Samsung S3F401F - Manual (Page 73)

S3F401F_UM_REV1.00 INTERNAL FLASH ROM
5-13
Flash Memory Key Register FMKEY (0x000) Access: Write Only
31 30 29 28 27 26 25 24
FMKEYDAT [31:24]
R/W-0 R/W-0 R/W-0 R/W-0 R/W-0 R/W-0 R/W-0 R/W-0
23 22 21 20 19 18 17 16
FMKEYDAT [23:16]
R/W-0 R/W-0 R/W-0 R/W-0 R/W-0 R/W-0 R/W-0 R/W-0
15 14 13 12 11 10 9 8
FMKEYDAT [15:8]
R/W-0 R/W-0 R/W-0 R/W-0 R/W-0 R/W-0 R/W-0 R/W-0
7 6 5 4 3 2 1 0
FMKEYDAT [7:0]
R/W-0 R/W-0 R/W-0 R/W-0 R/W-0 R/W-0 R/W-0 R/W-0
W: Write R: Read -0: 0 After reset -1: 1 After reset -U: Undefined after reset
Flash Memory Key
Key register data to do program, erase, protection operation
FMKEYDAT
To program any data into the flash memory by the user program mode, a specific key register
with 0x5A5A5A5A is required to prevent flash data from being destroyed under undesired
situations.
NOTE The FMKEY register will be cleared automatically just after the completion of erase or program.