[Ovmsdev] OVMS v3 - Microcontroller

Julien (JaXX) Banchet jaxx at jaxx.org
Thu Feb 4 22:55:19 HKT 2016

On 02/04/2016 03:29 PM, Mastro Gippo wrote:
>  Well, to add my 2c, I've been working on a new version of the my own 
> "OVMS" I talked about earlier with a LPC1768. I chose that MCU as it's 
> better supported by the mbed with easy USB libraries. Mbed is 
> disappointing me too lately, but that chip is well supported by 
> FreeRTOS too and other toolchains are available.
> I think that a USB/serial/SD bootloader can reduce flash needs (I have 
> 512k), as multi-car firmware will not be needed as users can upload a 
> different version easily. I have a microSD expansion slot for logging 
> and various storage.
> I'm still using a GPRS module, because here in eu I see no signs of 
> that being discontinued anytime soon, and I can't find a 3G-4G module 
> small enough. The GPS is a Ublox 7.
Actually, 3G might disappear before 2G in EU, simply because too many 
vital services depend on it, down to railway track switches...
> The board is 4x2cm and can be directly stacked on top of an OBD connector.
> I was also planning on a LoRa/sigfox connection, but they're not 
> exactly "realtime" (a Sigfox packet can take up to 6 minutes to reach 
> the server).
The more I read about it, the more Sigfox is to be excluded, the 100bps 
throughput gives up to 2 seconds of over-the-air time for the limited 
payload of 12bytes, the infrastructure is good though, I know the team a 
little bit and they do good stuff (when you end up living in Toulouse, 
you have to be part of the hackerspace mouvement :-) ), but the tech 
itself has it's limitations, and a 2s transmit time makes it likely to 
make it impossible to get a complete message in a moving vehicule, and 
without ACK, the message is transmitted 3 times "just in case"... it's a 
big handful of time occupation where you'd like realtime telemetry. And, 
you're allowed 140 messages/day, with back-off punishments if you go 
beyond that.

LoRa suffers less from this, but then it will depend on the operators 
density and the economic model they'll push out...

I'm sure there are SigFox lovers here: don't get me wrong: It's great 
technology for static or mostly static, event triggered sensors, that 
can be today deployed in vast areas and/or dense cities, with clean and 
easy APIs and frontend to set up your callback URLs...
I can imagine half a billion applications to it, from a moisture 
detector in a middle of a football field to smoke detectors in a forests 
canopees. I just don't think that specific tech is adapted to the 
automotive industry


> I think that kinetics are still not user-friendly enough, and that was 
> my main reason to stick with something mbed/arduino compatible to 
> allow more developers to make changes.
> Pic: http://www.mastrogippo.it/ct-1.jpg
> Regards
> MG
> On Thu, Feb 4, 2016 at 2:47 AM, Mark Webb-Johnson 
> <mark at webb-johnson.net <mailto:mark at webb-johnson.net>> wrote:
>     Arthur, and others,
>     I’m hitting roadblock after roadblock with these automotive
>     microcontrollers. The chips are expensive, but we could live with
>     that. However, the bigger issue is development environments. It
>     seems that none of the free and open development environments
>     support these automotive processor cores (and a development
>     environment free of encumbrance and easy to get into is one of the
>     fundamental requirements for this project). Kind of frustrating,
>     but when looking at US$30 for a processor, when the Cortex M4 ones
>     are US$7, makes me rethink things.
>     I am kind of narrowing down on the Kinetics range from NXP. In
>     particular, MK66FN2M0VLQ18 seems to give us what we need:
>       * ARM Cortext M4, at 180MHz max
>       * Kinetics free development environment
>       * 2MB flash
>       * 256KB RAM
>       * 2x CAN
>       * 6x UART
>       * 3x SPI
>       * USB
>       * Ethernet
>     Couple it with a CMSIS-DAP (I’m looking closely at IBDAP
>     <http://www.seeedstudio.com/depot/IBDAP-CMSISDAP-JTAGSWD-Debug-Adapter-p-2568.html> as
>     a base for this because of their free open source approach based
>     on a simple US$4 LPC11U35FHI33 and gcc-compileable firmware) for
>     firmware loading, serial over USB console, and low-cost debugging.
>     Should work fine with Kinetics Design Studio (KDS). Windows and
>     Linux support is complete, and OSX is basic but ok. Includes a
>     RTOS (MQX), but also supports FreeRTOS.
>     That gives us two full high-speed CANs directly on the processor.
>     Extras would be via MCP2515 SPI on an expansion card.
>     The above seems like a workable plan. I’ve already got
>     some FRDM-K64F boards, which are pretty close to the above and
>     readily available to start the software development work on. At
>     the moment, I’m trying out the Kinetics Design Studio, to see how
>     it behaves with this arrangement and to make sure it will give us
>     what we need in a simple development environment freely available.
>     I should know in the next few days whether that is ok, and then we
>     can start to nail things down. If anyone else wants to look at KDS
>     and let me know what you think, that would be appreciated. From my
>     understand, it is just GCC with an eclipse plugin GUI built on top.
>     Regards, Mark.
>>     On 4 Feb 2016, at 3:28 AM, Arthur Hebert <ahebert at gmail.com
>>     <mailto:ahebert at gmail.com>> wrote:
>>     Speaking of modularity, how about having 1 or 2 CAN buses
>>     standard built-in, and additional CAN buses being optional
>>     add-ons? The additional CANs could be MCP2515 based via SPI, like
>>     http://www.mikroe.com/click/can-spi-3.3v/.
>>     With plenty of speed, flash, RAM and I/O pins, the software can
>>     tidily abstract the SPI comms so that CAN rx/tx functions appear
>>     the same whether built-in or module-based.
>>     The advantage I see is that it doesn't constrain the primary MCU
>>     selection so much, and there are plenty of options available
>>     today. Many people will be happy with 1 or 2 CAN channels, and
>>     those who want 6 CAN channels will happily pay an extra $100 for
>>     the additional hardware.
>>     -Arthur
>>     On Tue, Feb 2, 2016 at 11:10 AM, Julien Banchet <jaxx at jaxx.org
>>     <mailto:jaxx at jaxx.org>> wrote:
>>         Mark,
>>         I'm a bigger fan of standardized LoRa networks than SigFox
>>         but was going to share the latter's little faire in London on
>>         Feb 16th until I realized you where in HK and not UK.
>>         Nevertheless, I bet it might get some curious on the list :
>>         http://makers.sigfox.com/tour/
>>         They have already deployed in 10 major agglomerations
>>         (Londres, Manchester, Liverpool, Birmingham, Glasgow, …) and
>>         are still extending.
>>         JB./.
>>         On Mon, Feb 1, 2016 at 2:35 PM, Mark Webb-Johnson
>>         <mark at webb-johnson.net <mailto:mark at webb-johnson.net>> wrote:
>>             Well, the new year is here and OVMS v3 is on the front
>>             burner now.
>>             As you know, I’ve been waiting for the MBED system to
>>             settle down and the news is … it hasn’t. Sure, they’ve
>>             finally released some open beta code, but only really 1
>>             board supported. No more online compiler. Complicated
>>             tools. RTOS worse than the old MBED. And worse is a
>>             proprietary closed-source server platform for their
>>             Internet-of-things MBED O/S. Luckily, the one board they
>>             support is the NXP FRDM-K64F that I love. I’ve tried it,
>>             and it sucks. Maybe in a year’s time…
>>             I’ve been waiting and waiting for this. Can’t say how
>>             disappointed I am with the whole direction of the MBED
>>             project and closed development, closed, source approach.
>>             Anyway, OVMS v2 is end of life. We can’t get the SIM908
>>             GSM modules any more. Even if we could, 2G really doesn’t
>>             have that much longer. There are a lot of M2M devices out
>>             there, but the frequency space is just too valuable. Over
>>             the next year or two, more and more 2G capable cell
>>             towers are going to be turned off.
>>             So, time to take the plunge and get on with it. I’m
>>             guessing an open source development environment, some
>>             free RTOS, and an adapted boot loader to allow us to
>>             flash from SC-CARD, USB, or something like that.
>>             From an overall system architecture point of view, I
>>             think we know what we want. A board with a fast micro
>>             controller, lots of ram and flash, several CAN buses, and
>>             easy development environment, easy firmware upload for
>>             the novice, SD card, USB, ethernet, wifi, bluetooth, and
>>             some digital I/O. Then, expansion slots to plug in 3G/4G
>>             connectivity and whatever else we want.
>>             We’ve now got lots of options on the wifi+bluetooth
>>             front. Within the next couple of months, the ESP32 is
>>             going to be out, and that looks really nice. Same story
>>             with 3G/4G modules. I don’t see this as an issue.
>>             So let’s discuss the micro controller.
>>             Let’s say we want at least 1MB flash, and at least 256KB
>>             RAM. At least. Now, we need multiple CAN ports. 2 at a
>>             minimum, but 3 or 4 would be much better. A lot of the
>>             newer cars split their stuff over multiple CAN buses, and
>>             having that support would be great. Remember that we want
>>             one system that can be used as a logger, development
>>             environment, and final production system. That puts us in
>>             ‘automotive’ territory, which is not a bad place to be.
>>               * ST have some brutal micro controllers, like
>>                 the STM32F769. M7 core. Up to 2MB flash, 512KB SRAM,
>>                 and 3x CAN buses. All the older stuff is 2 CAN bus
>>                 max, but availability of the new 3xCAN bus stuff is
>>                 summer 2016. A couple supposedly available now, but I
>>                 can’t find them.
>>               * NXP have a nice automotive range in the MPC micro
>>                 controllers (in particular MPC56 has lots of choice,
>>                 and 10 year product life time), but a strange e200z0
>>                 core that I’ve never seen/used. Again, brutal on the
>>                 flash and RAM, and up to 6 CAN buses. These are their
>>                 SPC5 32bit automotive MCUs. They have a ‘free’ GCC
>>                 based development environment.
>>               * The NXP S32K looks good, but seems not available yet.
>>             My preference is the NXP range, but I am concerned about
>>             that e200z0 core. Really never heard of it. Anyone got
>>             any experience with this?
>>             The ST stuff also looks good, but availability is tight.
>>             Thoughts? Anybody have a good contact with NXP for some
>>             advice?
>>             Regards, Mark.
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