[Ovmsdev] Getting started

Stephen Casner casner at acm.org
Mon Apr 23 13:57:02 HKT 2018

On Sun, 22 Apr 2018, Craig Leres wrote:

It is interesting to see names from past lives pop up in new contexts!

> I got my module up on the bench without too much trouble. The V2 and V3 server
> config was confusing to me since I knew almost nothing. I think I had read
> that V2 was legacy and V3 was where new development effort was happening so I
> thought that's what I wanted. But I didn't find much info on io.adafruit.com
> vs. ovms so I ended up configuring the V2 server for starters.

The purpose of the V2 server is to allow the v3 devices to replace v2
devices and be useful in the near term while the v3 capabilities are

> My canbus car is a second generation CTS-V. Once I plugged that in I could see
> my car with the iphone app. But the app didn't show much (I completely
> understand that most work so far as been on plugin vehicles). Once I turned
> the car on the battery percentage starting showing how full my gas tank was.
> I'm still a bit confused about how GPS works. I was expecting it to use the
> GPS periodically but what I've found is if I don't turn on the GPS at startup,
> I never see location info even when I'm driving. And if I enable GPS at
> startup, it seems to always be on even when the car is not. Maybe this is
> because my car isn't supported and the module doesn't know when it's running?
> I also found that trying to press any of the homelink options crashes the
> iphone app.

The CAN bus protocols seem to be unique for each EV and unrelated to
any standard functionality on the OBD-II connector.  So to have OVMS
be useful for the CTS-V would require adding support specifically for
that vehicle.  There is work underway to simplify that process.

> Initially I could not get ssh to work. This wasn't surprising since my FreeBSD
> desktop runs openssh 7.7p1 and I know there is a push to disable or even
> remove less secure and insecure crypto. But after joining the ovmsdev list the
> solution was revealed (create a Host block with "Ciphers aes128-cbc") so that
> is working for me now.

The algorithm support I have available in the WolfCrypt library is
somewhat limited.  As I mentioned, AES-GCM is possible but may be too
expensive in memory and speed.

> I like the way ssh.keys work (mapping the remote username) but I use hard
> tokens with ssh it sure would be nice if you could configure more than one ssh
> key.

I'm not sure what "hard tokens" means here.  Since the username has no
function other than as an index to a key, you can install multiple
keys with different usernames if that helps.

> When learning about how ssh works I was using the google doc (15Mar18)
> and it says when you login you start in non-secure mode. I find ssh always
> puts me in secure mode.

Since authentication is required to establish the ssh connection, it
makes sense to be in secure mode automatically.  That sounds like the
doc being behind the times.

> I'd like to get a build environment up. ... What do I need to be
> able to build for v3? I normally work/play on FreeBSD but I have an ubuntu
> system handy for when I need it.

The first step would be to get the ESP-IDF running, if you have not
already (you mention working with esp32).  Espressif provides
documentation and example programs.  If that works on FreeBSD then
you're set for OVMS as well, but if not you may need to use linux.

Then clone openvehicles/Open-Vehicle-Monitoring-System-3 with
--recurse-submodules and set IDF_PATH as you would for any of the
example projects, and you should be able to build.

                                                        -- Steve

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