AT45DB021E datasheet(23/69 Pages) RENESAS

23 / 69 page

DS-AT45DB021E-8789 Rev. N

Page 23

3/24/26

AT45DB021E Datasheet

9.3

Sector Protection Register

The nonvolatile Sector Protection Register specifies which sectors are to be protected or unprotected with either

the software or hardware controlled protection methods. The Sector Protection Register contains eight bytes of

data, of which byte locations 0 through 7 contain values that specify whether Sectors 0 through 7 are protected or

unprotected. The Sector Protection Register is user modifiable and must be erased before it can be

reprogrammed. Table 8 illustrates the format of the Sector Protection Register.

Table 8. Sector Protection Register

Note: The default values for bytes 0 through 7 are 00h when shipped from Renesas Electronics.

Table 9. Sector 0 (0a, 0b) Sector Protection Register Byte Value

Note:X = Don’t care.

9.3.1

Erase Sector Protection Register

In order to modify and change the values of the Sector Protection Register, it must first be erased using the Erase

Sector Protection Register command.

To erase the Sector Protection Register, a 4-byte command sequence of 3Dh, 2Ah, 7Fh, and CFh must be

clocked into the device. After the last bit of the opcode sequence has been clocked in, the CS pin must be

deasserted to initiate the internally self-timed erase cycle. The erasing of the Sector Protection Register must take

place in a maximum time of tPE. During this time, the RDY/BUSY bit in the Status Register indicates that the

device is busy. If the device is powered-down before the completion of the erase cycle, then the contents of the

Sector Protection Register cannot be guaranteed.

The Sector Protection Register can be erased with sector protection enabled or disabled. Since the erased state

(FFh) of each byte in the Sector Protection Register is used to indicate that a sector is specified for protection,

leaving the sector protection enabled during the erasing of the register allows the protection scheme to be more

effective in the prevention of accidental programming or erasing of the device. If for some reason an erroneous

program or erase command is sent to the device immediately after erasing the Sector Protection Register and

before the register can be reprogrammed, then the erroneous program or erase command is not processed

because all sectors would be protected.

Table 10. Erase Sector Protection Register Command

Figure 8. Erase Sector Protection Register

Sector Number

0 (0a, 0b)

1 to 7

Protected

See Table 9

FFh

Unprotected

00h

Bit 7:6

Bit 5:4

Bit 3:2

Bit 1:0

Data Value

Sector 0a

(Page 0-7)

Sector 0b

(Page 8-127)

N/A

Sectors 0a and 0b Unprotected

0Xh

Protect Sector 0a

CXh

Protect Sector 0b

3Xh

Protect Sectors 0a and 0b

FXh

Command

Byte 1

Byte 2

Byte 3

Byte 4

Erase Sector Protection Register

3Dh

2Ah

7Fh

CFh

3Dh

2Ah

7Fh

CFh

Each transition represents eight bits

AT45DB021E датащи(PDF) 23 Page - Renesas Technology Corp

AT45DB021E датащи(HTML) 23 Page - Renesas Technology Corp

Html Pages

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69

датащи скачать

ссылки URL