Mazda MX-6 Forum banner

1 - 20 of 31 Posts

·
Registered
Joined
·
235 Posts
Discussion Starter #1 (Edited)
Home made digital boost gauge

I am in the process of making a small boost to fit in the dash of my MX6. I don't know why this was not a factory fitment, I have a 1990 Capri Turbo that has one, and I think that the Probe GT might have come with one?
I ended up by getting this small one, as I wanted something un-obtrusive, and I wanted to put it close to my line of sight.




What I really want is something in the instrument cluster itself. I did think about dismantling the current boost gauge and making it fit in somehow, but a lot a messing around.
I wnet looking and found this, OLED digital single boost gauge . Looked pretty much right for the job, but by the time shipping was included it came to NZ$180. I could live with this, but decided to see what i could do for myself. I am able to get the screen alone, they are a common item, and after some searching came across quite a few examples of boost gauges built using Arduino boards. So that is what I have done, pretty cheap to make my own. So far the cost for a single unit is, in NZ$
Arduino Mini Pro 5V (clone)$7.50
OLED 0.98" screen $12
mpx4250ap MAP sensor $25
bmp180 barometric sensor $6.50
5V output DC-DC rectifier $8.30
Plus a few more dollars for the prototyping stuff - breadboard, connectors etc.
Although there are a lot of people doing something like this, on forums and youtube, there is not a lot of actual how they did them, or much code. I have come accross some code examples, but nothing that was written for the OLED display. I have taken what I found as examples, plus a few more examples in the Arduino software, and managed to get a working boost gauge.


Atmospheric pressure. Just a fixed compensation value, my baro sensor is not here yet for getting the true value. The mpx4250ap gives the absolute pressure from vacuum, not relative to atmosphere, so needs the atmosphmeric value removed from the reading to get the relative boost/vacuum.


Simulated vacuum using a vacuum pump. The photo has just caught the last number as it was changing.


Simulated boost with a pump.

My idea is to put this in the tachometer, as there is room under the tach mechanism to fit the screen. I will just remove the paint on the dial face to make a square window to show the numbers through. Another alternative would be to put the screen in one of blanking plates at the top left or right of the instrument cluster. I did also think about using the rectangular LCD that is most commpmly used for something like this and fitting it where the clock is, but I do use the clock and it is not in line of sight anyway.
I decided to just make the gauge show the numbers for ease of use. There are other examples out there that also shoiw a bar graph as well, and a peak boost number seems to be common also. The peak boost number is easy enough to incorporate, not sure how hard it is to do the bar graph though. Doing other gauges, such as AFR, oil pressure etc would also be doable as well, I have seen at least one example of a wideband AFR gauge.
Interested in any thoughts or comments.
 

·
Registered
Joined
·
235 Posts
Discussion Starter #2
Well, a little further along. The barometer module arrived, so I managed to get it working to give the baseline atmospheric pressure to zero the gauge. This means that the gauge should always give the right boost figures at any elevation.
I test fitted it into a spare tach I have. I dropped the OLED screen onto the floor and cracked it, these are really delicate. The screen is now only showing what looks like every second pixel row, so not as sharp as it shoiuld be.



Once my DC-DC adapter gets here, and I get a replacement screen, I will fit this tach into the car and see how it works. My main concern is how bright it may be at night, I need to see if it is possible to dim these screens, and get it to read the light switch.
 

·
Registered
Joined
·
235 Posts
Discussion Starter #4
Trying to clean up the edges of the window I created with a sharpie was a mistake though, I certainly won't try that for the production piece.
 

·
Registered
Joined
·
235 Posts
Discussion Starter #6 (Edited)
I have been having fun doing this, so I am going to play around and try some other stuff. Change it to show PSI/inHG, although I will leave it i bar for my own use, try adding a peak boost display and anything I can dream up. The boost text is probably pretty redundant, as I know what it is displaying, so I can utilise that space, or make the current numbers bigger. I am ging to put up a how to and the code up on a web site for any one else to use.
 

·
Registered
Joined
·
550 Posts
Ha you beat me to it..
I was looking into this myself for the same reason. I wanted something hidden and non intrusive.

Good work.. i like it.
 

·
Registered
Joined
·
235 Posts
Discussion Starter #8 (Edited)

·
Registered
Joined
·
771 Posts
This is excellent. I wanted to do something like this for ages but I have never used Arduino before. I was searching around for a decent way to read before and after intercooler air temps and some of the gauges online are expensive. I came across this

https://www.youtube.com/watch?v=EyhhnYygpok

It would be perfect to fab into the dash cluster somewhere. Do you have any ideas on how it was made?
 

·
Registered
Joined
·
235 Posts
Discussion Starter #11 (Edited)
That would not be too difficult to make, I think that I came across some examples in my searching on boost gauges. Mainly a case of getting a couple of temp sensors that had known data values and calculating the temp values. Even getting the display to work is not that hard to do. Maybe I could play around with one later. I have wanted to get or make a full digital dash for my MX6 for a while, this is but the first step along that path. I was looking using a Raspberry Pi, but I think that Arduino is the better way to go for this.
 

·
Registered
Joined
·
235 Posts
Discussion Starter #12 (Edited)
My replacement screens have now arrived and I have now assembled the whole thing and installed it.


