[Ovmsdev] OVMS v3

Mastro Gippo gipmad at gmail.com
Mon Jun 16 23:41:43 HKT 2014

Hi all, I'd like to resurrect an old conversation. As we know, the current
PIC is quickly running out of resources and maybe it's time to switch to a
better platform. Two CAN buses are now desirable too. A microSD slot and
direct USB connectivity wouldn't hurt either.
I will probably have to design a similar hardware for myself, so I'd like
to contribute to the OVMS by sharing the HW platform if you want; no
strings attached of course, if you decide that there's no need for the
upgrade, I'll keep on working on my project by myself! :)
That said, I'd like to throw a few ideas to the table.

- MCU: I'd like to use an STM32 micro. They seem to be emerging as the
standard choice for diy ARM projects, and this offers a few interesting
 -Programming it in c/c++ with the manufacturer CMSIS standard libraries
 -Programming it with the mbed.org SDK. Unfortunately no dev boards are
available with dual CAN bus, but it will be easy to move to the correct
micro of the same series once most of the software is ironed out on a dev
board like the https://mbed.org/platforms/ST-Nucleo-F302R8/
 -Programming it with an RTOS. NuttX would be my choice, as it's the one
used in the Ardupilot Pixhawk platform, and I'd like to learn it. This
would mean a steeper starting curve, but a lot of flexibility later as a
lot of stuff is handled on the OS level (network stacks, SD card &
filesystems, multitasking...). FreeRTOS is a nice option too.

I'd like to use the STM32F405RG as it's the most similar to the one found
on the Pixhawk, but of course I'm biased because of that, and that micro is
quite overkill for the task. We can of course use a lower specced part and
lose some RTOS fuctionality as long as it has 2 CAN buses.

- MODEM: I have no experience in this field; is the SIM908 still a good
choice or does anyone think that we should try new platforms?
I like this, but I don't know if the price puts it out of budget:
On the bright side, it can be programmed in python, so we can offload some
of the work to the modem. This *could* allow us to free some space on the
PIC, and keep that platform without changing MCU..

- Enclosure: I think that, even with the new MCU, we can still fit the old
enclosure. Is that ok, or should we think about a more automotive-friendly
one? Maybe waterproof for the twizy?

And that's it. I think that the core SW developers should voice their
opinion, as there is a lot of work to be done on that front. A huge problem
will be keeping backwards compatibility to add features for the v2 users,
so we should discuss about this too.

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