AT45DB041B
Figure 2. Algorithm for Randomly Modifying Data
START
provide address of
page to modify
MAIN MEMORY PAGE
If planning to modify multiple
bytes currently stored within
a page of the Flash array
TO BUFFER TRANSFER
(53H, 55H)
BUFFER WRITE
(84H, 87H)
MAIN MEMORY PAGE PROGRAM
THROUGH BUFFER
(82H, 85H)
BUFFER TO MAIN
MEMORY PAGE PROGRAM
(83H, 86H)
(2)
AUTO PAGE REWRITE
(58H, 59H)
INCREMENT PAGE
(2)
ADDRESS POINTER
END
Notes: 1. To preserve data integrity, each page of a DataFlash sector must be updated/rewritten at least once within every 10,000
cumulative page erase/program operations.
2. A Page Address Pointer must be maintained to indicate which page is to be rewritten. The Auto Page Rewrite command
must use the address specified by the Page Address Pointer.
3. Other algorithms can be used to rewrite portions of the Flash array. Low-power applications may choose to wait until 10,000
cumulative page erase/program operations have accumulated before rewriting all pages of the sector. See application note
AN-4 (“Using Atmel’s Serial DataFlash”) for more details.
Sector Addressing
PA10
PA9
PA8
0
PA7
0
PA6
0
PA5
0
PA4
0
PA3
0
PA2 - PA0
Sector
0
0
0
0
1
1
0
X
X
X
X
X
X
0
1
2
3
4
5
0
0
X
X
X
X
X
0
1
X
X
X
X
X
1
X
X
X
X
X
X
0
X
X
X
X
X
X
1
X
X
X
X
X
X
27
1938F–DFLSH–10/02
ATMEL [ ATMEL ]
