I'm interested in creating my own digital dashboard for my '72 VW Karmann Ghia in lieu of all the physical gauges, and would like any guidance on how to get started. I'm new to Arduino, but am a mechanical engineer with some exposure to programming and electronics.
My thought are this....
connect sensors (oil pressure, tachometer, etc.) to the arduino in the engine compartment.
communicate with smart phone over wifi or bluetooth to display data while driving
send data to be stored on the cloud
I've looked at the tutorials and seen some project examples, but so I have an idea how to get the sensors and tach set up. What's challenging me is the display and storage of the data. I checked out Blynk; it looked like it would work, but it needs a wireless network to function and, well... don't got one in the car.
So, anyway, I've been trying to figure out...
what board(s) should I use for this?
what's the best wireless connection (or is wired better)?
is there a data display app I can use, or would I need to make my own?
can I use my iPhone, or would I need a dedicated screen?
Before you invest a lot check your local laws regarding speedometers. Here even the car manufacturers were required to keep the original speedometer connected even when prototyping speedometers. This prevented the speedometer from being set back. The engine compartment ambient is rated at 125C, the Arduino nor its chips are rated to operate in that environment. Next look at the electrical environment, you can have transients above 60 Volts positive or negative. The operating voltage is from about 7 to 24 VDC (double battery jump). Car electronic design is some of the most difficult to do.
@gilshultz ... ok, I won't use it as a speedometer/odometer (wasn't going to anyway) and won't put it in the engine compartment. So, any thoughts on the meat of the project. BTW, where'd you find the engine compartment rating for a '72 Karmann Ghia? I've been looking for that...
Each instrument has its own interface. Oil pressure might use a simple switch to let you know when the pressure is low. That can probably be replaced with an actual transducer that can drive an oil pressure gauge. Tachometer usually senses the points in the ignition system opening and closing and uses the openings (sparks) per second to calculate the RPS (divide by the number of cylinders) and RPM (multiply RPS by 60). Each measurement will likely use a different interface.
Probably from Volkswagen but in that time frame they did not put much electronics in the engine compartment so it was not a problem. I am not sure if they were even rated in that time frame. The ratings came about with the electronic revolution in automotive. Follow johnwasser statements they are correct. You can get some service manuals to see how the readings were actually accomplished. In that time frame most everything was electromechanical and not electronic. You probably will have to purchase new sensors.
#1) do not locate the electronics in the engine compartment. an UNO is about the size of an Altoids tin and will not take much room.
bluetooth will not work between the engine compartment and the passenger compartment
you should be able to make a simple holder that is unobtrusive and easy to get to. #2) start simple. engine RPM, oil pressure and oil temperature, are all easy to get.
since you want to use bluetooth then just find a place to mount your phone.
if you are not altering or removing any manufactures gauges, the addition of the electronics would not adversely affect the legal concerns.
#3) use plenum shielded wiring. you can get it for network cable. the outer sheath is much harder to damage and would be advised in such an application.
#4) secure the cable. the final bit of wire should not be used as a support where it connects.
#5) use plug in connectors they can be found in old cars in junk yards if you are so inclined. or you can get decent ones at the suppliers.