[Ovmsdev] Incentivising / Rewarding

HONDA S-2000 s2000 at sounds.wa.com
Tue Sep 3 06:24:01 HKT 2013

How much is your CAN expansion board for the MBED?

I'm not sure what the difference is between the LPC1769 that you  
recommend and the LPC1768 that MBED lists as currently available. One  
obvious difference is that the LPC1769 is about US$118. The LPC1768  
is $49


My concern is that by the time you make the CAN expansion board, with  
all the costs associated with that, you might as well put the main  
CPU on the same board and not be stuck buying a retail platform.  
Buying two boards is surely going to cost more than one, unless there  
is something tricky like radio antenna design involved.

As for PIC versus ARM or even AVR or MSP430, it doesn't really matter  
what the processor is. All of these CPU chips have $49 or even $5  
(MSP430) evaluation boards and device support libraries.

Brian Willoughby
Sound Consulting

On Sep 2, 2013, at 04:11, Mastro Gippo wrote:
> Hi Mark,
> I'd like to throw my 2 cents to the discussion.
> I'm a professional developer specialized in automotive bus reverse  
> engineeging, in the past I worked for an automotive diagnostic  
> company and later for another company that developed electric car  
> conversion kits, and now I'm the technical director @ eV-Now!  
> foundation Italy.
> A while ago I was developing an open source ECU that would allow  
> anyone to do the CAN bus study with the CAN-USB function and then  
> program the same device to be an ECU emulator to simulate the  
> presence of a combustion engine in a converted electric car.  
> Unfortunately, the project was put on standby for various reasons.
> The board, as you can see in the picture, is just an expansion  
> board for the awesome MBED project (www.mbed.org ) and features an  
> sd card slot, 2 CAN transceivers, an ethernet port and an USB  
> device port. The MBED is awesome because it offers a lot of cool  
> libraries and even a ready to use and free RTOS; there is even a  
> library to connect a 3G modem to the usb host port of the mcu. The  
> compiler is online and allows an easy management of the project  
> with an integrated cvs system, and if you don't like it, switching  
> to the offline (proprietary :( but some open source alternatives  
> based on gcc are already available) IDE is as easy as downloading  
> the source file. A demo board that is fully compatible with the  
> MBED is available from http://www.embeddedartists.com/products/ 
> lpcxpresso/lpc1769_xpr.php , and that includes a programmer and  
> debugger for less than the price of the PICKIT alone.
> I know that switching from a well known platform to ARM may seem  
> like a very hard choice, I was a PIC lover too, but the MBED  
> library greatly reduces the effort of porting the code to the new  
> device. For example, adding an usb serial port is this easy:
> #include "mbed.h"
> #include "USBSerial.h"
> //Virtual serial port over USB
> USBSerial serial;
> int main(void) {
>    while(1)
>    {
>        serial.printf("I am a virtual serial port\r\n");
>        wait(1);
>    }
> }
> So, IMHO, basing the OVMS v3 on the LPC1769 will solve the code  
> space problem and transform it into an integrated CAN bus  
> developing tool, providing some cool features at the same time like  
> more power an memory, sd card data logging and dual CAN channels,  
> for a price per MCU just slightly higher than the PIC solution.  
> Another advantage is that we can develop a nice GUI that will help  
> the user for the initial configuration of the SIM card connecting  
> the OVMS to the USB port.
> On the topic of the protocol, I agree on the CAN232 data format, I  
> have that device too and all the software I've written is  
> compatible with that protocol API (I may consider sharing some in  
> the future, but it's very hacked together and specific for my job).  
> Also, friends from the linux community have already integrated the  
> support on the socketcan driver, and provided a very nice  
> comparison of different devices APIs here: ftp://ftp.heanet.ie/ 
> disk1/sourceforge/s/so/socketcan.berlios/SLCAN-API.pdf
> I think that it will be a breeze to implement that protocol, and I  
> can help making it happen for very cheap (or even for free if I  
> find some spare time and motivation), on the mbed platform.
> Let me know if you need a PCB to test, I have some spare ones that  
> you can solder components on, but as (I seem to understand that)  
> you are based on hong kong, it may be cheaper to reproduce them  
> locally from gerbers than to ship them from here.
> Regards
> Cristiano
> Il giorno 29/ago/2013 03:25, "Mark Webb-Johnson" <mark at webb- 
> johnson.net> ha scritto:
>> P.S. What I would really like to do is get the OVMS CAN-USB  
>> adaptor working, and then give those out in large quantities. The  
>> more people decoding vehicle CAN communications, the more cars  
>> become open vehicles. But, to do that I need some one / people to  
>> step forward and help with this. The China manufacturer is  
>> standing by and asking me for the circuit diagram, but I've got  
>> too much on my plate at the moment to take on the CAN-USB hardware  
>> and firmware as well. Using a PIC32 microprocessor (with built-in  
>> USB support), and MCP2551 CAN controller, we can do this for a  
>> materials cost perhaps around US$30 (vs US$150 retail for the  
>> cheapest commercial units). I'll send out a separate 'appeal' for  
>> this, and see if anyone will step forward to help.

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