31.2.14.4 User-OTP Write Protect
One page in the Flash boot region (for each panel) is implemented as One-Time Programmable NVM called “User-OTP”. It can only be written and cannot be erased (by page or chip erase). It is intended for the storage of user system calibration data that must survive a Flash erase.
User-OTP can be used to store and preserve identification values such as an Ethernet MAC address, OEM/ODM version numbers, board version numbers, etc. Another use would be for calibration values of circuits external to the chip but constant for a board design in which the chip exists.
The UOWP.UOnWP [3:0] (n = 1 or 2) field is used to write protect each of the four rows in the User-OTP page separately.
UOWP Lock/Unlock Sequence
The UOWP register requires a lock/unlock sequence as described in SFR Write Unlock Values. Any attempt to write to this register when locked has no effect.
Local Lock Bits
The user may optionally select to prevent further writes to the write protect by also setting associated UOWP.UOnWPRLOCK bit (in the same register) when writing the UOnWP value.
When a local lock bit is set, subsequent writes to change the corresponding UOnWP bit (even if the unlock sequence is followed) have no effect, creating a “write once’ register. Local lock bits revert to the unlocked state at reset.