Help with Fan Control

[Francesco.C]

Hi there,
I would like to control a 4-pin fan (with PWM facility).
I can see how to implement a PWM of my choice, but I am lost when I try
to read read the tacho from the fan.

I need to to count the number of pulses so I can change the PWM value.

I suppose I need to set a timer, then read the number pulses every second.
I have never used the timer that way. I have looked at the data sheet
(PIC18F242), but I am lost.

Any advice is welcome.

Regards

Francesco