Sensor data for a android app I'm making

idiambulance

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Im working on a project to get the sensor data off my 6.9IDI Ambulance into a Android app im developing. The idea is a phone on the dashboard with real time engine data. I'm Looking to monitor all the sensors on the cluster as well as voltage amperage and cabin temperature. I think a volt meter in the line for the fuel sending units is all i need for that. I don't have an idea yet about the other sensors on the cluster though. I guess any suggestions on how to tackle the other sensors? Which ones might be easier and which ones harder? Here's the ride and the app.

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franklin2

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All the gauges work the same except the voltmeter gauge. Voltage is fed to the gauge first, the ground for the gauge is the sensor which is a variable resistor. So as the ground is farther away from zero volts, or closer to zero volts, that makes the gauge move up and down the scale.

Tapping directly to the sensor wire to measure volts, you may run into a accuracy issue. The vehicle voltage can vary quite a bit depending on the electrical loads and if the batteries are up or are a little low. The gauge needles are pulled by two coils in the gauge. It is the difference in the coils that sets the position of the needle, not the overall voltage feeding the gauge. That is how they self regulate no matter what voltage they are fed.

In the Fords 1986 and down, they had a different set up and used a instrument voltage regulator mounted in the cluster to avoid this problem.
 

idiambulance

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If I understand what your saying correctly the two coils help float the voltage spikes and drops which keeps the needles from jumping around?
 

hacked89

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everything is pretty easy in theory you’re just gonna be spending a lot of time converting the various signal data into appropriate UX/UI in your apps
 

hacked89

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I should clarify - pretty easy if you replace all the factory sensors with electric sensors that you know play nice with whatever controller you are using with your app, not going to be fun if you’re trying to tap the factory

Check out mouse:
 

idiambulance

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I should clarify - pretty easy if you replace all the factory sensors with electric sensors that you know play nice with whatever controller you are using with your app, not going to be fun if you’re trying to tap the factory

Check out mouse:
Thank you soo much for this information. I guess i had assumed nobody else would do something like thison a idi.
 

franklin2

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If I understand what your saying correctly the two coils help float the voltage spikes and drops which keeps the needles from jumping around?
The two coils fight for control of the needle, and it ends up somewhere in the middle. If the voltage feeding the gauge goes up, the voltage on both coils goes up, but the difference is still the same, so the needle stays in the same place. If the voltage goes lower, same thing, the voltage on both coils is lower, but the difference between them is still the same and holds the needle in the same place. Only the sensor unbalances the coils, which makes the needle move to a different spot.

Keep going with your plans, but in the end if all your readings go up and down with the rpm of the engine, then the voltage fluctuations is whats causing it.
 

idiambulance

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I can set it in the software so that the voltage change goes at a set increase/decrease speed over time. Im thinking video it see how fast the gauges moves and set it roughly to that change in the app gauge. Does that seem like the direction to go?
 

hacked89

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Why not just take your voltage reading off of one of the hot sides of the relays? That's what I do. Mechanical voltage regulators bounce but that's how I know it's working. Solid state regulators dont bounce much but stay in a familiar pattern.
 

idiambulance

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hacked89 that is what i will do for the voltage at the alternator. I also plan a independent one on each of the batteries so I can detect a bad cell. luckily I have a independent voltage and amperage gauge that I will be able to tap into right where my microcontroller is going luckily.
 

ifrythings

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Your best bet is to ditch all the factory gauges and put useful sensors in, not sure what your using for a micro but an esp32 would give you Bluetooth and wifi and a ton of processing power if you need it.

Here’s a little something I’ve been playing with to replace the 4 useless gauges with 9 useful ones, just need to 3D print the bezel

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idiambulance

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I've made a fair amount of progress since the last update. I was able to read from the rear sending unit on the Arduino. Unfortunately the newer Arduino I need still hasn't arrived. Once I get that I should be able to get the android and Arduino communicating fairly easy. Below is a short video of the data I'm getting back as I read it. It was fairly easy to read it with a multimeter and the Arduino. It was interesting that the resistance doesn't flow linearly across the arm but that's easy to deal with in the software.

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For the first wave of this project I am trying to get both fuel tanks and the coolant sensor. All three just measure resistance and are fairly easy to install. The Tach sensor uses ac volt pulses to measure the magnet clicks as it goes around. I have the hardware ordered I think that will let me read it. Not sure if it will be sensitive enough though. I am also adding voltage to both batteries and the alternator as well as amperage. The Speedometer is cable driven making it nearly impossible. I am trying to figure out how to add a speedometer using the sensors in the phone. Other apps do it so it isnt impossible.

The app is coming along well but hasn't been a high priority. I have a spreadsheet with any info I've collected. This is what I have for it soo far. I have question marks by a couple things I was told but haven't confirmed myself. Any information I should add or that might be wrong Id love to know.

I have uploaded all the code ive made for this on Github. As I make more updates it will uploaded there.

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Azidiguy

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This is interesting, could have a stock appering cluster (maybe even functioning albut inaccurtly) then have the actual data on your phone where you can see it like a gps?
 

idiambulance

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This is interesting, could have a stock appering cluster (maybe even functioning albut inaccurtly) then have the actual data on your phone where you can see it like a gps?
Ive also been curious if measuring some sensors will cause the gauges on the cluster from having the right value. for things like the fuel tank that measures resistance I was thinking of putting the sensor after the gauge. The value would be lower than before the gauge but I think I can deal with that in the software.
 

Azidiguy

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Ive also been curious if measuring some sensors will cause the gauges on the cluster from having the right value. for things like the fuel tank that measures resistance I was thinking of putting the sensor after the gauge. The value would be lower than before the gauge but I think I can deal with that in the software.
The factory guages are questionable at best so no harm there. Just think it would be cool to keep a stock looking dash but still have accurate info
 
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