Design and Implementation of a Low-Cost Smart System for Controlling Home Appliances via Telephone Using GSM and DTMF

Abstract

This study aims to design and implement a low-cost intelligent system for remote control of household appliances based on cellular communication technology and Dual-Tone Multi-Frequency (DTMF) signaling, thereby providing a practical and reliable solution for home automation applications. The proposed system is built around the Arduino Uno, which functions as the main processing unit. It receives user commands transmitted via a phone call through the SIM800L cellular communication module. The DTMF signals generated by pressing mobile phone keypad buttons are decoded and converted into digital control commands to switch electrical loads on and off through electromechanical relays, ensuring safe electrical isolation between the control circuitry and the power loads. The system incorporates a state-retention mechanism using the embedded EEPROM memory of the microcontroller, enabling automatic restoration of the last operating status of connected devices after power interruptions, thus enhancing operational stability and reliability. Additionally, user feedback is provided through the DFPlayer Mini module, which delivers voice prompts confirming command reception and execution, thereby improving user interaction and minimizing operational errors. Experimental results demonstrate fast response time and high accuracy in command execution, with reliable performance in managing multiple electrical loads. The proposed design is characterized by simplicity, cost-effectiveness, and scalability, making it suitable for deployment in resource-limited environments and providing a foundation for future integration into Internet of Things (IoT) systems.