Rainbow Electronics AT45DB021D - Manual (Page 42)

42
3638K–DFLASH–11/2012
AT45DB021D
Figure 20-2. Algorithm for Randomly Modifying Data
Notes: 1. To preserve data integrity, each page of an DataFlash sector must be updated/rewritten at least once within every
10,000 cumulative page erase and program operations
2. A Page Address Pointer must be maintained to indicate which page is to be rewritten. The Auto Page Rewrite com-
mand 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 and program operations have accumulated before rewriting all pages of the
sector. See application note AN-4 (“Using Adesto’s Serial DataFlash”) for more details
START
MAIN MEMORY PAGE
TO BUFFER TRANSFER
(53H)
INCREMENT PAGE
ADDRESS POINTER
(2)
AUTO PAGE REWRITE
(2)
(58H)
END
provide address of
page to modify
If planning to modify multiple
bytes currently stored within
a page of the Flash array
MAIN MEMORY PAGE PROGRAM
THROUGH BUFFER
(82H)
BUFFER WRITE
(84H)
BUFFER TO MAIN
MEMORY PAGE PROGRAM
(83H)