3
AT45DB321B
2223D–DFLASH–10/02
Memory Architecture Diagram
Device Operation The device operation is controlled by instructions from the host processor. The list of
instructions and their associated opcodes are contained in Tables 1 through 4. A valid
instruction starts with the falling edge of CS
followed by the appropriate 8-bit opcode
and the desired buffer or main memory address location. While the CS
pin is low, tog-
gling the SCK pin controls the loading of the opcode and the desired buffer or main
memory address location through the SI (serial input) pin. All instructions, addresses
and data are transferred with the most significant bit (MSB) first.
Buffer addressing is referenced in the datasheet using the terminology BFA9 - BFA0 to
denote the ten address bits required to designate a byte address within a buffer. Main
memory addressing is referenced using the terminology PA12 - PA0 and BA9 - BA0
where PA12 - PA0 denotes the 13 address bits required to designate a page address
and BA9 - BA0 denotes the ten address bits required to designate a byte address within
the page.
Read Commands By specifying the appropriate opcode, data can be read from the main memory or from
either one of the two data buffers. The DataFlash supports two categories of read
modes in relation to the SCK signal. The differences between the modes are in respect
to the inactive state of the SCK signal as well as which clock cycle data will begin to be
output. The two categories, which are comprised of four modes total, are defined as
Inactive Clock Polarity Low or Inactive Clock Polarity High and SPI Mode 0 or SPI
Mode 3. A separate opcode (refer to Table 1 on page 10 for a complete list) is used to
select which category will be used for reading. Please refer to the “Detailed Bit-level
Read Timing” diagrams in this datasheet for details on the clock cycle sequences for
each mode.
CONTINUOUS ARRAY READ: By supplying an initial starting address for the main
memory array, the Continuous Array Read command can be utilized to sequentially
read a continuous stream of data from the device by simply providing a clock signal; no
additional addressing information or control signals need to be provided. The DataFlash
incorporates an internal address counter that will automatically increment on every clock
SECTOR 0 = 4224 bytes (4K + 128)
SECTOR 1 = 266,112 bytes (252K + 8064)
SECTOR 15 = 270,336 bytes (256K + 8K)
Block = 4224 bytes
(4K + 128)
8 Pages
SECTOR 0
SECTOR 1
Page = 528 bytes
(512 + 16)
PAGE 0
PAGE 1
PAGE 6
PAGE 7
PAGE 8
PAGE 9
PAGE 8190
PAGE 8191
BLOCK 0
PAGE 14
PAGE 15
PAGE 16
PAGE 17
PAGE 18
PAGE 8189
BLOCK 1
SECTOR ARCHITECTURE BLOCK ARCHITECTURE PAGE ARCHITECTURE
BLOCK 0
BLOCK 1
BLOCK 62
BLOCK 63
BLOCK 64
BLOCK 65
BLOCK 1022
BLOCK 1023
BLOCK 126
BLOCK 127
BLOCK 128
BLOCK 129
SECTOR 2
SECTOR 2 = 270,336 bytes (256K + 8K)
SECTOR 16 = 270,336 bytes (256K + 8K)
BLOCK 2
