Debug Interface Access Prevention

The SECUMOD can be used to block access to the system through the Arm processor Debug Access Port interface. This feature is implemented via SECUMOD_JTAGCR, which enables assertion of the nDBGRESET reset input of the debug interface. Writing SECUMOD_JTAGCR.FNTRST_DEBUG to ‘1’ in this register prevents any activity on the TAP (Test Access Port) controller.

On standard devices, FNTRST_DEBUG resets to ‘0’ and thus does not prevent debug access.