CAN ya bisi irwanya ubusanzwe ni 120 oms.Mubyukuri, mugihe cyo gushushanya, hariho imirongo ibiri 60 ya ohms irwanya umurongo, kandi muri rusange hariho bisi 120Ω kuri bisi.Mubisanzwe, abantu bazi bisi ya CAN ni bike.Abantu bose barabizi.
Hano hari ingaruka eshatu zo kurwanya bisi ya bisi:
1. Kunoza ubushobozi bwo kurwanya interineti, reka ibimenyetso byumuvuduko mwinshi ningufu nke bigenda vuba;
2. Menya neza ko bisi yinjiye vuba muburyo bwihishe, kugirango ingufu za capacitori za parasitike zigende vuba;
3. Kunoza ubwiza bwibimenyetso hanyuma ubishyire kumpande zombi za bisi kugirango ugabanye ingufu zo kwerekana.
1. Kunoza ubushobozi bwo kurwanya
Bisi ya CAN ifite leta ebyiri: "bisobanutse" na "byihishe"."Expressive" igereranya "0 ″," ihishe "igereranya" 1 ″, kandi igenwa na CAN transceiver.Igishushanyo gikurikira nigishushanyo mbonera cyimbere cyimbere ya CAN transceiver, hamwe na bisi ihuza Canh na Canl.
Iyo bisi isobanutse, Q1 y'imbere na Q2 irakinguye, kandi itandukaniro ryumuvuduko hagati yigitereko nigitereko;iyo Q1 na Q2 byaciwe, Canh na Canl biri muburyo bworoshye kandi butandukanye nigitutu cya 0.
Niba nta mutwaro uri muri bisi, agaciro ko kurwanya itandukaniro mugihe cyihishe ni kinini cyane.Imiyoboro ya MOS y'imbere ni leta-irwanya cyane.Kwivanga hanze bisaba gusa imbaraga nkeya cyane kugirango busisi yinjire neza (voltage ntoya yumurongo rusange wa transceiver. 500mv gusa).Muri iki gihe, niba hari intera itandukanye yo kwivanga, hazabaho ihindagurika rigaragara kuri bisi, kandi ntahantu na hamwe izo mpinduka zishobora kubakira, kandi bizashyiraho umwanya ugaragara kuri bisi.
Kubwibyo, kugirango uzamure ubushobozi bwo kurwanya-busa bwa bisi yihishe, irashobora kongera imitwaro itandukanye, kandi agaciro ko guhangana ni ntoya ishoboka kugirango ikumire ingaruka zingufu nyinshi z urusaku.Ariko, kugirango wirinde bisi irenze urugero kugirango yinjire neza, agaciro ko guhangana ntigashobora kuba nto cyane.
2. Menya neza ko winjira vuba muri reta yihishe
Mugihe gisobanutse neza, capacitor ya parasitike ya bisi izishyurwa, kandi izo capacator zigomba gusohoka mugihe zisubiye muri reta yihishe.Niba nta mutwaro wo guhangana ushyizwe hagati ya CANH na Canl, ubushobozi bushobora gusukwa gusa nubudasa butandukanye imbere muri transceiver.Iyi mbogamizi ni nini.Ukurikije ibiranga akayunguruzo ka RC, igihe cyo gusohora kizaba kirekire cyane.Twongeyeho ubushobozi bwa 220pf hagati ya Canh na Canl ya transceiver kugirango igerageze.Igipimo cyimyanya ni 500kbit / s.Imiterere yumurongo irerekanwa mumashusho.Kugabanuka kwiyi miterere ni leta ndende.
Kugirango usohore vuba ubushobozi bwa bisi ya parasitike kandi urebe ko bisi yinjira vuba muri reta yihishe, hagomba gushyirwa imbaraga zo kurwanya imizigo hagati ya CANH na Canl.Nyuma yo kongeramo 60Ω résistoriste, imiterere yumurongo irerekanwa mumashusho.Uhereye ku gishushanyo, igihe cyo gusubira mu buryo bweruye cyaragabanutse kugera kuri 128ns, ibyo bikaba bihwanye nigihe cyo gushiraho cyeruye.
3. Kunoza ubwiza bwibimenyetso
Iyo ikimenyetso kiri hejuru kurwego rwo hejuru rwo guhindura, ingufu zumurongo wikimenyetso zizatanga ibimenyetso byerekana mugihe impedance idahuye;imiterere ya geometrike yumurongo wogukwirakwiza igice cyimihindagurikire, ibiranga umugozi bizahinduka noneho, kandi no gutekereza bizatera gutekereza.Ibyingenzi
Iyo imbaraga zigaragaye, imiterere yumurongo itera gutekereza irarengerwa numwimerere wambere, uzatanga inzogera.
