21

3704BX–DFLASH–11/2012

AT25BCM512B [Preliminary]

Figure 12-1. Read Manufacturer and Device ID

12.2

Read ID (Legacy Command)

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

and identify the device while it is in system. The preferred method for doing so is the JEDEC

standard “Read Manufacturer and Device ID” method described in Section 12.1 on page 20;

however, the legacy Read ID command is supported on the AT25BCM512B to enable back-

wards compatibility to previous generation devices.

To read the identification information, the CS pin must first be asserted and the opcode of 15h

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 of 1Fh followed by a single byte of data represent-

ing a device code of 65h. After the device code is output, the SO pin will go into a high-

impendance state; therefore, additional clock cycles will have no affect on the SO pin and no

data will be output.

Deasserting the CS pin will terminate the Read ID 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 read.

Figure 12-2. Read ID (Legacy Command)

SCK

CS

SI

SO

6

0

9Fh

8

7

38

OPCODE

1Fh

65h

00h

00h

MANUFACTURER ID

DEVICE ID

BYTE1

DEVICE ID

BYTE2

EXTENDED

DEVICE

INFORMATION

STRING LENGTH

HIGH-IMPEDANCE

14

16

15

22

24

23

30

32

31

Note: Each transition

shown for SI and SO represents one byte (8 bits)

SCK

CS

SI

SO

MSB

23

1

0

00010101

67

5

410 11

9

812

21 22

17

20

19

18

15 16

13 14

OPCODE

MSB

01111

1

0

0

MSB

10010

1

1

0

MANUFACTURER

ID

DEVICE

CODE

HIGH-IMPEDANCE