The purpose of the PTI (Packet Trace Interface) is to support analyzing the packets sent / received by the firmware using the built-in network analyzer of Simplicity Studio. This interface uses three signals: PTI Clock, PTI Data and PTI Sync (often referred as PTI Frame).
Most of the radio boards' PB13 pin is connected to the board controller's PTI Sync input. If a customer firmware uses PB13 as an arbitrary output and there is a high frequency signal on this pin (for example a few hundred kHz) the board controller cannot tolerate it and stops communicating on USB interface. As a result, if the radio board with that kind of firmware is inserted into the WSTK, it is not possible to erase the firmware since the tools (Simplicity Studio, Simplicity Commander) will be unable to connect to the WSTK.
If it happened that a firmware renders the WSTK unusable, follow the guide below:
There is one side effect of this method: the PTI (and thus Network Analyzer) will not work.