Optimizing power consumption of Wi-Fi inbuild IoT device : an MSP430 processor and an ESP-03 chip provide a power-efficient solution

摘要

The Internet of Things (IoT) -- connection of small smart sensors, actuators and other devices to the Internet -- is a key concept within the smart home. To ease deployment, such devices are often wireless and battery powered. An important question is the wireless interface used. The ubiquity of Wi-Fi in homes today makes this an attractive option, but the relatively high power requirements of Wi-Fi conflict with the requirement for long battery life and low maintenance. Lower power alternatives, such as Bluetooth and Zigbee, have been proposed, but these have a much smaller installed base. In addition, many Smart Home products are currently available using 433MHz technology. This paper considers whether it is possible to reduce Wi-Fi power usage to the point where cheap Wi-Fi based products can be used instead of other protocols. The paper undertakes power analysis of a wireless sensor with an SoC Wi-Fi module, with and without a separate microcontroller optimised for low power usage which can be used to switch the Wi-Fi module on and off. This paper is an extension of previous work comparing Wi-Fi and 433MHz devices, and so we compare 433MHz to the optimised Wi-Fi sensor. Finally, the paper considers the energy usage of DHCP, demonstrating that further energy savings can be made if the application handles IP addressing and presents a static IP address to the Wi-Fi module.