# School Project! BMW computer dashboard...



## ssm42 (Oct 8, 2007)

I've had to put all my personal computer projects aside for the time being, because my gpa needs some serious attention. I will resume them after the semester and respond to anyone who I owe replies too...


I am coming to the end of my engr 201 course (evaluation and presentation of experimental data) and I need to start my final soon. Originally I wanted to propose an alternative final to a dept. head that would somehow make use of the extensive amounts of time I spend on my computer. But my group decided most of my ideas were a little too ambitious and we're sticking with the bicycle speedometer. 

One of my more feasible ideas, however, I would still like to tackle once the semester is over. I have a BMW gauge cluster from the time I worked there that I would like to have display information from my computer. I would like the speedo to show the RAM usage and I would like the tachometer to display the CPU usage. I want to have the cluster all lit up and the needles constantly moving. (Once the two largest dials are functional I would eventually like the two smaller fuel and temp gauges working also)

So I need to "forward" my computer's performance monitor to this BMW gauge cluster. I"m not really sure where to go from there. The course I'm in is mainly learning how to use this program called LabView. Although my knowledge is limited, I believe the program can be used to create a "virtual" circuit board. Allowing me to wire things to and from a small National Instruments device that would have the same effect as a custom circuit board. The box is wired to my computer and in LabView I create the layout of the board.
The final project is to design a VI for a bicycle speedometer that would be tested on a rotating K'nex wheel. 

I figured if it's easy enough to monitor a physical spinning wheel, it'd be even easier to have it monitor something on my computer. (???)

I need to know how to send those two signals(?) out of the computer (through usb?)

After I manage that I'll have to figure out how to splice it into the clusters oem connection wires or open the thing up and take a look. I'm not too worried about this step, mostly because I can ask for my Prof.'s help, who luckily happens to be the head of electrical engineering. But I'd appreciate any suggestions. 

My main motivation is mainly that I'm a BMW freak and have been trying to find a cool use for the cluster for years. However, I would like to present the final product to my Prof. for some possible e.c. (It would probably have to use LabView for any points) ...But I'd much rather have it hooked up as best as possible than try and make use of LabView for e.c.

Any help/input is appreciated!! :up:


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## cimi1234 (Nov 25, 2008)

The parameters of the performance that you want to monitor can be transferred from the PC or server through the serial port or through Ethernet and forward to serial.
For the serial port method you have to connect a device to the serial port which should be able to convert the digital input signal from the PC to the analog which then will drive your BMW dashboard.
For the Ethernet maybe you want a application server like host monitoring which will collect data (CPU,RAM,HD usage) from the PC in case and that application should transfer the data to dashboard through serial port.
So in both cases you need a serial device for converting from digital to analog.
I really cannot suggest to you what serial device you need to have, but the most interest part is related with the software that you need to design for converting CPU,RAM usage into serial data(the format) acceptable from the serial device.
For example if the RAM usage is 50% what signal should you have to transmit to serial ? maybe it can be the number 50 % * your ram size in or just 50 % (1/2) in binary, but converting decimal point in binary can give you strange results. It think is better to use the integers.So in case of 50% usage you have to transmit the number 50 (110010 binary) to the serial port. That signal (110010) going in input port of the serial device should generate a voltage able to move the arch to the half of the scale of BMW dashboard.

I think that you got the idea.

BR
Cimi


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## ssm42 (Oct 8, 2007)

cimi-
awesome post... welcome to techguy.

I actually just learned binary at the beginning of this semester. 
I think I'd rather go the seriel port route primarily because I don't want to have to be connected to the internet to get the cluster to display. I think(?) the seriel port would give me a little more "permanent-looking" assembly. As far as the device... Would LabView be able to help me? http://www.national.com/ds/LM/LM2907.pdf (HUGE?)


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## cimi1234 (Nov 25, 2008)

Hi,

As far as I understand that LM2907 is frequency converter which means that you have to pilot it using a frequency.
Maybe it can be done,but I really cannot help you on that.
While googling I found this http://www.dghcorp.com/analogoutputs/ and the circuit you are looking for will be something similar to that.
You need also the max.value of voltage that dashboard can support.
If its is for instance 12 V (DC) that you have to apply this ratio for converting the load into analog signal :

12 * (load value)/100

So if the load of RAM will be 50% the output that DAC converter will generate should be 6V.

Regards !
Cimi


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