OBD MPGuino gauge

[cmags]

So I've been working on the MPGuino and just noticed this OBDguino project. Since I've got an '05, tying into the OBD-II port would be much easier I think than the VSS and injectors. I've already got a pair of MCZ33290EF's from when I was going to attempt an OBD-II -> CarPC interface (www.obddiag.net), and just ordered an OBD plug.

How far along is this code? Is it comparable to the MPGuino project yet - i.e, does anyone have a working MPG readout? Also, I haven't worked with much smaller than 0.10" components - is everyone just tacking wires onto the SIOC to connect to the board? Has anyone tried one of these adapters? Adapter Product Information

Finally, think there's any issue with splicing directly into the OBD wires? Having an OBD plug sticking out of the dash permanently may be a bit of a pain. I'm less afraid of splicing into OBD wires than ECU wires for VCC and injector pulses, and at minimum, the OBD wires are easier to get to.

Thanks!

[Magister]

I am working on it alone for the moment (ISO only). I just received my freeduino kit, it's not soldered yet.
The code for the moment compile but is not tested, it's in the google project, code/trunk.

I soldered small wires on the MC and will solder them on a proto PCB, yep it's small!

I made a cable but if you know what to do, no problem with just tacking the signal from the wire before the plug.

Check also the wiki in the google project.
opengauge - Google Code

[jmonroe]

If I can get subversion access, I would be happy to contribute (monroe.josh@gmail.com). I have an '01 Civic that is ISO9141 so, I will be working on that. My MC should go in the mail tomorrow.

Has there been any discussion on calculating for cars with MAP and not MAF?

[cmags]

Ok, sounds good. I've got my MPGuino built and I built it modular so I can swap out the VSS+Injector board for a new OBD board. I'm willing to help out as I can.

I'll read through your code soon, but the first thing I noticed at a qiuck glance is that you're using the LCD4Bit library. That library is hard-coded for certain pins on the 'duino (and I believe they're required to be consecutive), but the schematic you have (from the MPGuino) doesn't conform. Unless you have some code to rearrange the LCD4Bit pins, the LCD won't work as wired. I can upload the code to my 'duino tonight to see what happens.

LMK if I'm way off.

[cmags]

Originally Posted by jmonroe

Has there been any discussion on calculating for cars with MAP and not MAF?

Oh, carp, I forgot about this. I gotta check but I think in '05 the Impreza changed from MAF to MAP. I guess that's up to you and me, Josh.

[dcb]

So CMags, are you done looking at the LCD code for mpguino?

Originally Posted by cmags

I'm going to try to re-code the LCD class to more closely follow Yoshi's timing suggestions and see if I can kick this issue.

re: LCD library, I left it out of mpguino for three reasons:

1. it didn't work for me at the time.

2. I had carefully selected the pin usage to allow for future mods (left several multi purpose pins open). The library had some lazy code with the data pins being consecutive.

3. It increases the level of difficulty in installing arduino and getting it working. With the embedded lcd code it is just cut and paste. With the library it takes some explaining, and some percentage of non-geeks will never get it, and it adds overhead for functions we do not use.

[cmags]

dcb, I tried to change all of your code to the equivalent LCD4Bit code but couldn't get it working either. Maybe I made some mistakes in the conversion, but I couldn't find them. I did discover that some of my LCD issue was seemingly due to breadboard capacitance - I hardwired and only saw the issue once or twice, then couldn't get it to reproduce. I was just about ready to call it car-testable (and still might) when I saw this thread and thought that the OBD interface might be easier to splice into.

[tom43571]

Originally Posted by jmonroe

Has there been any discussion on calculating for cars with MAP and not MAF?

So far the code is for MAF but there is mention in the code of later modifying it to calculate using MAP and IAT. In post #6 LostCause explains how to calculate MPG if you dont have MAF. I also have a useful link to vehicle PID but I cannot be sure of its accuracy as it is in wikipedia: OBD-II PIDs - Wikipedia, the free encyclopedia

[cmags]

LostCause mentioned the conversion's inacurracy due to assuming AFR=14.7 and VE guessing. Both the MAF and MAP formulas use AFT=14.7 - maybe that could be adjusted by the fuel trim percentage for more accuracy? (Just thinking out loud)

[n8thegr8]

in case anyone cares, the lcd4bit.h file can be edited to change the pin assignments to fit your needs. you just need to make sure to assign the right pins to the right wires connected to your lcd. I didn't change mine, only used it as a reference when wiring it up, so my code should still work with the standard pinout.