Isimiso esijwayelekile sokusebenza kwe-ADCs

Ake sicabangele uhla oluyinhloko lwezinkinga ezingabhekiswa ekusetshenzisweni kokuguquguquka kwe- analog-to-digital (ADC) zezinhlobo ezahlukene. I-akhawuntini elandelanayo, ukulinganisa okuncane-yini efihliwe ngemuva kwala magama? Iyini isimiso se-ADC microcontroller? Lezi, kanye nezinye izinkinga eziningi, sizocabangela kohlaka lwendaba. Sizobeka izingxenye ezintathu zokuqala kwi-theory jikelele, futhi kusukela esihlokweni sesine sizofunda isimiso somsebenzi wabo. Ungakwazi ukuhlangabezana nemigomo ye-ADC ne-DAC ezincwadini ezahlukene. Isimiso sokusebenza kwala madivayisi sihlukile, ngakho ungawafihli. Ngakho-ke, lesi sihloko sizocabangela ukuguqulwa kwesignali kusuka kwifomu ye-analog kuya kwedijithali, kanti i-DAC isebenza ngenye indlela.

Incazelo

Ngaphambi kokucabangela isimiso se-ADC, ake sithole ukuthi yiluphi uhlobo lwedivayisi. Abaguquli be-Analog-kuya-digital kukhona amadivaysi aguqulela ubuningi obungokwenyama ekumelekeni kwezinombolo ezihambelanayo. Njengengqamuzana yokuqala, cishe noma yini engayenza: okwamanje, amandla, amandla, ukumelana, i-shaft rotation angle, imvamisa ye-pulse, njalonjalo. Kodwa ukuze sibe nesiqiniseko, sizosebenza kuphela ngenguquko eyodwa. Lona "i-voltage-code". Ukukhethwa kwaleli fomethi akunjalo ngengozi. Phela, i-ADC (isimiso sokusebenza kwalesi sidivaysi) kanye nezici zayo kuxhomeke ekutheni isiphi isici esilinganiswa esetshenziswayo. Ngalokhu kuhloswe ngenqubo yokuqhathanisa inani elithile ngezinga elimisiwe ngaphambili.

Izici ze-ADC

Okuyinhloko kukhona ukujula nokuvama kokuguquguquka. Owokuqala uboniswa ngamabhitshi, kanti okwesibili kuboniswa ekubalweni ngomzuzwana. Abaguquli be-analog-to-digital banamuhla bangaba nomthamo wamandla angu-24 noma ukuguqulwa, okufinyelela ezingxenyeni ze-GSPS. Qaphela ukuthi i-ADC ingakunikeza ngesikhathi esisodwa izici zayo. Njengoba kusebenza kakhulu, kunzima kakhulu ukusebenza ngedivayisi, futhi ngokwayo kuyabiza kakhulu. Kodwa inzuzo ingatholakala ngamadijithi adingekayo, ukunikela ngesivinini sedivaysi.

Izinhlobo zama-ADC

Umgomo wokusebenza uhluka phakathi kwamaqembu ahlukene amadivaysi. Sizocabangela lezi zinhlobo ezilandelayo:

1. Ngezinguquko eziqondile.
2. Ngokulinganisa okulandelanayo.
3. Ngenguquko efanayo.
4. Umguquleli we-analog-digital nge-balance balance (delta-sigma).
5. Ukuhlanganisa i-ADCs.

Kunezinye eziningi eziningi zokuhambisa kanye nezinhlobo ezihlangene ezinezici zazo ezikhethekile nezakhiwo ezihlukahlukene. Kodwa lezo sampuli ezizocatshangelwa ngaphakathi kohlaka lwendaba ziyakuthandeka ngoba zidlala indima ebonisa inamba yabo yamadivayisi walesi sici. Ngakho-ke, ake sifunde isimiso se-ADC, kanye nokuthembela kwayo kudivayisi yomzimba.

