m45pe40 STMicroelectronics, m45pe40 Datasheet - Page 19

• Manufacturer Part Number: m45pe40
• Description: 4 Mbit, Low Voltage, Page-erasable Serial Flash Memory With Byte-alterability And A 50 Mhz Spi Bus Interface
• Manufacturer: STMicroelectronics

M45PE40
6.3
Read Identification (RDID)
The Read Identification (RDID) instruction allows the 8-bit manufacturer identification to be
read, followed by two bytes of device identification. The manufacturer identification is
assigned by JEDEC, and has the value 20h for STMicroelectronics. The device identification
is assigned by the device manufacturer, and indicates the memory type in the first byte
(40h), and the memory capacity of the device in the second byte (13h).
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. This is followed by the 24-bit device identification, stored in
the memory, being shifted out on Serial Data Output (Q), each bit being shifted out during
the falling edge of Serial Clock (C).
The instruction sequence is shown in
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 Standby Power mode. Once in
the Standby Power mode, the device waits to be selected, so that it can receive, decode and
execute instructions.
Table 4.
Figure 8.
Manufacturer identification
S
C
D
Q
Read Identification (RDID) data-out sequence
Read Identification (RDID) instruction sequence and data-out sequence
20h
0
High Impedance
1
2
Instruction
3
4
5
6
7
MSB
Manufacturer Identification
8
Figure
Memory type
9 10 11 12 13 14 15
40h
8.
Device identification
MSB
15 14 13
16 17 18
Device Identification
Memory capacity
3
28 29 30 31
2
13h
1
Instructions
0
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