Thread: New, Free, OBD and GPS Tool

Very nice. Just bought my first motor last week. Been reading allot of OBD II stuff. This seems one of the more usefull tools iv come across. Mainly 'cos im a linux fan!!

Good Job!

will look forward to trying it out when i finally settle on a converter!

Neat.

Originally Posted by chunkyks

Heya All,

This is my first time posting here, I'm mostly trying to drum up a bit of interest for a new project I've been working on.

The itch I've been trying to scratch [ie, software whose availability is sorely lacking] is twofold:
1) No good software for OSX and Linux [and other POSIX-type systems]
2) No software for logging OBDII data alongside GPS data and trying to do something useful with it afterwards

<cut>

Anyways. Lemme know what you think, if anyone tries it [or would like to suggest features or something]

Gary (-;

Welcome fellow "newbie"

Some ideas for your program might be:
Log speed and if possible, throttle possition. (realy nice to check if the walleyparker is to be trusted the next time, or to check if the garage have used the car for anything else than to fix a problem, ie. driven around half the city and all of the freeways).

Or where I mistaken on the green and red bars? (I though they where signal strength).

Log speed and if possible, throttle possition. (realy nice to check if the walleyparker is to be trusted the next time, or to check if the garage have used the car for anything else than to fix a problem, ie. driven around half the city and all of the freeways).

Already have both speed and throttle position. In the screenshot posted above, height of the graph is the speed you're going, and the color indicates the MPG you're getting. For now, it just divides the mpg into five 20-percentile groups, so whatever you're seeing is normalised over the car you're driving.

Short version, green good, red bad. Red when you're accellerating, green when you're slowing down :-)

Throttle position isn't indicated on the google earth export, but...

I want to calculate fuel consumption. Momentary, since start and since reset.

=710.7*vss/maf

I've added a new tool called obd2csv to the package [currently only in svn, will be in 0.3 release]. If you run obd2csv on a log, it exports everything in the database, plus a couple extras calculated [eg instantaneous mpg]


The trivial way to add things to log is by looking in obdservicecommands.h. In the big table, if you make the middle column something human-readable instead of NULL, then the software will log that too. I haven't verified that I have the correct codes there.


Keep in mind that this software still runs on a laptop, which you probably don't want to leave at your mechanic. If your mechanic going on a joyride is a concern, perhaps you could check the odometer before and after, or maybe get a more trustworthy mechanic :-)

Gary (-;

I have downloaded the code, and maybe I can work out how to implement a COM module for win32 from it!

... COM? ew. Isn't that dead already?

A windows port may be nontrivial [in the sense of "easier to write completely new code"]. I'm using gpsd for logging gps, which is POSIX-only and maintained by ESR, who is notoriously windows-hostile. I'm using POSIX apis to access and control the serial port, so again... might be hard to get working on windows.

On the other hand, there's nothing at all complicated in my software, so cygwin might handle it just fine. I see some people have gpsd working on cygwin, and I think you need a total of about six #defines and the tcsetaddr function to do 90% of the hard work I'm doing to access the OBD port. All the sqlite code should be perfectly portable. All of obd2kml and obd2csv should be nothing more than C99+sqlite.

If you port it to windows, I'd be interested in taking a look :-D

Gary (-;

Hm, I thought I posted answering some other stuff, but evidently not!

I want to calculate fuel consumption. Momentary, since start and since reset.

mpg = 710.7*vss/maf

There's a new tool if you check out the recent svn [will be in 0.3], called obd2csv. obd2csv dumps everything that was logged into a .csv file which you can open in any spreadsheet and use your favorite graphing tools from there. In addition to that, it does a couple calculations, and one of the columns exported is instantaneous mpg.

Log speed and if possible, throttle possition. [...] Or where I mistaken on the green and red bars? (I though they where signal strength).

In the chart you see there, height indicates speed at each point. Color indicates mpg at the time. Note that the mpg is divided into 20-percentiles which is cheesy but about 2 minutes coding, vs anything else which was a lot more. In short, green == good mpg, red = not good mpg, and it's normalised over that trip [only calculated when moving]. Hopefully your prius will actually show the same graph colors as your viper in this scenario.

Future graphs [once I figure out better ways of doing the statistical analysis] will make it clear that an M6 wasn't as efficient as a Trebant.

Throttle position and instantaneous speed are two of the things stored in the log, and using obd2csv will dump it for you. They're trivial to add to google earth too, but ... well, throttle position just isn't a very interesting thing to show on google earth. RPM is much more interesting [to me], and you'll see that that's a trace in the google earth file [off by default, just check the checkbox to see it].

Gary (-;