International Journal of Computer Applications (0975 – 8887) Volume 175 – No. 27, October 2020 28 Implementation the LM35 Sensor AS Control Room Temperature using IC ATMega 8535 Muchdar D. Patabo Electrical Engineering Dept Manado State Polytechnic North Sulawesi - Indonesia Samsu Tuwongkesong Electrical Engineering Dept Manado State Polytechnic North Sulawesi - Indonesia Nikita Sajangbati Information Technology Dept Manado State Polytechnic North Sulawesi - Indonesia ABSTRACT One of the electronic technologies that have been developed in this research is to create a room temperature control prototype by implementing the LM35 sensor as a temperature controller, using the ATMega 8535 IC which is a microcontroller as a data control center, and using the C language with CodeVison AVR software, adjusting the display on the LCD, translating the analog signal from the LM35 sensor as temperature control and control the room so that the temperature remains stable. The results obtained with room temperature control on the prototype can be seen on the LCD, if the controlled room temperature is greater than 25°C, the input received from the LM35 sensor will be processed by the ATMega 8535 microcontroller then it will activate fan1 to blow cool air that is entered in the room and fan2 to remove hot air from inside the room. But if the temperature display on the LCD is lower than 260°C, fan1 and fan2 will not be activated (Off). General Terms LM 35 Sensor, IC ATMega 8535 Keywords Driver Relay, Fan, LCD 1. INTRODUCTION Every day humans need fresh air to be able to live, but every day the air they breathe is reduced due to global warming, inevitably the air temperature around us changes according to the density and operation of existing factories or vehicles. Conditions of unstable or changing air temperature make it uncomfortable to be everywhere. The comfort of an air- conditioned room is wanted by people who live today. However, have we ever thought that even cold is not sufficient for the needs of the human body, because there is a need for a balance between cold and hot temperatures or temperatures ranging from 25˚C - 28˚C, which is the normal temperature needed to make our bodies always feel good. If the room temperature is controlled greater than 25oC, then the input received from the temperature sensor will be processed by the microcontroller then it will activate Fan1 to blow cold air to the room and Fans2 to remove hot air from the room. So that the controlled room still feels comfortable. This research includes planning and making a prototype of an indoor temperature control system that is developed to support technological developments in terms of control systems so that it will provide benefits to its users. 2. LITERATURE REVIEW 2.1 Control System Each control system has at least one controller and an actuator which is also referred to as the final control element. As shown in Figure 1., the controller is the intelligence of the system and is usually electronic. The input to the controller is called a reference (setpoint), a signal that represents the desired output system. An actuator is an electromechanical device that receives a signal from the controller and becomes a kind of physical activity. The last block in Figure 1 is a process and has an output that is a controlled variable. The process block represents the physical process by the actuator and the controlled variables with measurable results of the process. Figure 1. Control system block diagram There are two general configurations of control systems, namely, open-loop systems and feedback control systems or often called closed-loop systems. 2.2 LM35 Temperature Sensor The temperature sensor in this study uses the LM35 sensor, where the output of the LM35 sensor can provide 8-bit data output which states the changing conditions of the ambient temperature. When there is a change in temperature, there will be a change in the resulting output data, where the change is in the form of a difference in voltage generated. LM35 is a temperature detection tool has the following characteristics: 1. Working at a voltage rating of 4V to 30V. 2. The temperature reading ranges from -55 °C to 150°C. 3. With an increase in temperature of 1 °C, the output voltage will increase by 10 mV. 4. Has a drain current of less than 60 μA. Figure 2. The Physical Form of Sensor LM35