Yuav ua li cas yog hais tias ob txoj cai ID ID yog tib yam?
Cov koom hauv lub tuam txhab TSIS pub ob node kom muaj tib daim ntawv teev npe hauv tus txheej txheem, tab sis ua li cas yog tias ob qhov ntawm daim ID ID yog tib yam?
Ua ntej txoj kev sim, peb yuav tsum muaj kev to taub meej txog cov qauv ntawm cov lus CIM thiab cov qauv ntawm kev sib tw.
Ua ntej, YOG lus qauv
Qhov txuj ci siab tshaj plaws siv daim npav TUAJ yog qhov V2.0 version. Cov qauv no tseem muab faib ua dua A thiab B. Lawv lub ntsiab qhov txawv yog daim ID cim ntev hauv cheeb tsam hauv tsoom fwv. Ntawm lawv CAN2.0A (cov qauv txheem) yog 11 daim ID, CAN2.0B (nthuav thaij) yog 29 daim ID. Cov lus 1 hauv qab no qhia txog tus qauv hauv tsab ntawv xov xwm:
Cov rooj lus 1 muaj peev txheej lus
| Hom Lub Npe | Theem ntev / ntsis | Kev piav qhia | |
| SOF | 1 | txhais tau tias cov theem pib lub sij hawm pib, thiab tsim los ntawm ib qho tseem ceeb | |
| Kev Tawm Tsam Qib | Txuj num | 12 | Qhia tias qhov tseem ceeb ntawm tus qauv, tsim los ntawm 11 tus ID chaw thiab 1 RTR |
| ncua kablus | 32 | Qhia tias qhov tseem ceeb ntawm cov kab lus, tsim los ntawm 29 ID chaw, 1 ntsis SRR, IDE ncua thiab RTR | |
| Tswj cov theem | 6 | txhais tau hais tias pawg neeg thiab muab cov khoom khaws tseg ntawm cov ntaub ntawv ntev ntawm cov ntaub ntawv ntu | |
| Cov Txheej Txheem Teev Tseg | 0 ~ 8 | cov ntsiab lus ntawm cov ntaub ntawv, tswj theem tswj cov ntaub ntawv ntev | |
| CRC | 16 | xyuas cov kablus hloov ntawm cov qauv, ntawm SOF rau cov ntaub ntawv theem, tag nrho cov ntsiab lus, tsuas yog sau cov khoom | |
| ACK | 2 | lwm qhov ntawm cov lus qhia meej tias qhov no yuav tsum tau txais kom raug | |
| Ncej xaus | 7 | txhais tau hais tias tus ncej kawg | |
Thib ob, txoj ntsiab cai ntawm tsoom fwv
YUAV TSIS TAU KEV PAB THEM NQI YOG TUS NEEG UAS YUAV TSUM TAU LI CAS? Thaum xa cov lus, tus neeg tswj xyuas MOV yuav saib xyuas seb qhov kev caij npav yog tib yam li qhov xa nws los ntawm nws tus kheej. Yog hais tias qhov kev tsis sib haum xeeb tshwm sim hauv daim tshev ID, kev sib tw yuav tshwm sim. Yog tias nws tshwm sim hauv lwm cheeb tsam, qhov yuam kev muaj qhov teeb meem yuav raug ua.
Cov nram no yog lub ntsiab lus tseem ceeb. Yuav ua li cas yog hais tias ob txoj cai ntawm ID ID yog tib yam? Peb pib qhov kev sim ua nrog ob daim khov nabHCR thiab ib tug Canscope. Daim MUAJ CAI sim ua tus txheej txheem ntawm CAN xa tuaj thiab tau txais cov lus, thiab CANScope ua qhov kev sib txuas lus, raws li qhia hauv daim duab 2.
Fig.2 sim siv Platform
Qhov thib peb, sim ib qho "Daim cim ID yog tib yam tab sis cov ntaub ntawv sib txawv"
Ib daim MUAJ CAI yog siv xa ib daim duab nrog daim ID 000H rau 01020304050607H thiab lwm daim CAN card xa ib daim phiaj xwm nrog daim ntawv 000H rau 02020304050607H. Cov ntaub ntawv uas CANSCOP tau mloog rau yog tshwm nyob hauv daim duab 3. Nws tuaj yeem pom tias muaj ntau cov ntaub ntawv sau yuam kev.
