We are designing the gadget that can be connected to the Android phone over USB-C port.
Here are the requirements:
The gadget contains the FTDI USB to RS-232 adaptor ( USB 2.0 )
The Android phone will always be the DFP
The gadget will always be the UFP
The gadget must be the DRP
1. Gadget has the external 5V power connector.
2. If gadget detects the voltage on external 5V connector it should use this 5V to charge the phone and power itself.
3. If gadget does not detect the voltage on external 5V connector it should use 5V coming from the phone to power itself.
4. The role determination must be done when phone is connected to the gadget.
5. The role maybe swapped if the external power connected/disconnected. (It's just nice to have requirement)
Now the questions:
Q1: What USB PD chip do you recommend to use?
Q2: Do we need to customize chip firmware or it can be done by changing the configuration of the existing one?
Q3: If custom firmware is required what project should be used as a baseline?
Q3.1: Is exchanging of PD messages required for #4 or it can be done by playing with Rd/Rp?
