CAN BUS: What is it and what does it do?

[@davidmccaughan2710]

I'll never use 90% of the info on these Thursday videos (NA), but I really enjoy learning , watching, and geeking out! Thanks!

[@1987RX7TII]

This is really cool information. Thanks for taking something I’ve heard several times before (CANBUS) and breaking it down in such and understandable way. I’ve always told myself I would always try to stay current on technology, but now in my 30s, I’m realizing that’s going to take lot more effort than I realized as I’m just now starting to understand the simple old electro-mechanical systems using relays, 0-5V signal wires, Boolean logic, and PWM. One day if I can ever afford to fund it, id love to buy a turnkey V8 ND from you guys as a really appreciate just how deep you guys had to go to pull it off. FM is such a great company and I’m loving my nearly decade old FM turbo setup on my 91 NA.

[@michaelcohen5076]

Will you publish your reverse engineering of the ND control modules ecm, etc.

[@gedavids84]

Thank you so much for this video. I thought CAN messages were standardized like an OBD-II, I had no idea that each manufacturer effectively made up their own. I'm doing an LS swap into my S10 and I want to make the stock dash work, this video has been invaluable. Especially calling out the GM spec document. I was worried that would be hundreds or thousands of dollars, but I found it on the internet for $60. Totally worth it for what I want to do.

[@FlyinMiataVideo]

Glad it was helpful! A lot of people do have the same impression you did. That document is a big hefty unit but it's basically three parts, and you'll figure your way around it. Good luck with the swap!

[@gedavids84]

@@FlyinMiataVideo Yeah, I work in IT for my day job. Boring technical documents are my everyday. :P What software and can device are you using here to read the CAN network? It looks like it works really well and is easy to read.

[@FlyinMiataVideo]

@@gedavids84 The hardware is a Peak PCAN interface, which is not at the low end of the market. There are lots of DIY options that can be put together, especially if you're a *nix kinda person. But the Peak unit works well. Software is the free PCAN View for logging and sending messages, the not-free PCAN Explorer for the graphing. There are definitely some open source options out there for the latter, such as CANplot. I've seen one where it highlights values that are changing which makes it much easier to figure out which value is affected by whatever you're doing, but I don't remember the name offhand. SavvyCAN, maybe?

[@gedavids84]

@@FlyinMiataVideo Thanks for the info. I'll check out the open source tools you suggest, but I'll keep the PCAN stuff in mind. Sure I might be able to brute force my way through a cheap solution, but sometimes it's way easier to just buy the thing that works and get on with the rest of the project. :)

[@seekingalpha1651]

Interesting. I used to program in assembly, compile and program 8086 microcontrollers. That changing of a byte for the blinker is what powers the actual light. As it goes up and down more pins become 1, have positive voltage. That's how a byte actually does something. Wipers work another way by "strobing" the bits to move a digital motor, if I remember correctly. It is truly fascinating how these bytes, which are seen in hexadecimal, when used in binary are made to make physical things happen. Nice video. Without being able to reprogram the code receiving the information. The control logic are control feedback loops. I am also an engineer with controls experience, there isn't much more than listening one can do. There is math to these loops. They are proprietary. That's the tech they are selling. Key variables in the feedback loop are empirically determined. That is by testing. Control loops anyone can learn, the maths. But key variables are gathered with data. The control program is constantly reading the A/F Sensor and triming feul for example to tune the engine and calculating O2 volumes and adjusting combustion temps. Thanks. I can buy a raspberry pi from sparkfun and goof around with my controls. Too, you said "check bit" so I guess these are serial data streams coming off a transmission pin.

[@FlyinMiataVideo]

It’s a well documented and defined digital communication standard. Think more TCP/IP than analog control loops.

[@seekingalpha1651]

@@FlyinMiataVideo I guess my comment was an observation of the blinker you showed. The hexadecimal went from 00 to FF. So, it looked. That is how a light is made to go smoothly from dark to light and back to dark again. So, the value stored in an address was made to change--over the CAN in real time. The coding is done to do just that. Coding first picks an address and then puts a value in it. Some of the other bytes most open "gates" to let a data/address pair through. I will figure this out. I have some ideas. The only interesting thing would be to put controller and receiver together across the CAN, so long as your controller addressing only opened you gates. This would be better than running secondary wires. For one could put a switch in the box to the left of the wheel to turn fog lights on/off and whatever and use the CAN network to connect a receiver, much like the "fan controller" to receiver to values from the controller, "the switch".

[@jakegreen3852]

All I needed to know is that it's 2006 and up. Thank you 😊

[@brendanmccabe8769]

Very interesting and useful video. Obviously most of this content was centred on the ND model, I’m interested in the NC which I’m assuming, based on its release era, is much simpler but still CAN enabled. Do you have any information or areas you could point me (us) to for information on the NC models. I’m particularly interested in how many networks are involved and which devices hook up to each but any additional information would be interesting. I’m currently trying to think up a cool/fun project to implement on the car so I can’t be specific but a good starting point would be to know which devices are talking CAN and which can talk to each other.

[@FlyinMiataVideo]

The NC has far less information on the CAN chatter than the ND because it's basically a 2003 platform. The factory wiring diagram shows what's on it. It's primarily used for stability control (DSC talking to ABS and the PCM along with associated sensors like steering angle), information sent to the instrument cluster and some PRHT coordination.

[@richarddietzen3137]

I would never need CANBUS data, but, so your saying an ECU tune (like for a turbo) doesn’t affect the car’s response to engine/exhaust data from the ECU or other data sources? I really appreciate the depth of Flying Miata research, communication and product support.

[@FlyinMiataVideo]

Can't see how it would affect it. Tuning a factory ECU isn't really changing how it works, it's just changing the tables so it has different targets to work towards.

