Internal Interrupts

Hi I am new to the ardiuno platform and have tried searching endlessly regarding a comprehensive reply on generating internal interrupts. The project I am working on needs to take an 8bit value from the computer via serial communication and then use it as a desired pressure value and then use a control loop to adjust the pressure on a load cell. The force is being exerted by a linear actuator and simply said I control which direction the motor for the linear actuator rotates in and at how much speed it does that (which will be obviously controlled by PWM where the duty cycle = error). My question is; 1. do i need to generate an interrupt to check the desired value has changed or not every few milli seconds and then run the control loop to achieve desired status. can I make do with out it. if so any suggestions on the quickest most efficient way? 2. If I do need the interrupt, how do I generate an internal interrupt to do that. Most posts have comprehensively discussed on how to deal with external interrupts. 3. If an internal interrupt is not possible, can I input a square wave to the external interrupt pin on the ardiuno using 555 timers, where on each rising edge an interrupt is generated and my action is performed.

Any geniuses out there who can perhaps help me figure this dilema out!

thanks for your time and suggestions Regards

no you don't need an interrupt.

YOu should start with a routine that monitors serial line for a new value. And if a byte comes in process it. It there is a new value (you receive e.g. a return) then adjust the reference value. In the mean time you can continuously adjust the force cell to the desired value. and when latter changes, chase that value.

sorry for the late reply!!

Thanks for the reply! :) the project is going good so far :D