AT25DF321A_10 Datasheet, PDF (37/52 Pages) ATMEL Corporation – 32-Mbit 2.7V Minimum Serial Peripheral Interface Serial Flash Memory

Atmel 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 f_CLK. 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.
1
2
3
4
Data Type
Manufacturer ID
Device ID (Part 1)
Device ID (Part 2)
Extended Device Information String Length
Value
1Fh
47h
01h
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
0
0
0
1
1
Sub Code
Product Version Code
0
0
0
0
0
0
0
Hex
Bit 0 Value Details
1Fh JEDEC Code: 0001 1111 (1Fh for Atmel)
1
1
47h
Family Code: 010 (AT25DF/26DFxxx series)
Density Code: 00111 (32-Mbit)
1
01h
Sub Code: 000 (Standard series)
Product Version:00001 (First major revision)
37
3686D–DFLASH–12/09