Abaguquli be-analog-to-digital ngqo

Bathandwa kakhulu ema-60-70s ekhulwini lokugcina. Ngendlela yama- circuits edidiyelwe akhiqizwa kusukela kuma-80. Lezi zilula kakhulu, ngisho namadivaysi amancane angakwazi ukuziqhayisa ngezinkomba ezibalulekile. Ukujula kwabo kuvame ukuthi kube ngu-6-8 bits, futhi isivinini singavamile ukudlula i-GSPS engu-1.

Isimiso sokusebenza kwe-ADC yalolu hlobo kufana nalokhu: isignali yokufakwayo ifaka ngesikhathi esisodwa kulezi zimpendulo zokufaka abafana. Ama-terminals angalungile anikezwa nge-voltage yenani elithile. Futhi-ke idivaysi inquma imodi yayo yokusebenza. Lokhu kwenziwa ngenxa ye-voltage reference. Ake sithi sinedivaysi lapho kunabalingisi abangu-8. Uma i-½ yocingo lokubhekisela isetshenziswa, kuphela okungu-4 kubo kuzofakwa. I-encoder yokuqala izokwenza ikhodi kanambambili, eqondiswe irejista yokukhipha. Mayelana nokufaneleka nokudangala, kungashiwo ukuthi isimiso sokusebenza esinjalo sivumela ukudala amadivaysi aphezulu. Kodwa ukuthola isidingo esincane esidingekayo kufanele ugijime kakhulu.

Ifomula jikelele yenani labaqhathanisa libukeka kanje: 2 ^ N. Ngaphansi kuka-N, udinga ukusetha inani lamadijithi. Isibonelo esibonwe ekuqaleni singasetshenziswa futhi: 2 ^ 3 = 8. Kudingeka inani elingu-8 lokulinganisa ukuze uthole idijithi yesithathu. Lona ngumgomo we-ADC, owadalwa kuqala. Akuyona elula kakhulu, ngakho-ke okulandelayo kwakukhona ezinye izakhiwo.

I-Analog kuya ku-Digital Converters

Lapha sisebenzisa i-algorithm "yokulinganisa". Ngamafuphi, amadivaysi asebenzisa le nqubo abizwa ngokuthi ama-ADC nje ngokubala okulinganayo. Isimiso sokusebenza kanje: idivaysi inquma inani le signal signal, bese lifaniswa nezinombolo ezikhiqizwa ngokwendlela ethile:

1. Ingxenye yombhalo ongase usebenzise umthamo wesethi isethwe.
2. Uma isibonakaliso sinqobe umkhawulo wexabiso kusuka iphuzu # 1, bese kuqhathaniswa nenombolo ephakathi nendawo ephakathi kwenani elisele. Ngakho-ke, kithi, lokhu kuzoba yi-¾ ye-reference voltage. Uma isignali yesibonakaliso ayifinyeleli kule nkomba, khona-ke ukuqhathaniswa kuzokwenziwa ngenye ingxenye yesikhashana ngendlela efanayo. Kulesi sibonelo, yi-¼ ye-reference voltage.
3. Isinyathelo sesi-2 kufanele siphindwe izikhathi ezingu-N, esizosinika umphumela we-H-bit. Lokhu kungenxa yenombolo H yokuqhathanisa.

Lesi simiso sokusebenza ikuvumela ukuthi uthole amadivayisi anejubane eliguquguqukayo eliguquguqukayo, eliyi-ADC yokulinganisa okulandelanayo. Isimiso sokusebenza, njengoba ubona, silula, futhi la madivayisi ahle kakhulu kumacala ahlukene.

Abaguquli be-analog-kuya-digital abafana

Zisebenza njengamadivayisi we-serial. Ifomula yokubala iwu (2 ^ H) -1. Kulo cala elibhekwe ekuqaleni, sidinga (2 ^ 3) -1 abaqhathanisi. Ukuze usebenze, kusetshenziselwa uhlobo oluthile lwamadivayisi, ngayinye yazo engaqhathanisa okufakwayo kanye nezintando zomuntu ngamunye. Abaguquli be-analog-to-digital abafana nama-parallel amadivayisi asheshayo. Kodwa isimiso sokwakha la madivaysi siwukuthi ukugcina ukusebenza kwabo kudinga amandla amakhulu. Ngakho-ke, akusiluleka ukuwasebenzisa ngamandla ebhethri.

Umguquleli we-analog-kuya-digital ngokulinganisela okuncane

Isebenza ngokulandela uhlelo olufanayo njengedivayisi yangaphambilini. Ngakho-ke, ukuze kuchazwe ukusebenza kwe-ADC ngokulinganisela okuncane, isimiso somsebenzi wabaqalayo sizobhekwa njengempela ngeminwe. Enhliziyweni yalezi zinsiza kuyisici se-dichotomy. Ngamanye amazwi, ukuqhathaniswa okungajwayelekile kwesilinganiso esilinganiselwe ngenxenye ethile yezinga eliphezulu liyenziwa. Amanani ku-½, 1/8, 1/16 nokunye angathathwa. Ngakho-ke, umguquleli we-analog-to-digital angenza yonke inqubo ye-H iterations (izinyathelo ezilandelanayo). Futhi H lilingana nobubanzi be-ADC (bheka amafomula ahlinzekwe ngaphambilini). Ngakho-ke, sinenzuzo enkulu ngesikhathi, uma ijubane lezinqubo libaluleke kakhulu. Naphezu kwejubane elikhulu, la madivaysi abonakala futhi ngephutha eliphansi eliphansi.

Abaguquli be-Analog-digital nge-charge balance (i-delta-sigma)

Lolu uhlobo lwethakazelisa kakhulu, hhayi okungenani ngenxa yesimiso salo sokusebenza. Iqukethe ukuthi i-voltage yokufaka iqhathaniswa nalokho okwakungenwe yi-integrator. Imipula ene-polarity engalungile noma enhle ifakwa ekufakweni (konke kuxhomeke emphumela wokusebenza kwangaphambilini). Ngakho-ke, kungashiwo ukuthi umguquleli onjalo we-analog-to-digital uyindlela elula yokulandelela. Kodwa lokhu kuphela njengesibonelo sokuqhathanisa, ngakho ungaqonda ukuthi i- ADC ye-delta-sigma ingubani. Isimiso sokusebenza yisistimu, kodwa ukusebenza okuphumelelayo kwalolu guqula i-analog-to-digital akwanele. Umphumela wokuphela uwukugeleza okungapheli kwamayunithi nama-zero ahamba nge-LPF yedijithali. Kulezi, kulandelwa ukulandelana okuncane. Ukwahlukaniswa phakathi kwe-ADC abaguquli bemilayezo yokuqala neyesibili.

Abaguquleli be-analog-to-digital abahlanganisiwe

Lesi yisikhathi sokugcina esikhethekile esizocatshangelwa ngaphakathi kohlaka lendaba. Okulandelayo, sizochaza ukusebenza kwala madivayisi, kodwa ezingeni elijwayelekile. Le-ADC iguqula i-analog-to-digital ne-push-pull ukuhlanganiswa. Ungakwazi ukuhlangabezana nedivayisi efanayo kumamitha amaningi we- digital. Futhi lokhu akumangazi, ngoba banikeza ngokunemba okuphakeme futhi ngesikhathi esisodwa bacindezela kahle umsindo.

Manje ake sigxile esimisweni sakhe somsebenzi. Iqukethe ukuthi isignali yokufaka ikhokhisa i-capacitor isikhathi esinqunyiwe. Ngokujwayelekile, le nkathi iyunithi yemvamisa yenethiwekhi eyenza idivayisi (50 Hz noma i-60 Hz). Kungabuye ibe yiningi. Ngakho-ke, umsindo ophezulu wevolumu uyasuswa. Ngesikhathi esifanayo, umphumela wezintambo ezingaguquki zomthombo wegridi wokukhiqiza ugesi ngokuqondile komphumela wenziwa.

