INTRODUCTION
This application note discusses digital filter implementation of Proportional, Integral, Differential (PID) con-
trol algorithms. The implementation takes advantage of the control-oriented digital signal processing capa-
bilities of the Freescale M68HC16 family of modular microcontrollers.
Microcontrollers have come a long way in the past two decades. Once relegated strictly to computer appli-
cations, these devices have steadily encroached on domains previously dominated by analog technology.
Closed-loop control systems are among the most recent bastions to fall. Control systems based on digital
processing of measured values are inherently less sensitive to changes in temperature and to aging than
systems implemented with analog circuitry. In addition, digital system performance can be changed by de-
veloping new software rather than by physically altering a PC board. In fact, many emerging controller tech-
nologies, such as adaptive control, would be economically unattainable if not for digital processing
capabilities.