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Automotive Gauges and Controls

Posted: Mon Jun 15, 2015 9:05 pm
by BamBam460
I have been looking into raspberry but haven't found anyone doing exactly what I want.

I have an 86 F250 powertrain and a 76 f250 body. The problem is the electronics on the 86 are slightly more advanced than the 76 electronics. I could easily remedy this with a couple relays circuits etc. I however think it would be really cool to have electronic display.

The couple of problems I am having now and how I plan to solve them are as follows;

The speedometer set up for the two vehicles are completely different. I want to make my dash out of small screens and use the RP as gps to give me speed, direction and related info on the screen.

Another problem is the powertrain from the newer truck has electronic fuel pump and will need electronic fans. I want to use the RP to read and display a few crucial sensors (engine temp, oil pres, fuel lev etc) as well as use these signals to trigger the appropriate motor ie fan, fuel pump.

My truck is pre obd 1 and 2 so I will be able to hand pick the needed sensors but have not seen anyone feeding the signal directly from the sensor to the module. Is this a problem and will I be limited to say 1 or 2 sensors?

I believe I will have to use an external power module to use the pcm signal to actually trigger related relays is this correct?
Is this something that the RP could handle?

Basically can you point me in the direction I need to go? I have some electronics and programming knowledge.

Re: Automotive Gauges and Controls

Posted: Tue Jun 30, 2015 12:08 pm
by joker31
I would think a GPS would be the simplest solution, get a module for GPS and then you could switch it back and forth. I use a Garmin one I got off of Ebay really cheap for my boat and Racecar (120mph speedo dont cut it) I would think that a GPS board with a NEMA output to a display output would be easy, but the old gps from ebay may be cheaper (Some are $20) and are good for what you waant to do. They sell cheap because the maps are out of date and its almost a cheap to buy a new unit as get new maps.

Re: Automotive Gauges and Controls

Posted: Tue Jul 14, 2015 4:57 am
by sommersoft
Totally doable. I'm working on a similar, albeit newer car, display system. I was doing it with a Parallax Propeller, but now I'm on a Pi.

To read analog sensors (typically read by 0-5V signals) you'll need an Analog-to-Digital Converter (ADC). The MCP3XXX series are popular (I'm using the MCP3208, 8 channels, 12bit resolution). Easy to get examples with a search [Raspberry Pi ADC, Raspberry Pi MCP3XXX]

For the fans, I'm assuming you're talking about the radiator fans. You'll need a way to read the coolant temp, post radiator (i.e. "upper hose") to know when the fans should kick on/off. Most cars kick them on around 202­­°, and turn them off around 185-190°. You can find the sensors readily at autoparts stores (online or otherwise), but you'll need to be able to find out how to decode the readings (x voltage = x temperature). Again, searching can yield results of people who've gathered the data. Or, you can trial and error with a second RELIABLE temperature reading (thermometer) alongside.

The other sensors will all work the same way. Bosch makes more sensors than you can throw a stick at...and they can get pricey. Places like Summit Racing also have other brands, and some will give you voltage curves so the math is "easy".

The speedo MIGHT be possible without GPS. Depends on the speed sensor setup. My experience, again on newer cars, is that it's calculated by a gear off the main shaft, then fed to the Odo/Speedometer. Oh, and that's another thing. It is against Federal regulations to disable/tamper with the Odometer reading. So you may want to find a way to keep that with the swap.

Now, the fuel pump might be tricky. You'll need to find out how to calculate the pump duty that the engine is requesting. I have no experience with this on an analog/pre-obd car. And I probably wouldn't touch it on an OBD-II era car with a Pi.

For the relays, you can use transistors for the RPi side of the relay. Could also look into using MOSFETS and skipping the relays. Depends on your power requirements and budget.

And finally, standard disclaimer; this is all for informational purposes. Anything you decide to do, you do so at your own risk/liability.

Re: Automotive Gauges and Controls

Posted: Fri Jul 17, 2015 11:12 am
by shrey
Hey people. I'm new to the game of programming and am still just a beginner.
The background info
Im trying to do a small project where im trying to connect my raspberry pi to my bluetooth ELM327 OBD2 connector to read the data off of it.... I am trying to do this while SSHing the raspberry pi onto my windows 8.1 laptop using putty. I have found the open source codes for reading the data off of the the OBD from github. The issue I am facing is from the connection of the raspberry pi to the ELM327 via bluetooth.
The problem
The USB bluetooth dongle is scaning the device when i use hcitool scan. But when I try to actually connect to the device using hcitool cc --role=m and then the bluetooth address, it says that the operation is not permitted. I thought it may be that the device may be the reason but it connects to my android phone easily. When I tried to connect the pi to my phone it showed the same error.

I appreciate all the help in advance. Thanks a lot guys

Re: Automotive Gauges and Controls

Posted: Fri Jul 17, 2015 10:26 pm
by sommersoft
It is general forum etiquette to post your particular problem/request/etc in your own thread. Thread-jacking is rarely tolerated on any forum.

I would suggest that you post your question in a separate thread. Also, I would pick a different forum. Troubleshooting would be a good one.

I hope you get your Bluetooth connection working.

Re: Automotive Gauges and Controls

Posted: Tue Jul 28, 2015 5:18 pm
by shrey
I am very sorry if I offended anyone in any manner. I never intended to. I'm new to forums as well and did not know about this unsaid rule followed. please forgive me and I have created a new forum on it as well. thank you