Steve Karg - 2018-03-16

There is an example ATmega MS/TP project in ports/bdk-atxx4-mstp/ but it would require you to do it without Arduino, or to port BACnet MS/TP to Arduino.

Alternately, there is already a library that supports BACnet on Arduino:
https://www.cimetrics.com/blogs/news/running-ubacstac-device-on-arduino-mega-with-an-rs485-module