Fig.3 Cov ntaub ntawv sau teb sau rau hauv
Vim li cas qhov no thiaj li? Peb tau txais thawj lub suab sib txuas sib npaug ntawm ob daim card CAN daim ntawv sib txuas lus, raws li pom hauv daim duab 4. Vim tias ob lo lus sib txuas lus yog ib qho qauv ntaub ntawv thiab txhua thav duab muaj 8 bytes ntawm cov ntaub ntawv, cov ntawv ntaws sib thooj rau ob ntu ntawm cov pob ntawv raws nraim tib yam hauv daim ID cim, RTR, IDE, R0, thiab DLC ntu. Yog li no, lub luag hauj lwm ntawm kev sib cav yog tsis muaj txiaj ntsim thiab ob qho tib si nos yog lawv tus kheej ua qhov muaj feem thib thiab xa cov ntaub ntawv mus ntxiv.
Tam sim no peb tsom rau ntawm cov ntaub ntawv ntu, thawj cov ntaub ntawv byte yog tib yam, muaj 00H; cov ntaub ntawv thib ob byte yog txawv, ntsig txog 01H, 02H. Cov xib xub hauv daim duab 5 qhia tau tias qhov logic ntawm cov khoom coj sib txawv yog 0 thiab 1 ntsig txog. Yav dhau los peb tau hais tias qhov CAN ntawm yuav los xyuas seb lub tsheb npav puas zoo ib yam li qhov nws tau xa thaum xa cov lus. Yog hais tias lub inconsistency tshwm sim hauv cheeb tsam uas tsis yog kev txiav txim siab, qhov yuam kev coj tau txhais, yog li yog tias ob lub thav ntawv xa mus rau lub npav rau tib lub sijhawm B tias qhov teeb meem yuav tsum tshwm sim. Vim hais tias qhov kev xa me ntsis tuaj yeem ua rau lub hauv paus xa 6 qhov khoom siv uas ua txhaum cov cai ntawm kev ua txhaum (qhov yuam kev ua haujlwm raug rhuav tshem ntawm cov ntaub ntawv), cov ntaub ntawv teb sau yuam kev tshwm sim, raws li muaj nyob hauv daim duab. 3.
Fig.5 Cov ntaub ntawv teb tsis sib haum
Plaub, sim ob "tib cov ntaub ntawv nrog tib tus ID"
Tib lub sijhawm, siv ob daim khoj xa daim ntawv TSIS xa nws daim ID yog 000H rau 01020304050607H, thiab CANScope kev sib txuas lus. Ua ntej tshaj plaws, peb tsis tuaj yeem tshawb xyuas qhov "kev caij tsheb npav" uas ua rau CANScope ua haujlwm hauv hom suab nkaus xwb. Cov kev sim tau tshwm sim nyob rau hauv Xya 6, thiab cov lus tshaj tawm yog cov hom tsis yog.
Daim duab 6 ntawm qhov teeb meem
Vim li cas qhov no tshwm sim? Lub node xa cov lus yuav xa ob cov khoom noj khoom haus rau hauv ACK ntu. Yog hais tias theem kev xub thawj tau txais thaum lub sij hawm thawj zaug, tus ncej raug txiav txim siab kom raug txais. Vim hais tias ob tug neeg txiav txim siab xav tias lawv tau txais qhov kev sib hais haum thaum lawv muaj qhov kev hloov tib qhov kev sib tw, lawv tos ib lo lus teb hauv ACK ntu, tiam sis tsuas muaj ob lub pob hauv lub network. Yog li, tsis muaj ib qho lus teb tau txais hauv ACK ntu, thiab muaj qhov yuam kev ntawm qhov kev txiav txim. Tsuas hais lus, qhov teeb meem no zoo li qhov tseeb tias tsuas yog ib qho ntawm lub npav yuav tsis xa cov ntaub ntawv. Daim duab 7 qhia tau hais tias lub suab yeem sib piv thaum tsis muaj lus teb rau ntawm ACK ntu.
Daim duab 7 ACK Reply
Peb txheeb xyuas lub tsheb npav thiab pib qhov kev sim dua (ntawm lub sijhawm no muaj 3 pob nyob hauv npav). Nyob rau lub sij hawm no, raws li pom hauv daim duab. 8, cov ntaub ntawv npav muab xa tawm thiab tau txais txhua zaus.
Fig.8 Pib BUS Teb
Daim Summary: Thaum ob pob hlav xa cov ntawv nrog tib tus ID thiab cov ntaub ntawv tib lub sij hawm, cov ntaub ntawv teb padding yuam kev tshwm sim. Thaum ob pob hlav xa cov ntawv nrog tib tus ID thiab tib cov ntaub ntawv, tsis muaj qhov yuam kev tshwm sim yog tias muaj lwm cov ntshav. Lwm cov voj cev nrog cov lus teb yuam kev. Yog li, peb yuav tsum zam qhov teeb meem qub hauv daim ntu ID thaum tsim qhov caij tsheb npav.