Write Password Enable (WPE): If enabled (WPE = “0”), the user is required to verify the write password to allow write operations in the user zone. If disabled (WPE = “1”), all write operations are allowed within the zone. Verification of the write password also allows the read and write passwords to be changed.
Read Password Enable (RPE): If enabled (RPE = “0”), the user is required to verify either the
read password or write password to allow read operations in the user zone. Read operations initiated without a verified password will return $00 (or the status of the fuse bits, if either CMA or
PER are still intact). Verification of the write password will always allow read access to the zone.
RPE = “0” and WPE = “1” is allowed but is not recommended.
Authentication Enable (ATE): If enabled (ATE = “0”), a valid authentication sequence is required for both read and write and must be completed before access is allowed to the user zone. If disabled (ATE = “1”), authentication is not required for access.
Authentication Only for Write (AOW): If enabled (AOW = “0”), a valid authentication sequence
must be completed before write access is allowed to the user zone. Read access to this zone is
allowed without authentication. This bit is ignored if ATE is enabled.
Password Select (PWS): This bit defines which of the two password sets must be presented to
allow access to the user zone. Each access register may point to a unique password set, or access registers for multiple zones may point to the same password set. In this case, verification of a single password will open several zones, combining the zones into a single larger zone.
Write Lock Mode (WLM): If enabled (WLM = “0”), the 8 bits of the first byte of each user zone
page will define the locked/unlocked status for each byte in the page. Write access is forbidden
to a byte if its associated bit in byte 0 is set to “0”. Bit 7 controls byte 7, bit 6 controls byte 6, etc.
Modify Forbidden (MDF): If enabled (MDF = “0”), no write access is allowed in the zone at any
time. The user zone must be written before the PER is blown.
Program Only (PGO): If enabled (PGO = “0”), data within the zone may be changed from “1” to
“0” but never from “0” to “1”.