Microcontrollers
Arduino/Firmata
Nodes for communicating with Arduinos (or other microcontrollers) running the Firmata Protocol are shipping with vvvv. Reference the VL.IO.Firmata package via the NodeBrowser.
nanoFramework
Want to use plain C# to write code for your microcontrollers? Try the nanoFramework which allows you to write C# with a reduced set of .NET libraries that run on hardware like ESPs and more.
Meadow
Want to use full C#/.NET on a microcontroller? Try Meadow.