Application note from ON Semiconductor on USB Type-C connector supporting non-USB standard charging protocol, Link here (PDF)
When designing hardware systems with Type−C connectors, a designer also has to consider all legacy, standard, and non-standard specifications that exist in the USB connector eco system. With the introduction of the Type−C connector and the Configuration channel (CC Pin) new challenges occur trying to ensure overall system robustness. This note addresses some of the concerns with the CC pin in a robust system environment.