M25P20
Instructions
6.3
Read Identification (RDID)
The Read Identification (RDID) instruction allows to read the device identification data:
Manufacturer identification (1 byte)
Device identification (2 bytes)
A Unique ID code (UID) (17 bytes, of which 16 available upon customer request).(2)
The manufacturer identification is assigned by JEDEC, and has the value 20h for Numonyx.
The device identification is assigned by the device manufacturer, and indicates the memory
type in the first byte (20h), and the memory capacity of the device in the second byte (12h).
The UID contains the length of the following data in the first byte (set to 10h), and 16 bytes
of the optional Customized Factory Data (CFD) content.
The CFD bytes are read-only and can be programmed with customers data upon their
demand. If the customers do not make requests, the devices are shipped with all the CFD
bytes programmed to zero (00h).
Any Read Identification (RDID) instruction while an Erase or Program cycle is in progress, is
not decoded, and has no effect on the cycle that is in progress. The device is first selected
by driving Chip Select (S) Low. Then, the 8-bit instruction code for the instruction is shifted
in. After this, the 24-bit device identification, stored in the memory, the 8-bit CFD length
followed by 16 bytes of CFD content will be shifted out on Serial Data output (Q). Each bit is
shifted out during the falling edge of Serial Clock (C).
The instruction sequence is shown in Figure 9.
The Read Identification (RDID) instruction is terminated by driving Chip Select (S) High at
any time during data output.
When Chip Select (S) is driven High, the device is put in the Stand-by Power mode. Once in
the Stand-by Power mode, the device waits to be selected, so that it can receive, decode
and execute instructions.
Table 5.
Read Identification (RDID) data-out sequence
Device identification
UID
Manufacturer identification
Memory type
20h
Memory capacity
CFD length
CFD content
20h
12h
10h
16 bytes
2. The UID feature is available only for process technology T9HX devices, identified by with process identification
digit "4" in the device marking and process letter "B" in the part number.
19/55
NUMONYX [ NUMONYX B.V ]
