AT32UC3L0256_14 Datasheet, PDF (85/852 Pages) ATMEL Corporation – Read-modify-write Instructions and Atomic Bit Manipulation

AT32UC3L0128/256
• Programming Error: A bad keyword and/or an invalid command have been written in the
FCMD register.
• Lock Error: At least one lock region is protected, or BOOTPROT is different from 0. The erase
command has been aborted and no page has been erased. A “Unlock region containing
given page” (UP) command must be executed to unlock any locked regions.
8.5.3
Region Lock Bits
The flash memory has p pages, and these pages are grouped into 16 lock regions, each region
containing p/16 pages. Each region has a dedicated lock bit preventing writing and erasing
pages in the region. After production, the device may have some regions locked. These locked
regions are reserved for a boot or default application. Locked regions can be unlocked to be
erased and then programmed with another application or other data.
To lock or unlock a region, the commands Lock Region Containing Page (LP) and Unlock
Region Containing Page (UP) are provided. Writing one of these commands, together with the
number of the page whose region should be locked/unlocked, performs the desired operation.
One error can be detected in the FSR register after issuing the command:
• Programming Error: A bad keyword and/or an invalid command have been written in the
FCMD register.
The lock bits are implemented using the lowest 16 general-purpose fuse bits. This means that
lock bits can also be set/cleared using the commands for writing/erasing general-purpose fuse
bits, see Section 8.6. The general-purpose bit being in an erased (1) state means that the region
is unlocked.
The lowermost pages in the flash can additionally be protected by the BOOTPROT fuses, see
Section 8.6.
8.6 General-purpose Fuse Bits
The flash memory has a number of general-purpose fuse bits that the application programmer
can use freely. The fuse bits can be written and erased using dedicated commands, and read
85
32145C–06/2013