Thread: Arduino Modular Engine Sensors Unit (~$50)

Originally Posted by haydent

that's very interesting, do you have any links. ill keep googling...

No links, just some interesting old guy told me so I tried it myself. I was getting a range of 4-5mV with a multimeter onto one of my 24v 4BD1T glow-plugs at cruising . These aren't connected so I had no risk of blowing up any thermocouple driver.

You can find type B thermocouple charts online for reference.

Just one think - I have very bad experience with sofisticated LCDs for last 3 years. When the stock is empty, it is very hard to find some more (my job is development of electronic devices and small quantities manufacturing). For few last years the manufacturers don't make them for stock. This is the main reason, why I have choosed standard 40x4 LCD. Second reason is price. And touch screen in offroad car? Nice idea, but not, when you are moving off road. Also the needle type indicators - nice idea, but I prefare to look on the road, not on the instruments, when I'm driving. So an audible alarm is an option. And last but not least is the temperature range of the LCD - here in Central Europe I need -25°C in winter to +60°C in summer when the sun is shinning directly on the car.

heres my progress so far, i found a great menu library that handles the buttons and lcd with setting menu's, splash and home screens.

it support various lcd sizes:
https://github.com/brunialti/MENWIZ

so far i got it set up and showing the voltage on a input pin adjustable by a pot. if the voltage is below a certain level it makes pin 13 "high" and a led is illuminated.

eventually all alarm levels will be set via lcd menu.

ive also been getting some good tips from felow member here via email about a simple circuit to build to access eg coolant temperature sensor without effecting its signal

if anyone is interested in more details about my circuit or code so far please ask otherwise ill update again as i get more done.

It's coming together nicely. I've just ordered:

1 x Arduino Mega 2560 R3 $65.00
1 x 2.8" TFT Touch Shield for Arduino - 2.8" $59.00

$12 postage. Not sure how long it will take, I ordered it from the USA. Will let you know once I have it and can start coding that touch screen!

sure. youll have to look for a different library for that sort of lcd than the one i use. it will make it alot easier rather than coding everything from scratch. checkout the playground section on the arduino website.

Ive been thinking lately about how to setup glow plugs to monitor combustion temps but only started scratching the surface...pre-determined resistance of the glow plug is a good start as most of us know..
B type thermocouples good for upto 1800*c and reading a mV output which we can cross reference onto a Btype chart eg(750*c = 2.782mV) I am yet to figure out a display or means of easily displaying a temp read out rather than a mV reading....

Just some quick input from me. From the times when I was playing around with microprocessors to monitor sensors and control devices. I found one of the single biggest issues with this sort of system on a car is filtering out noise, especially on a petrol engine.

If you are planning on feeding a voltage signal to the analogue inputs, I think you will need to consider having some low pass filters in your circuitry to filter out ignition noise out of your signals. Or convert the voltage signal to a 4 to 20mA current signal at the sensor, run the signal cable to the location where you have the Arduino (inside a shielded box) and covert the signal back to a voltage. A current signal is much more immune to noise when compared to voltage so shielding and filtering isn't quite as important.

Also, another area which I tended to have issues with was getting a nice clean power supply to the microprocessor. The power supply on a car (again especially petrols) is very noisy and can cause microprocessors to behave strangely due to noise getting through the voltage regulators to the chip. So again, you may need to consider a nice filtered supply in your design to get the chip stable.

I really like the idea of the project, and I may implement something using an arduino on my project car also.

On a side note, for anyone that has an OBD enabled vehicle, you can consider simply hooking in a OBD to bluetooth adaptor (or OBD to USB ) and use an Iphone or Android device to run an app called Torque. I use it all the time in my car to monitor coolant temperature (along with other sensors) and also set some alarm trigger points on the sensors also should something go wrong.

Originally Posted by c.h.i.e.f

Ive been thinking lately about how to setup glow plugs to monitor combustion temps but only started scratching the surface...pre-determined resistance of the glow plug is a good start as most of us know..
B type thermocouples good for upto 1800*c and reading a mV output which we can cross reference onto a Btype chart eg(750*c = 2.782mV) I am yet to figure out a display or means of easily displaying a temp read out rather than a mV reading....

You would need to calibrate using an oven and a known/reliable temperature guage.