Go Back  RX7Club.com - Mazda RX7 Forum > Tech and Performance > Interior / Exterior / Audio
Reload this Page >

Cluster issues? My solution...Speedhut gauges retro fit.

Interior / Exterior / Audio Talk about interior and exterior mods including audio.
Sponsored by:

Cluster issues? My solution...Speedhut gauges retro fit.

Old 09-13-16, 08:41 PM
  #201  
Make an assessment...
iTrader: (2)
 
speedjunkie's Avatar
 
Join Date: Aug 2004
Location: Colorado Springs, CO
Posts: 4,146
Liked 6 Times in 6 Posts
Cruise Control update

So as it turns out the little circuit board my buddy made does work, I just didn't have one of the wires spliced into the stock wire well enough, it wasn't even making contact. There is still an issue but I think it can be fixed. It won't hold speed above 50mph, but I tried everything between 10mph and 50mph and they all worked, and all the stock buttons worked.

SO CLOSE!
speedjunkie is offline  
Old 09-17-16, 01:06 AM
  #202  
Goodfalla Engine Complete
iTrader: (28)
 
Monkman33's Avatar
 
Join Date: May 2005
Location: Kennewick, Washington
Posts: 3,201
Liked 9 Times in 8 Posts
Originally Posted by speedjunkie View Post
So as it turns out the little circuit board my buddy made does work, I just didn't have one of the wires spliced into the stock wire well enough, it wasn't even making contact. There is still an issue but I think it can be fixed. It won't hold speed above 50mph, but I tried everything between 10mph and 50mph and they all worked, and all the stock buttons worked.

SO CLOSE!
your issue is the signal is not being halved.

I believe it is supposed to function from approximately 20-100mph. This means your pulse count/time is currently about double what the cruise computer is expecting to see at a given speed.

At least, that is my ever-so-slightly educated guess on this topic.

Last edited by Monkman33; 09-17-16 at 01:09 AM.
Monkman33 is offline  
Old 09-17-16, 01:45 AM
  #203  
Make an assessment...
iTrader: (2)
 
speedjunkie's Avatar
 
Join Date: Aug 2004
Location: Colorado Springs, CO
Posts: 4,146
Liked 6 Times in 6 Posts
Well your ever-so-slightly educated guess HAS to be more accurate than my not-even-close-to-an-educated-guess lol.

I'll run that by the two mad scientists and see what they think about how to remedy it. I'm very excited about having/getting cruise control again, although I hardly ever have a reason to use it lol.
speedjunkie is offline  
Old 09-17-16, 10:10 AM
  #204  
Goodfalla Engine Complete
iTrader: (28)
 
Monkman33's Avatar
 
Join Date: May 2005
Location: Kennewick, Washington
Posts: 3,201
Liked 9 Times in 8 Posts
Originally Posted by speedjunkie View Post
Well your ever-so-slightly educated guess HAS to be more accurate than my not-even-close-to-an-educated-guess lol.

I'll run that by the two mad scientists and see what they think about how to remedy it. I'm very excited about having/getting cruise control again, although I hardly ever have a reason to use it lol.
I recently contacted speedhut, and they said for a whopping $20, they can add the square wave cruise control output to their GPS speedometers. It is a square wave output at 4000 pulses per mile. I will see if the other person doesn't mind me posting our PM conversation on the topic. I am definitely not an expert, just really really hopeful for a solution to make cruise work and have been mulling it over off and on for a few years now.

Last edited by Monkman33; 09-17-16 at 12:19 PM.
Monkman33 is offline  
Old 09-17-16, 12:56 PM
  #205  
Goodfalla Engine Complete
iTrader: (28)
 
Monkman33's Avatar
 
Join Date: May 2005
Location: Kennewick, Washington
Posts: 3,201
Liked 9 Times in 8 Posts
Here is a conversation that HalfSpec and I had on this topic, posted with permission, and some personal chat has been removed to keep the post on topic:

Originally Posted by Monkman33
Lane,

If you decide to ever make anything electronic, I'm having a heck of a time trying to figure out how to keep cruise while going to speedhut gauges. I am currently looking at the electronic speedos they offer (non gps) since they have a cruise output. Just not sure if the cruise output will be the right pulse count for the FD cruise.

Nathan
Originally Posted by HalfSpec
Nathan

The cruise control wants a pulse count that's half of the speedo's pulse count. I.E., if you're getting a pulse count out of the speedo's sender unit of 8,200 ppm @ 60 mph (this is actually what it puts out), the cruise control would want 4,100 ppm @ 60 mph.

