[Ovmsdev] (Hardware) Sharing the bus, J4, J5, J6?

[Brian Greenberg]

Firstly, although the topic seems ripe for it, I couldn't come up with a
good pun involving buses or terminators for the subject line.  Apologies.

As I have previously mentioned, I have a '15 Nissan Leaf, which uses both
the CAN0 and CAN1 buses.  Everything that should work, works quite nicely
when the OVMS (V3.1) module is plugged in on its own. (Although it did take
a couple of attempts to find an OBD2 splitter that had all of the needed
pins connected....)  However, when I add a second OBD2 device (a Bluetooth
dongle to feed the Leaf Spy Pro app) the OVMS module appears to lose the
CAN1 bus -- vehicle status events like door locks and headlight state stop
updating almost (but not quite) entirely.

I suspect that both OVMS and Leaf Spy do at least some active polling for
status, but my (limited) understanding is that the devices *should*
coexist.  Any thoughts on what the issue may be?  Two possibilities that I
have thought of are that, with the OBD2 splitter cable, the high speed CAN
bus is formed into an unsupported star, instread of straight serial,
topology.  The other is that the OVMS module may not be properly terminated
-- the schematic and board show that the 120 ohm resistors that terminate
the CAN bus are included, but not connected by default -- there are three
sets of jumper pads that can be shorted to enable the respective
terminators.  Would soldering a wire across the J5 (CAN1) jumper help?
(And why isn't termination enabled by default?  Just curious....)

Thanks!


Brian.

PS:  A request to put in the wish list file for V4....  Can the internal
expansion bus pins be laid out with the standard 2.54mm pitch?  I'm looking
at creating a simple board to expose the EGPIO pins on the DB26 port, and
finding a 2mm pitch prototype board and headers is a huge pain.

-- 
Brian Greenberg
grnbrg at grnbrg.org
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