Multidisplay, a Open Source inCar Display, Logger


like the mpgduino, i want to make a display for the car what displays health data from the engine.

Planned are: Lambda, Exhausttemperatures, Intakepressure, and some more...

Currently it can show Lambda, but only on my Desk :smiley:

The Code is here: GitHub - designer2k2/multidisplay: The MultiDisplay Project, An opensource datalogger, boost controller and display for cars

and everything about the Powersupply: GitHub - designer2k2/multidisplay: The MultiDisplay Project, An opensource datalogger, boost controller and display for cars

The Prototype:

And a Example Display:

Planned is to have it installed next winter into my car, hope that works :sunglasses:

And here´s the Car-Forum where some Other People also follow this: Multidisplay, eine Open Source "Alles mögliche" Anzeige :) - VR6 Forum

Here is the old version from my lambda meter:

VW Golf 3 VR6 Lambda Anzeige Eigenbau - YouTube
what got killed by noisy voltage supply...


very cool. Where did you get the blue box?

What does the Lambda value indicate?

I had to look it up, I was curious , too.

Oxygen sensor - Wikipedia, the free encyclopedia
Automotive...|Diving...|Scientific...|See alsoAn oxygen sensor, or lambda sensor, is an electronic device that measures the proportion of oxygen (O2) in the gas or liquid being analyzed. It was developed by Robert Bosch GmbH during the late 1960s under supervision by Dr. Günter Bauman. The original sensing element...
Oxygen sensor - Wikipedia - 60k - Cached.

the blue box: %product-title% kaufen
Datasheet from it:

About Lambda:

when having a tuned engine the Lambda value is a great "health" indicator.

it shows how rich or lean the engine runs, during normal cruise it should be quite normal, but when hitting it hard it must always be slightly rich.
If you run lean (fuel system defect) during full load the exhaust temperatur will skyrocket and your piston/valves can melt away...

Thats way im also having exhaust temp probes installed:

and later the arduino will look up this this 2 Type K thermocouples.

have already some ideas about arduino with type k thermocouples: Thermoelement Typ K an Arduino
its german but the google translation to english is quite good!
Thermoelement Typ K an Arduino


So, how good is the air/fuel ratio control of your desk? ;D

after 1 week testing, the powersupply failed… :-[

it heats up to 75°C at 20°C ambient, in a car thats no good :-X

The “demo”:

its a 33Ohm 5Wats resistor, simulating a little bit more load than only the 3 led´s
With a thermocouple measuring the temp of the heatsink.

and that with a quite big heatsink:

Problem is the 7805, it must kill to much power. So a DC/DC converter will take its place:

This thing gives 5V at a 0,5A without Heatsink, with an huge input range (6.5V - 34V)

And a nice addon, its pin compatible with the 7805 :slight_smile:

So now parts are ordered, and the testing continues :sunglasses:

Goal is to get a decent source to supply the whole thing inside a car :slight_smile:

Here's another one of those type of pin-compatible switching regs:

Not sure they're any better or worse, but at least you have two possible sources now. :wink:

from the basic specs it looks nice (5V,1A) costs also the same, size is about the same (for the 1A Type)

problem is its not available from my "standart" sources (Conrad, RS-components, Segor)...

but if somebody in the US wants to build that they can just take this one, they are nearly identical from the specs :slight_smile:

I'm thinking about using your idea in my car for a summer project. I'm american, unfortunately, I can read grade school german but the forums you linked are a little much for me. I appreciate you writing this in english, as I can tell you're german.

I want to do an in dash LCD, with lambda among other things. Hopefully, you will keep me updated on your progress. I will be installing this into a Subaru WRX STI.

Is there anyway you could translate your lambdaanzeige page for me?

hello basic260,

im austrian, hope im not writing too bad :wink:

check out AutoSpeed - Monitoring Factory Oxygen Sensors, Part 2
that was my inspiration for the lambda display :slight_smile:

i will keep this for shure updatet, just now im on business travel, but parts ar ordered and within the next week the first prototype should find its way into my car :smiley:

the DC/DC converter is mounted, and the temperature dropped to 28°C, so only 8°C above ambient :smiley:

and ive got my 20x2 LCD (Displaytech 202A-CC-BC-3LP), what should be easier to mount in the car:

Next step is to get it hopefully next week into the car for a testrun, and then start with the RPM Input.

For RPM i will use a LM2907 (See page 10 for Example Circuit)

Its basically a Frequency / Voltage converter, so i will read it in on a Analog In pin.

But now i have to get a mothers day gift :-/

its getting close to put it in my car :slight_smile:

current code: GitHub - designer2k2/multidisplay: The MultiDisplay Project, An opensource datalogger, boost controller and display for cars

looks a bit like this:

im using a MCP3208 as ADW, so i have enough pins for some buttons...

besides the LCD its streaming all 8 ADW pins as csv over the serial interface, including a "milis" timestamp.
So it can be used for logging in combination with a notebook :slight_smile:

i still need to get the RPM measurement running, not so easy as i thought... :-?

how exactly are you powering everything?
i can proboly tell your going to say car battery right?
well, heres a sugesston.
buy another car battery, use a resister to get it to 5 volts, and then, plug everything in ;D

now with custom characters, and a baragraph display implemented with some custom characters:

its getting close to put it in my car :slight_smile:

how do you make custom characters?

it runs :smiley:

and so md_001p0 is released (GitHub - designer2k2/multidisplay: The MultiDisplay Project, An opensource datalogger, boost controller and display for cars)

the car installation is a mess right now, but who cares, it works ::slight_smile:

a very nice addon is the datalogging:

a short run:


very detailed:

it updates every 15ms, fastest i can get is every 7ms, but there is no need for that...

Wow, excellent work! I hope you give more details of the car interface once you get done. I know it's hard to do a write up when you're elbow deep in a project. :slight_smile:

Also, thanks for that snippet of the power circuit. I hope to have it together soon.

im writing it all into the wiki from google.code:

its not much up to now but i will keep updating this :slight_smile:

thanks to my VW, its quite easy, most signals are already 0-5V ;D

got some schematics done, and more infos put into the wiki :slight_smile:

the "base print":

The arduino can be put onto it, also a LCD, Powersupply, 3 Buttons, 5 VDO Sensors, 1 Boost Sensor, a Shiftlight, a LM35 and quite some more stuff ::slight_smile:

in 3d:

and then there ist the Typ K Thermocouple print:

in 3d:

more infos about the TypK Print: GitHub - designer2k2/multidisplay: The MultiDisplay Project, An opensource datalogger, boost controller and display for cars

now im working on getting some nice double sided prints ::slight_smile: