Iyo CAN bhazi terminal kuramba kazhinji 120 ohms. Muchokwadi, pakugadzira, kune maviri 60 ohms kuramba tambo, uye kazhinji kune maviri 120Ω node mubhazi. Chaizvoizvo, vanhu vanoziva diki CAN bhazi ishoma. Munhu wose anoziva izvi.
Pane matatu mhedzisiro yeCAN bhazi terminal kuramba:
1. Kuvandudza simba re-anti-interference, rega chiratidzo chepamusoro-soro uye simba shoma riende nokukurumidza;
2. Iva nechokwadi chokuti bhazi rinokurumidza kupinda munzvimbo yakavanzika, kuitira kuti simba reparasitic capacitors riende nokukurumidza;
3. Kuvandudza unhu hwechiratidzo uye uiise pamigumo miviri yebhazi kuderedza simba rekuratidzira.
1. Kuvandudza anti-kupindira kugona
Bhazi reCAN rine zvirevo zviviri: "zvakajeka" uye "zvakavanzika". "Expressive" inomiririra "0", "yakavanzika" inomiririra "1", uye inotemerwa neCAN transceiver. Nhamba iri pazasi ndeye yakajairika yemukati chimiro dhizaini yeCAN transceiver, uye iyo Canh neCanl yekubatanidza bhazi.
Kana bhazi rakajeka, iyo yemukati Q1 neQ2 inovhurwa, uye mutsauko wekumanikidza pakati pegaba negaba; kana iyo Q1 neQ2 yagurwa, iyo Canh neCanl iri muchimiro chekusagadzikana nekumanikidza musiyano we0.
Kana pasina mutoro mubhazi, kupikisa kukosha kwekusiyana munguva yakavanzwa yakakura kwazvo. Iyo yemukati MOS chubhu inzvimbo yakakwirira-yekudzivirira. Kupindira kwekunze kunongoda simba shoma shoma kuti bhazi rikwanise kupinda mune zvakajeka (iyo shoma voltage yechikamu chikuru che transceiver. Chete 500mv). Panguva ino, kana pane kukanganiswa kwemuenzaniso wekusiyanisa, pachava nekushanduka kuri pachena mubhazi, uye hapana nzvimbo yekuti kuchinja uku kunotora, uye ichaita nzvimbo yakajeka mubhazi.
Naizvozvo, kuitira kukwidziridza kugona kwe-anti-kupindira kwebhazi rakavanzika, rinogona kuwedzera kusiyanisa mutoro wekupokana, uye kukosha kwekupokana kudiki sezvinobvira kudzivirira kukanganisa kwesimba rakawanda reruzha. Zvisinei, kuitira kuti udzivise bhazi rakawandisa razvino kuti ripinde pachena, kukosha kwekupikisa hakugoni kuva kuduku.
2. Iva nechokwadi chekukurumidza kupinda munzvimbo yakavanzika
Munguva yemamiriro akajeka, iyo parasitic capacitor yebhazi ichabhadharwa, uye aya macapacitor anoda kuburitswa kana adzokera kune yakavanzika nyika. Kana pasina mutoro wekupikisa wakaiswa pakati peCANH neCanl, iyo capacitance inogona kudururwa chete nekusiyana kwekupikisa mukati me transceiver. Iyi impedance yakakura. Zvinoenderana nehunhu hweRC sefa wedunhu, nguva yekuburitsa ichave yakareba zvakanyanya. Isu tinowedzera 220pf capacitor pakati peCanh neCanl yetransceiver yeanalog test. Chiyero chenzvimbo ndeye 500kbit / s. Iyo waveform inoratidzwa mumufananidzo. Kudzikira kweiyi waveform inyika yakati rebei.
Kuti ikurumidze kuburitsa bhazi parasitic capacitors uye ive nechokwadi chekuti bhazi rinokurumidza kupinda munzvimbo yakavanzika, kupikisa kwemutoro kunoda kuiswa pakati peCANH neCanl. Mushure mekuwedzera 60Ω resistor, iwo waveforms anoratidzwa mumufananidzo. Kubva pahuwandu, nguva iyo inodzoka pachena mukuderera inoderedzwa kusvika ku128ns, iyo yakaenzana nenguva yekugadzwa kwekujekesa.
3. Kuvandudza chiratidzo chemhando
Kana iyo chiratidzo ichikwira pachiyero chekushandura, chiratidzo chemupendero simba chinoburitsa chiratidzo chekuratidzira kana iyo impedance isingaenderane; iyo geometric chimiro cheiyo yekuchinjisa tambo yemuchinjikwa chikamu chinoshanduka, hunhu hwetambo huchachinja ipapo, uye kuratidzira kuchaitawo kufungisisa. Essence
Kana simba racho richiratidzwa, iyo waveform inokonzera kutaridzika inokwidziridzwa neiyo yekutanga waveform, iyo inoburitsa mabhero.
