Design and implementation of a room temperature control system: Microcontroller-based

Dedicated control over room temperature is not only a key issue in providing work conditions that ensure employee satisfaction and hence increased work output; it is now a health and safety issue. The design considered the flexibility of using a microcontroller, PIC16F876A along with other peripheral devices such as LM35 temperature sensor, LCD display unit to form all-encompassing single system. In this work the microcontroller was programmed using MP LAB IDE. It accepts inputs from a simple four-key keypad providing users with ease of adaptability and flexibility in selecting desired temperature range of choice. The microcontroller compares the measured room temperature with the reference input. The output from the controller was used to drive a relay through an Opto-coupler which switches between AC and Room Heater according to the control decision. The result obtained was adequate within the scope of the work with 95% accuracy index. The design could be improved upon by making use of silicon-controlled switches (SCS) that are not noisy in operation rather than the electromagnetic relays (EMR) used as actuator in construction of the prototype automatic room temperature reconditioning device. The MATLAB/simulink platform was used to selectively study the behaviour of the two actuators and the SCS has a time-constant of 0.0047 second while the EMR was 0.0094 second.