For the USB Type-C solution, two pins on the connector, CC1 and CC2,

are used to establish and manage the Source-to-Sink connection.

1. Detect attach of USB ports, e.g. a Source to a Sink

The general concept for setting up a valid connection between a Source and Sink is based on being able to detect terminations residing in the product being attached.
To aid in defining the functional behavior of CC, a pull-up (Rp) and pull-down (Rd) termination model is used – actual implementation in hosts and devices may vary.

Initially, a Source exposes independent Rp terminations on its CC1 and CC2 pins, and a Sink exposes independent Rd terminations on its CC1 and CC2 pins, the Source-to-Sink combination of this circuit configuration represents a valid connection.

To detect this, the Source monitors CC1 and CC2 for a voltage lower than its unterminated voltage. This indicates that either a Sink, a powered cable, or a Sink connected via a powered cable has been attached.

2. Resolve cable orientation and twist connections to establish USB data bus routing

Only one CC pin is connected through the cable to establish signal orientation and the other CC pin is repurposed as VCONN for powering electronics in the USB Type-C plug.

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