Question 1: CP2615 GPIO.9/Buttons can be configured to report common consumer control buttons through HID interface, do the same predefined buttons can be assigned to more than one slot?
Answer: Yes. The HID media buttons can be assigned to more than one slot using Xpress Configurator. When the feature is enabled, USB Host can see the predefined HID consumer reports when associated buttons are pressed. Here note that the report will not contain any slot number information, hence host does not know which slot generated the report.
Question 2: Is GPIO.9/Buttons readable through CP2615 IO Protocol?
Answer: No CP2615 IOP message supports reading GPIO.9/Buttons pin state directly per AN1139. However, there are three IOP messages related analog pin input, GPIO.8/ADC analog input pin, user can use these IOP messages to read the current voltage on GPIO.9/Buttons pin by tying GPIO.8 to GPIO.9 together if desired.
For more information about the GPIO.9/Buttons connection, please see the GPIO section in CP2615 Datasheet.