STA304

20/30

and read or write mode.

The 8th bit (LSB) is the read or write operation RW, this bit is set to 1 in read mode and 0 for write mode. After

a START condition the STA304 identifies on the bus the device address and, if a match is found, it acknowledg-

es the identification on SDA bus during the 9th bit time. The following byte after the device identification byte is

the internal space address.

12.3 WRITE OPERATION

Following a START condition the master sends a device select code with the RW bit set to 0. The STA304 ac-

knowledges this and waits for the byte of internal address. After receiving the internal bytes address the STA304

again responds with an acknowledge.

12.3.1Byte write

In the byte write mode the master sends one data byte, this is acknowledged by STA304. The master then ter-

minates the transfer by generating a STOP condition.

12.3.2Multibyte write

The multibyte write mode can start from any internal address. The transfer is terminated by the master gener-

ating a STOP condition.

Figure 13. Write Mode Sequence

Figure 14. Read Mode Sequence

DEV-ADDR

ACK

START

D98AU825B

RW

SUB-ADDR

ACK

DATA IN

ACK

STOP

BYTE

WRITE

DEV-ADDR

ACK

START

RW

SUB-ADDR

ACK

DATA IN

ACK

STOP

MULTIBYTE

WRITE

DATA IN

ACK

DEV-ADDR

ACK

START

D98AU826A

RW

DATA

NO ACK

STOP

CURRENT

ADDRESS

READ

DEV-ADDR

ACK

START

RW

SUB-ADDR

ACK

DEV-ADDR

ACK

STOP

RANDOM

ADDRESS

READ

DATA

NO ACK

START

RW

DEV-ADDR

ACK

START

DATA

ACK

DATA

ACK

STOP

SEQUENTIAL

CURRENT

READ

DATA

NO ACK

DEV-ADDR

ACK

START

RW

SUB-ADDR

ACK

DEV-ADDR

ACK

SEQUENTIAL

RANDOM

READ

DATA

ACK

START

RW

DATA

ACK

NO ACK

STOP

DATA

RW=

HIGH