9.3.4 Program Memory

User program Flash stores code and data for Mission mode execution. Unless restricted by access control, there is full access (execute, data read, write, CRC) to user program Flash in all modes. User program Flash access controls include the protection regions and code-protect.

Programming the UCB write-protect word permanently prevents modification of all UCB Configuration bits settings. Protection region and code-protect access controls apply to all of the user program space. The chip erase operation erases all of the user program Flash except for permanent (OTP and IRT) protection regions. If permanent protection regions are configured and UCB is either erase-protected (EPUCB (UCPROT[0]) = ‘1’) or write-protected (WPUCB (UCPROT[1]) = ‘1’), only the user program memory Flash outside the permanent regions is erased. In this case, UCB, which stores the permanent region descriptors and the permanent region contents, is not affected by the chip erase. If UCB is not erase-protected (EPUCB (UCPROT[0]) = ‘0’) and not write-protected (WPUCB (UCPROT[1]) = ‘0’), then UCB and the entire user program and user data Flash are erased by a chip erase. UCA is always erased by a chip erase. Chip erase is only allowed in ICSP Programming mode. If Secure Debug is enabled, IRT firmware authorization is required for a chip erase. If Entire Flash OTP by ICSP Write Inhibit is enabled, external tools will be unable to chip erase the device. Chip erase overrides firmware configurable (non-permanent) protection region write protections. Firmware configurable region contents are erased on a chip erase. Regardless of UCB erase or write protections, if permanent protection regions are configured, only user program Flash outside the permanent regions is erased.