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Thread: Pic + software based digital dash

  1. #21
    Raw Wave shotgunefx's Avatar
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    Quote Originally Posted by lez
    And they are ll crap because...(qutoe)

    But on most applications, a tire has to loose anywhere from 8 to 14 pounds of air pressure before there's enough of a difference in diameter to be detected by the wheel speed sensors

    (end quote)

    thats crap.

    I can tell just from the feel of my vehicle when driving if I am down by about 5lb, so if you need a machine to tell you why your car is flopping around corners like a dead fish, you should not be driving the car, or having a pc in it as you obviously dont need the distraction of music playing...(you may not know the engine is on..)

    This is not aimed at anyone on the group, but if you need to know its 8-14lb down.....

    obviously a system dreamed up not to actually work effectively, but just to satisfy laws etc.
    Keywords, "most applications".

    I've got the wheel speed sensors already, I've got to screw with them anyway to seperate traction from abs, so to me, it's worth trying it out as it's no cost as I have dozens of PICs. I've also got a memsic dual axis accelerometer that's going into the steering wheel as a tilt sensor (as soon as I figure out how to wedge it into the clockspring or alternatively find an oem steering sensor I can rob). So maybe I can get much better accuracy, maybe not. No harm in trying. If I found a direct tps that I could interface serially or something, I'd probably just buy that, but couldn't find one. Don't want a big ugly box hanging on my dash.

    I like how you imply it's stupid to try out when you have no experience with it. Yes 8-14lbs is worthless, but that doesn't mean that's what I'll get.

  2. #22
    lez
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    If those big companies cant get it more accurate than to detect best case 8lb's, what can be achived by _anyone_ with a few dollars worth of pics?

    Its all down to resolution of the revolutions(!), the difference is too small to measure amongst the big difference of wheel rotation.

    Plus you will need to re-calibrate everytime you wore the tyre more on one side of the vehicle than the other, and for the way some of us drive that could be more than once a day!

    you need to measure about 1/100 of a mm of wheel size, once you brake too hard and the tyre slides, more than 1/100 of a mm is gone in smoke.

    Its not practical, Its not accurate, it wont work, head, hitting and wall.

    I'm not saying you cant do it, I'm just saying I dont think you can beat the giants on this, use your time to find something else to measure like what we are on about in this thread, find a way to measure the rpm of a rotating cog/shaft that can be fitted to all cars and is passive so none of the car needs to be modified then we have the rpm for the dash sorted etc, or wheel speed from shaft rotation etc

  3. #23
    Raw Wave shotgunefx's Avatar
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    Quote Originally Posted by lez
    If those big companies cant get it more accurate than to detect best case 8lb's, what can be achived by _anyone_ with a few dollars worth of pics?

    Its all down to resolution of the revolutions(!), the difference is too small to measure amongst the big difference of wheel rotation.

    Plus you will need to re-calibrate everytime you wore the tyre more on one side of the vehicle than the other, and for the way some of us drive that could be more than once a day!

    you need to measure about 1/100 of a mm of wheel size, once you brake too hard and the tyre slides, more than 1/100 of a mm is gone in smoke.

    Its not practical, Its not accurate, it wont work, head, hitting and wall.

    I'm not saying you cant do it, I'm just saying I dont think you can beat the giants on this, use your time to find something else to measure like what we are on about in this thread, find a way to measure the rpm of a rotating cog/shaft that can be fitted to all cars and is passive so none of the car needs to be modified then we have the rpm for the dash sorted etc, or wheel speed from shaft rotation etc

    Maybe, maybe not. I haven't gotten that far with it. I would imagine the general implementations of it are generic. Collected some parts and put it on the todo list. We'll see when I try it. It's not a real high priority which is why I looked into it in like March and still haven't touched it.

    As far as solving most of the other problems you mention, I don't have to for my application. My car has most of those signals as nice 5v outputs out of the ecus. Tach & Speedo & wheel speed sensors are just nice 5v 4 pulse per revolution. I've been able to get my hands on just about every piece of factory service documentation which has helped immensely. Particulary the electrical training manual for my model.

