3 Term Control Routine?

[BigMax]

Hello,

 

This is probably a big ask, and I don't want to scare newbies off this topic for life, but does anyone know where I may be able to find a (Pseudo) 3 term loop control routine suitable for the PIC 16Cxx series uControllers?

 

I have so far (over 2 years!) developed a simple proportional routine for the process I'm working on, but this process is subject to 'bump' disturbances and my simple routine totally lacks dynamic response and stability.

 

Simple would be good, source code would be great, although even some basic ideas would be appreciated.

 

Thanks in advance and Cheers!

 

BigMax;f;