[Ovmsdev] V3 CAN frames missing last four data bytes

HONDA S-2000 s2000 at audiobanshee.com
Wed Oct 25 12:46:00 HKT 2017

Thanks for this!

One of my first experiments will be CAN logging, in an attempt to isolate the TPMS programming commands for the Tesla Roadster (I’ve got two sets of wheel for summer and winter, and I hate scheduling time at the dealer twice a year just to swap them). I’ll probably find some way to detect “out of ordinary” messages and log them for analysis - especially since the 32-bit ID for each TPMS sensor is probably the bulk of the payload.


On Oct 24, 2017, at 7:19 AM, Mark Webb-Johnson <mark at webb-johnson.net> wrote:
> This was fun. And I need some fun after that GSM 07.10 stuff.
> I made a first pass at putting in a CAN Reverse Engineering framework. Seems to work ok, but there are so many opportunities here.
> For normal operation, all you need to do is ‘re start’ and it will start recording statistics on CAN bus activity. The default key is the canbus/ID (with extended/standard formatted differently to differentiate them). For each key, it will create a record and store a count of the number of records received, as well as the last CAN frame of that type received.
> The ‘re list’ command will show you the keys, and their records. You’ll see the record count, the time interval between records (in milliseconds, calculated as now-started / number of records), and the data bytes of the last packet seen. You can use ‘re clear’ to clear the records, and restart the counters for a new capture. You can also add a search filter to ‘re list’ to restrict the records shown.
> For more advanced users, you can set the key bytes for particular IDs. The example given is for Tesla Roadster, where CAN ID 0x100 has a sub-command key in the first byte. So, ‘re key set 100 1’ tells the RE system to treat CAN 100 keys as 100:<databyte1>. Another example would be ‘re key set 100 1 2 3’ to cause the key to be 100:<B1>:<B2>:<B3>.
> Remember you can use ‘can <canX> rx …’ to simulate reception of data and play with this.
> Regards, Mark
> P.S. I moved ‘reset’ to ‘module reset’, to make it a bit harder to mis-type when using ‘re’.

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