AT25SF641B datasheet(43/59 Pages) DIALOG

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AT25SF641B

DS-AT25SF641B–191D–12-2020

12.2 Read ID (Legacy Command) (90h)

Identification information can be read from the device to enable systems to electronically query and identify the

device. The JEDEC standard “Read Manufacturer and Device ID (9Fh)” method, described in Section 12.1, is

preferred; however, the legacy Read ID command is supported on the AT25SF641B to enable backwards

compatibility to previous generation devices.

To read the identification information, the CS pin must first be asserted, and the opcode 90h must be clocked into

the device, followed by three dummy bytes. After the opcode and three dummy bytes are entered, the device

begins outputting the identification data on the SO pin during the subsequent clock cycles. The first byte output is

the Manufacturer ID of 1Fh, followed by a single byte of data representing a device code 16h. After the device code

is output, the sequence of bytes repeats.

Deasserting the CS pin terminates the Read ID operation and puts the SO pin into a high-impedance state. The CS

pin can be deasserted at any time and does not require that a full byte of data read.

Figure 12-2. Read Manufacture ID and Device (Legacy Command)

SCK

MSB

10010000

OPCODE

HIGH-IMPEDANCE

31 32

38 39

35 36

XXX

3 DUMMY BYTES

MSB

DDDD

DEVICE ID

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