7

AT25FS040

5107D–SFLSH–09/06

Functional

Description

The AT25FS040 is designed to interface directly with the synchronous serial peripheral

interface (SPI) of the 6800 type series of microcontrollers.

The AT25FS040 utilizes an 8-bit instruction register. The list of instructions and their

operation codes are contained in Table 5. All instructions, addresses, and data are

transferred with the MSB first and start with a high-to-low transition.

Write is defined as program and/or erase in this specification. The following commands,

PROGRAM, SECTOR ERASE, BLOCK ERASE, CHIP ERASE, and WRSR are write

instructions for AT25FS040.

Note:

1. Either one of the OP CODES will execute the instruction.

WRITE ENABLE (WREN): The device will power up in the write disable state when V

CC

is applied. All write instructions must therefore be preceded by the WREN instruction.

WRITE DISABLE (WRDI): To protect the device against inadvertent writes, the WRDI

instruction disables all write commands. The WRDI instruction is independent of the sta-

tus of the WP pin.

READ STATUS REGISTER (RDSR): The RDSR instruction provides access to the sta-

tus register. The READY/BUSY and write enable status of the device can be determined

by the RDSR instruction. Similarly, the Block Write Protection bits indicate the extent of

Table 5. Instruction Set for the AT25FS040

Instruction Name

One Byte OpCode

Operation

Binary

Hex

WREN

0000 X110

06

Set Write Enable Latch

WRDI

0000 X100

04

Reset Write Enable Latch

RDSR

0000 X101

05

Read Status Register

WRSR

0000 X001

01

Write Status Register

READ

0000 0011

03

Read Data from Memory Array

FAST READ

0000 1011

0B

Read Data from Memory Array (with

dummy cycles)

PROGRAM

0000 X010

02

Program Data Into Memory Array

0010 0000

20

Erase One 4kbyte Sector in Memory Array

1101 0111

D7

0101 0010

52

Erase One 64kbyte Block in Memory Array

1101 1000

D8

0110 0000

60

Erase All Memory Array

1100 0111

C7

1001 1111

9F

Read Manufacturer and Product ID

1010 1011

AB