pcmhacking.net

Thought you guys might be interested in this new, open source adapter that allows you to interface with your car's OBD-II bus. It provides you a serial interface using the ELM327 command set and supports all OBD-II standards:

SAE J1850 PWM
SAE J1850 VPW
ISO 9141-2
ISO 14230-4
ISO 15765-4 CAN
http://www.obddiag.net/allpro.html

Interesting. It looks gutsy enough to handle 4x vpw which is what interests me, but would need to be extended to support it. Being open source I assume there is no reason that could not be done with enough work. I think I will look in to that.

Where is VPW used and why would you need 4 chanels?

Here: http://pcmhacking.net/forums/viewtopic.php?f=3&t=3111 and not 4 channels, 4 times the speed (high speed) used for pcm flashing.

That was an interesting read (Intel tech note on J1850 implementation)

Are genuine vpw cables hard to come by? expensive? or just not that common?

Expensive. Mostly > $200. I used the AVT-852 which is a really nice interface that does a lot of the work for you with bus management in firmware but its costly to begin with and then postage from the USA is also expensive. Then there are J2543 cables in many forms, including expensive options like drewtech mongoose pro GM 2 and cheaper options like MDI clones from China. All of these are expensive also, and the J2543 spec is overly complex and hard to write for. A cheap device like the above which does support 4x and large packets would solve the hardware problems. The hardware looks capable and the software is GPL so I think I feel a plan coming on. I hope he sells hardware cheaply, soon.

I like where this is going

Antus, what is required at the hardware end? Is it simply a media converter from J1850 to RS232? Or must bus management be handled in firmware?

Minimum requirements is media converter, better if the interface can detect bus collisions and retry. The protocol isnt too hard, implementation of the day is here https://github.com/ObdDiag-Net/allpro/b ... bd/vpw.cpp

4x is literally 4x times faster, and should support packet size up to 4096 bytes plus header.

antus wrote:Minimum requirements is media converter, better if the interface can detect bus collisions and retry. The protocol isnt too hard, implementation of the day is here https://github.com/ObdDiag-Net/allpro/b ... bd/vpw.cpp

4x is literally 4x times faster, and should support packet size up to 4096 bytes plus header.

Looks good actually. But does need to check the bus a second time when it begins SOF incase of collision.