wrx, in car computers, and a bad idea
+ Reply to Thread
Results 1 to 13 of 13

This is a discussion on wrx, in car computers, and a bad idea within the Interior Mods forums, part of the Tech & Modifying & General Repairs category; H'lo all. Before I enter into the whole story, my question is this: Has anyone used a data acquisition cable ...

  1. #1
    Registered User inky's Avatar
    Join Date
    Jul 2002
    Location
    san francisco
    Posts
    10

    wrx, in car computers, and a bad idea

    H'lo all. Before I enter into the whole story, my question is this: Has anyone used a data acquisition cable (such as this:http://www.dataq.com/products/startkit/di194rs.htm), with a laptop or PC, to monitor the WRX's ECU? Beyond that, what about attempting both data aq. and control?

    Now the story.

    I've just purchased a harddisk-based Mp3 car stereo called a Riocar (aka empeg2). Although masquerading as an mp3 car stereo, it's really an in-car computer based on Linux, running on Intel's StrongArm chip, w/ 16megs of RAM, two IDE drive bays, and a serial port. It's developed an active hacking community behind it (see http://www.riocar.org). Aside from being able to store and play thousands of mp3s, GPS Navigation and OBD-II monitoring applications are in the works.

    The thought -- albeit a bold one -- is to use the Riocar in place of a Unichip. I'd use a data acquisition and control dongle to monitor the same wires that the Unichip monitors (crank angle, map, maf), and get the signals into the riocar's serial port. Then, I'd write the software to first, monitor the signals, and -- if all goes well -- look into controlling the signals piggyback style with the ECU.

    There are, of course, lots of unknowns, like whether it's wise to even consider using a linux based computer in a real time control application such as this. Also i'm sure tuners would be reluctant to assist me in tuning via such an unorthodox mechanism. I'm also reluctant to hack into the ECU wiring harness, but the Vishnu wiring harness runs about $120-$150 without a Stage Zero purchase, which is rather pricey for this experiment. (Anyone have an extra or unneeded one lying about, even if slightly hacked?)

    If you've thoughts or are interested in pursuing this, please feel to respond publicly or by email.

    -Vann

    P.S. Although the riocars are discontinued, they periodically appear on Ebay, and group buys of old stock are sometimes annouced in the "forums" off of http://www.riocar.org
    Last edited by inky; 07-31-2002 at 01:50 PM.

  2. Remove Advertisements
    ClubWRX.net
    Advertisements
     

  3. #2
    Registered User
    Join Date
    Mar 2002
    Location
    East Stroudsburg, PA
    Posts
    103
    I'd be concered about using a non-specialized computer. The goals are lofty, but I'd be worried about not just the realtime performance of the linux kernel, but also the throughput of the serial link.

    I mean.. I don't know what kind of throughput is required to not only monitor, but control the ECU.

    Just my $.02, but it's not worth it....

  4. #3
    Registered User inky's Avatar
    Join Date
    Jul 2002
    Location
    san francisco
    Posts
    10

    serial speed

    That's a good point: what are the limitations of the serial input?

    The DI-194RS data acquisition tool claims 240 samples/second, so I'm not so concerned with speed as a bottleneck, but perhaps with resolution. With only 10bit resolution, or 1024 bits to distinguish +/-10VDC (a 2000mV range), that's only about a 2mV resolution.

    What's the resolution of the Unichip? Maybe I should pose this question on the Cobb tuning boards.
    Last edited by inky; 07-31-2002 at 01:34 PM.

  5. #4
    Registered User Trypsin's Avatar
    Join Date
    Mar 2002
    Location
    ATX
    Posts
    584
    National Instruments makes a daq real time board that apps can be loaded into and ran independent of a pc. this sort of board is very stable and robust with very high sampling rates. i think taht if this was used it could be accomplished. i run various types instrument control on pc's and would never try to run an auto off one. unichip is a much more cost effective, personaly i do not think i would use a piggyback, but there are alot of people on this board making mucho HP with them.

  6. #5
    Registered User gryphon's Avatar
    Join Date
    Jul 2002
    Location
    DFW, Texas
    Posts
    363
    I am currently using the DeltaDash software (www.ecutek.com) to monitor my ECU via a laptop.

    I have wanted to build some sort of ECU control, being decent at programming. However, being very new to electronics, I decided against it. My first attempt was to be an electronic boost controller and progress from there.

    Let me know if you get anywhere with this, I'd love to learn more about it.
    2002 Subaru Impreza WRX
    Midnight Black Pearl

  7. #6
    Registered User inky's Avatar
    Join Date
    Jul 2002
    Location
    san francisco
    Posts
    10
    Trypsin, are you referring to devices like the NI PXI-814 ?

