Uniform Sector

Standard and Dual Serial Flash

GD25WD40C/20C

13

7. COMMANDS DESCRIPTION

All commands, addresses and data are shifted in and out of the device by the host system, with the most significant

bit first. On the first rising edge of SCLK after CS# is driven low, the one-byte command code must be shifted into the device,

with the most significant bit first on SI, and each bit being latched on the rising edges of SCLK.

See Table4, every command sequence starts with a one-byte command code. Depending on the command, this might

be followed by address bytes, or data bytes, or dummy bytes. CS# must be driven high after the last bit of the command

sequence has been completed.

For the command of Read, Fast Read, Read Status Register or Release from Deep Power-Down, and Read Device

ID, the shifted-in command sequence is followed by a data-out sequence. All read instruction can be completed after any

bit of the data-out sequence is being shifted out, and then CS# must be driven high to return to deselected status.

For the command of Page Program, Sector Erase, Block Erase, Chip Erase, Write Status Register, Write Enable,

Write Disable or Deep Power-Down command, CS# must be driven high exactly at a byte boundary, which means the clock

pulse number should be an exact multiple of eight. Otherwise the command is rejected to executed. Especially for Page

Program command, if at any time the input end is not a completed byte, nothing will be written into the memory array, neither

would WEL bit be reset.

Table4. Commands

Command Name

Byte 1

Byte 2

Byte 3

Byte 4

Byte 5

Byte 6

n-Bytes

Write Enable

06H

Write Disable

04H

Read Status Register

05H

(S7-S0)

(continuous)

Write Status Register

01H

S7-S0

Read Data

03H

A23-A16

A15-A8

A7-A0

(D7-D0)

(Next byte)

(continuous)

Fast Read

0BH

A23-A16

A15-A8

A7-A0

dummy

(D7-D0)

(continuous)

Dual Output

Fast Read

3BH

A23-A16

A15-A8

A7-A0

dummy

(continuous)

Page Program

02H

A23-A16

A15-A8

A7-A0

D7-D0

Next byte

Sector Erase

20H

A23-A16

A15-A8

A7-A0

Block Erase(32K)

52H

A23-A16

A15-A8

A7-A0

Block Erase(64K)

D8H

A23-A16

A15-A8

A7-A0

Chip Erase

C7/60 H

Deep Power-Down

B9H

Release From Deep

Power-Down, And

Read Device ID

ABH

dummy

dummy

dummy

(DID7-

DID0)

(continuous)

Release From Deep

Power-Down

ABH

Manufacturer/

Device ID

90H

00H

00H

00H

(MID7-

MID0)

(DID7-

DID0)

(continuous)

Read Identification

9FH

(MID7-

MID0)

(JDID15-

JDID8)

(JDID7-

JDID0)

(continuous)

NOTE:

1. Dual Output data

IO0 = (D6, D4, D2, D0)

O1 = (D7, D5, D3, D1)