27.5.5 Region Lock Bits

The NVM main address space is accessible through the AHB0 or AHB1 interfaces, and grouped into 32 equally sized regions regardless of BOOTPROT or SmartEEPROM settings. The region size is dependent on the flash memory size, and is given in the table below. Each region has a dedicated lock bit preventing writing and erasing pages in the region. After production, all regions will be unlocked.

To lock or unlock a region, the Lock Region and Unlock Region commands are provided. Writing one of these commands will temporarily lock/unlock the region containing the address loaded in the ADDR register. ADDR can be written by software, or the automatically loaded value from a AHB write operation can be used. The new setting will stay in effect until the next reset, or the setting can be changed again using the lock and unlock commands. The current status of the lock can be determined by reading the RUNLOCK register.

To change the default lock/unlock setting for a region, the user page must be written (See Memories chapter). Writing to the auxiliary space will take effect after the next reset. Therefore, a boot of the device is needed for changes in the lock/unlock setting to take effect. Refer to the ‘Physical Memory Map’ for calibration and auxiliary space address mapping.