6-speed gear indicator display

[John Bates]

Here is a new thread just for developing a 6-speed gear indicator for the GS.
   
A discussion was started on starwalt's  thread by werase643 but I think this topic should have a thread of its own.

If interest develops, it will become quite involved, but fun.

I purchased a GSXR 3-wire neutral switch, mounted it on my GS in place of the original and IT WORKS!  
The switch on the 04 GS (Part no. 37720-01D00 I believe) may also work and may not need a spacer.

I did have to make a 1/8" (3mm) spacer because the GSXR switch is too deep for the GS.

I believe the part no. is 37730-35F10 and it's from the GSXR750 years 2000-2003.  
I believe it was also used on the other versions of GSXR.

It is a three wire system.  The pink wire carries a unique resistance depending on the current gear selection,
 the blue wire is the traditional switched ground to light the neutral lamp.
A third wire is for a ground contact which we don't have on the GS.

If any one is interested, chime in.  The more the merrier.

We will have to develop a small panel for a digital display and a small circuit board for the logic to convert
six resistance values (on the pink wire) to LED drive signals.

While we're at it, how about monitoring the system voltage with a LED or two to indicate too low/too high.

Soooooo:
Who can design a logic ckt with the lowest parts count?
Who can make ckt boards?
Who can build a small weather proof panel to mount a digital display and a couple LEDs?

I have already breadboarded a logic ckt  for two gear positions and it seems to work well.  
It uses comparator IC's, some transistors, resistors and a bunch of diodes to derive the signals
for a seven segment digital display. I'll post a parts count soon.

The resistance values (two readings each) and associated gear positions are:

1  825 - 830 ohms
2  570 - 573
3  14.97K - 15.1K
4  6.79K - 6.88K
5  2.74K - 2.76K
6  1.5K - 1.5K


Lets have some input!:mrgreen:

 

[werase643]

geeeeee
my 5speed indicator used 5 12V bulbs
and the gear indicator assy grounds a diff bulb in each gear
easy peasy japaneesy

and i might even add a 6th bulb....but no indication...would be 6th

[TheGoodGuy]

i will ask ppl i know if they want to do it.

JeffD would be our best bet at this.. he might know how to build it.

By the way there are 7LED  figure 8 box led's sold for a few bucks so that isnt a problem. The logic of shifting analog shoudltn be too hard. I will see if i can remember my early electronic days.

[goat]

Maybe I'm making this too hard, but my first thought is to use a low-power microcontroller with an analog to digital converter.

This is an example (specifically PIC12C671). I thought of a PIC microcontroller becuase I am using one at work right now and I know I can get ahold of a PIC programmer for free. In quantities of 25 or more, they are $1.93. Less than 25, $3. Thats just for the microcontroller+a/d, though. There would have to be other parts, too.

There is also a design contest for PIC microcontrollers. The winner gets free PCB made by the sponsoring company.

Granted, this is probably overkill but we could add stuff to it, too. The battery condition is one idea. Another thing that comes to mind is an O2 sensor, but I'm not even sure that's really useful to make or even possible using the PIC I mentioned above. Maybe I'm just trying to find a use for this 1-wire O2 sensor I have  :lol:

I'm definately interested in helping with this. It sounds like fun, but I'm a nerd like that  

[JeffD]

K I'll bite.

I tossed around the Idea of having a counter for each time the shift lever was used.  However this way would get "confused" if there was a mis-shift.

Then I though about some Hall effect switches but this would require chopping up the case.

Hmm....

I think using the resistance to calculate the gear would take quite a few parts, then the TTL for the display, this thing could end up rather large.    Here is what I see required to build a 6 gear display.

1 comparitor per "gear"  so thats 6
logic for a neutral condition.
power regulator
output LED's  or alot of logic for a 7 segment display

I dislike the 7 seg display Idea because it requires alot more logic/parts, and I dont see the benifit of being able to read "5" rather than see a blue LED on or Green... whatever.  Basically do the benifits outway the cost.  I dont think so.

I can do logic math to get the least amount of parts to implement a function, I just need the inputs, and outputs.  K-maps anyone?

Ok I'll stop babbling now.  Good Idea but there has to be a better way to implement this than using a bunch of comparitors.


 

[John Bates]

geeeeee
my 5speed indicator used 5 12V bulbs
and the gear indicator assy grounds a diff bulb in each gear
easy peasy japaneesy

and i might even add a 6th bulb....but no indication...would be 6th

Actually the six wires could probably be easily added to the GSXR switch.  That would allow for the simplest electrical solution.  Six contacts, six wires, six LEDs, but not very elegant.  