  4. #24
    lez
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    Quote Originally Posted by shotgunefx
    Maybe, maybe not. I haven't gotten that far with it. I would imagine the general implementations of it are generic. Collected some parts and put it on the todo list. We'll see when I try it. It's not a real high priority which is why I looked into it in like March and still haven't touched it.

    lol know that feeling, I started the car pc thing last year with my 'spare' vehicle, not drove it in 18 months, only just got touch screen wired to find I was sold a duff unit, cant find half what I bought as I put it away for when the build starts etc etc

    Should have it back on my drive today then I can get going.

    I have 2 months before the road tax expires on the one I use now, so I need to get a move on.......

  5. #25
    Raw Wave shotgunefx's Avatar
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    Quote Originally Posted by lez
    lol know that feeling, I started the car pc thing last year with my 'spare' vehicle, not drove it in 18 months, only just got touch screen wired to find I was sold a duff unit, cant find half what I bought as I put it away for when the build starts etc etc

    Should have it back on my drive today then I can get going.

    I have 2 months before the road tax expires on the one I use now, so I need to get a move on.......
    I hear you. I spend half of my "working time" looking for stuff that's buried somewhere. Finally found my backup cam today.... buried in the trunk under the spare.

  6. #26
    lez
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    Lol I have one here in the bedroom I have only powered for about 60 seconds to test it when it arrived 2 years ago........

    Well my car is going to be brought home tomorro, just spoke to a friend back off his hols so we can move it now.

    I can then start my install for real instead of 'bench testing' all the hardware, its never even been connected to its proper amps yet.

  7. #27
    Super Moderator. If my typing sucks it's probably because I'm driving.... turbocad6's Avatar
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    see, now just wheel speed makes sense.... if it's only going to warn for a severely low or uneven condition...... tires should be checked periodically..... it's not to uncommon for a tire to loose a few pounds over a few months..... if your monitoring system is like your talking about it's entirely possible to have 23 -24 in the front & 22-24 in the rear without any warning at all..... that's a potentialy dangerous condition....seems pretty useless if the reason for a tire monitoring system is supposed to be for monitoring the tires....that system is nothing more than a false sense of security.

    I looked into tire monitoring systems & everything I ever saw was with transmitting pressure transducers..... I even found a system that will give a digital readout of exact pressure on each tire.... now that's cool & worth the effort, but I think it was like $400

  8. #28
    Raw Wave shotgunefx's Avatar
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    Quote Originally Posted by turbocad6
    see, now just wheel speed makes sense.... if it's only going to warn for a severely low or uneven condition...... tires should be checked periodically..... it's not to uncommon for a tire to loose a few pounds over a few months..... if your monitoring system is like your talking about it's entirely possible to have 23 -24 in the front & 22-24 in the rear without any warning at all..... that's a potentialy dangerous condition....seems pretty useless if the reason for a tire monitoring system is supposed to be for monitoring the tires....that system is nothing more than a false sense of security.

    I looked into tire monitoring systems & everything I ever saw was with transmitting pressure transducers..... I even found a system that will give a digital readout of exact pressure on each tire.... now that's cool & worth the effort, but I think it was like $400
    The smarttire system can be had from tirerack for $250.

    Another 50 gives you the "smart display" with all the info. If I could figure out how to interface with the basic system, I'd probably go for that.

  9. #29
    Super Moderator. If my typing sucks it's probably because I'm driving.... turbocad6's Avatar
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    I have a wholesale account with the tirerack...gotta check that out.... I want to do it stand alone if the display can be worked with... I'd rather have it as a seperate display & always working, independant of the pc

    I found a really nice unit that was made for rv's.... quality stuff & nice display.... all the cheaper stuff I found looked cheap

  10. #30
    Raw Wave shotgunefx's Avatar
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    Quote Originally Posted by turbocad6
    I have a wholesale account with the tirerack...gotta check that out.... I want to do it stand alone if the display can be worked with... I'd rather have it as a seperate display & always working, independant of the pc

    I found a really nice unit that was made for rv's.... quality stuff & nice display.... all the cheaper stuff I found looked cheap
    Well, my ultimate goal is to have the pc driivng the dash, so if it could be just one interface, I'd prefer it. Also don't have much room to embed stuff. I would imagine it's some sort of serial output though.

    Like to hear what you find out.

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