[Ovmsdev] Leaf info?

Mark Webb-Johnson mark at webb-johnson.net
Mon Feb 9 14:57:32 HKT 2015


Welcome aboard.

Answers below, inline.

Regards, Mark

On 6 Feb, 2015, at 7:53 am, Lee OVMS <ovmsdev at varga.co.uk> wrote:

> Hi All,
> I'm Lee, I've just picked up an OVMS unit from Kevin Sharpe, with a view to doing some development for the Nissan Leaf.
> So I've got a few questions I'd like to ask/clarify surrounding the current state of OVMS on the Leaf if I may.
> Does the current firmware include all the stuff found during last years Hack-a-Leaf day in the UK?


> Either way, are there any notes from the day that may help me get up to speed? Or pointers as to directions to head in?

Everything we learned we put in the code. We were really just trying to create the core structure and get some logs from the cars themselves. In particular, we were looking for codes for stuff like charging voltages/current, vehicle state, etc.

> Is the "Leaf ODB-II" cable that FastTech now sell different to the old ODB2 left/right cables?

Yes. Around the hack-a-leaf-day time, we decided to switch away from the normal OBDII vehicle CAN bus to the EVCAN bus. That is a different pinout, so the "Leaf OBD-II" cable is wired differently (it brings through the EVCAN bus on the two standard OVMS v1/v2 port connectors, and then wires the vehicle CAN bus to two unused pins for possible future use in a dual-bus capable OVMS v3).

> Can the older cable be modified into a Leaf cable?

Yep, you can re-wire the cable. Not too hard a job, but probably easiest to just change the DB9 end by replacing it with a new DB9 connector. I think the connectors you

The standard OVMS OBDII cable uses pinout A, and the Leaf-specific one uses pinout B:

Pinout A

J1962-M   DB9-F   Signal
4         3       Chassis/Power GND
6         7       CAN-H
14        2       CAN-L
16        9       +12V Vehicle Power

J1962 end should be MALE plug with right angle cable. DB9 end should be FEMALE.
Both ends should be enclosed in shells, and cable should be 1metre in length.
Pinout B

J1962-M   DB9-F   Signal
4         3       Chassis/Power GND
6        5      CAN-H (alternate CAN)
14       4      CAN-L (alternate CAN)
13        7       CAN-H (primary CAN)
12        2       CAN-L (primary CAN)
16        9       +12V Vehicle Power

J1962 end should be MALE plug with right angle cable. DB9 end should be FEMALE.
Both ends should be enclosed in shells, and cable should be 1metre in length.

> I assume the new firmware needs this new Leaf cable?


> Does the Leaf firmware use the internal GPS from the car or is it better to get an external GPS antenna plugged directly into the OVMS module?

It requires an external GPS antenna.

> What programmer should I buy? The PicKit 2 or the PicKit 3?
> I've read the 2 is easier to use, but I need the 3 if I'm developing and it's more complicated. Is this still the case?

If you are developing (building from source), the pickit 3 is probably better for you.

> If it's the 2, does anyone have the software, as it's gone from Microchips site (seems to be discontinued).


> If it's the 3, is there a similar guide to using the 2 covering the extra complexity?

Not really. The PICKIT-3 is supported by MPLAB-X directly (as is the PICKIT-2). Really, if you are building from source, either would be fine.

> Does anyone have a modifiable form of the Tesla Roadster User Guide PDF? As I'd like to convert it into the Leaf User Guide, but it gets a little bit broken when I edit it in LibreOffice.

The .docx format is here:


> On the same note, the Twizy Guide appears to be a broken link on the site.

Fixed. Thanks.

> Is there is decent/easy to understand ODBII spec/site somewhere that is being used to get cribs/pointers to reverse engineering the recorded CANbus chatter? Or is it just knowledge in devs heads? :(

There are two threads that we know of on the Leaf forums. One for passive and one for active CAN bus monitoring. That is the best information we have at the moment.

> Lastly does the CAN Re Tool work OK with the Leaf? As there are mentions Tesla rules in the other files?

It should work on any CAN bus. But, you'll need a USB-CAN adaptor.

> I thin k that will do for now, more questions as I run into problems! :)
> All the best,
> Lee
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> OvmsDev at lists.teslaclub.hk
> http://lists.teslaclub.hk/mailman/listinfo/ovmsdev

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