SparkFun According to Pete #55 - How CAN BUS Works

It’s the first Monday in May, and that means… new ATP! Today, I’m going to talk about CAN bus. What’s that? “CAN” stands for “Controller Area Network”, and it’s a twisted-pair, multi-master data bus that’s really resilient against noise, along with having framing, error detection and lossless bus arbitration built into its spec. If you’re looking for a short-range (40 meters) data bus with good throughput (1Mb/s) and good noise immunity, CAN bus has a lot to offer. So much so that it’s used in automotive and industrial applications where nothing else will work.
In today’s video, I dig into the CAN bus esoterica to give you a look into how it does what it does. This video also tee’s me up for the next ATP, which is a natural extension to the CAN bus topic: OBD2. (spoiler: CAN bus is sort of a subset of OBD2).

[@chrisgonzales]

Perfect timing on this video working on a project myself and will be attempting to read off of CAN BUS of my '16 Ford Mustang GT

[@KeithCooper-Albuquerque]

Excellent video Pete! I am new to the CAN-BUS: This really helped me a whole bunch! I can't wait for your follow-up video!

[@NyxOne81]

Wonderful presentation!!!

[@travelsGivesPeace]

Love your tutorials Pete! You explain such complex stuff in very simple and joyful way. Thanks mate! very helpful ;)

[@TanmayPanchal46]

Amazing job. The way you presented keeps people attached. Thank you.

[@harshwardhanwadikar793]

You are a great teacher. Have to be an awesome guy

[@protuningaustralia6795]

I really enjoyed that, both educational and funny. The humour keeps you interested in something that can become somewhat brain draining after awhile. Top job.

[@ahaha731]

Thank you. It easy to understand.

[@Psi105]

Good timing, im being pressured to get onto an overdue CAN bus upgrade to an existing product. This video answered a lot of my questions about how CAN bus actually works

[@snakeoilification]

Perfect. Glad I could help.

[@krsnadaassa5016]

this video was absolute fun to watch and easy to understand kudos

[@33798]

Am a technician when ever there's a no communication with any of the module in cars, I observed the fault code of No comm with particular module is showing up in adjacent module data. The stuff transceiver,nodes, arbitration all are sound that now to me. Thanks man for the briefing CAN bus network, loving this so much ❤️

[@devil2005iscool]

There isnt 120ohms between them, there is 60ohms between the CAN H and CAN L with two 120ohms in parallel = 60ohms, this is useful to know when diagnosing an obd port as you can measure the resitance between pin 6 and 14 and if you have 120ohms then your bus is missing a resistor meaning a module may be shorted to ground. :]

[@lllllltar]

Thanks for this video!

[@ekanugraha7024]

Really love this video. Great job

[@KRKUN]

Bro u make electronic studies more funny, i really appreciate that thx :)

[@1978jra]

CAN-bus is called sometimes as "känni-väylä" here in Finland (literally drunk(en)-bus) because of pronunciation. Nice video! I was going to make a project where I would have needed to know isobus (ISO 11783), used in agricultural machines, but that did get barely started.... Unfortunately.

[@MrDawen1997]

Could you make video About transfer function in complex filters like for low high and bandwith?

[@electron-1979]

Thanks Pete, from Pete

[@ahmedzain6270]

very good illustration i hope to see some code implementation even as a sudo code thank you

[@davecooper5951]

I think it would be better if you gave some examples - eg Let's turn on the headlights....now let's see how the data changes on the bus. Then you could get deeper into the detail.

[@JohnnyBorg90]

To bad i didn't had a teacher like this in school. Really good explanation, Thanks

[@funkynerd_com]

Pfft.. OBD2. I only watched this to learn how nodes know not to stomp on another nodes transmission. Which you answered. Thank you!

[@LordPhobos6502]

5:40 Ppl who like network wossnames are freaky, but we love em. They happily deal with the freaky so we can get back to our silicon & soldering irons ❤

[@UpcycleElectronics]

Wow that seems complicated. As a former motorhead prior to disability, your car should be direct injected, the duty cycle of those injectors would be interesting to know IMO. -Jake

[@psy0rz]

i also read the ISO specs: they are indeed a mess :)

[@jasmany19]

It turns out that CAN bus is still being used in large 1100 kVA UPSs (Uninterruptible Power Systems) for module communication.

[@richeckert5400]

Great Explanation of Arbitration yet please note examples of actual NODE ID's , the "missing link" not shown: note each NODE is unique by binary address.

[@Build_the_Future]

Can you send something like an encoder down a CAN BUS or is CAN-BUS to slow for something like that.

[@skrame01]

23:45 funny stuff man

[@12around1]

now thats what I call a teacher

[@jonnyestell5708]

I us can a lot in robotics, but have never really understood how it worked so thanks for making it so simple

[@willybee3056]

Oh,, wow,, that brings back memories of school... Grampa would s***,, Now,, what would be neat,, is to have a lab kit for hands on play. Uart a good teacher.. Sorry,, just had to do that...😆

[@jasonrussell6534]

CAN and OBD2 have no direct relation at all until 2008. Some manufacturers (mostly those that use Bosch parts, go figure) have vehicle specific CAN networks that are not publicly documented and a gateway to put the pertinent information in the OBD2 format on the data link appropriate for that generation (k-line for early OBD, CAN for late OBD). I think it's also imperative to make clear CAN is the network transport but the data can be and is free-form with no standards at all in place with regard to ID and data. That's all up to the engineers designing the system.

[@magikben]

Yep. I am guessing he researched this and didn’t actually understand the relationship.

