G Meter




I have a late 80's VW and the gauge cluster has 5 dummy LED locations underneath the other warning lights.  Well I was tired of the m not doing anything, so I decided to do something about it.  I came up with the idea to put a lateral gravitational force mater (G Meter)  in there place.

Step 1:

Gather up the needed supplies

If you wish to use your Arduino:

1- Arduino
5- RedGrenBlue LEDs (Mine are common anode)
1- Project box (if you don't want it in your dash)
1- 9v Battery
1- Accelerometer (I used ADXL 335 from adafruit)   http://www.adafruit.com/products/163
1- piece of Perf board
5- Resistors 1K ohm
5- Resistors 500 ohm
And some small wires for jumpers.

All parts needed if you wish to make it standalone:

1 -Circuit Board
1- ATmega168/328
1- 28 Pin socket
5- RGB LEDs (Mine were common anode)
5-Resistors 1K ohm
5-Resistors 500 ohm
1- 16MHZ Resonator
1- 104 cap
1- 10uf cap
1- 3.3v rg. (LM1117T)
1- ribbon cable
1- header connectors
1- Acceleromoter
1- 9v Batt. Connector

Here is the picture of the wiring needed for a breadboard setup.
The orange wires hook to the 500 ohm resistors and then hook to the RED LED cathode.
The Green wires hook to 1kohm resistor the hook to the GREEN LED cathode.
The common anode is hooked to +3.3v
X axis output of ADXL335 goes to PIN 0  (Picture is slightly different)
+3.3v and Gnd are hooked to power and ground pins of ADXL335
The AREF pin on the Arduino is hooked to +3.3v

Step 2:

Because I used COMMON ANODE LEDs:

"digitalWrite(led1G, HIGH);"    turns the LEDs to OFF not ON.
If you use common cathode you will need to change the code.

If you wish to change the pin number just change the beginning of the code:

int led1G = 2;
int led1R = 3;
int led2G = 4;
int led2R = 5;
int led3G = 6;
int led3R = 7;
int led4G = 8;
int led4R = 9;
int led5G = 10;
int led5R = 11;
int X_AXIS = 0;

Step 3:

Here is an image of the circuit board I designed using expresspcb  I also attached the PCB file and a parts list for doing this.  You can make this board or leave all of you components on the arduino and try to fit it all in project box.

Note: the pin numbers labeled on the arduino board DO NOT correspond directly to the actual pin on the ATMega chip.

Step 4:

Here is a video of my project completed on a bread board.  The LEDs go up in .1g intervals Red=.2g  Green= .1g

It starts with .2g to get rid of any false readings from bumps.  So if there is 1 Red and 1 Green lit then that = .3g

On a breadboard:

Step 5: Final Project in a Box

Here is my completed project and the code. I will try to add the actual wire hook ups for those of you making it while attached to the arduino.  Also here is my code (be kind it is my first EVER attempt a writing code)


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    24 Discussions


    7 years ago on Introduction

    For this to be accurate, wouldn't the accelerometer need to be place very close to the center of gravity?

    1 reply

    Reply 5 years ago on Introduction

    I don't think so as all parts of the car would be accelerating at the same rate with the exception of front or rear parts of the car when pitching but this is not going to impact the project noticeably.


    Reply 7 years ago on Introduction

    You clearly don't drive fast enough. :) :)

    (Of course, the better question is, "what use is a G-meter in a late 80's VW." :) )


    Reply 7 years ago on Introduction

    To answer the use of a G meter in an 80s VW- My brother jetta is currently pushing close to 350Whp. :)


    Reply 7 years ago on Introduction

    Well, if you know what how much lateral acceleration your vehicle can pull without slipping, you can use a G-meter to turn as fast as possible.


    7 years ago on Introduction

    I knew that dash as soon as I saw it! I had an 84 Jetta GLi, man I miss that car, so much fun to drive.


    7 years ago on Introduction

    And... what about the battery?
    Could you adapt the project to work in 12V or 5V to get power from the car?
    Good idea...hummm my car has "lazy spaces" too!!!

    3 replies

    Reply 7 years ago on Introduction

    If you want to use the arduino I suggest using a USB 5v adapter or a 9v battery. If you use the board I designed it has a 3.3v regulator that will let you power it from car's power supply.


    Reply 7 years ago on Introduction

    The illustration of the breadboard, connections and Arduino is very nice, what software is that, please.

    I'd like to use that same style of illustration for my Instructables (yet to do one).


    7 years ago on Introduction

    I like this idea but won't build it - it would only give the wife something else to complain about.


    7 years ago on Introduction

    How about adding a voice warning:

    Level 1 says "Pathetic, can't you do better?"
    Level 2 says "Marvellous, now she's beginning to tip."
    Level 3 says"Yippeeee, nearly on our side."
    Level 4 says "Call an ambulance and a tow-truck."


    7 years ago on Introduction

    Very nice!
    I am actually building one myself with small Dot-Matrix display and ADXL345 sensor.
    As for powering the unit, The boards specify 12V as their maximum supply voltage, and in the car the voltage can get slightly higher (13V is not uncommon), so I would refrain to directly power it from the 12V, but you could easily use a USB car charger to get 5V or put a 7805 regulator.


    7 years ago on Introduction

    That is a very nice idea.

    Maybe it should make sounds too, the higher the G the higher the pitch...

    2 replies

    Reply 7 years ago on Introduction

    That would be helpful in competing acrobatic airplanes but I think it would get really annoying really fast =P