The only tricky part is that the FD's speed sensor outputs a true sine wave. 0Hz for 0MPH, 137Hz for 60MPH, and 410Hz for 180MPH. That's a true sine wave which oscillates between a positive and negative voltage. This goes straight to the Speedo and it moves the speedo's needle:

http://vid917.photobucket.com/albums...psqlimrbmq.mp4

The speedo then 1/2s this frequency and sends it to the CC as a open collector signal. The CC unit expects an input that provides a GROUND at the half the frequency of the speedo. This may sound strange if you aren't familiar with open collector + pullup resistor waveforms, but the end result is that a pulse train waveform is created from this grounding pattern which is input into the CC unit at half the frequency of the speedo's sender output. This is the best diagram I have that explains the process:



I say all that to say, the Dakota SGI-5E technically has the hardware to do the job:

Universal Speedometer Signal Interface

I wrote the above description so you can get an idea of what needs to be done so you can have a conversation with Dakota or Speedhut if you wish. I certainly can't spare the time to work through or debug an installation with the SGI-5E, but if Dakota will take the time to walk you through the process, maybe it will be a viable solution. Same goes with Speedhut. If they can confirm their speedo can accept a sinewave input and output an open collector signal at half the frequency of the input signal you should be in business, but your on your own with either option.

Looking at the SGI-5E manual I'd say you'd want to use the Signal In to accept the FD speedo sender's sinewave output and use the calibrated 'oc' output signal (Out 2) to send the open collector signal to the CC at half the frequency of the input signal.

Hope that helps
Lane
Originally Posted by monkman33
Lane,

You're going to **** a brick. I looked at the different speedos from speedhut. The programmable digital has the output for a cruise control, and get this; its at 4000 ppm, square wave 0-5v. The GPS speedo does not.

However, I called speedhut, and for $20, they can add the cruise output to the GPS speedo.

And for 10$ they can change the backlighting color on the lcd.

My entire problem just simplified into a $20 upgrade.

Thank you for the technical insight that will allow me to move forward with this project.

Nathan Monk
Originally Posted by HalfSpec
0-5V square wave output ≠ open collector output. I seriously doubt this is an insurmountable problem, but the fact of the matter is that the Q-01 pos E input to the CC module already has a built in pullup resistor to 5v, because it's anticipating that it needs to pull up the waveform to 5v when the connection to ground via the open collector transistor in the stock cluster has finished its pulse. Two parallel pullups may produce unexpected results. Honestly I don't know exactly what would happen in this situation. Best case, they work together and you simply pull up the waveform faster on the rising edge. Worst case, the parallel pullup is no longer "weak" and overpowers the OC transistor making it so it can't pull the waveform to ground. Medium case, the 5V reference at the other end of each pullup resistor (CC input and the Speedhut speedo output) are not exactly the same 5V which may result in a less precise square wave on the rising edge.
Most designs I've seen that tackle this job at a universal level usually have a pullup resistor that you can disable if there is already a pullup in the circuit which would cancel out any potential problems. If that's not an option, it's still worth a try at $20, but go into it open eyed.

4000 ppm ≠ 4100 ppm. Again, probably not an issue, but a ~2.5% difference in what the CC is told and what the car is actually doing may perhaps cause a noticeable transition when switching over the CC.

I say all that not to dissuade you but rather pick at the details so if it doesn't work straight off the bat you'll have things you can investigate to iron out any problems that could potentially pop up.
If it does work, please let me know. I still get a good bit of PM/Emails from folks like you asking about my old plans and I'd love to have somewhere I can send them for a real solution

Lane
Originally Posted by Monkman33
Lane,

Very good point on the double pull-up. I will ask the guys at speedhut to compare the circuits for compatibility.

As for the 4100, vs 4000.

Since pulses per mile is a distance not a speed, the only parameters that will be affected will be the speed that the cruise control computer thinks the car is going.

So if the cruise compute only activated between 25mph and 100mph, it will now only work between 26 and 102.5 mph.

All cruise does is modulate throttle to match the 'set' speed of the pulses. So if 60mph is 4100 pulses per mile and minute, it will try to keep receiving 4100 pulses per minute.
So the difference would be it would see 4000, and just try to match 4000 pulses per (approx) minute/mile @ 60mph, while it thinks it's at 59 mph or so. But the job of the cruise computer is just a comparator. Read pulse count rate and attempt to keep it. I bet they use a PID style programming. But I don't know for sure.

