[Ovmsdev] SWCAN and enhanced Ampera/Volt support

Michael Balzer dexter at expeedo.de
Fri Jul 19 04:11:42 HKT 2019

Hi Marko,

wow, now that's an intro :) Great work!

If your MCP2515 driver changes are fully compatible with the base hardware, or can be switched on by a config, we can merge them into the master. Send a pull
request when you think it's time for that.

Some testing from developers using the MCP2515 buses would be good.


Am 18.07.19 um 10:14 schrieb Marko Juhanne:
> Hi all,
> I've been tinkering with OVMS and Opel Ampera these few past months, and the I've made some progress with the SWCAN support. 
> As you know, the SN65 transceiver cannot do High-Voltage Wake Up, so many of the nice-to-have polling and remote controlling functions are not available on
> those cars that rely on it, such as Volt/Ampera. So I've created an add-on SWCAN board that attaches to the internal OVMS extension header. The board uses
> TH8056 transceiver, which is specifically designed for SWCAN bus. As for the controller, same MCP2515 is used as in OVMS.
> Here's the link to the boards GitHub page: https://github.com/mjuhanne/OVMS-SWCAN
> For the firmware patches, here's my OVMS branch: https://github.com/mjuhanne/Open-Vehicle-Monitoring-System-3
> There are a lot of changes, especially MCP2515 code add-ons and refactoring, of which some are specific to the new swcan-bus, but some could be beneficial
> otherwise as well. Then there's the support for the new board and TH8056. On the other hand, if a car can be woken up without HV WakeUp, the board is not
> really needed and the SN65 can be used with 33.3 kbps speed to communicate on SWCAN bus.
> Since ESP32 supports only 3 hardware CS on one SPI bus and all the CS lines are now already used, there's also patches for software CS (that's what the
> additional MCP2515 is using). With my OBD cable I wire SWCAN to use CAN2 lines and put the 2nd MCP2515 on OVMS to sleep, but there's no reason why all the 4
> CAN controllers couldn't work independently at the same time (untested at this time).
> There's also patches to the Ampera/Volt module code base to include SWCAN support, add handling of several new CAN messages (still work in progress, more to
> come!), as well as VoltStar-like capabilities (locking/unlocking doors, remote preheat) similar to Brian Batista's MyVolStar app/OBDLink MX-combo. Sadly, I
> haven't been able to get the VoltStar-specific functionality to work on my 2014 Ampera, but other non-Voltstar SWCAN messages do work (waking up the car,
> controlling windows etc.). This is is similar to other reports of MyVolStar on 2014 Volt/Ampera, so maybe something has changed in the ECU behaviour between
> MY13 and MY14. 
> It would be really nice to get other OVMS developers with SWCAN/GMLAN enabled cars to test these. SWCAN specific patches can be tested also without the board,
> but naturally the HV Wakeup functionality is not available.  Let me know if you're interested so I can send a PCB or two for testing (I have bunch of leftovers). 
> Best regards,
> Marko
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Michael Balzer * Helkenberger Weg 9 * D-58256 Ennepetal
Fon 02333 / 833 5735 * Handy 0176 / 206 989 26

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