    I agree that something like the above wouldn't be cost effective compared to a Unichip. In my case however, I already have a $500 220mhz StrongArm based Linux computer in my car -- with a serial port -- so I'm trying to leverage that.
    Last edited by inky; 07-31-2002 at 01:47 PM.

  8. #7
    Registered User Trypsin's Avatar
    Join Date
    Mar 2002
    Location
    ATX
    Posts
    584
    yes, just from my experience a pc based controller has a much better chance of failing as well as data transfer rates, i have a 200MHz wintel based pc(hacked i-opener) i was planning to run deltadash on and also had the idea of piggyback pc on my miata, a coworker that worked at NI has a buddy that has LabVeiw on his rx7 and he recomended the R/T boards. , i am no expert in the field of ecu's, i do work in automation though and some of my robots have failed due to PC issues, would hate to be cruising and the car shut off. it would probably come down to some really crafty code and very quick data protocals to accomplish but could probably be done. let us know how it goes, i maybe way off in my reasoning.

  9. #8
    Registered User Trypsin's Avatar
    Join Date
    Mar 2002
    Location
    ATX
    Posts
    584
    Originally posted by gryphon
    I am currently using the DeltaDash software (www.ecutek.com) to monitor my ECU via a laptop.

    I have wanted to build some sort of ECU control, being decent at programming. However, being very new to electronics, I decided against it. My first attempt was to be an electronic boost controller and progress from there.

    Let me know if you get anywhere with this, I'd love to learn more about it.

    what sort of board were you using, i am also new to designing electronics and was told to check out PIC microcontrolers, they are suposed to be easy to work with and cheap.

    Inky,
    look on e-bay, my friend always finds good NI Daq stuff on there.

  10. #9
    Registered User inky's Avatar
    Join Date
    Jul 2002
    Location
    san francisco
    Posts
    10

    dataq instruments

    I'm just using the riocar device as a PC, with this serial data aq tool, DI-194RS, available at: http://www.dataq.com/products/startkit/di194rs.htm

    If all goes well, I'll buy a more expensive one that does control as well.

  11. #10
    Registered User Trypsin's Avatar
    Join Date
    Mar 2002
    Location
    ATX
    Posts
    584
    cool, i havent seen a daq device at such a good price, great place to start without pouring in the money, with a couple of sensors that could be used for egt, pressures and such, as well as ecu params. let us know how it goes, i may get one to.

  12. #11
    Registered User
    Join Date
    Dec 2001
    Location
    NC
    Posts
    90
    I think this would be the way to go:
    http://www.ecutek.com.au/
    '02 WRX Sport Wagon
    Midnight Black Pearl
    Godspeed Uppipe
    K&N filter
    Synthetic Oil
    more to come

  13. #12
    Registered User portablevcb's Avatar
    Join Date
    Jun 2001
    Location
    New Mexico, USA
    Posts
    44
    The RIO stuff is not the right way to go. Essentially it is just a big hard drive with a microprocessor and not much of anything else.

    What you really need is an imbedded control processor. They are common in the computer controls world. They are designed for real time processing and com e in a variety of flavors, from less than $1000 to tens of thousand.

    What seems like an attractive alternative is to buy an old laptop, load it with a real time operating system and a data acquistion/control interface and start programming. I have done this for gages using RTLinux and it works well. After using one for monitoring I would NOT use one for full engine control. They are too fragile.

    If you want to control the engine it is probably less expensive to buy a TEC3, Link, etc. After all, they are embedded controllers and are designed for the auto environment. They also already contain the basic programming for auto ignition and fuel controls as well as calibrated I/O for common engine sensors.

    After having looked at this problem for a number of years the cost and trouble of doing it yourself easily justifies the cost of the TEC3 type processor.
    vcb

  14. #13
    Registered User inky's Avatar
    Join Date
    Jul 2002
    Location
    san francisco
    Posts
    10
    Thanks for the input. I'm wary about using the riocar for control as well, so I'm going to try using it as a monitor tool and see where that takes me. I understand OBD-II on the WRX updates slowly, and I already have a cheap data acquisition serial cable.

+ Reply to Thread

Quick Reply Quick Reply

Register Now

Please enter the name by which you would like to log-in and be known on this site.
If you do not want to register, fill this field only and the name will be used as user name for your post.

Please enter a password for your user account. Note that passwords are case-sensitive.

Please enter a valid email address for yourself. We strongly suggest that you stay away from using aol, yahoo, msn, and hotmail accounts. Sometimes the mail server blocks the emails from our server. As a result you will not receive any notifications including the confirmation email.

Log-in

Human Verification

In order to verify that you are a human and not a spam bot, please enter the answer into the following box below based on the instructions contained in the graphic.


Posting Permissions

  • You may post new threads
  • You may post replies
  • You may not post attachments
  • You may not edit your posts
  •