LE25S40FD

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10. Silicon ID Read

ID read is an operation that reads the manufacturer code and device ID information. The silicon ID read command is

not accepted during writing. There are two methods of reading the silicon ID, each of which is assigned a device ID.

In the first method, the read command sequence consists only of the first bus cycle in which (9Fh) is input. In the

subsequent bus cycles, the manufacturer code 62h which is assigned by JEDEC, 2-byte device ID code (memory

type, memory capacity), and reserved code are output sequentially. The 4-byte code is output repeatedly as long as

clock inputs are present, "Table 7-1 JEDEC ID code " lists the silicon ID codes and "Figure 15-a JEDEC ID read"

shows the JEDEC ID read timing waveforms.

The second method involves inputting the ID read command. This command consists of the first through fourth bus

cycles, and the one bite silicon ID can be read when 24 dummy bits are input after (ABh). "Table 7-2 ID code " lists

the silicon ID codes and "Figure 15-b ID read" shows the ID read timing waveforms.

If the SCK input persists after a device code is read, that device code continues to be output. The data output is

transmitted starting at the falling edge of the clock for bit 0 in the fourth bus cycle and the silicon ID read sequence

is finished by setting CS high.

Table 7-1 JEDEC ID code

Table 7-2 ID code

Output code

Output Code

Manufacturer code

62h

1 byte device ID

3E

(LE25S40FD)

2 byte device ID

Memory type

16h

Memory capacity code

13h(4M Bit)

Device code

1

00h

Figure 15-a JEDEC ID Read

Figure 15-b ID Read

CS

High Impedance

13h

16h

62h

SCK

SO

SI

9Fh

15

MSB

MSB

MSB

0

1

2

3

4

5

6

7

8

23

16

24

31

39

8CL

Mode0

Mode3

32

00h

MSB

62h

MSB

CS

High Impedance

3Eh

3Eh

SCK

SO

SI

ABh

X

X

15

MSB

MSB

0

1

2

3

4

5

6

7

8

23

16

24

31

39

8CL

Mode0

Mode3

32

X