I am hoping this all works out well. I definitely need to address the signal conflict possibility though. Would suck to get it all together and not have it work.

Nathan Monk
Originally Posted by HalfSpec
I must admit, I have been stuck on signal matching, vs understanding what the CC is actually doing with the signal. Up to this point, I haven't really considered how the CC is doing what it does, I just knew that giving it what the stock cluster gives it would be the best chance for success. That being said, I expect you're 100% correct in how the CC works. That would definitely be the safest / most foolproof way of doing it. If it works as you described, I would agree; the difference between 4100ppm and 4000ppm wouldn't matter.

Lane
Originally Posted by Monkman33
Lane,

Considering all of the information and insight you've given me, I am honored I could help at all.

So, I was looking at the instructions on the speedo. The bottom has an interesting "optional" method of wiring. Makes me think there is a better chance of it working straight wired.

Or am I getting something backwards in my wiring logic?


Originally Posted by HalfSpec
Good news, based on that diagram and the fact that they recommend a resistance value range, I'm almost certain that the pullup is something they expect you to add/handle. In that case, just leave it off and the CC input will pull the signal up to it's expected 5v.

Just a note, on that diagram they have you connecting the pullup to 12V, which would make a 12V pulse train, not 5V.

Personally, I'd hook it up first without a pullup and see if it works. If it doesn't work as expected and you're out of options, you could try hooking up the external pullup to 12v as a last resort. I feel like it's a band-aid vs solving the root issue, but I know that some folks have solved automotive OC waveform problems by boosting the amplitude of the waveform. In this case you'd be boosting to a 12V waveform. Like I said, I wouldn't try it first, but worst case, its something you could try before giving up and it shouldn't hurt anything.

Best of luck
Lane
HalfSpec/Lane has been beyond helpful even though he is busy with other things, so a big thank you for his input is merited.
Monkman33 is offline  
Old 09-19-16, 01:23 AM
  #206  
Make an assessment...
iTrader: (2)
 
speedjunkie's Avatar
 
Join Date: Aug 2004
Location: Colorado Springs, CO
Posts: 4,146
Liked 6 Times in 6 Posts
Thanks for posting that! I sent a link to this thread to my two buddies to see what they say. The guy that made the board is going to make another one a little different and see if it works.

I read the first few posts and skimmed through the link for the Dakota Digital interface. I think I have an idea of what the modified Speedhut speedo and Dakota interface would do. But probably not lol.
speedjunkie is offline  
Old 06-29-17, 08:43 PM
  #207  
Junior Member
 
Join Date: May 2017
Location: British Columbia
Posts: 13
Liked 1 Time in 1 Post
Looks great!
lcfd is offline  
Old 11-28-17, 08:30 PM
  #208  
Goodfalla Engine Complete
iTrader: (28)
 
Monkman33's Avatar
 
Join Date: May 2005
Location: Kennewick, Washington
Posts: 3,201
Liked 9 Times in 8 Posts
I finally placed my order for my gauge set!

I am going to be using their pulsed output to see if the cruise control is functional from that.
Monkman33 is offline  
Old 12-05-17, 07:06 PM
  #209  
Make an assessment...
iTrader: (2)
 
speedjunkie's Avatar
 
Join Date: Aug 2004
Location: Colorado Springs, CO
Posts: 4,146
Liked 6 Times in 6 Posts
Sweet! I'm excited to hear back about that. I think I'm just gonna try to go that route myself if it works.
speedjunkie is offline  
Old 08-28-18, 06:06 PM
  #210  
Make an assessment...
iTrader: (2)
 
speedjunkie's Avatar
 
Join Date: Aug 2004
Location: Colorado Springs, CO
Posts: 4,146
Liked 6 Times in 6 Posts
I got my speedo back from getting modified to run cruise control. Now I just need to figure out what to hook the new wire to. I'll report back once I finish testing it out.
speedjunkie is offline  
Old 10-22-18, 12:52 AM
  #211  
Make an assessment...
iTrader: (2)
 
speedjunkie's Avatar
 
Join Date: Aug 2004
Location: Colorado Springs, CO
Posts: 4,146
Liked 6 Times in 6 Posts
Turns out the first time I got the gauges back they weren't right, so I sent them back. I got it in and working and cruise control works. It was well worth the $20.
speedjunkie is offline  
Old 02-13-19, 04:52 PM
  #212  
Junior Member
iTrader: (2)
 
Join Date: Jun 2016
Location: Rochester NY
Posts: 26
Liked 1 Time in 1 Post
Originally Posted by speedjunkie View Post
Turns out the first time I got the gauges back they weren't right, so I sent them back. I got it in and working and cruise control works. It was well worth the $20.
Am I correct in assuming you do not have the GPS speedo? You have the programmable speedo? Or, if you do have the GPS speedo, is that was they were able to modify for the $20?

