Abstract A research on the design of temperature and light control system in the room by using the LM35 temperature sensor and light sensor LDR. This system uses ATmega16 microcontroller. Used as control the fan and lamp are connected to the relay. The function of relay is a switch to turn on the fan and three lights. The results of this design is the system can control temperature and light in the room If the room temperature exceeds the specified setpoin, then the system will turn on the fan. And if the light in the room less than setpoin is specified, then the light will turn on. The number of lights that turn on depends on light conditions in the room. Keywords: control system, temperature, light, LM35, LDR, ATMEGA16
