9

2048 2.4. 3/1/01

SMS24

SUMMIT MICROELECTRONICS, Inc.

The SMS24 will respond with an ACKnowledge after

recognition of a START condition and its slave address

byte. If both the device and a write operation are selected

the SMS24 will respond with an ACKnowledge after the

receipt of each subsequent 8-bit word. In the READ mode

the SMS24 transmits eight bits of data, then releases the

SDA line, and monitors the line for an ACKnowledge

signal. If an ACKnowledge is detected, and if no STOP

condition is generated by the master, the SMS24 will

continue to transmit data. If an ACKnowledge is not

detected the SMS24 will terminate further data transmis-

sions and await a STOP condition before returning to the

standby power mode.

Device Addressing

Following a start condition the master must output the

address of the slave it is accessing. The most significant

Figure 2. Programming the SMS24

Write Configuration Register

Master

SDA

S

T

A

R

T

A

C

K

XX X

R

/

W

A

C

K

C

2

C

1

C

0

T

3

T

2

T

1

T

0

A

C

K

S

T

O

P

1

0

10

Master

SDA

Device Type

Address

Bus

Address

00 0 00 0 1 1

2046 Fig02 2.0

L

O

C

K

Program Register 0

S

T

A

R

T

A

C

K

XX X

R

/

W

A

C

K

A

C

K

S

T

O

P

1

0

10

Device Type

Address

Bus

Address

00 0 00 0 0 0

X

R

T

1

R

T

0

R

R

4

R

R

3

R

R

2

R

R

1

R

R

0

Program Register 1

S

T

A

R

T

A

C

K

XX X

R

/

W

A

C

K

A

C

K

S

T

O

P

1

0

10

Device Type

Address

Bus

Address

00 0 00 0 0 1

O

V

A

D

D

T

W

D

2

W

D

1

W

D

0

L

O

C

K

X

SMS24

SMS24

four bits of the slave address are the device type identifier.

upon the DT bit of PR1. The configuration and Program

Registers have a device type address of 1001.

The next three bits are the high order address bits.

The last bit of the data stream defines the operation to be

performed. When set to “1” a read operation is selected.

When set to “0” a write operation is selected.

WRITE OPERATIONS

The SMS24 allows two types of write operations: byte

write and page write. A byte write operation writes a single

byte during the nonvolatile write period (tWR). The page

write operation allows up to 16 bytes in the same page to

be written during tWR.