Smart Sensors and Actors with BACnetTM and Mbed OS on Cortex-M Microcontrollers

The increasing use of intelligent sensors and actors in automation proportionally increases the need for suitable interfaces to either interact with, or to provide the means, to participate alongside a common interface. Without appropriate system prerequisites, the integration of sensors or actors, not equipped with such interfaces, into an Ethernet based network, is not possible. As part of a R&D (research and development) project of the University of Wismar, a modified open-source BACnet™1 (Building Automation and Control Networks) stack is used as protocol stack for device-to-device communication between sensors and actors. As hardware, Mbed OS compatible ARM Cortex-M based microcontrollers are used. The target is a, by protocol supported, device-to-device communication for virtually any sensor or actor. The primary tasks of devices utilizing a modified embedded BACnet stack therefore are the extension or provision of Ethernet communication abilities via BACnet/IP. The flexibility of BACnet to project virtually any source of information as a group of standardized objects and services allows integrating a wide range of individual devices into Ethernet networks via a common interface. Combining an established and well-proven, royalty-free protocol with a microcontroller operating system provides all necessary means for a universal interface for the integration of "things" into Ethernet based IP networks via BACnet/IP.