This is a small library that lets you easily communicate with and configure a Hynetek HUSB328 USB-PD negotiation chip.
get_capabilities() queries the HUSB for the USB-PD supplies capabilities. This is called in begin, but if the supported capabilities have somehow been re-negotiated, this can re-fresh that.
begin() initializes the Wire instance, and queries the the HUSB IC for the USB-PD capabilities.
set_voltage() attempts to negotiate the requested voltage from the USB-PD supply.
update_pd_status() Queries the HUSB and updates the internal status object.
get_pd_voltage() Calls update_pd_status and returns the currently negotiated voltage.
get_pd_current() Calls update_pd_status and returns the currently negotiated current.
The capability struct serves as a way to read the supported currents at the different voltages. If the current is 0, the voltage isn't supported.
for example:
capability.ma_5V might be 5000 mA
This struct is packed, so can be iterated over with pointers. ma_5V is the first element in the struct.
The library has a status object.
It's a 16-bit union providing access either to the entire 16bits through status.combined,
to the PD_STATUS0 and PD_STATUS1 bytes,
or to the individual bit fields as defined in the HUSB datasheet.
For example status.VOLTAGE_5V will be 1 if a legacy apple 5V contract is active (I think)