The study of microprocessors and PWM interfaces, applied on automation of continuous variables, force to reconsider the energy injection equations at control systems due to the PWM interface dose the energy differently. These new equations must be known by students and engineers due to the possibility of doing fast, cheap and efficient automatic control applications. Current automatic control books show a compendium of mathematics modelling, however none of these show an integration of mathematics modelling, physical analysis, digital electronics, analog electronics, power electronics and algorithms design in machine language. This article intends to integrate the preceding knowledge and proposes the application of the previously deduced equations in order to implement the control strategies of Proportional Integral (PI) and Proportional Integral Derivative (PID) controllers in a microprocessor that has a PWM digital interface.