Ok, i got a question for you all. i've been working around PIC micro's for a little time now, done a Engine immobiliser / Central locking based around a 16F84 with a RF receiver.

Anyways, i'm working on a new little project. Its called a "Electronic Ratio Box" basically its used on Electronic Speedo's within Automobiles.
a simple description on why i require it..

I've got a modified car, where as i've changed the Diff Ratio gears, and for those who have done this, you will notice your speedo is now also incorrect.. also in cases when you change the size of your Wheels. in my case. both. for those who are interested, original Diff gears were 2.77:1, now i'm running 3.45:1 (but i've also got 4.11, 3.25 gears). anyways.. the principle is simple.

the Speedo Sender is a Hall Effect sensor, which is a square wave output, varied depending on the speed.
i need this little circuit too interface between the Sender, and the speedo itself.

Also, i want to work with a PIC12C672, as it has a A/D conversion, where i want to connect a trimpot upto (for adjustability, so i can adjust it depending on tyre size, diff gears. ie 80% faster, or slower)

just say the sender is sending 100 pulses
i require this to send out <so many pulses> in the same time span. i believe you all understand what i mean


the problem is, i'm still fairly new to ASM, and i have no idea how i can do this.. any suggestions?

Sent by YAP P/L at http://www.yap.com.au/