻，以降低di/dt，這也就是所謂"跳變沿軟化技術(shù)"，從而消除大電流瞬變時(shí)產(chǎn)生的噪聲。 </p>

23、<p><b>　　2、采用低頻時(shí)鐘 </b></p><p>　　高頻外時(shí)鐘是噪聲源之一，不僅能對(duì)單片機(jī)應(yīng)用系統(tǒng)產(chǎn)生干擾，還會(huì)對(duì)外界電路產(chǎn)生干擾，令電磁兼容性不能滿足要求。對(duì)于要求可靠性較高的系統(tǒng)，低頻外時(shí)鐘有利于降低系統(tǒng)的噪聲。在一些單片機(jī)中采用內(nèi)部瑣相環(huán)技術(shù)，則在外部時(shí)鐘較低時(shí)，也能產(chǎn)生較高的內(nèi)部總線速度，從而保證了速度又降低了噪聲。Motorola公司的MC68HC08系列

24、及其1 6/32位單片機(jī)就采用了這種技術(shù)以提高可靠性</p><p>　　Foreign documents</p><p>　　一 Microcontroller introduction</p><p>　　SCM is A kind of integrated circuit chips, is to use very large scale integrat

25、ed circuit technology has the ability to handle data CPU CPU, RAM random access memory read only memory ROM, A variety of I/O mouth and interrupt system, timer/timer function (may include display driver circuit, pulse wi

26、dth modulation circuit, simulation way more converter, A/D converter circuits, etc) integrated into one of these forms of A small and perfect computer system.</p><p>　　SCM is also called micro controller (Mi

27、crocontroller), because it was the first used in the industrial control area. By chip microcontroller within the CPU only dedicated processor. The first design concept is through the huge amounts of peripheral and CPU in

28、tegration in a chip, make the computer system more small, more easily integrated into the complex and demanding to volume control of equipment. The INTEL Z80 is the earliest according to this design thought of the proces

29、sor, and from then on</p><p>　　二 The development trend of the single chip microcomputer</p><p>　　Now can say MCU is let flowers blossom and schools of thought contend period, the world each big

30、chip manufacturing companies have launched their own microcontroller, from 8 bits, 16 to 32 bit, countless, everything, and the mainstream C51 series compatible, also have compatible, but they have their special features

31、, complementary to each other, for the application of the single chip microcomputer provide vast heaven and earth.</p><p>　　Throughout the development process of single chip microcomputer, predicts the devel

32、opment trend of the single chip microcomputer, roughly:</p><p>　　1．Low power consumption CMOS</p><p>　　MCS-51 series of 8031 when the power consumption of the launch of the 630 mW, but now the s

33、ingle chip microcomputer universal in 100 mW or so, as the SCM power consumption demand more and more low, each single chip manufacturers now basic using CMOS (complementary metal oxide semiconductor process). Like 80 C5

34、1 had adopted HMOS (namely high density metal oxide semiconductor technology) and CHMOS (high density complementary metal oxide semiconductor process). Though low power consumption CMOS, bu</p><p>　　2．Miniat

35、ure sheet piece of</p><p>　　Now the single chip microcomputer universal conventional is will the central processing unit (CPU), random access memory (RAM), data read only memory (ROM) program, parallel and s

36、erial communication interface, the interrupt system, regular circuit, clocking circuit integration in A single chip, enhanced the single chip micro computer integrated as A/D converter, PMW (pulse width modulation circui

37、t), WDT (watchdog), some SCM LCD (LCD) will drive circuit are integrated in A single chip, this singl</p><p>　　3．The mainstream and many kinds of coexistence</p><p>　　Now, while the single chip

38、microcomputer variety, each characteristic, but still with 80 C51 single chip microcomputer as the core of the mainstream, compatible with its structure and instructions of the system PHILIPS products, ATMEL company prod

39、ucts and China Taiwan's Winbond series microcontroller. So as the core of the single chip microcomputer occupy C8051 heavily-accented screams. Microchip company and the PIC reduced instruction set (RISC) also have a

40、strong momentum of development, China</p><p>　　三The development of the simulator</p><p>　　Throughout the domestic nearly 20 years of simulation technology development course, according to the si

41、mulation implement use technology to differentiate, the design of the domestic simulator can be divided into the following several period about:</p><p>　　(1) 70 s-the mid 80's</p><p>　　This

42、period is mainly the adopted technology of the simulation system development, and now it is not high technical content, user requirements is not high also.</p><p>　　(2) the 80 s-90 s</p><p>　　Th

43、is period mainly use HuaBang a simulation of production function with chip, using technology called Bondout. Adopting the single chip can greatly simplified the design of the simulation system, therefore the domestic sim

44、ulators level have improved, basically can do not take up the user resources.</p><p>　　It is due to the improvement of the performance of the simulation, the domestic simulator in nearly 10 years of making t

45、ime no progress, has been using this kind of production mode. Although individual manufacturer has also tried other technology to improve simulation level, such as HOOKS technology, but because of its technical limitatio

