AT25DF021 datasheet(26/41 Pages) ATMEL

26 / 41 page

3677D–DFLASH–04/09

AT25DF021

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 ven-

dor specific Extended Device Information.

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 fre-

quency 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 out-

putting 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)

43h

Device ID (Part 2)

00h

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 Atmel)

Device ID (Part 1)

Family Code

Density Code

43h

Family Code:

010 (AT25DF/26DFxxx series)

Density Code:

00011 (2-Mbit)

Device ID (Part 2)

Sub Code

Product Version Code

00h

Sub Code:

000 (Standard series)

Product Version: 00000 (Initial version)

AT25DF021 Folha de dados(PDF) 26 Page - ATMEL Corporation

AT25DF021 Folha de dados(HTML) 26 Page - ATMEL Corporation

Html Pages

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41

Folha de dados Download

Ligação URL