Power efficient wireless monitoring system based on ESP8266

Nowadays, the demand for monitoring in buildings is only growing. Understanding the current situation in buildings is the key to energy efficient building management system control. Unfortunately, at the moment, most buildings are equipped with an insufficient number of measuring points. Due to lack of data, it could be impossible to assess how the dynamics of a building might be improved, and what economic effect might be achieved by supplementing its BMS system, or by installing one. For the study of such objects, a system is necessary that can be quickly installed and adapted to the existing infrastructure. Similar systems are also crucial to understanding the behavior and testing new building materials in experimental buildings. To conduct such monitoring studies, many authors use various wireless monitoring systems. One of the essential criteria for the convenient use of such systems is the autonomous working time of a sensor node. The battery life of the sensors is affected by numerous parameters such as the communication protocol, its speed, current in different modes, operating voltage ranges etc. As a result, many combinations of MCUs and radio communication methods are unsuitable for this purpose due to height energy consumption. Popular solutions for such systems are boards based on Atmega and STM MCUs. However, due to political unrest and the disruption of supply chains for electronic components, most of these solutions in 2022 have become unavailable due to the lack of parts in stock for production. This motivates us to explore other possible solutions that are available. In this study, as a solution, the authors explore the ESP8266 microcontroller under different configurations to achieve longer autonomous time. Several authors have previously used this MCU for similar needs in combination with the MQTT protocol. However, is not clear whether such systems are suitable for longterm monitoring. In this paper, authors experimentally evaluated and optimized the energy efficiency of a sensor node based on ESP8266. During optimization, authors relied on detailed energy profile measurements across different variables such as various sleep mode configurations, as well as different approaches to communication. Measurements indicate that, with a certain configuration, ESP8266 can work autonomously for up to 10 years on an 18650 battery.