Since I will be wanting to use two of the arduinos interrupts (one for car speed, and one for engine speed), I thought I could use a divide by counter to reduce the processing load on the arduino.
The engine is a 6 cylinder 4 stroke, so thats 6 igniton events every 4 revolutions. I was thinking I could use a divide by 6 counter, so that the output would be 1 event for the arduino to process each 4 revolutions.
The speed output is 9 (i think) pulses per revolution.
I thought that with two interrupts triggering rather fast and trying to write stuff to a serial LCD could slow the arduino down a fair bit.
Is this how divide by counters work? What would be some suitable counters? A divide by 6 counter (for the rpms), and a divide by 9 counter (for the speed)?