65.5.4.2.4 Software Prevention for JTAG Debug

It is possible to prevent JTAG Debug accesses by forcing the reset signal of Debug Access Port by software.

While the reset signal is maintained low, the JTAG Debug interface cannot be used. To maintain the Debug Access Port in reset state, set SECUMOD_JTAGCR.FNTRST (in this case, Boundary JTAG is also disabled).

The key used for the BUREG256b scrambler/descrambler is derived from the BUSRAM4KB key and thus benefits from the same protection.