TXZ Family
Flash Memory
2018-06-05
98 / 120
Rev. 2.0
(3) Password Setting/Releasing/Verification
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Password setting
Password system uses a part of a user program. Therefore, special process is not required for password setting.
At the time when a password is programmed to the code flash, a password is set.
・
Password releasing
To release a password, chip erasing (entire erasing) of code flash is required. A password is released at the time
when the code flash is initialized to “0xFF” except the user information area.
・
The case where password verification is unnecessary.
When the entire area of the code flash and data flash are “0xFF”, the product is determined as a blank product.
At this time, password verification is not performed.
For example, even if code flash area is all “0xFF” a password error occurs as long as data remains in data flash.
In this case, perform chip erasing.
(4) Password Setting Values and Setting Ranges
A password must be set according to the condition described in “Table 6.12
Password setting values and setting
ranges”. Unless the condition is met, a password error occurs.
Table 6.12 Password setting values and setting ranges
Password
Blank product (Note 1)
Non blank product
PNSA
(Address where the number of
passwords is stored)
0x5E001000 ≤ PNSA ≤ Maximum
memory address
0x5E001000 ≤ PNSA ≤ (Maximum
memory address)
PCSA
(Address where the start
address used for password
comparison)
0x5E001000 ≤ PCSA ≤ Maximum
memory address
0x5E001000 ≤ PCSA ≤ (Maximum
memory address) – (N x 4) + 1
N (The number of passwords)
Necessary (Note 2)
8 ≤ N
Password
Necessary (Note 2)
Necessary (Note 1)
Note1: Over the same three bytes consecutive data cannot be used as a password string.
Note2: When the flash memory erasing command is used, a dummy password string should be sent to
the blank product.