It doesn't show up too well in the direct sun, I think that the window that I cleared for the screen is not clear enough and is clouding in the sunlight. Not having the cluster surround installed may also have added to the reflection. I have now cut out the area in front of the screen, just need to see what it looks like in the sun tomorrow and grab another photo.
I made the boost gauge in two parts, I put the MAP sensor in an enclosre mounted on the firewall, and put the arduino board and barometric sensor in another enclosure fitted behind the cover in the drivers footwell where the fuses are.
I ended up redoing the code for the sensor, as I couldn't work out how the code that is available on the internet was derived. I ended up using the formula from the data sheet for the MAP sensor, and I am getting what looks like beleivable readings.
I have installed this with a USB cable fitted, so that I can easily make changes. I am going to play around with a max boost reading, and also displaying boost as PSI and vacuum as inchHG. I will also try at getting a bar graph display working as well.
 

·
Registered
Joined
·
235 Posts
Discussion Starter #13 (Edited)
A bit bored tonight, so I have made the first cut of using PSI/inHg instead of Bar. I haven't compensated yet for the displacement of going from 3 digits to 4, like I did with the - symbol for the Bar readings. The digit positions are set from the bottom left of the first digit, it would be easy if I could set the position from the right, but I can't see that the software library allows that.





Next up, to work out to get a bar graph working.

(Edit) I did get bar graphs working, but wasn't very effective in use, so went back to just figures.
 

·
Registered
Joined
·
235 Posts
Discussion Starter #14 (Edited)
New version

This has been in the car working well, quite happy with it. I also wanted to get AFR set up as well. What I wanted to do was use a second one of these OLED screens, but the I2C addressing on these screens have only 2 settings, one of which conflicts with the barometer sensor.
What I did was to get a 128x128 LED LCD screen with SPI connections. I initially set this up with both screens, but I found that SPI has a limited cable length, having the control board down by the fuse box with the screen in the top corner of the instrument panel caused the screen to turn into garbage after a short period of time as the screen timing got out of sync.
I re-did this, putting the control board behind the instrument cluster and going to just the one screen, see below.



I used a wideband controller, the spartan2, and bosch sensor from 14point7.com. I installed the wideband sensor in the exhaust at a point just before the flexi joint, it needs to be approx 1 metre (3 feet) from the turbo exit. The blue light at the right of the warning light panel is the blue staus LED supplied with the controller, flashes slowly when the sensor is cold, steady when within operating temp and flashes fast when sensor is too hot.
I decided to go to using 1 screen, as I originally had the larger screen for just AFR with a min and max reading, but proved to be pointless, as the wideband controller outputs two calibration readings while the sensor is warming up. I made the change when moving the controller board.
I have the readings set to different colours depending on where the readings are. The boost is green when in vacuum, white when in boost and red when the boost goes above 1 bar. The AFR is blue when rich, white when in normal range and red when too lean. This allows me to see a colour change without actually having to read the figures.
Overall this is working well, the only downside is readibilty when the sunlight strikes it, but otherwise it is OK.
 

·
Registered
Joined
·
90 Posts
Like the new version, that is very cool.
 

·
Registered
Joined
·
10 Posts
Just wondering if there has been any changes on this design or if you have kept it as is. Also wondering if you could possibly post the current code as I would love to do this project at some point for my mx6. Keep up the good work gbilski this is a really awesome project.
 

·
Registered
Joined
·
235 Posts
Discussion Starter #17 (Edited)
Still basically the same, I changed the red text to yellow, as I found the red was not visible enough, and would even appear to disappear when wearing sunglasses. I also added the calibration correction to readings for AFR.
I am happy to share the code, I will add comments to the code to make it easier to understand what I did and why and put up a link for downloading it.
I plan to add to this project as well. What I want to do is add data logging, so that I can get some graphs of the readings. I will add an RPM counter to the logging so that I can get a graph of AFR, vacuum/boost and RPM over time. Just for fun and to see what it looks like.
I have also started another little project, an error code reader for the ECU. Being a non US car, it does not have a check engine light. I did the trick with an LED on the diagnostic plug to read the errors I had and thought that it would be easier to use an arduino to do the counting and display the numbers directly.
 

·
Registered
Joined
·
10 Posts
That's interesting that the text is harder to see if red you'd think it'd be alright. That would be amazing if you could share the code especially with comments. I'm definitely interested in trying to replicate this project so the code would be invaluable. So if we don't have a check light how do we do the error code checking? I've never heard of this LED method but it sounds like error logging on an arduino would be much easier especially for checking logs of error codes.
 

·
Registered
Joined
·
90 Posts
I've been following your project too, I'm all about keeping that stock look and had already used one of the gauge cluster blanks to mount an oil pressure gauge out of a Honda Passport in it so when I saw this I got interested. Please keep updating and sharing!
 

·
Registered
Joined
·
235 Posts
Discussion Starter #20
Yes, I will get the code and components up in a few days.
While the screen works well, bright light makes it harder to read for me, my eyes are not the best. I am thinking about trying an E-Ink screen, they do not have their own light source and are much better in the light. They may be too slow though.
 
1 - 20 of 31 Posts
Top