CY3654 enumerates as 'Unknown Device'

Question: The keyboard reference design that comes with the CY3654 enumerates as "Unknown Device". What's wrong?

 

Answer:

Check the pull-up on D-. The D- line has a programmable pull-up controlled by the SDATA_PULLUP signal on pin 3 of Port 3 (P3.3). In firmware, writing 0 to P3.3 turns on Q1 and provides D- with the pull-up.  There is an alternate method to provide the pull-up by installing J6 and a shorting jumper. Refer to the CY3654-P02 Applications Board schematic for detailed information.