But I myself am not experienced enough In this topic so could someone please tell me how to perform this?
TGG3, you linked to the correct page. Are you having difficulty understanding it? Did you follow the link to Nick Gammon's page which explains it all?The pin-change interrupts have only one interrupt for each "port" of 8 pins. It is up to you to then read the pins and find out which one changed.It may also help to read www.xyproblem.info
You say you are using 2 for Serial? on a Micro for example the hardware Serial pins are 0 (RX) and 1 (TX). so indeed part of your 5. but you are still left with 3 interrupt pins available (2,3,7).isn't that enough? (if you use SPI/Wire library then 2 and 3 are gone but you still have 7)
Right - so you have 5 fans to monitor. that's an important information So 3 answers:Software solution: do use change interrupt. you need to understand that you won't get differentiated ISR for each pin, if there is a change on any of the pins in a group, then the ISR will fire.--> can you let us know which Arduino you use?
I use the Arduino micro with the MEGA32U4 chip.
Could it be that you mean something like that:http://playground.arduino.cc/Main/PinChangeInterrupt