Anyone knows how can I convert the mileage to digital values?

e1fnd · 06-13-2003, 03:42 AM

Hi... I am a newbie here... I have been refering to your forums and examples for the past 8 months.... Just a quick question... I am in the midst of developing a mileage calculator software... A few ideas I have... but none would be 100% accurate but mere estimation..... Is there a method where i can grab the values of the car's mileage to the carputer?

Hope anyone has any idea ...

chiark · 06-13-2003, 03:50 AM

Are you interfacing to the ECU?

e1fnd · 06-13-2003, 03:53 AM

That's what I heard ... need to interface the ECU... but I have no idea on the schematics and converting it to digital.... Is there a way u could recommend?

chiark · 06-13-2003, 04:00 AM

I'd start off by seeing if anyone else has done the same - have a good google.

If that fails, see if your car has a standard OBDII interface as that might greatly simplify things by defining standards etc.

If your car was an Impreza, either I or a friend could give you guidance, but as it isn't then I'm sort of stabbing in the dark.

FWIW, I'm going to interface to my ECU through a serial port connected to the car's OBDII connector using a Max232 chip to convert TTL to RS232 levels. The hardware is simple, it's the interrogation of the ECU that will be fun.

Or you could put a webcam pointing at your odometer, then OCR the resulting picture

Cheers,
Nick.

C4M · 06-13-2003, 06:13 AM

Do you have a GPS? This is how mine calculates distance travelled (although I didn't write the code, so don't ask me *how* it works!)

C!

aoLhaTer · 06-13-2003, 07:14 AM

Quote:

Originally posted by chiark
Or you could put a webcam pointing at your odometer, then OCR the resulting picture

lol
i like that one

oddcomp · 06-14-2003, 01:32 AM

go find a vehicle speed sensor off a older ford or otehr fuel injected beastie and a analog to digtal converter and use a rs 232 converter to run it into a comm port
i have some info on making a stand alone digispeedo but i don't think it would be too hard to adapt to computer .. but what do i know i just think up stuff i can't code to save my life

GTC · 06-14-2003, 11:27 AM

Might want to check out Vetronix.com (I think that's the spelling). They provided and ODBII interface called the "CarPort" with usb or com port interface (can't remember which) that connected to the Clarion AutoPC (Windows CE Radio), which was based on standard i/o ....

I don't know that they sell the device anymore, but you can sometimes pick them up on eBay, and they may have information on their website ...

GTC

dscustoms · 06-14-2003, 03:51 PM

OOh.. be careful. Any commercial hardware for interfacing with the computer will be severely protected from doing any damage to the ECU. Just because the scanner port is there doesn't mean you should be randomly hooking up your carputer to it. A glitch to the wrong pin could kill the computer. We've lost enough ECUs just trying to use them correctly at my local tuner shop, it would really suck to have it happen on the street instead of a track or garage.

DodgeCummins · 06-14-2003, 05:54 PM

I can't think of the name but...

You get a magnet, and a matching weight to put somewhere on the driveshaft, (or for you FWD cars on one of the axle shafts) then a simple reed relay (or other more sensitive sensor) closes every revolution.

Add up the revolutions, multiply by the distance traveled by the tire in one revolution...you have distance...

Not pretty but that is how the tachometer in my truck works...and the speedo on my bicycle.

GTC · 06-14-2003, 06:32 PM

I did some checking and the Vetronix unit has a USB interface, and as such should comply to the USB 1.1 standard (it's a few years older); since it was originally intended to hook up to the ODBII port and a small Windows CE computer, I wouldn't be overly worried frying anything ... There's no custom wiring involved (according to Vetronix, it's plug&play) unless you want to tap into door lock or window relays. I suspect the most involved part would be creating (or buying from Vetronix) the software compatible with standard Windows ...

GTC

cproaudio · 06-14-2003, 10:14 PM

GTC, why bother buying a WinCE OBD-II scanner and try to find win based software when you can get OBD-II scanner that's already windows based.
dscustoms, for OBD-II interface, There are 3 protocols VPW, ISO and PWM. When in doubt, get one that reads all 3 protocols and let the scanner auto detect. As for dianostic ports under the hood, those are propriatary. Each auto maker uses their own protocol. Those are the ones not to mess with unless you have the right scanner for them.
DodgeCummins, Or you can locate the VSS wire at the cruise control module. Or if you cant find it, you can goto the local cruise control installation center and ask them "hey which wire is the vehicle speed sensor wire for my 96 Dodge Ram 2500?"
He has a 99 Proton Pesona. It's new it's most likely fuel injected, There's gotta be a VSS wire somewhere going to the ECU. If it has ABS it definately has VSS wire.
BTW what do you mean by calculate the mileage? Do you mean calculate the vehicle speed as in how fast your going? or by actual "mileage" as in miles per gallon or in Malaysia kilometers per liter?

GTC · 06-14-2003, 11:59 PM

cproaudio - I agree 100% with you - I was only aware of the WinCE scanner since I had worked with the system before (other periferals, not that specific device), so I suggested it as a starting point ! There's certainly no reason to try to hack something together if a different "working" product(s?) on the market.

Can you recommend a good brand of scanner, and where more details might be found? I have basically zero knowledge about scanners, though I've managed to install a piggy-back computer into my car (VAFC controller) without doing any damage (made a custom harness instead of splicing!).

Thanks,

GTC

frodobaggins · 06-15-2003, 12:58 AM

Here is a good starting point

http://www.google.com/search?hl=en&i...=Google+Search

e1fnd · 06-15-2003, 10:22 PM

hahaha good one frodobaggins.... What I meant was on how can I take the miles that has been traveled by my car.... This is funny , good one... hahhaa: Or you could put a webcam pointing at your odometer, then OCR the resulting picture ... Just wanted to make use of carputer so it will calculate the distance travel... Anyhow... the suggestions that all of you made, is it already in your car? Or has it been tested out?