Slashdot Mirror
Making a Color LCD Dashboard Replacement?
DarkHand asks: "I've recently begun a project that would allow me to replace the analog gauges in my cars dash with a TFT LCD screen displaying a digital representation of the same. A number of animated analog-looking gauges would display the same information the physical gauges display, based on info from the ECU, as well as any other information the ECU has access to, such as intake air and coolant temperatures, throttle position, pop-ups for any warnings or error codes, etc. I'm looking to be able to add, remove, and customize the positions of the individual gauges, and possibly even make the background skinnable. Stability is crucial, so I'm leaning toward a Linux-based system. I have a few software friends who are willing to help on that end, but finding the proper hardware for such a project has proven difficult."
"I need something that either boots within a few seconds, or draws very little power when idle so as to remain active and run off the cars battery. A laptop or small computer boots too slowly, and draws too much power to stay on all the time. A high powered PDA with a larger screen would be perfect, but as far as I know it's not possible (or at least not easily doable, both in hardware and software) to change out to a larger display. The best option I've found so far is the venerable Gumstix board, but as far as I can tell, LCD support is still shaky. Has a similar homebrew project been done before, where I could go for wisdom? What kind of hardware would the Slashdot crowd use in such a situation?"
Wouldn't this kind of things have to be certified first? I mean, I can imagine a scenario where the driver would say to the police: I didn't know I was going 120 /h, look, my gauge pnly says 20 :-)
I'll do the stupid thing first and then you shy people follow...
Well, it strikes me that the obviously wisest choice here is to leave well enough alone. Mechanical components are so much more reliable, there's no comparison.
Plus, I'm not sure what the regulations are in your country/state, but here in in Australia it is an offence to reset an odometer unless an engine has been replaced (in which case the vehicle has to pass an inspection by agents for the authorities). I'm pretty sure that kind of modification, where the gadget could be easily reset without trace would be illegal.
I'm sure there must be more useful avenues to apply geeky talents.
You won't be able to see it in the sun, this is a bad idea...
Most manufacturers deliberately have their speedometers read high by several miles per hour (my MINI Cooper reads about 3mph high at low speeds - going up to 5mph high at 80 to 100mph).
They do this for liability reasons. If for some reason the gauge is off by a little bit and you get a speeding ticket (or worse, you get into a wreck) - then they don't want you to sue them claiming that the speedometer was reading too low. By making them read a little high - then even if they get mis-calibrated (eg due to tyre wear, higher-then-recommended tyre pressures, etc) they still won't be reading *LOW*.
So - if your LCD speedometer is off by a bit, you won't really be that much
worse off than with the stock speedo.
As someone previously suggested, you might want to look at the OBD-II specification. All cars sold in the USA in the last 10 or so years have a port located down under the steering wheel somewhere which delivers a wealth of interesting information in a more or less standard format. You can certainly read RPM for your tachometer - along with the rotational speed of each wheel independently and a bunch of other fun stuff. You could probably interpret the error code readouts it gives you to light up warning lights in a meaningful way.
www.sjbaker.org
We can provide you with hardware in exchange for writing the software.
We've been in this space for quite some time now and we're very familiar with it.
Our site: www.dashwerks.com
We're linux and RTOS embedded...
Don't think that a small group of dedicated individuals can't change the world. It's the only thing that ever has.
I drove a truck for about 1 year with no speedometer (because it broke). I didn't get pulled over once in that time frame - probably because I knew about what a safe speed was. I know people who've disconented their speedo for a while when they're planning to trade a car, so the odometer doesn't keep going up. :)
I've been puilled over and tried to get out of it with a "I just put in new rear-end gears" (which was true - going from a 2.73:1 to 3.46:1 is a big jump), but I got the same ticket I would've gotten if I'd just said "I don't know, how fast *was* I going?". I'm just glad that the cop didn't see me before the corner - when I'd just passed 3 cars in a row and had run up well into the 3-digit range (according to the tachometer - I knew damn well how fast I was going).
You bring up a good point, though. It's probably illegal to have no speedo in most places. It's not illegal anywhere in the US to replace a speedo, though. AFAIK.