單片機(jī)外文翻譯9-單片機(jī)-資料下載頁
2025-01-19 07:57本頁面
【導(dǎo)讀】一些廠家用這兩種特性區(qū)分程序存。特性，展示如圖3-5A-2。不少微機(jī)和單片機(jī)用于大批量應(yīng)。因此，經(jīng)濟(jì)的設(shè)備制造要求程序存儲(chǔ)器的內(nèi)容是在制造期間永久性的刻錄在芯。片中，這意味著必須采用嚴(yán)謹(jǐn)?shù)姆椒?，因?yàn)镽OM代碼不能在制造之后修改。雙方按照異步同步通信方案要求的規(guī)。有時(shí)候與定時(shí)器相關(guān)的是一個(gè)事件計(jì)。必須使用晶體以確保最大接近時(shí)鐘頻率。今天的PLC將面對(duì)日益復(fù)雜的挑戰(zhàn)。PLC技術(shù)的更新，我們將在PLC制造商會(huì)就這些主題提出更多問題.感覺到了，PLC將用于過程工業(yè)，但不一定是過程控制。為PLC將越來越多地使用食品、化工、石化等行業(yè)，在PLC的兩種類型應(yīng)用程序中，第一種是過程控制系統(tǒng)，它目前已經(jīng)隨著價(jià)格標(biāo)簽開始發(fā)展。統(tǒng)的業(yè)務(wù)將引用更多的PLC技術(shù)，PLC功能比以往任何時(shí)候都要多。造商規(guī)范沒有最終決定。標(biāo)準(zhǔn)被引進(jìn)后，以為基礎(chǔ)的產(chǎn)品將被淘汰”。正因?yàn)槿绱耍S多PLC廠商正在制定完整的規(guī)范。例如Omron，擁有一個(gè)完整
【正文】 oi ted for i nter fa ci ng s pec ial func tio n c hip s or li nki ng se ver al mi cr oco mp ute rs to ge the r . Bo th the c o mmo n a s ync hro no us s ync hr o no us c o mmu ni c a tio n s c he mes re q uir e p ro toc ols tha t pr ovi de fra mi ng (s tar t a nd s to p) i nfo r ma ti o n . T hi s ca n be i mp le me nte d a s a har dw ar e fa cili ty or US a s ync hro no us r ecei ver/ tra ns mi tte r) re lievi ng the p roc ess or ( a nd the ap plic a tio ns p ro gra mme r ) o f this low l evel , ti me c o ns umi ng, de tail . t is me rel y ne c ess ar y to sele c te d a ba ud ra te a nd po ssibl y o ther op ti o ns ( numb e r o f s to p b i ts, pari ty, e tc. ) a nd l oad (or r ea d fro m) the seri al tr a ns mi tter ( or r ecei ver ) b uffer. S eriali za ti o n o f the d a ta i n the a p p r o p riate fo r ma t i s the n ha nd l e d b y the ha r d w a re c i r c uit. Timing/counter facilities. Ma ny a p plica tio n o f si ngle c hi p mi cro co mp ute rs re q uir e acc ura te e val ua ti o n o f el aps ed real ti me . T his c a n be d e ter mi ne d b y c are ful a sse ss me nt o f the e xe c uti o n ti me o f e ac h b ra nc h i n a pr o gra m b ut this r api dl y bec o mes i ne ffi cie nt for all b ut si mp les t pr o gr a ms . T he p re ferre d ap pro ac h is to us e ti me r circ ui t tha t ca n i nd epe nd e ntl y c o unt pr ecis e ti me i ncr e me nts a nd ge ne ra te a n i nte rr up t a fte r a pres e t ti me has ela ps ed . T hi s type o f ti me r is us uall y arr a nge d to be r eloa da ble w i th the r eq uire d c o unt . T he t i me r the n dec re me nts this v al ue pr od uci ng a n i nterr up t o r s e tti ng a fla g w he n the co unte r r eac hes zer o. Be tte r ti me rs the n hav e the a bili ty to a uto ma ticall y r eloa d the i ni tial c o unt v al ue. T hi s reli eve s the pr o gr a mme r o f the r esp o nsibili ty o f rel oa di ng the c o unter a nd as ses si ng el aps ed ti me b e fore the ti mer re s tar ted ,w hic h o therw is e w o und be nece ssar y i f c o nti nuo us pr eci sel y ti me d i nterr up ts w ere r eq uire d ( as i n a cl oc k , for e xa mpl e). So me ti me s as so cia te d w i th ti mer is a n e ve nt c o unter. Wi th this facil i ty t here is us uall y a s pe cial i np ut pi n , tha t c a n d r i v e the c o unte r d i r e c tly. Timing ponents. T he cl oc k circ ui tr y o f mo s t mi cr oco mp ute rs re q uir es o nl y si mp le ti mi ng c o mp o ne nts . If ma xi mum p e r fo r ma nce is r eq uire d,a c r ys tal mus t be use d to e ns ur e the ma xi mu m c lo c k fre q ue nc y is a ppr oa c he d b ut no t e xc ee ded . Ma ny clo c k cir c ui ts a lso w or k w i th a r esis tor a nd c ap aci tor a s l ow c os t ti mi ng c o mp o ne nts or ca n be dri ve n fr o m a n e xter nal so urc e. T his la tter a rra nge me nt is use ful is e xter nal s ync hr o ni za ti o n o f the mi c r o c o mp ute r i s r e q ui r ed .
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