AT25PE20 datasheet(7/64 Pages) DIALOG

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AT25PE20

DS-25PE20–139C–8/2018

Device Operation

The device operation is controlled by instructions from the host processor. The list of instructions and their associated

opcodes are contained in Table 15-1 on page 35 through Table 15-4 on page 36. A valid instruction starts with the falling

edge of CS followed by the appropriate 8-bit opcode and the Buffer or main memory address location. While the CS pin

is low, toggling the SCK pin controls the loading of the opcode and the 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.

Three address bytes are used to address memory locations in either the main memory array or in the Buffer. The three

address bytes will be comprised of a number of dummy bits and a number of actual device address bits, with the number

of dummy bits varying depending on the operation being performed and the selected device page size. Buffer addressing

for the optional DataFlash-L page size (264 bytes) is referenced in the datasheet using the terminology BFA8 - BFA0 to

denote the nine address bits required to designate a byte address within the Buffer. The main memory addressing is

referenced using the terminology PA9 - PA0 and BA8 - BA0, where PA9 - PA0 denotes the 10 address bits required to

designate a page address, and BA8 - BA0 denotes the nine address bits required to designate a byte address within the

page. Therefore, when using the optional DataFlash-L page size, a total of 22 address bits are used.

For the default page size (256 bytes), the Buffer addressing is referenced in the datasheet using the conventional

terminology BFA7 - BFA0 to denote the eight address bits required to designate a byte address within the Buffer. Main

memory addressing is referenced using the terminology A17 - A0, where A17 - A8 denotes the 10 address bits required

to designate a page address, and A7 - A0 denotes the eight address bits required to designate a byte address within a

page. Therefore, when using the default page size, a total of 21 address bits are used.

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