Uma isikhathi sokushaja somguquli we-analog-to-digital siphelile, i-capacitor iqala ukukhipha ngezinga elithile elihleliwe. I-counter yangaphakathi yedivayisi ibala inani lezingxube zewashi ezikhiqizwa phakathi nale nqubo. Ngakho-ke, isikhathi eside isikhathi, isikhathi esibaluleke kakhulu izinkomba.

Ama-ADC we-push-pull ukuhlanganiswa anemba ngokunembile nokuxazulula amandla. Ngenxa yalokhu, kanye nesakhiwo esicacile sokwakhiwa, senziwa njenge-chips. Impendulo eyinhloko yalesi simiso somsebenzi ukuxhomeka kwenkomba yenethiwekhi. Khumbula ukuthi amakhono ayo ahlanganiswe isikhathi sobude besikhathi sokunikezwa kwamandla.

Nakhu ukuthi i-ADC yokuhlanganiswa kabili isebenza kanjani. Isimiso sokusebenza kwale divayisi, nakuba sinzima kakhulu, kodwa inikeza izinkomba zekhwalithi. Kwezinye izimo, lokhu kuyadingeka nje.

Khetha i-APC ngesimiso somsebenzi esiyidingayo

Ake sithi sibhekane nomsebenzi othile. Indlela yokukhetha idivayisi ukuze inelise zonke izicelo zethu? Okokuqala, ake sikhulume ngokuxazulula nokuchithwa. Ngokuvamile badidekile, nakuba ngokusemandleni baxhomeke kakhulu kunomunye wesibili. Khumbula ukuthi umguquli we-analog-to-digital angama-12-bit angaba nokunemba okuncane kune-8-bit eyodwa. Kulesi simo, isinqumo sinesilinganiso sokuthi zingaki izingxenye ezingasuswa ebangeni lokufakwayo lesignali esilinganisiwe. Ngakho, ama-ADC angu- ^8- b anama-2 ⁸ = 256 amayunithi anjalo.

Ukunemba ukuguqulwa okuphelele kokuguqulwa okuphumela ekutheni kube nenani elihle, okumele kube ngombono wokufaka owanikwa. Okusho ukuthi, ipharamitha yokuqala ibonisa amandla amakhono we-ADC, futhi okwesibili kubonisa lokho esikusebenzayo. Ngako-ke, singakwazi ukufinyelela kumhlobo olula (isibonelo, abaguquli abaqondisi-analog kuya ku-digital), okuzokwanelisa izidingo ngenxa yokunemba okukhulu.

Ukuze ube nomqondo walokho okudingekayo, okokuqala sidinga ukubala imingcele yemvelo nokwakha ifomati yesibalo sokuxhumana. Okubalulekile kuzo ziyiziphambeko eziqinile futhi ezinamandla, ngoba uma usebenzisa izingxenye ezahlukene nemigomo yokwakha idivayisi, bayoba nomphumela ohlukile ngezici zayo. Ukwaziswa okuningiliziwe kungatholakala kumadokhumenti ezobuchwepheshe ukuthi umenzi wedivaysi ngayinye unikeza.

Isibonelo:

Ake sibheke i-ADC SC9711. Isimiso sokusebenza sale divayisi sinzima ngenxa yobukhulu bayo namakhono. Ngendlela, ekhuluma ngezokugcina, kufanele kuqaphele ukuthi zihluke ngempela. Ngakho-ke, isibonelo, imvamisa yemisebenzi eyenzekayo isukela ku-10 Hz kuya ku-10 MHz. Ngamanye amazwi, lingenza izibalo ezingu-10 ngesigamu! Futhi idivayisi ngokwayo ayiyona into ebalulekile, kodwa inesakhiwo esimisiwe sokwakhiwa. Kodwa lisetshenziselwa, njengombuso, kumasu ahlukene, lapho kudingekile ukuthi usebenze ngenani elikhulu lamasignali.

Isiphetho

Njengoba ubona, ama-ADC ayenemigomo ehlukene yomsebenzi. Lokhu kusivumela ukuba sikhethe amadivaysi agcwalisa izicelo ezivela, futhi ngesikhathi esifanayo asivumele ukuba sisebenzise izindlela ezikhona ngokuhlakanipha.