AT25DF021A-DWFHT datasheet(37/59 Pages) RENESAS

37 / 59 page

DS-AT25DF021A-042 Rev. L

Page 37

8/7/23

AT25DF021A Datasheet

12. Other Commands and Functions

12.1 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.

Since not all Flash devices are capable of operating at very high clock frequencies, applications must be designed

to read the identification information from the devices at a reasonably low clock frequency to ensure all devices

used in the application can be identified properly. Once the identification process is complete, the application can

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 begins outputting the identification data on the

SO pin during the subsequent clock cycles. The first byte that is output is the Manufacturer ID followed by two

bytes of Device ID information. The fourth byte output is the Extended Device Information String Length, which is

00h indicating that no Extended Device Information follows. After the Extended Device Information String Length

byte is output, the SO pin goes into a high-impedance state; thus, additional clock cycles have no affect on the SO

pin and no data are output. As indicated in the JEDEC standard, reading the Extended Device Information String

Length and any subsequent data is optional.Deasserting the CS pin stops 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 13. Manufacturer and Device ID Information

Byte No.

Data Type

Value

Manufacturer ID

1Fh

Device ID (Part 1)

43h

Device ID (Part 2)

01h

Extended Device Information String Length

00h

Table 14. 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

JEDEC Assigned Code

1Fh

JEDEC Code:0001 1111 (1Fh for Renesas

Electronics)

00011111

Device ID (Part

Family Code

Density Code

43h

Family Code:010 (AT25F/AT25DFxxx

series)

Density Code:00011 (2-Mbit)

01000011

Device ID (Part

Sub Code

Product Version Code

01h

Sub Code:000 (Standard series)

Product Version:00001

00000001

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