Might end up doing this after all. :dunno:

Keep the ideas coming.

[stefman722]

someone build it, and ill buy it. lol.

[Blueknyt]

GS450 has one stock, Bulb for each gear, 7 position contact switch and bulbs sit under the gages with numbers to be illumenated, perhaps this its time to rip open the speedo, or tach and mount 6 LED's to the inside, have them running clockwise for next highest gear.

[airbrush]

yah...would be nice to integrate it into the existing gauges

[FFDougK]

I've never used an A-to-D converter but I think that one would work here if someone knew how to use one.  I've always been fairly good with digital circuits and rather crabby on analog.  Anyway...here's some thoughts.

The resistances are fairly discrete in that should one place either a steady current source (output voltage would vary) or a steady voltage source (ouput current would vary) then an appropriate A/D converter should be able to quantize the values into digital bits.  However, due to the range of impedances, there would probably have to be some sort of op-amp, or other amplifier, circuit to get the output from the gear selector massaged into the proper range for the A/D converter (most will take inputs of 2-4 volts, 1-5 volts, 2-3 volts...it depends on the package).  Lets say for the sake of argument that we used a pipelined 8-bit A/D converter.  On the output we'd have 8 exclusive bits with each representing a quantized value within the defined input range.  From there those 8 bits can be fed into an "8-BIT Line --> 4-BIT BCD" encoder which will encode the 8 exclusive bits into a 4 bit binary coded decimal word.  Then a BCD-To-7 Segment Display Latch/Decoder/Driver chip can be used to convert from the BCD to the 7 output lines necessary for your standard 7 segment display.  A "latched" display driver would be used because otherwise the display would possibly blink on the off-clock cycles unless we designed our own flip-flop logic (which is built into the "latched" driver).  Add in the necessary caps and resists to support the chips and that should round out the display portion.

Like I said...I have no idea how to get the signal manipulated to get it into the A/D converter, but once it's there these 3 chips (and perhaps a couple of TTL buffer chips to keep our signals strong as they propagate the chips) should be all that's needed.  Personally...I'm doing my capstone project for my BS in EE this fall...if no one has it figured out by then I'll make designing this my senior project and let you know how it turns out.  I'd do it now...but I've got the MCAT coming...and it's pretty scary.  Good Luck!

[V8Pinto]

The resistance values (two readings each) and associated gear positions are:

1  825 - 830 ohms
2  570 - 573
3  14.97K - 15.1K
4  6.79K - 6.88K
5  2.74K - 2.76K
6  1.5K - 1.5K


Lets have some input!:mrgreen:

 

Can you please confirm the resistance values vs. gear?  This is an afternoon project if the resistance values change proportional (or inversely proportional) to gear selection but these R numbers move around.

To clarify, if you graphed the gear vs. R values of that switch quoted above, it would move around like my company's stock price.  The simplest circuit to do this would require a ramp, either direction, of gear vs. R.  

If your gear vs. R is correct, then the Suzuki designers used something else, more complicated.

[John Bates]

The resistance values (two readings each) and associated gear positions are:

1  825 - 830 ohms
2  570 - 573
3  14.97K - 15.1K
4  6.79K - 6.88K
5  2.74K - 2.76K
6  1.5K - 1.5K
 

Can you please confirm the resistance values vs. gear?  

I agree with you, the sequence is out of order, but it is correct.  I just went through the gears and measured again to verify it.  

I think the GS shift drum rotates opposite from the GSXR.  If you notice, a shift sequence of 2, 1, 6, 5, 4, 3 give a reasonable order of increasing values.  In either case neutral is between 1 and 2.

Although the switch can be mounted two ways there is only one way it can be mounted that matches the neutral gear position with the neutral contact.

All I can say is buy your stock in 2nd gear and sell in 3rd.

Maybe the 04 GS switch would match up better? :dunno:

[gavin]

Yep, looks like a 6-step log pot rotating in reverse from gear 2.  Any way you can crack the cover and change the resistance?  If not, I'm sure there is still a simple analog solution -- just don't know what it is yet.  Hmm...

-Gavin

[John Bates]

I see some interesting ideas summarized here.  Not in any special order.

