Rainbow Electronics AT25DF081A - Manual (Page 38)

38
8715C–SFLSH–11/2012
AT25DF081A
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 spe-
cific 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. Data Type Value
1 Manufacturer ID 1Fh
2 Device ID (Part 1) 45h
3 Device ID (Part 2) 01h
4 [Optional to read] Extended Device Information (EDI) String Length 01h
5 [Optional to read] EDI Byte 1 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 Adesto)
0 0 0 1 1 1 1 1
Device ID (Part 1)
Family Code Density Code
45h
Family Code: 010 (AT25DF/26DFxxx series)
Density Code: 00101 (8-Mbit)
0 1 0 0 0 1 0 1
Device ID (Part 2)
Sub Code Product Version Code
01h
Sub Code: 000 (Standard series)
Product Version: 00001 (Second major version)
0 0 0 0 0 0 0 1