Jirka Jirout

So after some time spent by messing up with the OBD in an attempt to get a reasonable digital dashboard in our software, we gave up and built our own device.

We call it EDC-01 (Engine Data Connector) and it has inputs for the distance/speed sensor (so we can calculate the speed and distance driven), the injector output of the ECU (which allows us to measure the fuel consumption) and ignition output of the ECU (that gives us the current RPM) as a bonus, it measures the voltage of its power supply.

The device connects to the computer using USB and simulates a virtual serial port using standard FTDI drivers. The data packet is sent 10 times every second, which gives us relatively smooth-moving gauges. Distance is sent as number of pulses and the fuel information as time the injector spent in "open" state - both need to be calibrated and recalculated to human-readable units in the computer.

We also equipped the module with EEPROM (to be replaced by FRAM) where the totals for distance and fuel are stored, so the whole thing works and counts the distance and consumption even if the computer is off.

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Jirka Jirout

And here one photo of the second prototype (final layout and size, but still hand-made)

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RMerritts

that looks fricken awesome, will this work with all OBDII vehicles?

muldrick

I can't imagine that it would not/

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mrbean_phillip

Nope, it won't work with OBD-II if you want to connect to the Data Link Connector (Diagnostic Port) directly.

What you have to do, As Jirka has shown in in schematic, is to intercept the signals from the Speed input, as well as RPM from the coils, and Fuelinjector duty cycles, effectively bypassing the car's ECU.

If you want to connect to your car's DLC directly, you will need an interface, eg ISo/PWM/CAM/KWP that is compatible with the language (read protocol) that your car's network is using.

@ Jirka: Good attempt, will work well for your application. 100ms is a good update rate, and should provide jerk-free movement of your "pointers"

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goosey2099

Can't wait to pic one of these up. When will this be available and how much do you expect to charge for it.

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NiSlo

Wow, that look's great. Simple and elegant.
One thing you might like to consider however, is the addition of a small length of usb cable (even 5-10cm) between the board and the plug. It's just that as it stands in your pictures your bound to be blocking another port if you plug it straight into the back of thoe mobo or into a hub etc.

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Jirka Jirout

I am checking the manufacturing options at the moment, will have more at the end of this week - this will include prices and availability.


The production unit will have an internal USB header so you will be able to connect your own USB cable of desired length directly to the PCB. It will also come with a waterproof enclosure as an option. The prototypes were built using standard USB connector, because it is more sturdy which was useful for all the manipulation during the tests.

jpuype

*Mutter*

Now I'll have to buy a bigger USB hub for the front of the car. :P

But this is great news for the people (like me) that have pre-OBD2-cars.
It will give information that is much more accurate then the things
we have to work with (GPS distance, calculated fuel estimates, ....)
Will it also be possible to keep track of the amount of fuel used, and hence
being able to determine how much fuel should be left in the tank?

I'm just wondering if all makes of cars are sending the information from
the engine in the same way.

Sincerely,

Jurgen

Jirka Jirout

Yes. The data is very accurate (distance to 0.25m for my Tatra for example). Tyre wear or wrong pressure will probably be the major source of errors.


Absolutely, under two conditions: 1. You know the volume of your tank 2. You always fill the whole tank (which I guess most people do anyway). Personally I use Phidgets I/O board to watch the output fuel level sensor directly.


Good point. The signals are not the same and depend on many things. You will always have to calibrate the unit (or rather the software using its output) and in some cases (i.e. Jaguar) small change in the firmware may be needed (it sends several different pulses to the injector), but generally the EDC should be usable (the sample frequency is 6MHz, so we can deal with all types of signals I know about).

jpuype

Electronics not being my thing, would you have link to the board you are using to get the information from your fuel sensor, and a COM port version would be very nice as the computer is in the trunk and as I stated before I'm running out of USB ports

Sincerely,
Jurgen

Jirka Jirout

http://www.phidgets.com/

I use the 8/8/8 interface board with LCD, a colleague of mine is using the 8/8/8 board with an USB hub. Since my car's fuel level sensor is resistance-based, I could just connect its output to phidgets analog input. Some newer cars use capacitive sensors - if this is your case, you might need to build a little adapter to convert the capacity to voltage (in range between 0 and 5V).

jpuype

Any news on this, Jirka?


Jurgen

Jirka Jirout

So the price is Euro 99, payment only by wire transfer, first 10 pieces available first week in August, then a bigger batch (50-100) in the beginning of September.