What happens if you need to connect both a trackball and display over VIK? Or a trackpad and display? The Cactus Connector lets you split your split your microcontroller's VIK into multiple cables.
It's also useful for connecting Cirque trackpads, as these aren't natively compatible with the VIK connectors on the Lemon microcontrollers.
Even though there's 3 branches in the Cactus, for most cases connecting only 2 devices through it is supported. Check the documentation for full details!
