# Development of an Energy-Efficient Smart Socket Based on STM32F103
## 1 Introduction  
Standby energy consumption, commonly known as the energy drawn down by an electrical appliance when it is not in use, contributes a significant amount of energy waste and safety issues in the built environment. With the increasing integration of intelligent systems and involvement of customer electronics in the built environment, the standby energy waste increases rapidly, which has been attracting wide attention from both the academic studies and industries. A survey conducted by the International Energy Agency (IEA) on developed countries indicates that standby energy waste is responsible for up to 10% of household electricity consumption [1]. That means that for a typical household television (TV), with the standby power of 1.8 watts, a daily standby energy loss up to 0.018 kWh, which could be associated with 10 h' operating. Additionally, the associated greenhouseemissions (GHG) and cost expenditure with energy consumption cannot be ignored. The waste of resources and environmental impacts contributed by standby energy consumption have placed a heavy burden on human society, which correspondingly encourages the technological improvement on standby energy reduction. Over the years, a considerable amount of improvements have been applied to power sockets for function enhancement, such as wireless control and current monitoring. A great deal of these improvements have been developed to contribute standby waste reduction for families.  
To address the issues associated with standby energy consumption, this work proposes the development of a smart socket system that is expected to reduce the standby energy waste of electric appliances in the built environment. The major characteristics of the proposed system can be summarized as follows:  
1. A host-slave mechanism was applied to the control strategy for standby energy saving. The working status (switching on or off) of auxiliary/slave devices are controlled by that of the main/host equipment. Once the embodied power management unit built on microchip STM32F103 detected sharp current dropping in host plugs, which is supposed to be a switch-off operation conducted by the occupants, it will then respond quickly to power off the smart socket for the reduction of standby energy waste.
2. The smart socket is compatible with normal remote controllers of electrical appliances, which expanded its application and allows the occupants to switch off or power on the developed smart socket conveniently with normal remote controllers.
3. The safety protection measures have been employed to avoid overvoltage, which is normally recognized to be hazardous in electricity consumption.
4. The developed smart socket system can be easily integrated into the existing household power network. Neither extra wiring nor network connection is required, which promotes the economic attractiveness of the proposed system.
5. An energy-efficient switching power module was designed to power the proposed system, which can further reduce the energy consumption of the smart socket. This allows a reduction in the standby consumption of appliance to zero secondly at a cost of only 0.8 W operational energy use.  
With the characteristics mentioned above, the smart socket is a type of \"off-the-shelf\" product designed to reduce the standby losses of connected electrical appliances. The target end-users of this product are the dwellings with the lower home automation system integrated, but the occupants would like to improve the family energy performance without the involvement of costly high-tech intelligent systems.  
To present this research in a logic way, the rest of this paper was structured as follows. Section 2 reviews the recent state-of-the-art smart sockets, and the hardware framework and software design are detailed in Section 3. Section 4 is focused on the experimental validation and discussion. After that, Section 5 presents the precision testing for measurements and error analysis, and Section 6 contains the concluding remarks of this study.