AT25DF321A datasheet(37/53 Pages) ETC2

37 / 53 page

3686F–DFLASH–1/2014

AT25DF321A

12.2

Read Manufacturer and Device ID

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

it is in system. The identification method and the command opcode comply with the JEDEC standard for “Manufacturer and

Device ID Read Methodology for SPI Compatible Serial Interface Memory Devices”. The type of information that can be read

from the device includes the JEDEC defined Manufacturer ID, the vendor specific Device ID, and the vendor specific

Extended Device Information.

The Read Manufacturer and Device ID command is limited to a maximum clock frequency of fCLK. Since not all Flash devices

are capable of operating at very high clock frequencies, applications should be designed to read the identification information

from the devices at a reasonably low clock frequency to ensure that all devices to be used in the application can be identified

properly. Once the identification process is complete, the application can then increase the clock frequency to accommodate

specific Flash devices that are capable of operating at the higher clock frequencies.

To read the identification information, the CS pin must first be asserted and the opcode of 9Fh must be clocked into the device.

After the opcode has been clocked in, the device will begin outputting the identification data on the SO pin during the

subsequent clock cycles. The first byte that will be output will be the Manufacturer ID followed by two bytes of Device ID

information. The fourth byte output will be the Extended Device Information String Length, which will be 00h indicating that

no Extended Device Information follows. After the Extended Device Information String Length byte is output, the SO pin will

go into a high-impedance state; therefore, additional clock cycles will have no affect on the SO pin and no data will be output.

As indicated in the JEDEC standard, reading the Extended Device Information String Length and any subsequent data is

optional.

Deasserting the CS pin will terminate the Manufacturer and Device ID read operation and put 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 be read.

Table 12-1.

Manufacturer and Device ID Information

Byte No.

Data Type

Value

Manufacturer ID

1Fh

Device ID (Part 1)

47h

Device ID (Part 2)

01h

Extended Device Information String Length

00h

Table 12-2.

Manufacturer and Device ID Details

Data Type

Bit 7

Bit 6

Bit 5

Bit 4

Bit 3

Bit 2

Bit 1

Bit 0

Hex

Value

Details

Manufacturer ID

JEDEC Assigned Code

1Fh

JEDEC Code: 0001 1111 (1Fh for Adesto)

Device ID (Part 1)

Family Code

Density Code

47h

Family Code: 010 (AT25DF/26DFxxx series)

Density Code: 00111 (32-Mbit)

Device ID (Part 2)

Sub Code

Product Version Code

01h

Sub Code:

000 (Standard series)

Product Version:00001 (First major revision)

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