openinverter forum

Hi,

One topic that always seems to be big and scary in the EV conversion world is Can bus. Since I've discovered the Open Inverter project, I have learned that it's not as scary as people make out, but there is still a lot to learn and when converting a modern vehicle there are many potential concerns.

I am aware that it's possible to capture CAN bus messages from a working vehicle, to allow some basic emulation of what the rest of the vehicle expects from an ICE engine, gearbox, or other components, but there would be a concern about things you can't test, such as a crash sensor being set off, etc.

Additionally, if CAN capture isn't possible, say where the donor vehicle isn't running, how easy is it to find the relevant information about the CAN messages, to allow the vehicle function as expected?

It would be great if there was a Wiki with known codes for particular vehicles, and common OEM components.

Jamie

Every manufacturer has their own stuff, unfortunately. So some digging is definitely needed. There is J1939 standard for trying to line up known data with unknown data - you can ask 'throttle position please' and it responds, just try to sample one thing at a time and look for things which move in the same manner...
Things like actuating the brake pedal, or throttle make things easy to find with good software.
Most cars the powertrain control is separate from something like air bags, etc, so its hard to do something really bad on accident. But in terms of cutoffs, you should probably implementing your own as well.

Also, people who are figuring this stuff out do not give it away for the most part, because of the time and money investment involved. (Hint: Thousands of dollars, and hundreds of hours).

-Matt

The inevitable travel down the rabbit hole has begun. It seems that each manufacturer has DBC files to define what each CAN message means, to put them in a more human readable format. There seems to be a fair bit of work out there to reverse engineer CAN messages to build the DBC files.

George Hotz's company comma.ai, who is developing an open alternative to autopilot, has a project going to do just that, and they have a GitHub repository of what they've discovered so far - https://github.com/commaai/opendbc

It would be great to contribute data to it or to build something similar to suit Open Inverter. Obviously Comma.ai's focus is on driving dynamics, but it looks provide a lot of the important info that we'd need.

Jamie

That's a great resource, we should definitely link to it where appropriate.

I've been following GeoHot for a long time and didn't know Comma.ai was sharing that kind of data. That's awesome. I probably won't have the desire to EV swap a modern car at any point in time but I am certainly in the middle of trying to wrap my head around how Arduino CAN communication.

Wish I could attend the Ireland training courses :\

johu wrote: ↑Tue Oct 20, 2020 8:38 pm That's a great resource, we should definitely link to it where appropriate.

If I find any similar resources, I'll add links to them.

Is there an appropriate section of the Wiki to link from? Should pages be created for each OEM and then tables for models?

Has a DBC file been created for the Open Inverter CAN signals?

Here's another source for DBC information for the Model 3 (I assume US version?) - https://github.com/joshwardell/model3dbc

jalovick wrote: ↑Mon Oct 26, 2020 12:24 am Here's another source for DBC information for the Model 3 (I assume US version?) - https://github.com/joshwardell/model3dbc

Yep. It's pretty comprehensive for the main buses. Not so much for the High Voltage bus.

-Matt

mdrobnak wrote: ↑Mon Oct 26, 2020 12:31 am Yep. It's pretty comprehensive for the main buses. Not so much for the High Voltage bus.

Did you find anything useful in the OpenDBC link I posted above? I suspect it also won't have any HV data, but it may be worth a look.

Jamie

jalovick wrote: ↑Mon Oct 26, 2020 1:47 am

mdrobnak wrote: ↑Mon Oct 26, 2020 12:31 am Yep. It's pretty comprehensive for the main buses. Not so much for the High Voltage bus.

Did you find anything useful in the OpenDBC link I posted above? I suspect it also won't have any HV data, but it may be worth a look.

Jamie

No, most of that is from the S, which doesn't share much in common with the 3. That said, the EPAS data is useful if I want to make use of it. I plan on eventually retrofitting either the model S or 3 EPAS into my 330 conversion and hooking Open Pilot up to it.

-Matt

jalovick wrote: ↑Sun Oct 25, 2020 3:41 pm Has a DBC file been created for the Open Inverter CAN signals?

What we have is this: https://openinverter.org/wiki/CAN_table_CAN_STD

If someone wants to convert it to DBC.

Otherwise the open inverter CAN is so flexible that usually you adjust it to its environment.

Jon (who is on here) was helping Lars (also on here) with some iBooster mapping, and mentioned a source of more Tesla and other DBC's:
- https://github.com/thezim/DBCTools/tree/master/Samples