I'm wanting to have a bit of fun. I am experimenting with digitizing a fourteen-year-old Honda Accord. Specifically, this thread is about digitizing the dash.
I was able to locate a post on a different website that shows both the wiring and the code to make a digital speedometer with an Arduino Uno. This is helpful, but I can't find a similar post for a tachometer. I have been able to find the code but not both the code and wiring. Can anyone help with this?

Also, is it possible to run both off the same board or would I need a.) a different board, or b.) a second board no matter what?

I've looked around for Arduino Tachometer code in the past.  I found this guy who used a Volkswagen diesel on a home made log splitter.   He had multiple Arduino's running it, one had tachometer and governor I believe. 
I used the code to modify it for my own VW diesel to do some fancy stuff with a tachometer.  I had it turning on and off a relay at set RPM.  I started a thread here for it, I need to find it. 

Here is the guy's website:
http://mckgyver.pbworks.com/w/page/20654147/Firewood_Processor_Governor
http://mckgyver.pbworks.com/w/page/20654133/Arduino_Tachometer


I found my video on what I started doing:

https://www.youtube.com/watch?v=juKL2z20xIo#


Nate

I found it :)

http://open-source-energy.org/?topic=1259.0

N8,

Do you have anything for the OP that drives some sort of LED display from the Arduino?  Preferrably the same Arduino that is also collecting the data?

Thanks guys. Would I be able to use something other than the photo interrupt? Also, would it be possible to have the same arduino board run both scripts - or would I need a 1.) second or 2.) more advanced arduino?

I think you might be able to put it all on one Arduino, but I'm still really new at this stuff.  There may be problems with refresh rate, I'm not sure.  I haven't worked with digital LED read outs but I've figured out how the LCD works on the VIC Resonator project.  I do have monster 2.75 inch tall LED digits if someone wants them.  They don't have any driver circuits.
It's been so long since I worked on the tach project, maybe after I'm done working on this next VIC Resonator version I can try to put something in that code for an LCD.

Quote from PeterWood on October 30th, 2014, 09:36 AM

Thanks guys. Would I be able to use something other than the photo interrupt?

You could use a magnetic hall sensor rather than a photo interrupt.  Also, the purpose for a hall sensor or photo interupt on a diesel is because there is no ignition system to get a signal from.  If your car is gas you probably have a signal that you can use already.  You just need to figure out how many pulses per revolution it sends out and adjust the code accordingly.  Also have to make sure the input is 5 volts or lower.

How about this?

http://www.instructables.com/id/4-Digit-7-Segment-LED-Display-Arduino/

http://learn.parallax.com/4-digit-7-segment-led-display-arduino-demo

http://www.electroschematics.com/10512/arduino-4-digit-7-segment-led-display/

Looks simple enough.  Would these fit in a dashboard? lol

Just rebuild the dash. Do you really need to see? ;-)