[Ovmsdev] CFG commands on RT_Production

Julien NOZAIS julien.nozais at ext.uni.lu
Mon Sep 22 22:55:20 HKT 2014

Hello everybody,
my name is Julien, I am a soon-to-be CS engineer from France. I am working on an internship project that requires to modify the Renault Twizy's internal parameters via the CAN bus. I am very interested in the work done by the OVMS developers on that topic.

In the past few weeks I have learned quite a lot about Twizy's SEVCON through the documentation and also by browsing through the OVMS car module's source code. Thanks a lot for all the documentation and advice you provide!

I have some questions that I hope you guys can answer to (TL;DR below).

MSG commands

My current situation is that I have upgraded my OVMS module to 2.6.5 firmware with the .hex file provided on GitHub. I have also successfully connected to the module via SMS commands and Android App. Most of the basic commands that I tried worked.

I say 'most', because I have set the #15 'write' bit to '1' and cleared the #14 bit as well. However, I don't seem to be able to send CFG commands via SMS (such as CFG SPEED <speed> for example) in the way that the twizy manual describes it. All I get are push notifications forwarding my SMS to the app. Is there something I'm missing? :(

Compilation issues

On an other topic, I have installed MPLABX and acquired the C18 compiler thanks to someone hosting it on a personal website (note: it's nowhere to be found in the microchip archive and static links sourcing it on the website are all dead at the moment).

I have tried to compile the V2_RT_Production from the last source available on GitHub. However I ran into compilation errors in vehicle_twicy.c, caused by what I assumed were missing '#define' directives (i.e 'OVMS_TWIZY_BATTMON' & 'OVMS_TWIZY_CFG'). I didn't see them referenced anywhere but in the version comments at the start of the file:

> - Twizy battery monitor compiler switch: OVMS_TWIZY_BATTMON

So I added these two, but I don't know if they were supposed to be left out. Incidentally, I ran into a new compilation error:

> Error - section '.romdata_net_msg.o' can not fit the section. Section '.romdata_net_msg.o' length=0x000000a8

Which as I understand is an issue relative to the length of the file being too large to pass compilation. I'm fairly new to PIC programming, so I may have misinterpreted some of these compilation errors. I imagine there is a lot of work in progress on the code so maybe the version I pulled was not a stable one ? Any remark or advice is most welcome!

DIAG communication

Probably noob error: I tried connecting through the DIAG port with minicom. I set minicom to 9600 Bds / 8N1, as specified in the developers documentation, but had no success. I think that I'm closed since since I received data, but it was just gibberish encoding errors. Since these errors are often caused by a wrong baud setting, I tried different baud values without success. I hope somebody can point out something that I could have missed. I have read the manual, but, well... you never know.

- Can I send SMS CFG commands to Twizy 2.6.5 firmware?
- Is there any specific advice on how to get started on OVMS source and compile it for the Twizy?
- Communication with DIAG port on minicom only speaks gibberish although I have (supposedly) correct settings. Could I have missed something?

Anyway, I hope I'm not bothering you with all my questions. Sorry for the long e-mail.
I look forward to reading from you !

Julien Nozais

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