No. 1: Probably the simplest:  six wires, six bulbs, rebuild the gear switch to get discrete ground from each gear position or steal from the GS450.
Keep existing neutral lamp.  Design a display panel for the bulbs. (werase643 and Blueknyt)

No. 1A: Same as No. 1 but use a seven segment LED display instead of the six bulbs.  Would require seven diode array ICs and
seven resistors mounted in a logic module. (The_good_guy)

No. 2: Use a PIC microcontroller for the logic functions.  Since the PIC is a digital device, we will need some conversion from analog to digital.  
There are probably many ways to do this.  Ideas anyone?  Does a digital  display makes sense here? ( goat)

No. 3:  For A/D conversion use comparators. Two quad comparator ICs will give us eight.  
Six for the gears and the remaining two can be used to trigger a couple LEDs to indicate too low/too high voltage of the electrical system.
For the gears the comparators can drive discreet LEDs or a digital display like No. 1A.  Keep the current neutral lamp ckt. (JeffD slightly modified)

No. 4: This sounds a lot like No. 3 but with binary coded decimal conversion to drive the LEDs. (FFDougK)

Thanks to all the contributors.

What am I missing here?  Anyone have any comments, additions, clarifications, doubts, suggestions, new ideas?
Are any of these impossible considering the environment?

I am working on No. 3.  Mainly because I'm more comfortable with the components and it's fun.  
I have the first two gears working on my workbench, driving LEDs.
Not counting power components, the ckt uses 9 resistors, 2 comparators, 2 LEDs and one transistor.

Expanded out to six gears it looks like: 29 resistors, 2 quad comparators, 6 LEDs and 5 transistors.

If I use a digital display I'll need seven diode arrays and seven resistors in place of the LEDs.

 

[airbrush]

you guys are hardcore....keep us updated...would like to see the final result..

[starwalt]

Great find John! I've been in Cleveland (Aggh! SNOW!) all week and am just getting back.

I vote with Goat on this. The PIC is the simplest to adapt, has all the glue logic internal, and is very cheap. The programmer circuit and software is free. There are dozens of books on the device and multiple websites that probably have a similar application with RTD's.

The display can be 7 segment to start with and change at any time. Once the basic code is setup, the display subroutine can be modified for the device. Even LCD's are used with PICs.

I am working on Conan's regulator and won't be able to devote much brain/bench time to this for a couple of weeks (work and school and family also). Any resources I have are available though.

[fettcols]

John... If you need help I'm pretty mean with the soldering iron...


Yes another Devry drop out!

[John Bates]

John... If you need help I'm pretty mean with the soldering iron...

Good deal.   Thanks

[goat]

ok, i've been thinking about this most of today. That's a bad thing because I have homework I should be doing    oh well.

Anyhow, any of those methods would work. I'm not so sure how expandable/upgradable that microprocessor would be. The easiest method of implementing it would use all of the I/O for the 7-segment display. There could be 2 inputs if we used 6 LEDs but the output would be limited to 2 LEDs or something that is on/off and doesn't require much power.

The easiest way around that would be to use a bigger microprocessor, but that would add cost and space.

No matter how the electronics are implemented, an indicator is needed. A cheap, weatherproof, small indicator that can be easily mounted on the GS. I looked around for anything that was weatherproof and wasn't having much luck. If someone else has better luck, that may be our best option.

What about using a small auto/marine gauge of some sort? If we could get ahold of empty gauge housings that were small enough, it could be mounted between the speedo and the tach. Unfortunately, this would involve drilling in the installation process, but it would solve the whole water issue if it's done correctly.

I'm not sure how practical any of this is, but maybe it will give someone else an idea.

This is a rough idea of placement. (please forgive the roughness. I did it in paint   )


These are pics of the gauge ideas:

[goat]

:lol: ok, I put the last post up hoping someone might have better ideas and I just got another.

What about making a gauge out of plexiglass and a boss (like a thick washer) machined out of aluminum (or plastic, doesn't have to be Al)? If two pieces of plexiglass were glued to the boss like a sandwich, we would have a cheap, waterproof gauge.

It would have to be about .5"-.75" thick, as long as it's thick enough to hold the 7-segment display or LEDs or whatever is used.

This "gauge" could then be taped/glued onto the instrument panel like in the picture above and the wires could be run to a separate box with the rest of the circuitry in it.

I hope this makes sense. I'm really bad at drawings/CAD, but I can try if no one gets it. Theres a reason I'm not a Mechanical Engineer  :lol: