user2789: I am trying to build a fan controller for my pc, the problem is that the example code(http://playground.arduino.cc/Main/ReadingRPM) im using utilizes interrupts. On my uno I can then only read the rpm of one fan. I want to also control the rpm (via pwm) and monitor temperatures (via thermistors) Anyone know how I coud do it differently? I. E. Without interrupts. I would also like it to be as close to real time as possible

user2794: If temperature regulation is what you seek, why bother with the Tachometer signal at all?
Thermistors don't require interrupts. Why do you need fully closed loop fan control? A simple proportional control of each fan and each hot item would likely suffice in keeping your system cool. Noise concerns, perhaps?
A brief article on proportional temperature control
A data sheet on a TI chip that may have some inspiration for you

2789: <p>I am trying to build a fan controller for my pc, the problem is that the example code(<a href="http://playground.arduino.cc/Main/ReadingRPM" rel="nofollow">http://playground.arduino.cc/Main/ReadingRPM</a>) im using utilizes interrupts. On my uno I can then only read the rpm of one fan. I want to also control the rpm (via pwm) and monitor temperatures (via thermistors) Anyone know how I coud do it differently? I. E. Without interrupts. I would also like it to be as close to real time as possible</p>
 2794: <p>If temperature regulation is what you seek, why bother with the Tachometer signal at all?</p>

<p>Thermistors don't require interrupts. Why do you need fully closed loop fan control? A simple proportional control of each fan and each hot item would likely suffice in keeping your system cool. Noise concerns, perhaps?</p>

<p><a href="http://faculty.washington.edu/brengelm/neut_zone/pg4.html" rel="nofollow">A brief article on proportional temperature control</a></p>

<p><a href="http://www.ti.com/lit/ds/sbas386c/sbas386c.pdf" rel="nofollow">A data sheet on a TI chip that may have some inspiration for you</a></p>
