Tested this today: it works fine! In the meanwhile,I also found this: https://forum.mysensors.org/topic/2725/sensebender-micro/30 My platformio.ini file: [platformio] src_dir = WindowOpenSensor [env:sensebender-micro] platform = atmelavr board = pro8MHzatmega328 framework = arduino monitor_speed = 19200 lib_deps = 548 ; MySensors

@andy5211d Sorted. After trying to use different versions and combinations of the various files nothing made any difference; it had to be an issue with the include file to drive the Ethernet module. I discovered the default configuration for a new Ardunio IDE install uses includes from a different location compared to my original software build. Thus the Ethernet.h file was the default Ardunio sketch not the one for the SAMD board included in MySensors and as suspected the Ethernet module was not being communicated with. Using the verbose options for the compiler in the IDE preferences it is possible to see which 'includes' are used. So far I have not been able to 'drive' the compiler to use specific locations and the description of how and the order of Library preference is not that clear to me. There are now IDE warnings about nRF5 but as I don't use nRF5's its not important, these are different issues though.