Implementation of digital PID controller

The paper describes a digital PID controller realized in the framework of a student project at the Department of Automatic Control and Electronics of Faculty of Electrical Engineering in Sarajevo. This project included the complete solution, from hardware design to software implementation of control algorithms. Digital PID controller was implemented which was based on a microcontroller Microchip PIC16F877A. The device has the possibility of adjusting the value of PID controller parameters, with their display on the LCD display. Possibilities that the value of control error could be passed as an input signal on the analog input of the controller, or that the control error value might be formed internally in the controller itself were considered in advance. In this case, it was ensured that default value was either brought from outside through the analog input, or generated internally (with the possibility of setting the default value). PWM was used for output of the PID controller. Device is capable for proper connecting to the RS-485 bus. Realized controller has found great use in the teaching process.