STA309A
I
2
C bus operation
Doc ID 13855 Rev 4
17/67
address and if a match is found, it acknowledges the identification on SDA bus during the
9
th
-bit time. The byte following the device identification byte is the internal space address.
5.3 Write
operation
Following the START condition the master sends a device select code with the RW bit set
to 0. The STA309A acknowledges this and the writes for the byte of internal address.
After receiving the internal byte address the STA309A again responds with an
acknowledgement.
5.3.1 Byte
write
In the byte write mode the master sends one data byte, this is acknowledged by the Omega
DDX core. The master then terminates the transfer by generating a STOP condition.
5.3.2 Multi-byte
write
The multi-byte write modes can start from any internal address. The master generating a
STOP condition terminates the transfer.
Figure 4.
Write mode sequence
Figure 5.
Read mode sequence
DEV-ADDR
ACK
START
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
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