[@arcmode]

Is it worth adding a iDataLink Maestro RR to an NC with a Sony head unit? what info would I get? do I get tire pressure or anything at all?

[@FlyinMiataVideo]

We're not familiar with that unit but you can find the PID list for the Banks one here for a '13 docs.bankspower.com/bids/files/PID_2013_Mazda_MX-5_Miata_Club_2_DOT_0L_V_317_E.html

[@whoisstevencox]

I have a GT with Fox coilovers lowered to yalls suggested specs and have noticed a very weird steering issue ever since. The steering wheel will hold/gently lock at any given angle if I hold the wheel still. If I'm going around a long sweeping turn and I hold the wheel at some angle, I can completely let go and the car will hold that turn until I straighten with a little bit of force. Once I break that hold, then the wheel can turn and adjust with normal input force from me, but it makes making small adjustments and going in a straight line nearly impossible. I took it to a Mazda dealership and they have no idea what is going on. Have yall heard of this issue? Could the sensors at the wheels be confusing the CAN sending whacky signals that the electronic power steering module is getting confused from?

[@FlyinMiataVideo]

The rack reads wheel speed, lateral g and yaw from the CAN bus to determine the "neutral" steering position. This does take a little bit of driving to figure out, and on a GT it will default to the absolute position read off a position sensor on the column until this is done. All the decisions about assist come from inside the rack controller that's integrated with the motor. This sounds like a lack of caster. We'd check the alignment again, paying particular attention to the rack being centered as an off-center rack might lead to some discrepancy between the absolute sensor on the column and the calculated neutral position. We'd also check to see if there are any stored codes - there are about a half dozen that the rack will throw if it's upset about something and not all of them will illuminate a light. Not all OBD-II scanners will read these module-specific codes, but Mazda can. So can Ford, and so you can you using a program called Forscan.

[@whoisstevencox]

I thought it was caster related as well but then realized it felt very notchy and controlled by something electronic. The issue comes and goes, sometimes without happening during a 20 minutes drive, sometimes it happens an entire hour long drive. I can also feel that same notchy feeling at idle by gently and slowly turning the wheel. You can feel the power steering suddenly kick on or release the wheel and let it turn easier then off, causing it to sort of vibrate in a notched pattern. That same sensation of it notching and fighting to release is what I feel when I'm driving but much stronger. Almost like it's fighting the caster in the alignment. I'll try checking out Forscan and getting another alignment done and see what we can find. Thanks for the response! Yall are more helpful than Mazda has been already.

[@FlyinMiataVideo]

@@whoisstevencox Did you have a front sway bar installed? Check the three connectors at the rack motor/controller, including the one on the pinion. That second description sounds like a bad connection. The rack is sometimes removed/molested during a front sway installation.

[@whoisstevencox]

@@FlyinMiataVideo I did install a front sway bar and the reinforcement brackets. I'm putting on new wheels this week so I'll be sure to check that stuff when I have it in the air! Thank you!

[@After0522]

hello, All. I just purchased a 2001 Miata. As an electrical engineer, I have some background of how the CANBUS work. Also, I was able to program some Arduino projects so I could read the messages. HOWEVER, as mentioned in the video, the 'dictionary' is what I am looking for now before I can do some interesting projects on this Miata. I did some research but there seemed be limited/mixed information. I also learnt that CANBUS IDs are different in different gen. of Miata? Anybody know where I can find the 'dictionary' for NB Miatas? For example, what ID should I look for the engine RPM? Which byte for that ID? Thanks in advance! Zoom~ Zoom~

[@FlyinMiataVideo]

Manufacturers tend to use the same definitions across all of their models, so if you've figured out a Mazda3 you've probably got a good start on a Miata. Not all messages apply to all vehicles, of course - hybrid vehicles have a lot more going on than pure ICE. To our knowledge, CAN was not used in the NA and NB Miatas, and was used sparingly in the NC - mostly just to communicate between the PCM and the instrument cluster. The lack of twisted pairs in the wiring diagrams for the NA and NB seems to back that up. The data you're reading is probably not on CAN, I think the 2001 used the ISO9141-2 protocol. We haven't done much investigation into the communication on that specific platform.

[@israelalvarado1701]

the original project of CAN bus v8 is with gm e67 ecm, what about e99 ecm?

[@FlyinMiataVideo]

GM uses an internal standard for CAN messages so they should be the same. Note that being able to read and modify CAN messages is not the same as tuning an ECM.

[@israelalvarado1701]

@@FlyinMiataVideo so... I can use the same CAN Gateway module to swap an LT5 instead of LS3?

[@FlyinMiataVideo]

@@israelalvarado1701 You should be able to, yes. The LT5 will likely have more information being broadcast but all the information being provided by the LS3 should still be there.

[@suika301]

Unrelated question, when will the Fox coilovers be back in stock for the ND

[@FlyinMiataVideo]

The best way to get this sort of information is to contact our customer service team as that have the most up-to-date into. Right now, Fox is telling us early September for delivery.

[@Theadventurelane]

I have a question off topic, have you ever used MAZDA TWEAKS for the infotainment system ?

[@FlyinMiataVideo]

We have done a bit of playing around with the infotainment but stopped once SSH access was revoked. Never looked into MAZDA TWEAKS.

[@Theadventurelane]

@@FlyinMiataVideo thank you for your reply. And i have a 2018 club with apple car play and i have the version 70.00.352 NA N is the access revoked for all versions ? Thank you again

[@FlyinMiataVideo]

@@Theadventurelane SSH access is a way to log into the infotainement system. You can also use prepared SD cards to make changes, but we've never played with it. That's the method you'll have to use, it's more common than SSH. This is not something we've spent any time on.

[@Theadventurelane]

@@FlyinMiataVideo okay thank you