CAN tsheb npav (Controller Area Network) yog ib qho kev ntseeg siab, tiag tiag -lub sij hawm sib txuas lus raws tu qauv siv nyob rau hauv tsheb, industrial automation, thiab lwm yam. Nws ua rau ntau lub microcontrollers thiab cov khoom siv sib txuas lus nrog ib leeg yam tsis muaj lub khoos phis tawj tswj hwm.
Lub tsheb npav CAN yog thawj zaug tsim los ntawm Bosch hauv Tebchaws Yelemees thaum ntxov 1980s rau hauv - tsheb sib txuas lus. Xyoo 1993, ISO tau tshaj tawm CAN tsheb npav tus qauv (ISO 11898), suav nrog ob qho tib si cov ntaub ntawv txuas txheej txheej txheem thiab txheej txheej txheej txheej txheej txheej.
TS EN ISO 11898-1: Txhais cov ntaub ntawv txuas txheej txheej txheej txheem
ISO 11898-2: Txhais cov txheej txheem txheej txheem lub cev rau siab -CAN tsheb npav ceev, txhawb nqa cov ntaub ntawv siab tshaj plaws ntawm 1 Mbps. Nws pom zoo kom muaj linear topology thiab tsim nyog rau cov ntawv thov nrog lub sijhawm tiag tiag.
ISO 11898-3: Txhais cov txheej txheem txheej txheem lub cev rau qis-CAN tsheb npav ceev, nrog cov ntaub ntawv hloov pauv ntawm 40 Kbps txog 125 Kbps. Kuj tseem hu ua kev ua txhaum-kev ua siab ntev CAN, nws ua rau muaj kev sib txuas lus txuas ntxiv txawm tias ib txoj kab teeb liab tsis ua haujlwm, ua rau nws tsim nyog rau cov ntawv thov nrog cov kev xav tau qis dua lub sijhawm.
CAN Bus Nta:
Multi-Master Control:Lub tsheb npav CAN txhawb nqa ntau lub tswv yim sib koom ua ke ntawm lub network yam tsis muaj tus tswv- qhev hierarchy. Cov khoom siv sib txuas lus raws li cov lus tseem ceeb.
Differential Signaling:Siv ob lub xov hlau (CAN_H thiab CAN_L) txhawm rau xa cov teeb liab sib txawv, txhim kho kev tiv thaiv hluav taws xob cuam tshuam.
Tsis yog-Kev txiav txim siab tsis zoo:Thaum lub sij hawm xa xov, yog tias muaj kev sib tsoo, qhov siab dua - cov lus tseem ceeb yog xa mus thaum qis dua - cov lus tseem ceeb tos kom rov xa rov qab.
Kev Tshawb Fawb thiab Kev Ua Haujlwm:Cov yam ntxwv muaj peev xwm tshawb pom qhov ua yuam kev thiab tuav tau, suav nrog CRC checksum pov thawj thiab kev kuaj xyuas me ntsis yuam kev.
Flexible Topology:Txhawb ntau lub network topologies xws li linear, hnub qub, ntoo, thiab lub nplhaib configurations.
Ntawm lub npav CAN, qhov sib txawv ntawm qhov sib txawv ntawm cov logic "0" thiab "1" ua kom muaj kev sib txuas lus zoo. Xa mus rau cov lus piav qhia saum toj no, ob theem logic ntawm lub npav CAN yog:
Qhov loj me: 0
Recessive: 1
Cov theem teeb liab ntawm CAN tsheb npav qhia kab - thiab cov yam ntxwv. Cov kab no- thiab kev coj cwj pwm tsim lub hauv paus rau kev txiav txim rau lub npav CAN kev txiav txim siab: qib tseem ceeb (0) ib txwm npog cov qib recessive (1). Yog tias cov nodes sib txawv ib txhij xa cov qib tseem ceeb thiab rov ua dua, lub npav nthuav tawm qhov tseem ceeb (0). Tsuas yog thaum tag nrho cov nodes kis tau tus nqi recessive (1) lub tsheb npav qhia txog lub xeev recessive.
Qib Dominant:Logic 0. Nyob rau hauv siab -Speed CAN, tus CAN_H tus pin tsav mus rau 5V, thaum lub CAN_L tus pin tsav mus rau 0V.
Submissive Level:Logic 1. Tsis yog tus pin yog tsav.
High-Speed CAN thiab qis-Speed CAN tsheb npav txawv ntawm lawv lub cev txheej txheej teeb liab txhais:
Siab -CAN ceev txhais tau tias lub logic "1" thaum CANH thiab CANL voltages sib npaug (CANH=CANL=2.5V), thiab logic "0" thaum qhov sib txawv ntawm CANH thiab CANL yog 2V (CANH=3.5V, CANL=1.5V).
Hauv qhov sib txawv -mode voltage range (-12V txog 12V), high-speed CAN transceiver txhais qhov sib txawv voltage ntau dua 0.9V ntawm CANH thiab CANL raws li lub xeev tseem ceeb, thiab qhov sib txawv tsawg dua 0.5V raws li lub xeev recessive. Internal hysteresis Circuit Court txo kev cuam tshuam.
Tsawg- nrawm CAN txhais lub logic "1" thaum qhov sib txawv ntawm CANH thiab CANL yog 5V (CANH=0V, CANL=5V), thiab logic "0" thaum qhov sib txawv voltage yog 2.2V (CANH=3.6V, CANL=1.4V).
Siab -Speed CAN Signal Levels (ISO 11898-2)
Tsawg-Speed CAN theem teeb liab (ISO 11898-3)
CAN Error Handling Mechanisms:
CRC yuam kev:Tshawb xyuas qhov yuam kev los ntawm kev suav thiab txheeb xyuas tus nqi CRC ntawm cov ntaub ntawv.
Me ntsis yuam kev:Txheeb xyuas qhov ua yuam kev me me hauv lub sijhawm tiag tiag - lub sijhawm sib kis.
Qhov yuam kev Frames:Xa yuam kev thav ntawv thov rov xa rov qab thaum kuaj pom qhov ua yuam kev.
Cov ntsiab lus
Lub tsheb npav CAN tau txais kev pom zoo thoob plaws ntau qhov chaw vim nws txoj kev ntseeg siab, kev ua tau zoo tiag tiag - lub sijhawm ua haujlwm, thiab hloov tau yooj yim. Raws li kev siv thev naus laus zis, CAN tsheb npav txuas ntxiv hloov zuj zus ntxiv- piv txwv li, CAN FD (Cov Ntaub Ntawv Yooj Yim-Rate) tus qauv tso tawm los ntawm BOSCH ntxiv txhim kho cov ntaub ntawv xa mus kom tau raws li qhov xav tau ntawm cov ntawv thov uas xav tau ntau dua bandwidth.