April 14 2016
I am a bit confused by the PUR pin and why it is tied to both DP and GND. This is done on both the 5528 and 5529. This required some research into the MSP430 User Guide. I wish it had a cross reference to look up the external pin name, instead I am forced to search for the text "PUR", which turns up a lot of instances of the word "purpose".
The MSP430 User Guide (1.6 Connection of Unused Pins) has a hint:
PUR (2) DVss For USB devices only when USB module is not being used in the application
(2) The default USB BSL evaluates the state of the PUR pin after a BOR reset. If it is pulled high externally, then the BSL is invoked. Therefore, unless invoking the BSL, it is important to keep PUR pulled low after a BOR reset, even if BSL or USB is never used. A 1-MΩ resistor to ground is recommended.
Here is the full explanation, in the USB Module chapter:
42.2.1.1 D+ Pullup Via PUR Pin
When a full-speed USB device is attached to a USB host, it must pull
up the D+ line (DP pin) for the host to recognize its presence. The
MSP430 USB module implements this with a software-controlled pin that
activates a pullup resistor. The bit that controls this function is
PUR_EN. If software control is not desired, the pullup can be
connected directly to VUSB.
PUR means "Pull Up Resistor" and is used to notify the hub that the device is present by pulling D+ up after the MSP430 has booted up. This is a software-controlled output pin.
So the circuit is correct.