An Introduction to the CAN Bus: How to Programmatically Control a Car • Hacker News Board

Re: An Introduction to the CAN Bus: How to Programmatically Control a Car

#51

Post by luckydude » Tue, Jun 06, 2017, 8:44 PM UTC

So this not that thrilling but my BMW r1200gs has this bus. I dropped the bike recently and killed one of the turn signals. Canbus lit up saying you have a light out. I fixed the turn signal and it still lit up. I thought I needed to reset it or something.

Turns out I killed the headlight in the drop as well. Without the canbus it would have been months before I would have caught that. I thought it was a BMW over-the-top thing but it actually helped me, it was the daylight running headlight that went out. Good to have that one.

Like I said, not thrilling, not programming, but an upvote for the Canbus.

Re: An Introduction to the CAN Bus: How to Programmatically Control a Car

#52

Post by sokoloff » Tue, Jun 06, 2017, 8:44 PM UTC

weberc2 wrote: post #50

spotman wrote: post #37

CAN Bus is great. I highly recommend reading the CAN Open Spec if your going to be implementing new systems using CAN Bus. https://en.wikipedia.org/wiki/CANopen Many more things besides auto's use CAN. One of my current projects involves exercise equipment that internally speaks CAN Bus. There is great support in Arduino for interfacing with stuff like this.

Isn't CAN very limited in terms of bandwidth? Seems like this wouldn't be appropriate for most applications of interest? When I worked at an equipment manufacturer, everyone was very concerned about accidentally saturating the bus, and we even had a very compact data representation.

500kbps is typical. That's not super-slow, IMO.

Re: An Introduction to the CAN Bus: How to Programmatically Control a Car

#53

Post by Matheus28 » Tue, Jun 06, 2017, 8:45 PM UTC

maxxxxx wrote: post #3

Does anybody know where the trend is going? Do electric cars have standard buses or are they moving to proprietary (and not published) buses?

Yes, Tesla still uses CAN buses. It has 6 buses if I remember correctly.

Re: An Introduction to the CAN Bus: How to Programmatically Control a Car

#54

Post by chiph » Tue, Jun 06, 2017, 8:45 PM UTC

Declanomous wrote: post #46

chiph wrote: post #43

Earlier quoted context omitted.

At a previous job I interfaced with hospital beds that used CAN Bus internally. Turns out that Ford had laid off a lot of engineers a few years ago and the firm hired some of them to design the next generation bed. They knew CAN Bus, so they used it to control the hydraulics, pneumatics, lift motors, strain gauges, and so on.

Man, that's really cool. I'm really looking forward to all of this CAN Bus stuff being EOL in 10-25 years so I can get my hands on it at tinker with it.

There are used beds that use the bus available on eBay and other auction sites. Be aware that it's only on their high-end beds, If you're looking to bid on one, know that they weigh over 600 lbs and need wide doorways (ask me how I know..) Current prices are $900 and up, and often don't come with the inflatable mattresses (hospital may not want the potential biohazard liability, so disposes of it first).

Re: An Introduction to the CAN Bus: How to Programmatically Control a Car

#55

Post by DiJu519 » Tue, Jun 06, 2017, 8:46 PM UTC

Ya know Ford supports all this in the open right

http://openxcplatform.com/

Re: An Introduction to the CAN Bus: How to Programmatically Control a Car

#56

Post by throwaway899 » Tue, Jun 06, 2017, 8:48 PM UTC

kensai wrote: post #48

In the last picture in the blog post, does he really run a script for Celsius? Because at 67 degrees you are certainly dead! :D

Why would you be dead at 67 celsius..? I go in to a room near 100 Celsius every weekend (also known as sauna)

Re: An Introduction to the CAN Bus: How to Programmatically Control a Car

#57

Post by amenod » Tue, Jun 06, 2017, 8:48 PM UTC

exabrial wrote: post #35

donjoe wrote: post #26

I wonder - did you try to ask Ford for a .dbc-file containing the desired IDs to query? It's worth a shot plus those files save a ton of time.

IIRC, US Law mandates a bunch of CAN IDs for general engine diagnostics like fuel flow, o2 sensors, etc. The rest of the CAN IDs are unique to every manufacturer. GM (for instance) Tech Scan tool knows these CAN IDs. Independent 3rd parties can develop a simliar tool and license the CAN IDs from GM for a hefty fee. I imagine Ford has the same service available.

Would it be possible to feed CAN IDs to Tech Scan tool sequentially and thus decode their meaning? Would it be legal?

Re: An Introduction to the CAN Bus: How to Programmatically Control a Car

#58

Post by ingenieroariel » Tue, Jun 06, 2017, 8:51 PM UTC

kensai wrote: post #48

In the last picture in the blog post, does he really run a script for Celsius? Because at 67 degrees you are certainly dead! :D

I was using F, good catch :)

Re: An Introduction to the CAN Bus: How to Programmatically Control a Car

#59

Post by ajford » Tue, Jun 06, 2017, 8:51 PM UTC

zkms wrote: post #30

icebraining wrote: post #24

Earlier quoted context omitted.

You can't. It's not that hard to make a controller that lets you physically turn the wheel using an RC remote, it's just a matter of attaching a servo to some cords pulling it (there's a guide on Instructables). The reason terrorists don't do that has nothing to do with being hard.

> It's not that hard to make a controller that lets you physically turn the wheel using an RC remote > The reason terrorists don't do that has nothing to do with being hard. This is false. Remote-controlled VBIEDs are absolutely a thing

Um.... reread that comment. He's saying that VBIEDs are totally possible, and that this example of CAN Bus control isn't going to cause a new era of terrorist actions, because it's just as easy to do it with servos and/or ropes and cables.

What he's saying is not false.

Re: An Introduction to the CAN Bus: How to Programmatically Control a Car

#60

Post by fnordfnordfnord » Tue, Jun 06, 2017, 8:56 PM UTC

bsder wrote: post #18

eloff wrote: post #10

Can you imagine the havok when terrorists figure out they can program cars to hunt and kill pedestrians in crowded spaces? Currently the terrorist needs to drive the vehicle, which makes it a suicide mission. How much more deadly would it be if it was reduced to just the cost of the car and a low chance of getting caught? How can we defend against this?

The way we always defend a network--authentication and encryption. If your CAN nodes are all authenticated to one another, it's a lot harder to hack. The downside is that they're a lot harder to hack, in the good sense of the term.

>If your CAN nodes are all authenticated to one another, it's a lot harder to hack.

The problem with that is now how do you do the legitimate good things you want to do? Of course, these kinds of locks usually have their own problems and usually only keep "honest folks" out.

John Deere would love it though.