# Porsche Instrument Cluster



## falkman (Dec 12, 2011)

A fun little new project I have:

Beta (don't even bother watching this one anymore): https://www.youtube.com/watch?v=yYaTtUJI1D4
RC1: https://www.youtube.com/watch?v=n37dyzLkbLg
RC2: https://www.youtube.com/watch?v=VTNDxbgzEw0

Bit banging the DTR and RTS pins of a serial port.

-Brandon Falk


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## alie (Dec 12, 2011)

Wow interesting, may I know how to set up the system? Can I buy those things on eBay?


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## falkman (Dec 12, 2011)

They're all over the place on ebay, especially for BMWs. I found out mine has stepper motors with 4 pins on them (2 unique powers, 2 grounds), but I have no clue if other clusters operate the same way. If they do, my code would work just fine with some calibrating to the new cluster. Everything is directly run off of the serial port, which will change with the addressing. I'll post the source once I clean it up a bit and add addressing for other gauges.

-falkman


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## alie (Dec 12, 2011)

What do you think about these two
91/92 NIssan Presea speedometer cluster
84 Honda Accord speedometer cluster with frame

Would it better to buy single speedometer ?


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## falkman (Dec 12, 2011)

Those look just fine, but BMW ones are about the same price, but the style/brand is up to you. The only thing I could think of is that I think that older speedometers, probably that 84 especially, would use a deflection for a needle, which would be a different current to create a stronger magnetic field to deflect the needle more. Deflection is much harder to digitally run, especially over a serial port, compared to a stepper motor. It's kindof a risk you have to take when you buy a cluster, unless you can find technical details about the mechanisms before you buy it. I don't really know the cutoff date of when stepper motors became popular, perhaps they've been used for a long long time now... sadly I'm not sure.

A single speedometer would be nice too, but I think it would be neat to have memory usage, temperature, and network usage for other needles. Also I have 10 LEDs for the gear selection LEDs, which I have to find a fun use for...

Sidenote: Here's the unoptimized source. The header file just includes the needed headers and defines the functions. http://paste.rohitab.com/2743

It simply has a lookup table, and a global position value which it uses for finding where to put the needle for each percent.


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