46、ns without success. Instead of foreign simulators early use HOOKS technology, in early because of the complexity of the HOOKS technology itself, the simulation </p><p>　　Along with the IC technology developm

47、ent, the domestic production of the HOOKS technology conditions ripe, but domestic several major production manufacturer still lose themselves in Bondout technology in.</p><p>　　(3) started in 2000</p>

48、<p>　　2000 is the Chinese simulators market change is the biggest period, one of the most dramatic change is HuaBang simulation chip W78958 shut-down.</p><p>　　Sinocon corp. In W78958 chip design, its

49、 internal simulation function just for simulators manufacturers can make simulator in order to better promote W78958. But after years of change, W78958 evolved into a simulation device on the use of the special chip simu

50、lation and not users with the use of the standard chip, the scope of use for domestic, less than a year the dosage of only 20000 prompted sinocon corp. In the 2002 years later announced it will stop production the chip.&

51、lt;/p><p>　　W78958 after production, domestic simulation device manufacturers in a very embarrassing situation. Because in the domestic use W78958 nearly 10 years, domestic user group of very large, these users

52、 will not be able to get the ongoing support especially maintenance. In addition, China has done in W78958 around the technical work will be given continue and improve, many professionals think simulators industry will f

53、ace the drawing board or to shuffling of the situation.</p><p>　　HOOKS technology is undoubtedly simulator in W78958 lost after the manufacturer substitute, but with no long-term tracking and attention, the

54、short term most manufacturers can't will complex HOOKS technology applied to mature product. Experts think the whole transformation of the manufacturer may need to 2-3 year cycle, and so is the simulation of the fact

55、ory will be eliminated, the market will be mainly the ownership in a few simulation device manufacturers.</p><p>　　As the more and more manufacturers, resource is more and more strong, with JiaChang chip to

56、the simulation YiChang chips compatible simulation model, existing resources does not cover all (such as additional port, additional external interruption), address distribution different (such as P4 mouth), the operatio

57、n mode different (such as EXTRAM, WTD) shortcomings. Use special simulation chip or Philips chip to the simulation of a variety of more than 20 factory 400 chip, the simulation head is mor</p><p>　　But a new

58、 generation of patent technology of the simulator will make no economic ability unable to buy the beginners.</p><p>　　四With the single chip processor as the core of the embedded system</p><p>　　

59、SCM another name is embedded microcontroller controller, the reason is that it can be embedded into any miniature or small instrument or equipment. At present, the single chip embedded system and Internet connection is a

60、 kind of trend. But, the Internet has always been a server with fat, thin users machine technology. The technology of the Internet in the storage and access to large amounts of data is appropriate, but for control embedd

61、ed devices became "kill chicken por muson mortigi oni pafilo</p><p>　　At present, in order to put the single chip microcomputer as the core of the embedded system and Internet connected, has had a lot o

62、f companies in the more research. This aspect of the typical have emWare company and TASKING company. EmWare company to put forward the embedded system of the program-the net EMIT technology. This technology includes thr

63、ee main parts: that is emMicro, emGateway and a web browser. At present, the SCM put forward a new problem: this is how to make eight, 16 single-chi</p><p>　　五 The reliability of the microcomputer applicatio

64、n technology development</p><p>　　In the single chip microcomputer applications, the reliability is the primary factor in order to expand the application range of the single chip microcomputer and field, imp

65、rove the reliability of the single chip microcomputer itself is a kind of effective method. In recent years, the single chip manufacturers in the design of the single chip microcomputer to improve reliability of the new

66、technology, the new technology performance in the following:</p><p>　?。?） EFT (Ellectrical Fast Transient) technology</p><p>　　EFT technology is a kind of anti-interference technology, it is to

67、point to in the oscillating circuit by the sine signal interference, the waveform superposition of burr signal will, if use the plastic schmidt circuit, the burr would be triggered signals interferes with normal clock, i

68、n the alternate use schmidt circuit and the RC filter circuit, can eliminate the hair or make its function failure to ensure system clock signal normal work. So, improve the reliability of the single chip microcom</p&

69、gt;<p>　　In the traditional single chip microcomputer, the power and the ground is in integrated circuit of the shell of ChenYin feet, general is in the upper left, right or at the lower left, two for symmetry poi

70、nt. It is, it makes the power supply noise through the whole chip, the SCM internal circuit cause interference. Now, a lot of the single chip microcomputer and power pin arranged in two adjacent pin. So, not only reduces

71、 the through the chip of the current, and also in the printed circuit board </p><p>　?。?）the low frequency clock</p><p>　　The clock is one of high frequency noise sources, not only can the distu

72、rbance of SCM system, and also to the outside world circuitry interference and make the electromagnetic compatibility can't meet the requirements. Asking for high reliability system, the low frequency clock which hel

73、ps reduce system noise. In some of the single chip microcomputer by internal zohar cirtle technology, is in the external clock is low, also can produce high internal bus speed, and thus makes the speed and reduce</p&g