Android Based Home Automation

Abstract

This project is about home automation in LED lighting. The problem facing is that the traditional LED lamps are limited to its fixed brightness and color temperature which may not be suitable for different scenarios at home. Furthermore, scientists state that current LED lamps exist flickering problems which may induce biological human response such as malaise and headaches. To mitigate biological effects of light flicker, the PWM frequency of LED driving circuit should be chosen strictly based on the requirement of IEEE standard 1789-2015 which defines potential biological risk levels with respect to flickering frequency. LED dimming was achieved by providing PWM signal to the driving circuit. By controlling the duty cycle of PWM, different power can be delivered to the LEDs resulting in dimming effect. The adjustment to color temperature of LED used the method of mixing cool-white LED (2700K) and warm-white LED (6000K). By controlling the PWMs given to these two set of LEDs, color temperature ranging from 2700K to 6000K can be obtained. An Android app was developed as a role of controller and communicating with Arduino using Bluetooth. Driving circuits also need to be developed to control the characteristics of LEDs. Finally, users can use the app switching ON/OFF, controlling brightness from 0Lm to 1200Lm, and adjusting color temperature between 2700K and 6000K.