I'm tryng to develop a software that can connect an iPhone to a HMI Box in order to use CarPlay and test an app for CarPlay. Since the starting point is to ask the device, i.e. the iPhone, if it supports CarPlay, I have to write a USB Vendor-Specific Request that the accessory send to know for this capability. I would like to know what are the specific parameters to include in the control transfer request from accessory to device, especially: bRequest, wValue, wIndex. I've studied the whole Accessory Interface Specification Carplay Addendum, but i couldn't find anything. Thanks in advance for your support.