Pakupera kwetambo yebhazi, kukurumidza kuchinja kwe impedance kunokonzera chiratidzo chemupendero simba rekuratidzira, uye bhero rinogadzirwa pachiratidzo chebhazi. Kana bhero rakanyanya kukura, richakanganisa hutano hwekukurukurirana. A terminal resistor ine impedance yakafanana yetambo maitiro anogona kuwedzerwa kusvika kumagumo etambo, iyo inogona kutora chikamu ichi chesimba uye kudzivirira chizvarwa chemabhero.
Vamwe vanhu vakaita bvunzo yeanalogi (mifananidzo yakakopwa neni), chiyero chenzvimbo yaive 1MBIT/s, transceiver Canh neCanl yakabatana nezve 10m mitsetse yakamonyoroka, uye transistor yakabatana kune 120Ω resistor kuti ive nechokwadi yakavanzika yekutendeuka nguva. Hapana mutoro pamagumo. Iyo yekupedzisira chiratidzo waveform inoratidzwa mumufananidzo, uye chiratidzo chinokwira mupendero chinoratidzika bhero.
Kana 120Ω resistor ichiwedzerwa pamagumo emutsara wakamonyoroka, iyo yekupedzisira chiratidzo waveform inovandudzwa zvakanyanya, uye bhero rinonyangarika.
Kazhinji, mune yakatwasuka-mutsara topology, ese magumo etambo ndiwo magumo ekutumira uye magumo ekugamuchira. Naizvozvo, imwe terminal kuramba inofanira kuwedzerwa pamativi ese etambo.
Mukuita chaiko kwekushandisa, bhazi reCAN kazhinji harisi iro rakakwana bhazi -mhando dhizaini. Nguva zhinji iyo yakasanganiswa chimiro chemhando yebhazi uye nyeredzi mhando. Iyo yakajairwa chimiro cheanalog CAN bhazi.
Sei uchisarudza 120Ω?
Chii chinonzi impedance? Musainzi yemagetsi, chipingamupinyi kune yazvino mudunhu inowanzonzi impedance. Iyo impedance unit ndeye Ohm, iyo inowanzoshandiswa naZ, inova yakawanda z = r+i (ωl - 1/(ωc)). Kunyanya, impedance inogona kukamurwa kuita zvikamu zviviri, kuramba (chaiyo zvikamu) uye yemagetsi kuramba (chaiyo zvikamu). Kupikisa kwemagetsi kunosanganisirawo capacitance uye sensory resistance. Ikozvino inokonzerwa ne capacitors inonzi capacitance, uye ikozvino inokonzerwa ne inductance inonzi sensory resistance. Iyo impedance pano inoreva kuumbwa kweZ.
Iyo hunhu impedance yechero tambo inogona kuwanikwa nekuyedza. Pane imwe mugumo wetambo, square wave jenareta, imwe magumo yakabatana kune inogadziriswa resistor, uye inoona waveform pakupokana kuburikidza neoscilloscope. Rongedza saizi yehukoshi hwekupokana kudzamara chiratidzo pakupikisa chiri chakanaka bhero-yemahara square wave: impedance yekufananidza uye chiratidzo chekuvimbika. Panguva ino, kukosha kwekupikisa kunogona kutariswa kunoenderana nehunhu hwetambo.
Shandisa tambo mbiri dzakajairwa dzinoshandiswa nemota mbiri kudzikanganisa kuita mitsara yakamonyoroka, uye iyo impedance inogona kuwanikwa nenzira iri pamusoro inosvika 120Ω. Iyi zvakare ndiyo yekupedzisira kuramba kuramba inokurudzirwa neCAN standard. Saka Iyo haina kuverengerwa zvichienderana neiyo chaiyo mutsara danda maitiro. Ehe, kune tsananguro muiyo ISO 11898-2 standard.
Nei ndichifanira kusarudza 0.25W?
Izvi zvinofanirwa kuverengerwa pamwe nekumwe kutadza mamiriro. Zvose zvinosangana nemotokari ECU inoda kufunga nezvepfupi -circuit kune simba uye pfupi-circuit kusvika pasi, saka tinofanirawo kufunga nezvepfupi pfupi kune magetsi eCAN bhazi. Zvinoenderana nechiyero, isu tinofanirwa kufunga nezve pfupi dunhu kusvika 18V. Tichifunga kuti CANH ipfupi kusvika ku18V, ikozvino ichayerera kuCanl kuburikidza nekuguma kwekudzivirira, uye nekuda kwesimba re 120Ω resistor is 50mA * 50mA * 120Ω = 0.3W. Tichifunga nezvekudzikiswa kwehuwandu pakupisa kwakanyanya, simba reiyo terminal kuramba ndeye 0.5W.
Nguva yekutumira: Jul-08-2023
