Thread: Digital dash (instrument cluster).

How are you planning to have the neccessary data (speed, distance, fuel level, water temp, accu voltage, etc.) collected? By means of a PIC?
Also regard the boot time of a computer...
I personaly suggest the "one computer" variation. I think the computer is fast enough to serve both purpose.

The ECU probably isn't fast enough tho. My experience with OBD1 ecus is that they only have enough bandwidth to give out one sensor reading in realtime.

Originally Posted by bbalazs

How are you planning to have the neccessary data (speed, distance, fuel level, water temp, accu voltage, etc.) collected? By means of a PIC?
Also regard the boot time of a computer...
I personaly suggest the "one computer" variation. I think the computer is fast enough to serve both purpose.

Lostreception told me that the OBD-1 port can be hooked up to a laptop via a scanner (Actron) cable or something, and use software to view the car's stats. He also said this information is viewable in real time.

Originally Posted by bbalazs

How are you planning to have the neccessary data (speed, distance, fuel level, water temp, accu voltage, etc.) collected? By means of a PIC?
Also regard the boot time of a computer...
I personaly suggest the "one computer" variation. I think the computer is fast enough to serve both purpose.

If I were to go with two computers, the second computer would be bare bones, just enough to accompish the required task.

Maybe a Linux or Windows XP Lite install bootable to a flash drive or something.

If I go with one computer for both like you said, how would I go about setting up two monitors, one to display the main screen (front end), and the other to display the instrument panel? Would this be accomplished via a "second monitor" option in the Display options of the control panel?

You could add another video card or get a usb video card if your current one only has one vga output.

I think OBD1 is not fast enough to display rapid variations, eg. RPM.
If you have a separate RPM-meter and a speedometer, I think they are digital (receiving digital signal 12V or 0V). In that case, use a serial resistor about 8KOhms and a 4.7V zener diode reversely to the ground after resistor. From this point a TTL signal can be directly lead into any uProcessor, like PIC. And this pic can measure short-time signals. Connect this PIC to the PC and transfer the data in certain period. For speed it is disturbing to display the value more frequently than 1 pro second. (Personal experience).

I was going to do the same thing. But .......

The solution you are about to use has a few draw backs. The OBD 1 computers run at 160 Baud (at least my 1990 Chevy Van, but if I recall correct chevy didn't change the car until 1995) and have about 20 words (160 bits). So would get approx. 1 reading per variable per second.

For stuff like RPM and MPH that isn't good enough I think. So the OBD way isn't the best, for a dash replacement at least. For all the fault codes it is off course. There is a posting by someone here at mp3car uploading all datastream definitions of chevy ECU's. (if you can't find them search for my postings and you can)

The other drawback already mentioned is startup time. A PC can be fast I know, but I think you don't want to wait more than 3-4 seconds before the dash comes alive.

For "real" real time data you have 3 options in our cars (at least I think so)
1. Get the digital dash from another car e.g. the chevy icon of the 80's Corvette C4, if I am correct the dash of the chevy is at least electrical, but with analog displays. Problem is I can't tell how you should connect it, it probably won't be plug and play.

2. Get the electric feed from the dash and build yourself a pic to convert the electrics to programming. Make an embedded device so to speak.

3. Have a look at this link: http://www.gassavers.org/showthread.php?t=4250 There is some java code I haven't tried yet. I really want the OBD to work correctly first and after that this is what I am going to try.

4. OBD

The order I am going for is the following:
4, 3, 1, 2. If I could get the C4 dash to work that would be very sweet I think, retro but still modern. If you do want to proceed with OBD and you can program java, you could look at the code made by 84regaldriver. I am working on a newer version of these gauges inspired by his program, but from scratch. When I have something working I am going to open a source forge project.

BTW there are some guys here in The Netherlands trying too messing around with digital dashes in chevy vans.

Hi, I`m not expertise in this field, but a friend do something similar in his car, and basically has the same problem, display or computer ¿?, finally he decide to put an oldiest and basic computer and in stead of other monitor, I suggested him to put a lcd display (like the one in the pic), he connected to a paralell port, and now it is working fine, it is integrated to the dash and it seems elegant, as a serie part. The lcd displays all the info he wants, velocity, performance, bla, bla, bla. You can search for a display depending on your needs (I mean how many lines to display you need), and the cost of this was just 1/4 of fraction or less, than a complete computer + monitor system (7" new monitor $100 dls approx. Vs. $5-$20 dlls lcd display).

Hope this suggestion will be usefull for your proyect.

Saludos

This could lead to something

[media]http://youtube.com/watch?v=Cp1oGft96RU&feature=related[/media]

[media]http://youtube.com/watch?v=iqZTLZ0hEJk&feature=related[/media]

[media]http://youtube.com/watch?v=u6mO-G52HJU&feature=related[/media]

[media]http://youtube.com/watch?v=Y5i8F4BH424&feature=related[/media]

http://zcarcockpit.free.fr/