[Magister]

(from an old message)

Originally Posted by jmilk

First off, I think ELM is the wrong way to go.

Yes and no, for version 1.0 at least it gave me the opportunity to develop all the higher level code of the OBDuino easily.
Also the ELM327 can interface with a lot of Windows softwares and 30$ + a few components is still better than a $100 interface.
I had to deal with ELM support and they are great and very responsive, their chip is nicely programmed, stable, and powerful too.
In fact, the only "no" is the price...

Originally Posted by jmilk

Instead, I would go with the MC2515/MC2551 combination.

Now that the code is very stable, I am looking at the MCP2515/2551. I am using a free CAN library that interface with the 2515 thru SPI, I adapted the code to use this instead of the ELM (with some #define). I designed a schematic interface (I'll post it in the project wiki) and started to built it. All I need now is a 2515 but MC sample is temporarily unavailable but everything else is ready

Originally Posted by jmilk

Advantages:
- Less than $5 in single quantities, less than $3 in 100+.
- Available in DIP (and smaller form factors)
- SPI instead of RS23x -- forget baudrates, AT-commands and all that junk + run full-speed.
- ELM still calls their (expensive!!) chips "experimental", while Microchip is already on the 2nd generation of production.
- MC isn't going anywhere... ELM?
Disadvantages:
- Slightly more code.

I have to agree, luckily enough for the "disadvantge" there is CAN library and MCP2515 SPI library available freely.

Originally Posted by jmilk

Secondly, I think the arduino/ATMega platform is fine; AVR's automotive chips with built-in CAN are interesting, but beyond the reach of a hobbyist as far as handling goes. If code size really becomes an issue, there's the option of the ATmega328 with 32K flash. Additional advantages of the Arduino platform are the bootloader and IDE; and the 168 and 328 are available in DIP forms.

Right, an AT90CAN could do the job but there is no "arduino" like for it.

Originally Posted by jmilk

For my CAN scenario, I'm looking at $10-$12 in parts excluding the PCB, LCD and connector. The whole thing, in single quantity, should come in under $30 -- that's less than the ELM chip alone.

Right, the OBDuino "CAN only" is an MPGuino + $10 of components (or less).

Originally Posted by jmilk

- Replace the "trip computer"
- Add instant mpg
- Add avg mpg last x minutes/miles, since last stop, since beginning of trip, today, this week, this month.
- Track/log mpg for different drivers.
(and a few more)

Well, there is 2 separate trips for the moment, but adding more just add a few bytes so it's possible to extend it

In resume, ISO can be done with a Freescale 33290 (untested) and CAN with MCP2515. For VPW/PWM for the moment the only solution is an ELM322/320.