The CoreSight 20 connector can be used in either standard JTAG (IEEE 1149.1) mode or Serial Wire Debug (SWD) mode. It can also optionally capture up to 4 bits of parallel trace in Trace Port Interface Unit (TPIU) continuous mode.
When this connector is configured to be a parallel trace source, pins 12 to 20 switch to their alternate trace functions.
The following figure shows the CoreSight 20 connector pinout:
A polarizing key is fitted only at the target end of the cable.