A Security Lock Byte located at the last
 byte of Flash user space offers
 protection of the Flash program
 memory from access (reads, writes, or erases)
 by unprotected code or the C2 interface.
 The Flash security
 mechanism allows the user to lock
 n 512-byte Flash pages, starting at page 0
 (addresses 0x0000 to  0x01FF),
 where n is the 1’s complement number
 represented by the Security Lock Byte.
 Note that the page containing the Flash
 Security Lock Byte is unlocked when no
 other Flash pages are locked
 (all bits of the Lock Byte are ‘1’)
 and locked when any other Flash pages are
 locked (any bit of the Lock Byte is ‘0’)