AT45DB321
4
MAIN MEMORY PAGE TO BUFFER TRANSFER:
A page
of data can be transferred from the main memory to either
buffer 1 or buffer 2. An 8-bit opcode, 53H for buffer 1 and
55H for buffer 2, is followed by one reserved bit, 13
address bits (PA12-PA0) which specify the page in main
memory that is to be transferred, and 10 don’t care bits.
The CS pin must be low while toggling the SCK pin to load
the opcode, the address bits, and the don’t care bits from
the SI pin. The transfer of the page of data from the main
memory to the buffer will begin when the CS pin transitions
from a low to a high state. During the transfer of a page of
data (t
XFR
), the status register can be read to determine
whether the transfer has been completed or not.
MAIN MEMORY PAGE TO BUFFER COMPARE:
A page
of data in main memory can be compared to the data in
buffer 1 or buffer 2. An 8-bit opcode, 60H for buffer 1 and
61H for buffer 2, is followed by 24 address bits consisting of
one reserved bit, 13 address bits (PA12-PA0) which spec-
ify the page in the main memory that is to be compared to
the buffer, and 10 don't care bits. The loading of the
opcode and the address bits is the same as described pre-
viously. The CS pin must be low while toggling the SCK pin
to load the opcode, the address bits, and the don't care bits
from the SI pin. On the low to high transition of the CS pin,
the 528 bytes in the selected main memory page will be
compared with the 528 bytes in buffer 1 or buffer 2. During
this time (t
XFR
), the status register 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 com-
pare.
Program
BUFFER WRITE:
Data can be shifted in from the SI pin
into either buffer 1 or buffer 2. To load data into either
buffer, an 8-bit opcode, 84H for buffer 1 or 87H for buffer 2,
is followed by 14 don't care bits and 10 address bits (BFA9-
BFA0). The 10 address bits specify the first byte in the
buffer to be written. The data is entered following the
address bits. If the end of the data buffer is reached, the
device will wrap around back to the beginning of the buffer.
Data will continue to be loaded into the buffer until a low to
high transition is detected on the CS pin.
BUFFER TO MAIN MEMORY PAGE PROGRAM WITH
BUILT-IN ERASE:
Data written into either buffer 1 or buffer
2 can be programmed into the main memory. An 8-bit
opcode, 83H for buffer 1 or 86H for buffer 2, is followed by
one reserved bit, 13 address bits (PA12-PA0) that specify
the page in the main memory to be written, and 10 addi-
tional don't care bits. When a low to high transition occurs
on the CS pin, the part will first erase the selected page in
main memory to all 1s and then program the data stored in
the buffer into the specified page in the main memory. Both
the erase and the programming of the page are internally
self timed and should take place in a maximum time of t
EP
.
During this time, the status register will indicate that the
part is busy.
BUFFER TO MAIN MEMORY PAGE PROGRAM WITH-
OUT BUILT-IN ERASE:
A previously erased page within
main memory can be programmed with the contents of
either buffer 1 or buffer 2. An 8-bit opcode, 88H for buffer 1
or 89H for buffer 2, is followed by one reserved bit, 13
address bits (PA12-PA0) that specify the page in the main
memory to be written, and 10 additional don’t care bits.
When a low to high transition occurs on the CS pin, the part
will program the data stored in the buffer into the specified
page in the main memory. It is necessary that the page in
main memory that is being programmed has been previ-
ously erased. The programming of the page is internally
self timed and should take place in a maximum time of t
P
.
During this time, the status register will indicate that the
part is busy.
PAGE ERASE:
The optional Page Erase command can be
used to individually erase any page in the main memory
array allowing the Buffer to Main Memory Page Program
without Built-In Erase command to be utilized at a later
time. To perform a Page Erase, an opcode of 81H must be
loaded into the device, followed by one reserved bit, 13
address bits (PA12-PA0), and 10 don’t care bits. The 13
address bits are used to specify which page of the memory
array is to be erased. When a low to high transition occurs
on the CS pin, the part will erase the selected page to 1s.
The erase operation is internally self-timed and should take
place in a maximum time of t
PE
. During this time, the status
register will indicate that the part is busy.
BLOCK ERASE:
A block of eight pages can be erased at
one time allowing the Buffer to Main Memory Page Pro-
gram without Built-In Erase command to be utilized to
reduce programming times when writing large amounts of
data to the device. To perform a Block Erase, an opcode of
50H must be loaded into the device, followed by one
reserved bit, 10 address bits (PA12-PA3), and 13 don’t
care bits. The 10 address bits are used to specify which
block of eight pages is to be erased. When a low to high
transition occurs on the CS pin, the part will erase the
selected block of eight pages to 1s. The erase operation is
internally self-timed and should take place in a maximum
time of t
BE
. During this time, the status register will indicate
that the part is busy.
