A portable node of humidity and temperature sensor for indoor environment monitoring

Humidity and temperature are parameters those are commonly implemented for monitoring tasks, including monitoring within an indoor environment such as a smart home. In this study, we design, develop, and demonstrate the performance of a portable sensor system for indoor environment, which is connected to the smartphone-based user interface for monitoring humidity and temperature. This sensor system consists several components those are packed into a single small box, namely: a Zigbee communication module, STM32L100 microcontroller, DHT11 temperature sensor, BL-5C rechargeable battery, and a charger circuit. The sensor system and the application are then tested to gauge the performance. Based on the test, the system is able to communicate with the smartphone through the host. In addition, based on 24-hour battery testing, the system requires less than 0.53958 watts to operate, thus achieving the low-cost target.