DSP library from NXP, how does the PID work?

Discussion created by lpcware Employee on Jun 15, 2016
Content originally posted in LPCWare by riktw on Sat May 26 10:40:07 MST 2012

I am playing with the DSP library from NXP a bit.
You can find the DSP appnote from NXP here: http://www.nxp.com/documents/application_note/AN10913.pdf
I got most functions figured out, only the PID function confuses me a bit.
It required the well known variables, Kp, Ki and Kd but then we got integrated error, last error and si_error.
The information is a bit limited on what is what.

Last error is one I know, it's the feedback for the PID system, output - setpoint.
But si_error and integrated error are the ones I can't place.
And where can I enter my setpoint?

Anyone ever worked with this PID library?