[Ovmsdev] Basic OVMS concepts
leres at xse.com
Sun Jun 9 10:39:38 HKT 2019
After a long period of procrastination it's time for me to get a OVMS
module working in my Cadillac. If I can get it to the point where it
doesn't kill the battery and lets me see where the car is it'll be about
as usable as my free onstar account and I'll be able to kill that off.
The last time I worked on it I was able to decode/display/store the vin.
I thought I had figured out the car awake messages but a capture I made
today makes me doubt I have that correct. Either way I don't think I
understand what it is I need.
I assume when the vehicle is "off" the ovms module wakes up periodically
to check location, upload current status. And when the vehicle is "on"
it stays booted. And this driven by some metrics? Looking at other
vehicles I was using:
But I'm not sure what events should set/clear these. I'm used to
thinking of a car being a few different states:
So I guess "awake" is when something wakes up the bus (e.g. door unlock,
key fob press, door open, etc.) and everybody starts sending their "I'm
here" messages for awhile and if nothing else happens they go back to
sleep. I see logic for this in vehicle_nissanleaf.cpp (awake on certain
can ids, asleep from a 1 second watchdog if
Still looking at the leaf (which doesn't have an engine)
StdMetrics.ms_v_env_on seems to indicate the car can be driven. Does
that map to the engine running for a gas engine car? I also see logic
in the mitsubishi but it's not obvious if the transition is accessories
on or engine on.
Are there other metrics I need to manage for miminal support?
One of the things I was hoping to do with the Cadillac was capture the
frames that onstar sends to the navigation head unit when you use the
"send to in-dash navigation" feature of the onstar app. But the list of
things you can do with the free onstar account has constantly gotten
shorter over the last few years and it appears they've killed off this
feature in the last month or so. Too bad because this would have been a
neat feature to add to ovms.
While I'm here...
The J1850 tools I've built up are not at all helpful with canbus; but I
have a raspberrypi 2 that isn't doing anything and I believe I can use
it to get wireshark going with a skpang.co.uk "PiCAN2 CAN-Bus Board" so
I ordered one. Speaking of wireshark and canbus, this video shows an
it has a mode that has a billboard which shows which can ids have been
changing with lots of neat options like hiding and highlighting recently
changed octets. I suspect it won't be difficult to write something with
similar functionality. But I think my id mapping will go a lot faster if
I can do things while watching a display.
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