AT45DB321D datasheet(22/57 Pages) ATMEL

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3597N–DFLASH–04/09

AT45DB321D

11.2 Main Memory Page to Buffer Compare

A page of data in the main memory can be compared to the data in buffer 1 or buffer 2. To initi-

ate the operation for DataFlash standard page size, a 1-byte opcode, 60H for buffer 1 and 61H

for buffer 2, must be clocked into the device, followed by three address bytes consisting of

1 don’t care bit, 13-page address bits (PA12 - PA0) that specify the page in the main memory

that is to be compared to the buffer, and 10 don’t care bits. To start a main memory page to buf-

fer compare for a binary page size, the opcode 60H for buffer 1 or 61H for buffer 2, must be

clocked into the device followed by three address bytes consisting of 2 don’t care bits, 13 page

address bits (A21 - A9) that specify the page in the main memory that is to be compared to the

buffer, and 9 don’t care bits. The CS pin must be low while toggling the SCK pin to load the

opcode and the address bytes from the input pin (SI). On the low-to-high transition of the CS pin,

the data bytes in the selected main memory page will be compared with the data bytes in buffer

1 or buffer 2. During this time (tCOMP), the status register and the RDY/BUSY pin will indicate that

the part is busy. On completion of the compare operation, bit 6 of the status register is updated

with the result of the compare.

11.3 Auto Page Rewrite

This mode is only needed if multiple bytes within a page or multiple pages of data are modified in

a random fashion within a sector. This mode is a combination of two operations: Main Memory

Page to Buffer Transfer and Buffer to Main Memory Page Program with Built-in Erase. A page of

data is first transferred from the main memory to buffer 1 or buffer 2, and then the same data

(from buffer 1 or buffer 2) is programmed back into its original page of main memory. To start the

rewrite operation for the DataFlash standard page size (528 bytes), a 1-byte opcode, 58H for

buffer 1 or 59H for buffer 2, must be clocked into the device, followed by three address bytes

comprised of 1 don’t care bit, 13-page address bits (PA12-PA0) that specify the page in main

memory to be rewritten and 10 don’t care bits. To initiate an auto page rewrite for a binary page

size (512 bytes), the opcode 58H for buffer 1 or 59H for buffer 2, must be clocked into the device

followed by three address bytes consisting of 2 don’t care bits, 13 page address bits (A21 - A9)

that specify the page in the main memory that is to be written and 9 don’t care bits. When a low-

to-high transition occurs on the CS pin, the part will first transfer data from the page in main

memory to a buffer and then program the data from the buffer back into same page of main

memory. The operation is internally self-timed and should take place in a maximum time of tEP.

During this time, the status register and the RDY/BUSY pin will indicate that the part is busy.

If a sector is programmed or reprogrammed sequentially page by page, then the programming

algorithm shown in Figure 25-1 (page 46) is recommended. Otherwise, if multiple bytes in a

page or several pages are programmed randomly in a sector, then the programming algorithm

shown in Figure 25-2 (page 47) is recommended. Each page within a sector must be

updated/rewritten at least once within every 10,000 cumulative page erase/program operations

in that sector.

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