Automatic Room Temperature Control System Using Arduino UNO R3 and DHT11 Sensor

This paper presents designing and implementing an Automatic room temperature control system using the Arduino and DHT11 sensor. The fan speed control system has also been proposed. Here, the user sets the minimum and the maximum reference temperature range from the keypad. The DHT11 sensor senses the surrounding room temperature and gives the result in degrees Celsius. Both the reference and the measured values are displayed on the Liquid Crystal Display (LCD). The Arduino microcontroller, being the processing unit of the system, gets the sensor's measured value and compares it with the set threshold. The results are: when the measured room temperature is less than the minimum of the threshold value; then, the microcontroller turns on the heater. If the measured room temperature is greater than the maximum threshold value, then the fan triggered on. The speed of the fan will be controlled by the pulse width modulation (PWM) technique based upon the temperature difference between the sensor reading and the maximum threshold. The larger the temperature difference, the larger the fan's duty cycles, and the faster its speed. Finally, if the room's measured temperature is between the setpoint range, all the loads are turned off. That means the room temperature is maintained normal.