Closed-Loop Temperature Control Using MATLAB@Simulink, Real-Time Toolbox and PIC18F452 Microcontroller

Abstract

Today’s way of life is closely linked with technology and it would be impossible without a microcontrollers. They are represented in all spheres of life: in the automotive industry, robotics, computer systems, home appliances, etc. Also, today’s life is unthinkable without computers. The combination of computer and microcontroller provides a very great possibilities, which uses the good features of both. This chapter describes the use of a computer in combination with MATLAB@Simulink, Real-time Toolbox and PIC18F452 microcontroller for closed-loop temperature control. Control and settings for temperature are in MATLAB@Simulink and they can be very easily adjusted. Also, all the information: the refrence temperature, information from controller and the measured temperature are available at any time in MATLAB@Simulink and can be processed and stored. For real-time operation is used Real-time Toolbox. The information is sent from computer over serial port to PIC18F452 microcontroller. The PIC18F452 microcontroller receives information and processes them. Information from PIC18F452 microcontroller is amplified using a transistor that works as the switch and the thyristor which is used to turn on the heater. Turning off thyristor is automatically passing supply voltage through zero. Temperature measurement is performed using the temperature sensor LM335. Output signal from the sensor is amplified by using operational amplifier LM324 and after that sent in PIC18F452 microcontroller. The microcontroller processes information and after that send it over serial port to computer. In this way the loop of temperature control is closed using a computer and PIC18F452 microcontroller.