USB Type-C configuration necessary for battery charging only

The standard power over Type-C link works in the following way.

If both ports are Type-C, the initial state of provider is no VBUS.

DEVICE: The device must have 5.1k pull-down on the its port CC pin (on both pins).

HOST: The host must have pull-ups on both CC pins, in accord with its capability. With pull-ups to 5 V, 56k pullup means standard capability (500/900mA), 22k pull-up means 1.5 A capability, and 10k for 3.0 A capability. Alternatively this advertising can be done by means of corresponding current source.

CABLE: A C-C cable must have a wire connecting CC pins between both ends.

Initially, if no connection is made, the host side sees high voltage on CC pin, and the device sees low (zero) on its CC pin.

CONNECTION: Once the C-C cable is connected between two link partners, the DFP (host) will sense the drag by 5.1k resistor (from device side). As result, it will turn the VBUS on. This is how a host recognizes that a connection has been made. The connect event is essentially controlled by sink side having 5.1k Rd.

The UFP (device), upon receiving VBUS, should measure the voltage on CC pin, and should set its expectations in accord with the table provided by Tony Stewart.

So, the CC pin level is "measured" on both ends of the C-C link, by the host to detect connection and enable VBUS, and by device to determine power capability of the host.

If a legacy connection is used, the advertising is done by legacy cable assembly, inside its Type-C end (overmold), indicating lowest power capability using 56k (since the cable doesn't know what kind of host it is plugged in).