SLx 24C01/02/P

Semiconductor Group

22

1998-07-27

7.3

Protection Bit Read

The byte sequence for random bit read is shown in figure 17.

Figure 17

Byte Sequence for Protection Bit Read

The first command byte CSW followed by the control byte EEA addresses the protection

bit to be read. The second command byte CSW is followed by the control byte 00

protection bit read. The first bit (MSB) of the transferred byte is the protection bit of the

addressed page. The other 7 bits are not valid. The page protection status is indicated

as following

Protection Bit = 1: A normal write operation changes the data in the associated page

Protection Bit = 0: The data in the associated page are protected against changes.

If the master acknowledges a byte with a low state of the SDA line, the protection bit of

the next page can be read as the first bit of the following byte. If the master releases the

SDA line, a STOP condition has to complete the read procedure. Any number of bytes

with a page protection status at the first bit position can be requested by the master. If

the bit of the uppermost page has been addressed, the counter has its overflow to the

lowest address according to the first page.

0

SDA Line

EEPROM

Bus Activity

Master

Bus Activity

EEA n

Address

EEPROM

CSW

Byte

Command

S

R

T

A

T

0

S

S

0

000

C

K

A

R

T

A

T

CSW

Byte

Command

S

Data

Byte n

0

C

K

A

CTR

Control

Byte

0

C

K

A

Data

Byte n+1

C

K

A

C

K

A

...

IED02139

P

C

K

A

O

P

T

S

b

b

b

K

C

A

b = Protection Bit