AT25BCM512B_12 Datasheet, PDF (20/34 Pages) List of Unclassifed Manufacturers – 512-Kilobit 2.7-volt Minimum SPI Serial Flash Memory

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
1
Manufacturer ID
2
Device ID (Part 1)
3
Device ID (Part 2)
4
Extended Device Information String Length
Value
1Fh
65h
00h
00h
Table 12-2. Manufacturer and Device ID Details
Data Type
Manufacturer ID
Device ID (Part 1)
Device ID (Part 2)
Bit 7 Bit 6 Bit 5 Bit 4 Bit 3 Bit 2 Bit 1
JEDEC Assigned Code
0
0
0
1
1
1
1
Family Code
Density Code
0
1
1
0
0
1
0
Sub Code
Product Version Code
0
0
0
0
0
0
0
Bit 0
1
1
0
Hex
Value Details
1Fh JEDEC Code: 0001 1111 (1Fh for Adesto)
65h
Family Code:
Density Code:
011 (AT25F/AT25FSxxx series)
00101 (512-Kbit)
00h
Sub Code:
000 (Standard series)
Product Version: 00000
20 AT25BCM512B [Preliminary]
3704BX–DFLASH–11/2012