DirtyLude
Okay. I had to setup a new computer and getting CCS running on it turned out to be a pain, but I got it working. I modified my code, because the input range it accepted wouldn't have worked for this application. The code is now simpler and yet more complex, but it will handle just about anything any consumer engine can throw at it.
I also had to do a small modification to the hardware. I made this board with a PNP transistor in mind to drive the output tach, but wasn't until later I realized the MSP430 doesn't have output pins that will sink. I had to make it into an NPN with a pullup. You can see some creative soldering at the top of the picture.
Anyway, send me an address and I'll send it to you.