[@arjunremesh1395]

Can you please do a sample working example using Can modules/can boards .Thankyou for Good information .I have heard theory from every where but I didnt see any one doing a tutorial using Can boards .

[@snakeoilification]

Well, the next video is going to be predominantly about OBD2 and connecting to that port and poking around. But have you checked out our hookup guide for the CAN485 board? At least for that hardware, setting up a CAN bus seems a pretty simple exercise. learn.sparkfun.com/tutorials/ast-can485-hookup-guide

[@arjunremesh1395]

Pete Dokter thankyou.what is the maximum distance between a can transmitter and receiver to trasmit successfully .?

[@snakeoilification]

ISO 11898-2 gives you a ballpark figure of 1Mbit/s at 40 meters if you follow all the rules laid out in the spec. But if you're cool breaking rules and shunning norms, it really depends on your data rate, and the two are inversely proportional (also depends on the physical config of the network, but we'll assume two nodes at either end). First figure out how far you want to go, then back out a number for your necessary data rate to achieve that distance, dig? It's less about "how far can it possibly go" and more about "how much are you willing to pay to make it go further?"

[@kresha2621]

Hi. can i power on a car headlights out of car? i have removed full led headlights that are using CANBUS but i'm trying to repair and i want to power on for ex: turn signal, drl etc using a power supply? thanks

[@Mindfuak]

i still need an explanation about r0 and r1

[@martinbankjorgensen]

WOW you’re great! But dame, you talk fast!! I understand all your saying but when some of the stuff are new knowledge I can’t accumulate both the new knowledge AND concentrate to hear what you saying 😅 but I got about 25% of it 🤣

[@DTHRocket]

Where can I buy a CAN cable?

[@vasumadhamala1536]

👏👏👏👏

[@MiaKiesman]

I would think sparkfun would have an ISO subscription so Pete doesn't have to go searching for bootleg documents 😂

[@snakeoilification]

We're pretty big believers in the idea that information should be free. Or, at least, I am.

[@willybee3056]

Pete Dokter Schools are In the business to make money, ,, education is a sideline. .... I have to laugh at the commercials that claim friendship... Just how friendly would they be if you had no money.

[@MiaKiesman]

Pete Dokter Of course, and you guys do an amazing job of that. I just assumed that is was almost required to run an electronics company, but if you don't need to, don't give the bastards your money!

[@LordPhobos6502]

@@snakeoilification I agree... if these things are 'standards', they should be easily available, otherwise ppl with just make sh** up. Roadsigns have the same problem.

[@kuldeeppatil3370]

Suppose we have 2 wire CAN bus. CAN_H and CAN_L if CAN_H fails? Is CAN communication still continue ? or BUS will become off? what will happen? Please ans

[@eddersegura3260]

No, on can hi and can lo if one wire is damaged can data will not flow. You can test resistance on these wires when the bus is dormant and you're looking for 60 ohms. LSFT can will allow for data to travel on a single can wire if one is damaged.

[@717Fang]

If you use a fault-tolerant CAN bus, then it can work over a single wire.

[@TranscendentBen]

I'm 20 minutes in, stopping-and-starting the video to write down notes, as it seems this video has as much info as one can get on the CAN bus without going to those shady websites.

[@bonkyyumena8582]

I like you sir.

[@Product-Prints]

Hey Pete great video thanks! Helped me understand some core principles for a contract position I’m hiring for. You wouldn’t happen to be interested in some freelance work by chance... would you? If its an option lets chat it up! Regardless be well!

[@lasersbee]

The wheels of the bus go round and round.....

[@plageran]

your reading my mind lmao

[@bhavinrathod406]

Can layer 2 with 11 but identifier is sam as canbus 2.0 a

[@jakehealthx]

what are the nodes? Are they modules?

[@hereIam1965]

wizzy wurry things that give orange or red sparks go bang boom wizz wurr

[@upendergoud8240]

Nodes are ECU s

[@mallemang]

you didn't finish the part about arbitration... how nodes are prioritized by their address

[@carlh8256]

Where are your other CANbus vids?

[@AbnormalWrench]

I wouldn't worry about messing with your car. I can speak from experience, they are really robust systems. It is very hard to take out modules.

[@AbnormalWrench]

(and even if you did take out a module, there is no way the techs would know what you did, and they would warranty it)

[@snakeoilification]

Noted, thanks much.

[@AbnormalWrench]

No problem. Dealerships treat modules like magical black boxes. They don't question how they became bad. They assume you're a typical customer that can barely successfully insert the fuel nozzle in the fill hole.

[@allenklingsporn6993]

@@AbnormalWrench Dealerships actually track failures for the OEM's to follow up on. The OEM's contact guys like me at the Tier 1 suppliers that actually design and manufacture these devices. We work on whatever priorities the OEM has, and we work as hard and as fast as we can to make updates to the product lines and implement those lessons learned on new products.

[@plageran]

the can on the bus goes round and round, round and round, round and round. sorry had to get that out lmao XD

[@pepelapew483]

All of this so we can remove a few signal wires ( thin wire ) hum .

[@ovalwingnut]

You're hat is on backwards... just saying

[@testuser4365]

Are you gonna drink your coffee?

[@blackcat-mp7kh]

thanks but lecture would have been more pleasant if you had finished coffee 1st

[@chadkrause6574]

Still unsure how arbitration works. Good video otherwise!

[@OtherDalfite]

Ditch the cringe guy fawkes mask. It has literally NOTHING to do with arduino

[@markmartin5018]

Useless for real world diagnostics

[@allenklingsporn6993]

Only if you're an idiot. How do you think we test and engineer these systems in the first place?