SWJ-DP is a combined JTAG-DP and SW-DP that enables either a Serial Wire Debug (SWD) or JTAG probe to be connected to a target. FPGA pins are required for all outputs, with the exception of the SWDO, SWDOEN, and SWDITMS. To use package pins efficiently, serial wire shares, or overlays, the JTAG pins. It also uses an autodetect mechanism that switches between JTAG-DP and SW-DP, depending on which probe is connected. A special sequence on the SWDIOTMS pin is used to switch between JTAG-DP and SW-DP. The SWJ-DP behaves like a pure JTAG target if normal JTAG sequences are sent to it, see SWD and JTAG select mechanism.
For more information on the SW-JTAG, see JTAG-DP.
Figure 9.2 shows the external connections to the SWJ-DP.
The SWJ-DP external connections TDO, TDI, nTRST, SWIDIOTMS, and SWCLKTCK are always present, even if SW-DP or JTAG-DP is not present.
The SWJ-DP is described in more detail in: