Arduino to Modernize '86 MR2 Gauge Cluster

Projects General Guidance
1

Hello and thank you for any input you have on my potential project.

I have an '86 Toyota MR2 and am seeking to update the factory gauge cluster. The OEM gauge cluster uses 6 different needle gauges and the odometer. The plan is to find the right Arduino controller, a proper power supply, means to control 6 mini servos, a screen to replace the odometer, and a GPS sensor.

**Outputs: **
-6 RC Servo motors
-Small LCD Screen
Inputs:
-6 analog inputs (Voltage, Fuel, Oil Pressure, Coolant Temperature, Light/Dimmer)
-GPS Input
-Button input for trip meter
-Aux input for screen selection
-Accelerometer

If possible I am looking to use the Arduino to process the OEM dimmer switch (potentiometer) and replace the gauge cluster lighting with LEDs.

I have played with an older Arduino a few years back and have some experience with programming in C++. I am pretty well rehearsed with car 12v systems as well.

What I need guidance on is what Arduino and components would be best for this project. Any guidance on this project would be greatly appreciated.

2

OMG I had one of those in the early 90s it was my all time favourite car EVER. It got stolen and I could never find another quite as good.

Anyhow. The combination of all those analog inputs and PWM outputs along with the need for yet more input and display puts this beyond the UNO. I think I'd go for a Mega2560. As far as displays go, the world is your oyster. Something simple like a 16 x 2 character display is easy to come by, cheap as chips and wouldn't be over intrusive. Although you could possibly save yourself some of the clutter by getting a 95MM×62MM touch sensitive screen. Instead of having buttons you could simply have a well designed menu system.

Are you intending to completely remake the faces for the clocks too?

3

It is a fun little car! I have a few projects lined up on this car, but I figure this would be a semi-easy one to start with. Convert voltage input into rotation of the servo. Code wise, that should be fairly easy, and the screen I think would be the most difficult part for me.

The other projects I'd like to dive into is an updated HVAC control system that adjusts the temperature/fan speed automatically. This project would be easier, but the need isn't there just yet. My speedometer needle bounces constantly and the gauge cluster doesn't light up evenly, so the modernized gauge cluster project is a higher priority. The other project is to use 4 stepper motors to control the dampening settings on my struts.

The car:

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Servo motors that I am considering: TowerPro SG90 9G Mini Servo

What power supply should I be looking into? and are there any sites besides ebay to shop for screens? Will the Arduino Mega 2560 need a different interface to connect with the mini servos? I will be using small ones as they will only need to drive gauge needles. Also, will I need to alter the input signals to protect the board?

4

Probably the easiest method to supply the Arduino is a basic USB charger.

Servos are dead easy, they have 3 wires Gnd, Power and PWM. The PWM input sets their position. All that's required to tell them where to go is one line of code on the arduino (Servo.write(angleInDegrees); ) The power supply for them may need something but it's not going to be anything complicated. Depends on the servos you get your hands on.

Signal inputs shouldn't be too tricky. The Fuel sender I suspect will be an analog signal that goes from GND to 10v (for full scale deflection), This will need to be brought down to 0-5v for the arduino. If you just get a pair of identical resistors, conect one end of this chain to the output from the fuel sender, the other end to GND, then the junction between them will be perfect as an analog input for the arduino.

Oil pressure and Temperature will likely follow the same lines as the fuel sender. Battery Voltage will be a similar arrangement but the resisters will have slightly different values. (instead of halving the voltage, you'll want about a third of it)

You can get a GPS shield for the arduino but if you want it to act as your satnav, I doubt you'll achieve that. Another nifty little thing you can get is a GSM sheild. This will allow it to send (and recieve) SMS text messages. So, for instance, if it ever gets stolen, you could send it a text message and have it send one back with it's longitude and latitude. (or even tell it to disable the ignition circuit).

I can't, for the life of me, remember what the ignition setup is, but getting a signal for the Rev counter shouldn't be a problem.

For the speedometer, you'll probably need a sender that fits on the cable. It just produces pulses as the cable spins around. The biggest problem with these is that it's a bit of a pig getting it to fit behind the speedo and then getting the speedo back in place. But since you won't be using the existing speedo this won't be such a problem.

Accelerometers are simple enough. Another simple addition would be a flow meter in the fuel line so that you can get miles per gallon and estimated miles remaining in the tank.

Fabricating the faces is something you'll have to work out for yourself. I'd be inclined to experiment with photo etching some aluminium sheet, spray mat black, then backlight with LEDS so the figures are illuminated in the colour of your choice. You could even go for tricolour LEDS so that you can change the colours depending on your mood :slight_smile: