[Ovmsdev] Merging in Twizy and Volt/Ampera work

Michael Balzer dexter at expeedo.de
Sun Nov 4 20:37:50 HKT 2012

Am 04.11.2012 04:11, schrieb Mark Webb-Johnson:
> A while ago, Michael Balzer suggested to me that it would be best to 
> have one firmware supporting all cars.

That wasn't me. The idea sounds good, but...

- car platforms to be supported will increase steadily now, there are 
lots to come in the next years
- even cars with decent builtin online monitoring systems lack some 
functionality for nerds like us
- there will be a need for custom product configuration per car anyway, 
as cabling and antenna configuration will be different

ROM space is plenty, I'm more concerned about the RAM usage. Can those 
car specific #pragma udata globals easily be replaced by a dynamic 
object to be allocated on module init?

Also, not only the CAN module may need car specific adaption. I've not 
yet completely read into the server protocol (btw: I can only read up to 
line 201 of docs/OVMS_Protocol.doc using UTF-16 -- rest is garbled), but 
got the impression it contains some common and some Tesla specific data. 
If we have to integrate specific data from every model supported, the 
data stream can become quite fat. So it seems to be necessary to 
implement some dynamic data / protocol configuration model as well? I.e. 
divide into a common set of properties available on most car models plus 
a dynamic car special feature property set.

Example: one of my next ideas is a cell monitor to get a history of the 
cell voltage levels, so I can detect and alert about cell failures 
early. The Twizy has 14 cell packs (14S 2P we think) and we've got their 
voltages on CAN. Even for the small Twizy pack + data compression this 
will need some RAM (or server traffic + App support). The Tesla has an 
11S 9S 69P configuration (?), so that would need much more history RAM + 
possibly another data layout -- if the voltages are on CAN at all.

Another example I already stumbled on: the car_doors1 flag 0x04 (charge 
port open) is currently used by net_sms_stat(), if it's not set, it 
assumes "not charging". So even some standard functions rely on Tesla 
specific data.

So, maybe the data and protocol models need to be generalized first? Or 
am I missing something?


Michael Balzer * Paradestr. 8 * D-42107 Wuppertal
Fon 0202 / 272 2201 * Handy 0176 / 206 989 26

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