Edit: I re-read through the thread and see that Speedhut can modify the GPS speedo to include the square wave output at 4000 pulses per mile. I will give them a call tomorrow to get this moving. But, can you tell me what you connected the output to get your CC working? Appreciate the help!

Last edited by Four4; 02-13-19 at 05:07 PM.
Four4 is offline  
Old 02-13-19, 08:28 PM
  #213  
Junior Member
iTrader: (2)
 
Join Date: Jun 2016
Location: Rochester NY
Posts: 26
Liked 1 Time in 1 Post
I just got an email response from Speedhut. I too have a GPS speedo and they said they would add the analog output for $20 + $12 in return shipping. Ill be shipping mine out soon.

Then it appears we tie this new wire into the G/R wire on the OEM speedo plug. At least that is what I am getting from a few threads.
Four4 is offline  
Old 02-15-19, 10:25 AM
  #214  
Make an assessment...
iTrader: (2)
 
speedjunkie's Avatar
 
Join Date: Aug 2004
Location: Colorado Springs, CO
Posts: 4,146
Liked 6 Times in 6 Posts
Originally Posted by Four4 View Post
Am I correct in assuming you do not have the GPS speedo? You have the programmable speedo? Or, if you do have the GPS speedo, is that was they were able to modify for the $20?

Edit: I re-read through the thread and see that Speedhut can modify the GPS speedo to include the square wave output at 4000 pulses per mile. I will give them a call tomorrow to get this moving. But, can you tell me what you connected the output to get your CC working? Appreciate the help!
Yep, I have the GPS speedo. I don't remember which wire I connected it to, but I might have it documented somewhere. It might have been the G/R wire, I don't remember. I'll look for it and let you know.

EDIT: I couldn't find anything where I'd stated it before on any of the forums, but yeah it looks like it's the G/R wire, 3E.

Last edited by speedjunkie; 02-15-19 at 11:26 AM.
speedjunkie is offline  
Old 02-16-19, 12:17 PM
  #215  
Goodfalla Engine Complete
iTrader: (28)
 
Monkman33's Avatar
 
Join Date: May 2005
Location: Kennewick, Washington
Posts: 3,201
Liked 9 Times in 8 Posts
Found out that Speedhut will not do the analog output on the dual gauge gps speedo. i am a bit sad about that as I had done a bunch of planning around the hopes that I would be able to have that capability. Now I have to figure out a different way to condition the signal from the transmission to the proper type/rate.
Monkman33 is offline  
Old 02-17-19, 11:50 AM
  #216  
Make an assessment...
iTrader: (2)
 
speedjunkie's Avatar
 
Join Date: Aug 2004
Location: Colorado Springs, CO
Posts: 4,146
Liked 6 Times in 6 Posts
Originally Posted by Monkman33 View Post
Found out that Speedhut will not do the analog output on the dual gauge gps speedo. i am a bit sad about that as I had done a bunch of planning around the hopes that I would be able to have that capability. Now I have to figure out a different way to condition the signal from the transmission to the proper type/rate.
Yeah I had asked about that too, and was disappointed to hear that. I was thinking about doing a dual gauge also.
speedjunkie is offline  
Related Topics
Thread
Thread Starter
Forum
Replies
Last Post
Thor 18
Interior / Exterior / Audio
4
09-13-15 08:39 PM
Snook
3rd Generation Specific (1993-2002)
1
09-01-15 05:35 PM


Thread Tools
Search this Thread
Quick Reply: Cluster issues? My solution...Speedhut gauges retro fit.


Contact Us - Archive - Advertising - Cookie Policy - Privacy Statement - Terms of Service

© 2019 MH Sub I, LLC dba Internet Brands

We are a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for us to earn fees by linking to Amazon.com and affiliated sites.
 
  • Ask a Question
    Get answers from community experts
Question Title:
Description:
Your question will be posted in: