Obdii Vpw

[schu4647]

That wipes me out of ideas. I guess PIC's have limitations.

[DynamoBen]

More detail on VPW:

http://www.intel.com/design/intarch/papers/j1850_wp.htm

[DynamoBen]

After looking this over I think the inbound vpw could be read by either looking at the pin state and comparing it with Timer1 or using the CCP module and having this occur in the background. I have determined that Pulsin would be too slow to grab the whole packet.

I'm kind of leaning toward the CCP module after reading the following.
http://ww1.microchip.com/downloads/e...Doc/41215B.pdf
(see tip #3 and #4)

The problem is I have never used the CCP module before. Anyone have any experience with it? Advantages/Disadvantages to CCP versus Pin State/Timer1?
Examples might be helpful.

[Acetronics2]

Hi, Ben

as your injectors and odometer wiring are accessible, may be it would be simpler to take the infos at the very source ...

I remember Elektor magazine committed such a project ( in analog mode ...) 10 or 15 years ago ... If you want, I dig into my old papers ...

I crossed it some weeks ago ...

Alain

PS: from circuit cellar source, It would be much better to re-build the project from the C files downloaded ...ohhhhh, yeah , here it's PbP World ... sorry !!!

[DynamoBen]

Acetronics, you’re missing the point. I'm interested in creating code to read and write to the vpw buss. (I can't stress that enough) I'm not interested in a work around or using the off the shelf code from the circuit cellar project.

I have used the ELM devices in numerous projects and am now looking into bypassing this device and putting the pic directly on the buss.

[Acetronics2]

Hi, Ben

I see ... you were only talking of a fuel gauge, in your first post.

Alain

[srspinho]

Hi friend,

I know it´s a bit late for this post, but here we go ...

I was making some experiments with my new Opel Corsa (Brazillian version - small 1.0 litre engine - 79 Hp)

The car is good, but I don´t use gasoline, but Alcohol. The performance is good but the consumption is very high,
specially on heavy duty or high speed.

I did a small "on-board" (with lot of help from this forum) computer for my old Opel Corsa, but without Fuel Consumption display.

Now, i Would like to implement that function.

I Did some search on internet and I foud this :

http://www.eelkevisser.nl/fuel.htm

Don´t worry about the display. This display is just an I2C module made for GM/Opel cars, like Astra, Corsa Meriva etc.

They are monitoring the Car´s speed sensor and the Injector´s "on-time"

My doubt is : do you think the method used by the author really eficient ?

Did you have some progress on implementing the GM VPW ? (i´m still trying with an old GM´s corsa ECU on my desk - but with out success).

Regards

Sérgio