I need help devising something.....

I want to put in a gear display that will tell me what gear I am in on the dash. I figure I can take the RPM's and the MPH and write a small program that will determine what gear I am in and output the results onto a little screen.

Does anyone have the know-how to be able to build something like this or teach me how to do it? I know it cant be something that complex and could probably be done with stuff from Radio Shack, I just dont know how to do it.

Check out this thread to see more information about it:
http://forums.nasioc.com/forums/showthread.php?s=&threadid=488950

-Branden

Does the car have digital displays for RPM and MPH?

No it does not, its just the standard old MY00 gauges.

-Branden

They are analog gauges, but electronically pulse-driven.

You need to pick off the signals coming from the VSS (speed sensor) wire and RPM wire, then it should be possible to feed the signals into a programmable microprocessor and have it control an LED "digit" display. I'm a Mech Engr and haven't done this kind of thing for years, but any EE should be able to do it!

I'd be interested if someone figures it out. I think this would be cool. I'll have to talk to a buddy at work, maybe he can help.

Craig

Any help would be greatly appreciated, I would like to be able to figure this out.

-Branden

i'll ask my roomate to look at a schematic if you have one.. but if i remmeber right the cluster didnt have any chips on it.. it was all analog which would probably mean that the ecu is modulating the voltage to adjust the gauges. might be tricky to do w/o fubar'ing the cluster.. if you have the schematic i'll gladly run it past him he designs heart monitors for a living i think he could handle this :disco:

I will see what I can do, check out the other thread (link in first post) for more info.

-Branden

I bet you could do it without microcontrollers.

When I have more free time I can come up with something more concrete, but here's what pops into my head:

If you tap the ECU's "tachometer output" wire, you get a 0-12v square wave whose frequency depends on RPM.

If you tap the ECU's "vehicle speed sensor" wire, you get a 0-5v square wave whose frequency depends on engine speed.

If we're lucky, one of these is always at a higher frequency than the other. I would guess the tachometer signal is higher frequency than the VSS. Let's work with this assumption for the moment.

Set up a counter to count clock pulses from the tach signal (through a frequency divider if necessary). On the rising edge of the VSS signal, reset the counter. On the falling edge of the signal, store the counter's output into a latch. Connect the output of the latch to a decoder.

If done right, each of the decoder's outputs will be active only in a particular gear (modulo clutch slippage or being in neutral, although the latter can be detected via the neutral switch). These can drive a little LED single-digit display with a bunch of diode logic OR gates.

Hm, in words it probably sounds much more complicated than it is. And I'm sure someone well versed in microcontrollers could do it in like 2 seconds with almost any PIC or AVR. Oh well. :)

It would be useful to know the actual VSS and tach signal frequency specifications.

I have never looked under the boot but had an idea for a low tech approach.. would it be possible just to add some small push switches that hit the shifting shaft while in it's various positions? They could activate some different color bulbs? Well just a thought.

Even if there isn't room down there in the stock arrangement, maybe you could probably cut an appropriately-sized H-gate into some sheet aluminum or something with microswitches mounted on it, and mount it level with the center shifter console.

I like brunetmj's and vrg3's approach. You can use push buttons, Hall effect or reed switches with magnets, or optical sensors. Just run the switch outputs into an encoder, then to a decoder/driver and 7-segment display. Can't remember the CMOS chip numbers at the moment, I'm despondent over my Panthers -

if its a 5 speed, you could make a device that triggers a sensor that will display what gear you were in....I had a idea like that for my motorcycle....each time you shifted up or down, it hit a switch that then would increase the number up or down...

should of read the previous post....

space

I'm going to go with vrg3 on this one. That would be the way to go. Pipe that baby into a microcontroller and let it run the logic. Those things are cool as hell. I got an intelligent intercooler sprayer setup with one of those that is neat as hell.

Whatley.

What are they and where can you find them?

-Branden

Or shell out 90 bucks and be done with it.
http://www.bohnarmor.com/riderstations/datatool.html

or build this:
http://www.siliconchip.com.au/cms/A_30282/article.html

Originally posted by Silverwheels
I like brunetmj's and vrg3's approach. You can use push buttons, Hall effect or reed switches with magnets, or optical sensors. Just run the switch outputs into an encoder, then to a decoder/driver and 7-segment display. Can't remember the CMOS chip numbers at the moment, I'm despondent over my Panthers -

I was going to suggest using microswitches or optics as well. Somewhat akin to an arcade joystick.

You could have the 7-seg display wired so it showed a mirror image, then put it on top of the dash to do a HUD type thing.

Or you could put a gyroscope in the shifter knob :D