Kurangiza umugozi wa bisi, impinduka zihuse muri impedance zitera ikimenyetso cyingufu zerekana imbaraga, kandi inzogera ikorwa kubimenyetso bya bisi.Niba inzogera nini cyane, bizagira ingaruka kumiterere y'itumanaho.Kurwanya itumanaho hamwe ninzitizi imwe yibiranga insinga irashobora kongerwaho kumpera yumugozi, ishobora gukuramo iki gice cyingufu kandi ikirinda kubyara inzogera.
Abandi bantu bakoze ikizamini gisa (amashusho yandukuwe na njye), igipimo cyumwanya cyari 1MBIT / s, transceiver Canh na Canl bahuza imirongo igera kuri 10m, naho transistor ihuza 120Ω résistor kugirango yizere igihe cyo guhinduka.Nta mutwaro urangiye.Impera yerekana ibimenyetso byanyuma byerekanwe mubishushanyo, kandi ibimenyetso bizamuka bigaragara inzogera.
Niba 120Ω résistor yongewe kumpera yumurongo ugoretse, ibimenyetso byanyuma byerekana neza, kandi inzogera irazimira.
Mubisanzwe, muburyo bugororotse -buri topologiya, impande zombi za kabili nizohereza iherezo no kwakira impera.Kubwibyo, itumanaho rimwe rigomba kongerwaho kumpande zombi za kabili.
Mubikorwa nyabyo byo gusaba, bus ya CAN muri rusange ntabwo ari bus itunganijwe neza.Inshuro nyinshi nuburyo buvanze bwubwoko bwa bisi nubwoko bwinyenyeri.Imiterere isanzwe ya analog CAN bus.
Kuki uhitamo 120Ω?
Inzitizi ni iki?Mubumenyi bwamashanyarazi, inzitizi yibizunguruka mumuzunguruko bakunze kwita impedance.Igice cya impedance ni Ohm, gikunze gukoreshwa na Z, ni nyinshi z = r + i (ωl -1 / (ωc)).By'umwihariko, impedance irashobora kugabanywamo ibice bibiri, kurwanya (ibice nyabyo) no kurwanya amashanyarazi (ibice bifatika).Kurwanya amashanyarazi birimo na capacitance hamwe no kurwanya ibyiyumvo.Umuyoboro uterwa na capacator witwa capacitance, naho umuyaga uterwa na inductance witwa sensory resistance.Inzitizi hano yerekeza ku miterere ya Z.
Ibiranga inzitizi ya kabili irashobora kuboneka mubigeragezo.Ku mpera imwe ya kabili, imashini itanga umurongo wa kare, iyindi mpera ihujwe na résistoriste ishobora guhinduka, kandi ikareba imiterere yumuraba kuri résistance ikoresheje oscilloscope.Hindura ingano yagaciro kokurwanya kugeza igihe ikimenyetso kuri résistance ari inzogera nziza -umurambararo wubusa: guhuza impedance hamwe nuburinganire bwikimenyetso.Muri iki gihe, agaciro ko kurwanya karashobora gufatwa nkaho gahuye nibiranga umugozi.
Koresha insinga ebyiri zisanzwe zikoreshwa nimodoka ebyiri kugirango uzigoreke mumirongo igoramye, kandi impedance irashobora kuboneka muburyo bwavuzwe haruguru bwa 120Ω.Nibindi kandi birwanya kurwanya kurwanya ibyifuzo byasabwe na CAN.Ntabwo rero ibarwa ishingiye kumurongo nyirizina uranga.Nibyo, hari ibisobanuro muri ISO 11898-2 bisanzwe.
Kuki ngomba guhitamo 0.25W?
Ibi bigomba kubarwa hamwe nuburyo bumwe bwo gutsindwa.Imigaragarire yose yimodoka ECU ikeneye gutekereza kugufi -umuzunguruko kububasha na -umuzenguruko muto-hasi, bityo rero tugomba no gutekereza kumuzingo mugufi ugana amashanyarazi ya bisi ya CAN.Ukurikije ibipimo, dukeneye gutekereza kumuzingo mugufi kuri 18V.Dufashe ko CANH ari ngufi kuri 18V, ikigezweho kizatemba kuri Canl binyuze mukurwanya gutumanaho, kandi kubera imbaraga za 120Ω résistoriste ni 50mA * 50mA * 120Ω = 0.3W.Urebye igabanuka ryamafaranga ku bushyuhe bwo hejuru, imbaraga zo guhangana na terminal ni 0.5W.
Igihe cyo kohereza: Jul-05-2023